Sanguisorba minor Scop.: An Overview of Its Phytochemistry and Biological Effects

Abstract

Since ancient times, many plants have been cultivated for their nutritional and medicinal properties. The genus Sanguisorba has been used for medicinal purposes for more than 2000 years. These species are distributed in temperate, arctic, or alpine areas in the Northern Hemisphere. Elongated, imparipinnate leaves and densely clustered flower heads are characteristics of the genus Sanguisorba. While Sanguisorba officinalis L. is mainly known for its significant medicinal applications, Sanguisorba minor Scop. is beginning to attract greater interest for its chemical composition and biological effects. Our research collected extensive information on Sanguisorba minor, including its history, taxonomy, habitat, and distribution, as well as its bioactive components and biological activities. In addition to electron microscopy of plant parts (root, stems, and leaves), which is described for the first time in the literature in the case of S. minor, the study also provides information on potential pests or beneficial insects that may be present. Our goal was to provide important information that will serve as a solid foundation for upcoming research on Sanguisorba minor Scop.

1. Introduction

The genus Sanguisorba includes perennials belonging to the Rosaceae family and includes over 142 species and subspecies distributed throughout East Asia and Southern Europe [1,2,3]. Sanguisorba officinalis L. is the most widespread and investigated of all Sanguisorba species, but Sanguisorba minor Scop. recently has been a target of different research approaches due to the multiple beneficial effects on human health.

The term ‘‘sanguis’’ means “blood” in Latin, while ‘‘sorbeo’’ means “to soak up”; therefore, its name justifies the historical use of the Sanguisorba species—the plants were used to stop bleeding [4,5].

S. minor Scop. is found under trivial names: small burnet (the most common), salad burnet, burnet, pimpernelle, and Toper’s plant [1,6]. Sanguisorba minor Scop. owes its name to its size (minor—small), since it is considerably smaller in comparison to other burnets [6,7]. S. minor is edible (raw or cooked), and it is considered a good ingredient in salads, as its other popular name implies (salad burnet) [1,8,9].

Cultures of the past primarily utilized S. minor for therapeutic purposes that were not supported by scientific studies. This study consequently focused on S. minor information that was supported by scientific evidence and provides a history of S. minor.

Sanguisorba minor Scop. was named after Johannes Antonius Scopoli (Giovanni Antonio) (1723–1788), who discovered this species [10]. It was used in traditional medicine in the treatment of conjunctivitis, fever, and diarrhea, as a tincture or infusion [6,11,12,13,14]. The roots of S. minor have been used in ancient traditional Chinese medicine to stop internal bleeding and bleeding gums [1,15], while leaves were used for wine flavoring because it was believed that it can protect against contagious diseases [16,17]. American soldiers drank S. minor tea before battles in the Revolutionary War in order to prevent bleeding from wounds [17,18]. S. minor has been used for treating snake bites, especially the venomous snakes Vipera berus and Vipera ammodytes in South Europe [8,19].

Sanguisorba minor Scop. has been used as a food ingredient because young leaves are edible (cucumber-like taste). For this reason, S. minor leaves have been often used in mixed salads or as a flavoring agent in drinks [1]. As mentioned in 1633 in Gerard’s “General History of Plants”, the different medical preparations of the S. minor roots were used externally to treat wounds, as well as internally for dysentery and for the regulation of menstruation [12,20]. There is a proverb in Central Italy that praises S. minor: ‘‘L’insalata non è bella se non c’è la pimpinella,’’ which means “Salad is not good/if ‘pimpinella’ is not there”. Given its high polyphenol content, S. minor is considered one of the most promising food medicines [21]. In Romania, S. minor is believed to augment appetite, and that is why it may be added to salads, cooked dishes, spinach, soups, or borscht [22].

In addition, S. minor leaves have been used to enhance the taste of wine [12,20]. S. minor has been used in European folk medicine for healing external or internal bleeding and treating open wounds. S. minor is also used in woman’s health for the regulation of heavy or irregular menstruation [1,6].

The literature’s accessible data extensively detail S. officinalis L., but there are little data that mention S. minor [1,15]. Our search indicates that no reviews that are exclusively about S. minor have been published. We have gathered and investigated the efficacy of this plant in order to highlight the phytochemical profile of various plant parts, taking into account the plant’s prospective phytochemical and biological characteristics. Additionally, some information is provided regarding S. minor’s pests and beneficial insects.

Research Methodology

Data on the nutritional and phytochemical composition of S. minor and its biological activity were selected using PRISMA Flowchart 2020 based on the suggestion of Page et al., 2021 [23]. Stages and selection criteria, followed by the number of studies used in our review, are presented in Figure 1. The current literature about S. minor was collected from PubMed, Scopus, Science Direct, Elsevier, and Google Scholar. The Medical Subject Headings keywords included in the search were as follows: “Sanguisorba”, “Sanguisorba minor”, “nutrients”, “bioactive compounds Sanguisorba”, “phytochemicals Sanguisorba minor”, “antioxidant capacity/activity S. minor”, ”antimicrobial S. minor”, and “anticancer Sanguisorba”. Information systematized in the tables was obtained from research articles (in vivo or in vitro studies) between 2017 and 2022. Studies published in languages other than English were excluded. A total of 91 studies were selected and included in this review (Figure 1).

2. Taxonomy, Habitat, and Distribution

Family Rosaceae is a moderately large family with 85 genera and over 2000 species [2]. Sanguisorba belongs to the family Rosaceae, subfamily Rosideae, tribe Sanguisorbae, and genus Sanguisorba. This genus is distinguishable from others by having elongated, imparipinnate leaves and small flowers, tetramerous or trimerous, which lack petals. According to Nordborg’s categorization, both S. officinalis L. and S. minor Scop. have the chromosome number 2n = 28, 56 [1,2,3,24,25,26,27].

S. minor can be found in most parts of Europe, northern Africa, Asia, and America [1,28,29,30]. Nordborg provided a detailed account of the habitat of S. minor, which can be found from subtropical to temperate altitudes with a moist, cool climate [17]. S. minor prefers slightly dry calcareous soil with limestone rock on the surface or well-drained soil. It is well adapted to grow in nutritionally poor soils [17,29,31,32,33,34].

