Five Important Seeds in Traditional Medicine, Pharmacological Benefits and Seed Biology

1. Introduction

Aromatic and medicinal plants are gaining more importance because of their potential application in food, pharmaceutical and fragrance industry [1,2,3,4,5]. Medicinal and aromatic plants have been used in cosmetics, perfumery, pharmaceuticals and food flavoring since ancient times, because of the presence of essential oils and different components [6,7]. Anise or aniseed is an aromatic medicinal plants of the Apiaceae family [8], and its ethanol extract and essential oil are responsible for its efficacy [9]. It mainly contains trans-anethole, anethole, followed by estragole, sterols, scopoletin, coumarins, limonene, and pinens [10,11,12]. Its seeds are cultivated commercially and used for flavoring [13], and its aromatic seeds have been used in medicine as a mild expectorant [14,15].

Basil is cultivated for its essential oil, because it is used as odorizer and flavorant in perfumery and the food industry, as well as pharmaceutical industries [16,17,18]. In traditional medicine, it has been used in fold medicine to treat coughs, headaches, diarrhea, warts, constipation and kidney dysfunction, as well as to promote digestion and to stimulate appetite [19,20], because of presence of secondary metabolites like tannins, anthocyanins, phenols, flavonoids and steroids [21,22]. Its oil, linaloo, and estragole indicated nematocidal activities and acaricidal activities [23]. It has marvelous biological characteristics such as anti-angiogenic, anti-inflammatory, anti-tumor, anti-allergic, anti-depressant and anti-microbial [24,25,26,27,28,29].

Borage is an annual herb which is cultivated for culinary uses and medicinal applcation, even though, it is commercially planted for borage seed oil [30,31]. Borage seed oil is the plant rich in the gamma-linolenic acid which is utilized as food or dietary supplement [32,33]. Other than seed oil it contains a lot of fatty acids like linoleic acid, oleic acid, stearic acid, palmitic acid, erucic acid and eicosenoic acid [34,35]. It is consumed for the treatment of different diseases such as eczema, multiple sclerosis, heart diseases, diabetes and arthritis [36,37,38].

One of the most important and popular herbs in the Apiaceae family is Coriander [39,40], which is well-known for its antioxidant activity due to its natural phenolic-rich components [41,42]. The plants are utilized as pain reliever and sedative and the principle ingredient of coriander essential oil in linalool [43]. The coriander plants have different pharmacological effects like anti-cancerous, hypoglycemic, stomachic, carminative, spasmolytic, anti-mutagenic, antimicrobial, antioxidant and antifungal activity making it an important medicinal plant in pharmaceutical industries [44,45,46,47,48,49].

Chamomile is widely cultivated for its flowers and essential oils, and it has been considered as one of the oldest and most extensively used in traditional herbal medicine in different parts of the world [50,51,52]. It has been used to treat different kinds of complaints such as rheumatic pain, muscle spams, influenza, convulsions, anxiety, hemorrhoids, mucosal ulceration, skin inflشmmation, and gastrointestinal disorders [53,54,55,56,57,58]. A systematic review was conducted by searching electronic databases, including 550 articles. Relevant articles were selected on the basis of the nutritional, chemical, agronomical, and functional properties of anise, basil, borage, cilantro and chamomile seeds. The databases used were the Web of Science (https://clarivate.com/webofsciencegroup/solutions/web-of-science/), EBSCO (www.ebsco.com), and Scopus (www.scopus.com), among others. The keywords which have been used in this study were anise, basil, borage, cilantro, chamomile, seed production, seed biology, anatomy and germination, seed extract and pharmaceutical benefits. This work aims to provide an overview of medicinal effects and pharmacological benefits of the seeds of five important medicinal plants from recently published articles and studies.

2. Anise (Pimpinella anisum L.)

Pimpinella anisum L. belongs to the Apiaceae (Umbelliferae) family is an annual herb and a grassy plant with small green to yellow seeds and white flowers, which grows in Iran, Turkey, Egypt, India and many other warm parts of the world [59,60]. The major constituents of anise are anethole, eugenol, estragole, pseudoisoeugenol, anisaldehyde, methylchavicol, terpene hydrocarbons, coumarins, estrols, scopoletin, umberlliferon, polyacetylenes and polyenes [61,62,63,64,65]. Anise methanolic extract are molecular formula are Anethole (C₁₀H₁₂O), Eicosane (C₂₀H₄₂), Varidiflorene (C₁₅H₂₄), Docosane (C₂₂H₄₆), Pentadecane (C₁₅H₃₂), Nonadecane (C₁₉H₄₀), Butanoic acid (C₁₅H₂₀O₃), Octacosane (C₂₈H₅₈), Heneicosane (C₂₁H₄₄), Hexadecane (C₂₀H₄₂) and