WFO (World Flora Online) mentions six subspecies of S. minor, which are shown in

Table 1. The subspecies of Sanguisorba minor Scop.

1	Sanguisorba minor subsp. balearica	[36]
2	Sanguisorba minor subsp. lasiocarpa	[37]
3	Sanguisorba minor subsp. magnolii	[38]
4	Sanguisorba minor subsp. mauritanica	[39]
5	Sanguisorba minor subsp. muricata	[40]
6	Sanguisorba minor subsp. verrucosa	[41]

(World Flora Online Consortium, http://www.worldfloraonline.org/organisation/WFO) (accessed on 20 April 2023) [35].

The names given to this plant species vary depending on the nation. ‘Salad burnet’ in English, ‘Salvastrella minore, Bibinella’ in Italian, ‘Kleiner Wiesenknopf’ in German, ‘Cebarea’ in Romanian, and ‘Petite pimprenelle’ in French are a few examples (http://www.worldfloraonline.org/taxon/wfo-0001015888#preferredNames) (accessed on 20 April 2023) [42].

3. Botanical Characterization: Macroscopic and Microscopic Aspects of S. minor

S. minor is a perennial species with strongly branched rhizomes in the soil. S. minor has long and hard roots, with branched rhizomes that measure about 25–40 cm in length (Figure 2) [6,13,43].

The aerial stem is 20–50 cm high when erect. It can be angular or round; towards the top it is branched, and in the lower part it is hairy (Figure 2A). Leaves are imparipinnate-compound; the basal leaves are 5–15 cm long with 11 to 25 leaflets with a shape ranging from rounded to elongated-oval. The stem leaves can have up to 9–15 leaflets that are 0.7–2 cm long. The width can range from 0.5 cm to 1.5 cm for crenate or sharply serrated edges, respectively (Figure 2A,C) [43,44].

The floral formula of the family Rosaceae is K_{(3–)5(–10)}, C_{(0–)3–5(–10)}, A_{(1–)10–many}, Ĝ_1–many [45], but the Sanguisorba species has K₄C_oA_2-many Ĝ_1–many [46], where K means a calyx of 4 petals, C refers to the corolla and is not present in these species, A indicates the number of stamens and can be 2 or more (particularly in the S. minor, where this number is between 10 and 30), and Ĝ indicates the number of carpels, which can be more than 1. The flowers are grouped in capituliform, terminal inflorescences, with a globose-oval shape and a long peduncle. The upper flowers of the head are female, the middle bisexual, and the lower male (Figure 2B) [44,47]. The receptacle has four uncovered longitudinal stripes on roughly reticulated faces in Sanguisorba minor (Figure 2B) [48]. A flower consists of four green or reddish-brown sepals, which are deciduous after flowering and possess numerous stamens [49]. Nectarines are missing. The gynoecium is bicarpellary rarely, and it can have 1–3 carpels [6,47]. Fruits are achenes; they are round, smooth, or broad-winged, and closed in the receptacle (Figure 2B) [50].

The leaves of S. minor are green all year round, but the flowers bloom only from May to August, and the seeds appear from July to September [1,4,15,44].

There is no difference in germination percentages between seeds propagated from Sanguisorba plants grown in the presence or absence of light [51,52].

S. minor is one of the few wild species with edible greenery all year round. The flavor of S. minor is nutty, with a hint of cucumber [8,15].

Figure 2. Macroscopic aspects of S. minor: (A) whole plant, (B) flower and a vertical cross-section through the flower (Floral formula: K₄C_oA_2-many Ĝ_1–many) [46], (C) different types of leaves, (D) cross-section through the roots (personal photos).

Figure 2. Macroscopic aspects of S. minor: (A) whole plant, (B) flower and a vertical cross-section through the flower (Floral formula: K₄C_oA_2-many Ĝ_1–many) [46], (C) different types of leaves, (D) cross-section through the roots (personal photos).

SEM (Scanning electronic microscope) micrographs of the root, stem, and leaves of S. minor are presented in Figure 3A–D. The details related to the samples, materials, and methods for SEM analysis are presented in Supplementary Materials. In the roots, empty areas were seen in the shape of canals, which were probably formed as a result of cells dissolving; in the inner lumen of these canals, raphides were abundant. SEM analysis allowed us to conclude that raphide bundles were frequently associated with the collapsed areas of the phloem (Figure 3A). In the stem micrograph, open stomata can be observed (Figure 3B). The analysis of the leaves (abaxial and adaxial) revealed an epicuticular wax with a crust and granule layers (Figure 3C,D). Based on the wax distribution of the stomata, S. minor has a stomata rim and guard cell that are not completely covered by wax and is pore-free on the abaxial and adaxial sides. Because of the distribution on both sides of the stomata, S. minor is amphistomatic (Figure 3C,D). Strong environmental correlations exist between the occurrence of amphistomatic leaves (stomata on both surfaces) and hypostomatic leaves (stomata restricted to the bottom or abaxial surface). Amphistomy has the benefit of increasing CO₂ conductance for photosynthesis, but it may result in ineffective gas exchange if the stomata on both leaf surfaces cannot be independently controlled in response to environmental stimuli [53].

The highlighted microscopic details can provide researchers with some relevant information, as some identifying features were observed by SEM microscopic analysis of the root, stem, and leaves of S. minor. These SEM micrographs are special because this is the first time every organ of the S. minor plant has been thoroughly detailed. Overall, leaves and surface characteristics are useful for differentiating infrageneric taxa from different subgenera of a genus based on epicuticular ornamentation and stomata. The imaging effect, however, may differ depending on the species of a plant because of variations in leaf structure and composition [54].

4. The Nutritional Composition of S. minor

The fat, protein, ash, and carbohydrate content of the aerial parts and roots of S. minor Scop. were investigated, depending on the type of substrates (peat, peat:perlite (1:1), and peat:perlite (2:1)) by Karkanis et al. (2019) [28]. Perlite is volcanic glass processed through rapid heating and expansion, changing from rock to a foamy texture, while peat is organic matter: a decomposing sphagnum moss. The fatty acid content of S. minor roots and aerial plant parts shows a significant difference in their composition. Thus, the portions of aerial plants were rich in linoleic acid (12.9–13.1%), palmitic acid (14.6–15.6%), and linolenic acid (49.4–52.4%), while stearic, tricosylic, lauric, and eicosatrienoic acids were found in small amounts. By contrast, linoleic and tricosylic acids were more abundant in roots (20.5–24.1%), followed by linolenic (12.8%–15.4%) and palmitic acids (11.9–13.1%), while stearic, oleic, dihomo--linolenic, and behenic acids were found in smaller amounts. The linoleic acid and linolenic acid levels were significantly higher in the peat: perlite (1:1) treatment in both aerial parts and roots. Where S. minor was grown on peat substrates, the dry weight of the aerial parts was higher; however, the lowest dry weight was observed when the peat: perlite (1:1) treatment was used. Furthermore, the peat: perlite (1:1) treatment yielded the lowest values of root dry weight. Instead, the peat: perlite (2:1) treatment significantly increased the amount of α-tocopherol, glucose, and total sugars, mainly in the aerial parts. The major organic acids that were identified were oxalic acid and citric acid, which were found in higher levels in the roots of the plants than in the aerial sections for all substrate treatments. According to their results, the peat treatment produced better growing conditions from April to May than the other substrate treatments due to its superior water retention properties and the alleviation of stress caused by high temperatures. Karkanis et al. (2019) used various S. minor substrate compositions to recommend potential commercial cultivation [28].

In another study, Finimundy et al., 2020 used cultivated S. minor under different fertilization rates (using only peat and inorganic fertilizer at different doses). The amount of total phenolic acids in leaves was not considerably affected by fertilizer application, but the amount of the same class of phenolic compounds in roots was greatly enhanced by the administration of the half-rate regime (330 kg/ha). The higher concentration of flavonoids, primarily catechin and its isomers, were found in the roots of plants fertilized at full rate (660 kg/ha), whereas the highest concentration of total phenolic compounds was found in plants fertilized at half rate (330 kg/ha) [55].

The oil content of S. minor seed genotypes was between 8.85% and 15.66%. Palmitic acid, oleic acid, linoleic acid, and linolenic acid are the main components of S. minor seed oil. The range of palmitic acid, a saturated fatty acid, was 4.55–10.40%. Stearic acid was detected in only three genotypes ranging from 2.28% to 7.90%. Oleic acid was found in all genotypes investigated between 19.57% and 34.34% [50].

The protein content of the leaves and roots of S. minor varied between 10.18 and 12.00 g/100 g dw depending on the substrate used. Fructose and glucose were the major sugars identified in both aerial parts and roots, their level being significantly affected by substrate composition [28].

Additionally, S. minor has a carminative effect due to its beta-sitosterol, caffeic acid, kaempferol, and quercetin content. S. minor is believed to be a tonic plant and contains high levels of beta-carotene and vitamins C and E, as well as having antioxidant qualities that are even greater than those of lettuce or tomatoes due to the presence of polyphenols [21].

In accordance with a study by Ceccanti et al., 2019, S. minor leaves from wild edible species are abundant in bioactive components, which remain at initial levels even after being stored. According to the study, this type of plant could be a good substitute for other green plants that are frequently used in the preparation of salads. It also looks promising for the food and flavoring sectors that will require new food ingredients for dietary supplements [29].

The seeds or leaves of this plant are consumed by animals besides humans, including birds, deer, rabbits, and hares, and are a valuable source of food for them [18,20].

Some researchers suggest that the dry powder of S. minor could enhance the quality of vegetable oils, particularly those that are lower in antioxidant content, such as maize oil or sunflower oil [19,50,56,57].

5. Phytochemical Composition of Botanical Part of S. minor

S. minor includes a wide range of compounds, such as flavonoids, tannins, triterpenes, phenols, terpenes, and fatty acids [1,25,28,44,58].

Polyphenols, a class of secondary metabolites, play a significant and diverse role in the plant world. The total phenol content of aerial parts, roots, stems, and leaves from S. minor is presented in

Table 2. The total phenol content of S. minor roots, leaves, and aerial parts from the literature of the last few years (2017–2022).

S. minor Part	Extraction Solvent	Total Phenols	References
Roots	96% Ethanol	457.45 ± 4.59 μg GAE/mg	[25]
	70% Ethanol	3.89 ± 0.01 mg GAE/g dw	[4]
Aerial parts (stem + leaves)	Methanol	132.80 ± 3.87 μg GAE/mg	[11]
	Chloroform	67.87 ± 0.77 μg GAE/mg	[11]
Stem	70% Ethanol	0.18 ± 0.02 mg GAE/g dw	[4]
Leaves	70% Ethanol	1.19 ± 0.11 mg GAE/g dw	[4]

For GAE-gallic acid equivalent and RE-rutin equivalents, nr—not recorded. Data are expressed as the mean value ± SD. nd—not determined.

.

As shown in Table 2, the total phenol content of S. minor varies between studies. The factors that influence the amount of bioactive compounds are either related to external factors (soil, climate, and harvest season) or to the type of extraction solvent applied and the extraction technique of these compounds. The investigations measured total phenols using the Folin–Ciocalteu method.

S. minor was collected from Romania in September 2019 (during a period of low rainfall) for the investigation by Tocai et al., 2021, [4], whereas Cirovic et al., 2020 [25] obtained S. minor from Serbia on sunny days in the spring. Serbia has a hot, humid continental climate or a humid subtropical climate, but Romania has a more unpredictable temperate continental environment that can alter a plant’s features. In both of the experiments, the S. minor plant was dried at ambient temperature in a dark, open area [4,25]. The differences in the amount of root total phenolic compounds are caused by variations in the extraction method and the extraction solvent concentration (96% [25] versus 70% ethanol [4]). While Cirovic et al., 2020 [25] extracted the compounds with a solvent reflux at boiling temperature for four hours, Tocai et al., 2021 [4] performed the extraction of phenolic compounds at room temperature. According to the findings shown in Table 2, regardless of the area where the samples were obtained, the solvent used, or the extraction method, the roots of S. minor contain the largest quantity of total phenolic compounds, followed by the leaves and stem. The screening of the individual phenols identified in the roots, aerial parts (stems and leaves), or flowers of S. minor is shown in

Table 3. The level of phytochemicals (mg/g dw) of tannins, flavonoids, and phenolic acids from S. minor roots, leaves, flowers, and aerial parts identified by LC-MS using information from recent literature (2017–2022).

Compounds	Roots	Leaves	Flowers	Aerial Parts (Stems + Leaves)	References
	Tannins
2,3-Hexahydroxydiphenoyl-glucose	15.12 ± 0.21	11.59 ± 0.38	17.82 ± 0.60	nd	[44]
Sanguiin H-10 derivative	5.00 ± 0.06	1.75 ± 0.03	6.76 ± 0.02	nd	[44]
	13.0 ± 0.30	nd	nd	5.14 ± 0.02	[28]
	nd	nd	nd	18.3 ± 0.40	[59]
	6.12 ± 0.05	9.82 ± 0.03	nd	nd	[55]
Punicalagin gallate	28.58 ± 0.04	25.93± 0.02	18.67 ± 0.02	nd	[44]
	21.7 ± 0.70	nd	nd	nd	[28]
	11.5 ± 0.20	nd	nd	nd	[55]
Sanguiin H-1	9.53 ± 0.02	13.46 ± 0.04	26.03 ± 0.05	nd	[44]
Galoyl-bis-hexahydroxydiphenyl –glucoside, isomer 1	5.11 ± 0.22	nd	nd	nd	[44]
	11.1 ± 0.20	nd	nd	nd	[28]
	nd			5.5 ± 0.10	[59]
	12.25 ± 0.02	nd	nd	nd	[55]
Galloyl-bis-hexahydroxydiphenyl-glucoside, isomer 2	4.28 ± 0.03	nd	nd	nd	[44]
	13.13 ± 0.07	nd	nd	nd	[28]
Ellagic acid hexoside	nd	11.49 ± 0.04	0.89 ± 0.03	nd	[44]
	nd	nd	nd	3.8 ± 0.10	[28]
	nd	6.2 ± 0.10	nd	nd	[55]
Ellagic acid pentoside	0.24 ± 0.02	1.16 ± 0.02	1.02 ± 0.05	nd	[44]
	11.66 ± 0.04	nd	nd	nd	[28]
	5.47 ± 0.008		nd	nd	[55]
Pedunculagin	8.0 ± 0.20	nd	nd	nd	[28]
	nd	10.2 ± 020	nd	nd	[55]
Lambertianin C	92.9 ± 0.20	nd	nd	22.3 ± 0.30	[28]
	nd	nd	nd	18.6 ± 0.30	[59]
	nd	9.82 ± 0.03	nd	nd	[55]
	Flavonoids
C-type (epi)catechin trimer	6.27 ± 0.02	nd	nd	nd	[44]
Cyanidin-glucoside	nd	nd	0.13 ± 0.07	nd	[44]
B-type (epi)catechin dimer, isomer 1	3.44 ± 0.03	13.38± 0.03	10.26 ± 0.02	nd	[44]
	37.4 ± 0.90	nd	nd	15.4 ± 0.30	[28]
	8.2 ± 0.80	nd	nd	nd	[55]
Catechin	8.58 ± 0.02	15.42 ± 0.02	6.42 ± 0.01	nd	[44]
	28.0 ± 0.50	nd	nd	20.4 ± 0.10	[28]
Cyanidin-malonylglucoside	nd	nd	0.06 ± 0.02	nd	[44]
B-type (epi)catechin dimer, isomer 2	11.79 ± 0.05	9.77 ± 0.03	3.71 ± 0.03	nd	[44]
	48.8 ± 0.30	nd	nd	16.69 ± 0.07	[28]
Quercetin-galloyl-glucoside	nd	1.95 ± 0.02	1.08 ± 0.01	nd	[44]
Quercetin-glucuronide	nd	20.20 ± 0.02	8.33 ± 0.02	nd	[44]
	nd	nd	nd	18.0 ± 0.10	[59]
	nd	7.6 ± 0.20	nd	nd	[55]
	nd	nd		9.31 ± 0.05	[28]
Quercetin-glucoside	nd	8.17 ± 0.09	8.61 ± 0.04	nd	[44]
Quercetin-galloylhexoside	nd	nd	nd	1.320 ± 0.001	[28]
	nd	0.842 ± 0.04	nd	nd	[55]
Quercetin-O-hexoside gallate (isomer 1)	nd	nd	nd	4.5 ± 0.10	[59]
Quercetin-O-hexoside gallate (isomer 2)	nd	nd	nd	5.3 ± 0.20	[59]
Quercetin-O-pentoside	nd	nd	nd	1.521 ± 0.007	[28]
Kaempferol-glucuronide	nd	6.26 ± 0.02	2.12 ± 0.09	nd	[44]
	nd	0.944 ± 0.02	nd	nd	[55]
Kaempferol-3-O-glucoside	nd	nd	nd	11.3 ± 0.60	[59]
Kaempferol-O-hexoside	nd	nd	nd	9.84 ± 0.04	[59]
Apigenin-O-deoxyhexoside	nd	nd	nd	10.54 ± 0.01	[28]
	Phenolic acids
3-Caffeoylquinic acid (Neochlorogenic acid)	3.42 ± 0.02	3.79 ± 0.04	2.11 ± 0.02	nd	[44]
	nd	nd	nd	22 ± 1.00	[59]
Caffeic acid-glucoside	10.90 ± 0.02	4.73 ± 0.01	2.01 ± 0.02	nd	[44]
5-Caffeoylquinic acid (Chlorogenic acid)	2.10 ± 0.03	3.73 ± 0.01	3.96 ± 0.05	nd	[44]
p-Coumaroylquinic acid	4.08 ± 0.07	8.09 ± 0.07	11.48 ± 0.03	nd	[44]
	nd	6.05 ± 0.25	nd	nd	[55]
Gallic acid glucoside	nd	nd	nd	26 ± 2.00	[59]
Caffeoyl ester (isomer 1)	nd	nd	nd	14.8 ± 0.10	[59]
Digalloyl glucoside	nd	nd	nd	22 ± 1	[59]
	9.5 ± 0.10	7.4 ± 0.30	nd	nd	[55]
Caffeoyl ester (isomer 2)	nd	nd	nd	5.7 ± 0.20	[59]
Ellagic acid	2.85 ± 0.03	nd	nd	nd	[44]
	13.3 ± 0.40	nd	nd	nd	[28]
	4.3 ± 0.10	nd	nd	nd	[55]

Data are expressed as the mean value ± SD; nd—not detected.

. Flavonoids dominate among the phytochemicals found in S. minor. The two primary flavonoids found in the leaves of S. minor were apigenin and baicalein. Apigenin has been found to be beneficial for human health; it lowers plasma levels of low-density lipoproteins and inhibits platelet aggregation. Therefore, including apigenin in the diet may be essential [29]. S. minor’s leaves and stems are great sources of flavonoids (quercetin, kaempferol, and rutin), which possess antioxidant effects, preventing the oxidative stress associated with aging, cancer, and cardiovascular illnesses [28,44,55,59].

Numerous species of plants contain tannins. Young leaves and flowers are the plant components that have the highest levels of tannins. Due to the phytochemical composition as well as additional elements such as growth stages or environmental conditions (temperature, light, and nutrition), plants have different biological characteristics [60]. S. minor has no known adverse effects or contraindications; however, it shouldn’t be used by pregnant women or while breastfeeding because there are insufficient data on the biological effects and toxicity of the plant. Because S. minor contains a lot of tannins, it shouldn’t be used continuously for an extended period of time [19]. It may interfere with drugs including fluoroquinolones [61].

In a study [29], S. minor seedlings were grown in a nutrient solution, and at two intervals after sowing (15 and 30 days, respectively), the leaves were cut off at the base and subjected to metabolomics analysis. Cutting changed the secondary metabolite profile of S. minor in that it enhanced the amount of flavonoids, especially the subclass of flavones, in the leaves that resulted from the second cutting. Instead, the phenolic content and antioxidant capacity of S. minor leaves stored for 15 days as fresh-cut products did not significantly change. S. minor is a source of phenolic compounds, particularly flavonoids. The leaves of S. minor especially are rich in quercetin-3-glucoside and kaempferol-3-glucoside [62]. The aerial parts of S. minor (leaves and stems) have a high flavonoid content, with quercetin-3-glucuronide being predominant [28,49].

From an aqueous, ethanolic, whole-plant extract of S. minor, Ayoub et al., 2003, isolated and examined the structure of eleven phenols. In addition to the phenols that are typically found in plants (gallic acid, kaempferol, quercetin, ellagic acid, etc.), one of the compounds belongs to the coumarin class. This coumarin dicarboxylic acid derivative is a substance that is extremely infrequently encountered in nature and was isolated for the first time in S. minor [63]. The chemical structure of coumarin-3-carboxylic acid is shown in Figure 4.

The composition of the S. minor essential oil has only been the subject of one investigation as of yet. In order to explore the chemical composition of the essential oil of S. minor leaves from Iran, Esmaeili et al. 2010 observed 17 components, the majority of which were aliphatic hydrocarbons, followed by sesquiterpenes, an oxygenated monoterpene, and an aliphatic aldehyde. Farnesyl acetate, nonadecane, and docosane were the main components, followed by caryophyllene, nonanal, and linalool [64].

Reher et al. (1991) made an interesting observation, pointing out that from a systematic standpoint, Sanguisorba minor’s triterpenoid pattern more closely approaches Sarcopoterium spinosum (family Rosaceae) than Sanguisorba officinalis [58].

6. Antioxidant Capacity

Generally, the biological activities of S. minor were not investigated extensively. However, according to the literature, S. minor exhibits antioxidant [11,56,65,66,67], anti-ulcerogenic [68,69], antitumor [49], antimicrobial [28,44,55,70], neuroprotective [65,71], and anti-inflammatory activity [25,72,73]. Antioxidant activity is the most thoroughly investigated. Papers describing the biological activities of S. minor refer to it as a native species growing in Portugal, Spain, Serbia, Romania, and Italy.

The antioxidant capacity of S. minor extracts has been confirmed in numerous studies, both in vitro and in vivo. in vitro evaluation was conducted using different antioxidant assays: ABTS (2,2′-azinobis-(3-ethylbenzthiazolin-6-sulfonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays, CUPRAC (cupric reducing antioxidant capacity) assay, ferric-reducing antioxidant power assay (FRAP), total reducing power assay (TRP), and hydroxyl and peroxyl radical scavenging. The summary of the S. minor antioxidant capacity results, depending on the sample type and applied method, is presented in

Table 4. In vitro antioxidant activity of Sanguisorba minor—literature searching.

Sample	Method	Result	References
Essential oil of S. minor aerial parts 0.1 mg/mL (Portugal)	DPPH	11% of inhibition	[65]
	Carotene-linoleic acid assay	99% of inhibition
Ethanolic extract of S. minor aerial parts 0.1 mg/mL (Portugal)	DPPH	93% of inhibition
Decoction of S. minor aerial parts 0.1 mg/mL (Portugal)	DPPH	93% of inhibition
	Carotene-linoleic acid assay	95% of inhibition
Aqueous extract of S. minor leaves 5 mg/mL (Spain)	Peroxyl radical (H2O2) scavenging	64.35% of inhibition	[56]
	Hydroxyl radical (OH•) scavenging	33.50% of inhibition
Water/ethanol extract of S. minor leaves 0.1–0.01 g/mL (Italy)	Peroxyl radical scavenging	212 LOO•kg of fresh plant	[67]
	FRAP	257 mmol Fe2+/kg
Ethanolic extract of S. minor roots (Serbia)	ABTS	77.54 µg TE/mg	[25]
	DPPH	96.51 µg TE/mg
	CUPRAC	346.49 µg TE/mg
	FRAP	188.22 µg Fe/mg
	TRP	1.16 µg AAE/mg
Methanolic extract of S. minor roots (Serbia)	ABTS	76.97 µg TE/mg
	DPPH	97.29 µg TE/mg
	CUPRAC	34.35 µg TE/mg
	FRAP	214.02 µg Fe/mg
	TRP	1.19 µg AAE/mg
Chloroform extract of S. minor roots (Serbia)	ABTS	46.11 µg TE/mg
	DPPH	40.51 µg TE/mg
	CUPRAC	96.80 µg TE/mg
	FRAP	48.02 µg Fe/mg
	TRP	0.11 µg AAE/mg
Methanolic extract of S. minor aerial parts (Serbia)	ABTS	77.26 µg TE/mg	[11]
	DPPH	95.06 µg TE/mg
	CUPRAC	289.09 µg TE/mg
	FRAP	205.62 µg Fe/mg
	TRP	0.58 µg AAE/mg
Chloroform extract of S. minor aerial parts (Serbia)	ABTS	53.83 µg TE/mg
	DPPH	40.31 µg TE/mg
	CUPRAC	182.90 µg TE/mg
	FRAP	78.22 µg Fe/mg
	TRP	0.06 µg AAE/mg
Ethanolic extract of S. minor roots (Romania)	DPPH	92.93% of inhibition	[4]
	FRAP	10.81 μmol TE/g
Ethanolic extract of S. minor stems (Romania)	DPPH	0.32% of inhibition
	FRAP	0.16 μmol TE/g
Ethanolic extract of S. minor leaves (Romania)	DPPH	43.15% of inhibition
	FRAP	2.88 μmol TE/g

Where, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays; ABTS (2,2′-azinobis-(3-ethylbenzthiazolin-6-sulfonic acid)); CUPRAC (cupric reducing antioxidant capacity) assay; FRAP (ferric-reducing antioxidant power) assay; TRP (total reducing power) assay; LOO•, trapping peroxyl radicals; TE, Trolox equivalents; AAE, ascorbic acid equivalents; Fe-Fe (II) equivalents.

.

The antioxidant capacity of S. minor leaves was tested on aqueous and water/ethanol extracts, which demonstrated peroxyl and hydroxyl radical scavenging ability as well as ferric-reducing antioxidant power [56,67]. Ethanolic extract and water decoction of the S. minor aerial parts from Portugal in a concentration of 0.1 mg/mL exhibited the ability for DPPH radical neutralization at a high percentage (93% of inhibition). Additionally, essential oil and water decoction of the S. minor aerial parts in the same study showed significant inhibition of lipid peroxidation in the carotene-linoleic acid assay (99% and 95%, respectively) [65]. The antioxidant capacity of the methanolic and chloroform extracts of S. minor subsp. muricata aerial parts was investigated by five different in vitro methods. The results showed stronger antioxidant activity of the methanolic extract than non-polar extracts (chloroform) in all assays (Table 4) [11]. The extraction solvent has a direct effect on the final results of many different antioxidant assays. (Table 4). Generally, methanolic and ethanolic extracts exhibited stronger DPPH and ABTS radical scavenging potential than the chloroform extract. CUPRAC and FRAP assays emphasized a slightly higher antioxidant capacity of ethanolic extract in comparison with methanolic (Table 4) [25].

Multiple in vitro and in vivo studies indicate that total phenols and flavonoids significantly contribute to the antioxidant activity of medicinal plants [74,75]. There are several mechanisms by which plant polyphenols achieve their antioxidant effect. One of the proposed mechanisms is that they act as free-radical scavengers due to their chemical structure and ability for free-radical capture. Another proposed mechanism of action is the chelating of pro-oxidant metals such as iron and copper (Fe³⁺ and Cu²⁺), which prevents them from taking part in free-radical-formation reactions [76,77]. Reducing the activity of phenolic acids and flavonoids, identified in S. minor extracts, depends on the number, position, and substitution of hydroxyl groups in the molecule, primarily [28,55]. Many research investigations have shown an association between polyphenol levels and antioxidant activity in medicinal plant extracts [1]. The S. minor species’ evident antioxidant capacity has been linked to its high amount of chemical compounds, particularly phenolic compounds [55,56].

The only available in vivo investigation of the antioxidant activity of S. minor was conducted on an animal model of sepsis. Considering that oxidative stress is a nonspecific-but-crucial indicator of inflammation and energy disturbances in sepsis, the work of Cirovic T et al., 2020 showed that the ethanolic extract of the S. minor subsp. muricata root extract affects oxidative stress parameters in rats with induced sepsis [25,74]. Since the focus of up-to-date investigations in sepsis is on antioxidant therapy, as an adjuvant to conventional therapy, medicinal plant extracts with antioxidant and anti-inflammatory activity may play a significant role in the treatment of sepsis [78]. The experiment involved the administration of ethanolic S. minor extract to rats with sepsis, orally and intraperitoneally, and monitoring of effects on the level of pro-oxidants (total thiols, TBARS, nitrate and nitrite concentrations NOx, and superoxide anion concentration O²⁻) as well as the activity of superoxide dismutase (SOD). The ethanol extract of the S. minor root lowered oxidative stress in rats with sepsis by reducing the plasma levels of TBARS, NOx, and O²⁻, and increasing SOD activity without influencing the level of total thiols [25]. The reason for such a positive effect of S. minor on oxidative stress could be phytochemical composition, especially the presence of phenols and flavonoids, which are known to be able to alleviate oxidative stress [28,71,79]. Except for the free-radical scavenger ability, polyphenols can inhibit the activity of certain enzymes responsible for the generation of the reactive oxygen species (xanthine-oxidase and nicotinamide—adenine—dinucleotide—phosphate (NADPH) oxidase). Polyphenols also show an upregulation of endogenous antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) [76].

7. Biological Activities

7.1. Antimicrobial Effects

According to the increased need for new antibacterial drugs that can effectively combat drug-resistant infections, plants have been extensively investigated for their antibacterial abilities [80].

Under different growth conditions, Karkanis et al., 2019 examined the antibacterial properties of the root and aerial parts of S. minor and found that they depend on the phenolic content. Because roots have higher amounts of phenolic components than aerial extracts, root extracts are more effective antibacterial agents [28].

Another study showed that the bacteriostatic and bactericidal activity of the methanol extract of S. minor aerial parts were superior compared to the chloroform extract, with a minimum inhibitory concentration (MIC) range of 0.1–3.13 mg/mL and a minimum bactericidal concentration (MBC) range of 0.39–3.13 mg/mL. Gram-positive bacteria were more successfully combated by S. minor extracts (methanol and chloroform) than Gram-negative bacteria. The Staphylococcus aureus was the most sensitive (MIC = 0.10 mg/mL, MBC = 0.39 mg/mL) [11].

The study conducted by Cirovic et al., 2020 [25] investigated the antimicrobial activity of ethanol, methanol, and chloroform extracts of S. minor subsp. muricata roots in the presence of Doxycyclin as a positive control. The chloroform extract of S. minor radix showed the strongest antibacterial activity against all examined strains of bacteria: Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, and Salmonella Enteritidis, with an MIC range of 0.1–1.56 mg/mL and an MBC range of 0.39–6.25 mg/mL. Generally, B. cereus and S. aureus were the most sensitive to the chloroform extract (MIC and MBC values were 0.10 mg/mL and 0.39 mg/mL, respectively). In comparison to ethanol extract, the methanolic extract of S. minor showed more efficacy against S. enteritidis, E. coli, P. aeruginosa, B. cereus, S. aureus, and E. faecalis.

The antibacterial activity of samples of S. minor, both wild and cultivated, was examined against strains of eight different bacteria, including E. coli, K. pneumoniae, M. morganii, P. mirabilis, P. aeruginosa, E. faecalis, L. monocytogenes, and MRSA (Methicillin-resistant Staphylococcus aureus). All of the plant extracts showed antibacterial activity, with oven-drying samples displaying more antibacterial activity than freeze-drying ones. In all S. minor samples, the MIC ranged from 2.5 mg/mL to >20 mg/mL [59].

Other authors validated S. minor’s strong antibacterial activity, although they obtained lower MIC and MBC values [28,55]. According to Karkanis et al. (2019), S. minor samples (aerial parts and roots) had MIC and MBC values of 0.075–0.45 mg/mL and 0.25–0.60 mg/mL, respectively, against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Salmonella typhimurium [28]. In addition, Finimundy et al., 2020 examined S. minor roots and leaves grown under various fertilization regimes and reported MIC and MBC values between 2.31 and 0.44 mg/mL and between 4.61 and 0.88 mg/mL, respectively, against Staphylococcus aureus, Bacillus cereus, Mariniluteicoccus flavus, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhimurium, Enterobacter cloacae, and Escherichia coli [55].

7.1.1. Antifungal Activity

In the treatment of postharvest fungal infections, S. minor may be an effective alternative to synthetic fungicides. In vitro spore germination of Monilnia laxa, Penicillium digitatum, Pencillium italicum, and Aspergillus niger was completely inhibited by S. minor extracts, while that of Botrytis cinerea and Pencillium expansum was significantly reduced, according to the studies by Karkanis et al. (2014) and Gatto et al. (2011) [19,62].

Another study showed that the leaves of S. minor showed excellent antifungal activity (>80% inhibition) against Monilinia laxa, Monilinia fructicola, Penicillium expansum, and Penicillium italicum [81].

Nystatin was used as a positive control for antifungal activity by Cirovic et al., 2020, who reported an MIC of 7.81 mg/mL and an MFC of 15.61 µg/mL. S. minor roots showed limited antifungal activity against Candida albicans [25].

In another study, Ketoconazole was utilized as a positive control for antifungal efficacy against various fungi with an MIC = 1.25–2.50 mg/mL and MFC = 2.50–5.00 mg/mL depending on the fungus tested by Finimundy et al. in 2020. They found that S. minor root and leaf extracts from plants grown under the full fertilization rate regime had similar antifungal activity to S. minor root extracts supplemented with fertilizers, with MIC values of 2.50 mg/mL and 5.00 mg/mL, respectively, against Aspergillus fumigatus and Aspergillus niger [55].

7.1.2. Antiviral Activity

Abad et al., 2000 reported significant inhibition of the herpes simplex virus type 1 (DNA virus) and vesicular stomatitis virus (RNA virus) by S. minor subsp. magnolii aqueous extract in a concentration range of 50–125 µg/mL. The antiviral activity was evaluated on HeLa (human epithelial cervical carcinoma) cells infected with the viruses in vitro [1,82].

7.2. Cytotoxic Activity on Cancer Cells

Plant-derived chemicals have the ability to act as inhibitors of various phases of carcinogenesis and associated inflammatory processes [83].

The ethanolic extract of the whole plant of S. minor exhibits strong cytotoxic activity against some cancer cell lines, including HepG2 (hepatocellular carcinoma), and appears to be similarly efficient at stopping the migration of cancer cells caused by plasmin [49].

The cytotoxic activity of S. minor roots and leaves was examined by Finimundy et al. (2020) in relation to inorganic fertilization doses. The cytotoxic activity of the root extracts was most effective against the HeLa cervical carcinoma cell line, NCI-H460 non-small cell lung cancer cell line, MCF-7 breast carcinoma cell line, and HepG2 cell line. As opposed to the root extracts, the leaf extracts had less cytotoxic activity against the HepG2 and NCI-H460 cell lines. Their findings showed that the high fertilizer dose (660 Kg/ha) increased the phenolic component content and, as a result, the cytotoxic effects against tumor cell lines [55].

Cuccioloni et al., 2012 confirmed that quercetin-3-glucuronide, isolated from the ethanolic extract of S. minor, exhibited cytotoxicity activity in vitro by limiting plasmin-induced migration of MCF-7. Therefore, it seems that quercetin-3-glucuronide may serve as a good starting compound in developing a new pharmaceutical agent that may be used in the treatment of pathological states caused by the unregulated activity of plasmin [49].

7.3. Neuroprotective Effects

Polyphenol-rich medicinal plants have considerable antioxidant activity and protect neurons from oxidative damage [84].

S. minor aerial parts enhanced antioxidant defense in the brain, and the activity of the antioxidant enzymes (Superoxide dismutase-SOD and catalase-CAT) was significantly decreased in the hippocampus and cortex of the rats in the scopolamine group in comparison to those of the controls (p < 0.001) [71].

The Morris water maze test (MWM) revealed that after the treatment with the extract of S. minor, especially at the dose of 200 mg/kg, the rats’ capacity to recall the platform’s location improved. Additionally, the administration of the extract enhanced the memory indices in the scopolamine-treated rats during the PA (passive avoidance) test. These results revealed that the S. minor extract improved the rats learning and spatial memory capacities since the MWM task often indicated rodents’ ability to memorize spatial locations. Rivastigmine, a common anti-amnesia medication being an AChE (acetyl cholinesterase) inhibitor, produced similar effects in the rats that received it as well [71].

The hydroethanolic solution obtained from the aerial parts of S. minor protects against oxidative stress, as well as mitigates the concomitant histopathological changes induced by D-galactose in the liver and brain. In addition, S. minor aerial parts reversed the increased activities of AST (aspartate aminotransferase) and ALT (alanine aminotransferase), which may be correlated with liver dysfunction in the presence of D-galactose. Therefore, the antioxidant effects of S. minor aerial parts against brain and liver damage, at least partially, were attributed to its protection against oxidative stress. Additionally, phytochemicals such as quercetin and ellagic acid, compounds identified in S. minor, were found to suppress AChE activity [85].

The preventive effect of the S. minor extract (containing 11.06 0.55 mg GAE/ g extract dw) on beta-amyloid-induced toxicity in primary neural cell culture was pointed out by Akbari et al. in 2019.

When different doses of S. minor extract (5–100 μg/mL) and beta-amyloid were applied to cerebellar granule neurons, the cytotoxicity caused by beta-amyloid decreased significantly. The concentration of 75 µg/mL was observed to provide the maximum level of S. minor protection. At a dosage of 100 µg/mL, a considerable inhibition of AChE activity of over 80% was also observed. These findings are consistent with the theory that the AChE inhibitory action of the S. minor extract contributed to its neuroprotective effect against beta-amyloid neurotoxicity. The authors proposed that the neuroprotective effects were conferred due to the presence of phenolic compounds [86].

7.4. Antiulcerogenic Activity

S. minor subsp. muricata in the form of water decoction is used in Turkish traditional medicine in the treatment of abdominal pain, heartburn, and other gastrointestinal symptoms. Gurbuz et al., 2005 confirmed the significant anti-ulcerogenic activity of orally applied aqueous extract of S. minor subsp. muricata aerial parts on rats with ethanol-induced ulcerogenesis (62.2% of inhibition). Anti-ulcerogenic activity is a consequence of the presence of saponins, tannins, and flavonoids which exhibit gastroprotective effects [68]. Due to their ability to scavenge free radicals, flavonoids from S. minor help to have an anti-ulcerogenic effect. This can be explained because the pathogenesis of damaging and ulcerative lesions of the gastrointestinal tract is greatly affected by the production and excessive accumulation of free radicals [68].

7.5. Toxicity Studies

For the acute toxicity test, mice were used in just one trial in which oral doses of S. minor hydroalcoholic extract of aerial parts (stem and leaves) were administered at 300, 2000, or 3000 mg/kg. To assess subacute toxicity, the oral administration of S. minor hydroalcoholic extract at dosages of 100, 200, and 400 mg/kg was conducted for 4 weeks. In the 14 day observation period, neither mortality nor abnormal clinical signs were observed in animals treated with 300 or 2000 mg/kg extract doses. There was an approximate median LD₅₀ (lethal dose) of 3000 mg/kg for S. minor hydroalcoholic extract. Within 14 days, the animals treated with S. minor hydroalcoholic extract at a dose of 3000 mg/kg showed no changes in behavior patterns. A side effect of S. minor hydroalcoholic extract at 3000 mg/kg was muscle twinge and lethargy, which disappeared within 48 h. Skin, fur, eyes, and urine volume, however, were normal. For 4 weeks, S. minor hydroalcoholic extract did not cause mortality, morbidity, or toxicity signs at the doses used in this subacute toxicity test. Four weeks after treatment, both treatment and control rats were healthy in terms of behavior and skin, fur, and eyes. The results showed that this plant may be used as an herbal medication and was safe and well-tolerated [87].

There is ample evidence that S. minor has a wide spectrum of therapeutic effects from both in vitro and in vivo studies. Table S1 is a list of S. minor’s pharmacological effects.

8. Insects: Pest or Beneficial

Many ecosystems depend on insects, some of which are helpful, while others are pests [88].

Philaenus spumarius is a polyphagous xylem-feeding insect, widespread in the Holarctic, whose nymphs produce a protective foam (spit masses) from their liquid excretion. The eggs usually hatch at the beginning of spring, and the five nymphal stages feed on plant shoots covered by a mucilaginous foam that serves as a barrier that allows the diffusion of O₂ from the surrounding atmosphere [89,90,91]. Humidity and temperature are particularly limited in the earlier nymphal stages. Adults generally live through one breeding season in the spring/summer, and then in late summer/autumn, the females oviposit and the eggs overwinter in vegetation until they hatch the following spring/summer [89].

Nevertheless, biological, ecological, and ethological information is lacking and dispersed since this species has never been seen as a serious danger to agriculture [89,90].

Several species of S. minor were affected by Philaenus spumarius, as can be seen in Figure 5.

The most important beneficial insects are bees and bumblebees, which require honey from plants for survival. In their natural habitat, bees are essential for maintaining plant diversity. While the insects consume the plants’ nectar and pollen, the plants benefit from this symbiotic relationship through reproduction and genetic diversity [87,91]. Figure 6 shows how the flowers of S. minor have been colonized by bees.

Because the flowers of S. minor are filled with pollen, it is known to attract bees, beneficial insects, butterflies/moths, and other pollinators [1,88].

9. Conclusions

The taxonomy, phytochemistry, and biological activity of S. minor were reviewed. Various biological activities and applications of S. minor, including its antibacterial, antioxidant, anticancer, and antiviral properties, have been investigated. In-depth biochemical and clinical investigations are needed to understand the mechanisms by which this plant exerts its multiple benefits and how this plant can be used effectively in the food and pharmaceutical industry. In-depth studies (biochemical and clinical) are required for an understanding of the cellular or molecular mechanisms by which S. minor exerts its biological effects. Additionally, further studies on the plant’s pharmacodynamic activities must be performed to establish their efficacy. In order to support the safety of S. minor’s main bioactive compounds, investigations on their pharmacokinetics should be performed. In an attempt to establish a connection between the various biological activities and the primary bioactive compounds of S. minor, this review detailed the nutritional and phytochemical profile of the herbaceous plant, focusing in particular on the polyphenolic components found in all parts (roots, stems, leaves, flowers, and seeds). As a result, the species S. minor offers an invaluable resource of bioactive compounds that must be utilized as successfully as possible to produce either food supplements or pharmaceutical formulations with positive health effects. This updated study, in our opinion, will encourage more research into the phytochemistry and biological impacts of S. minor.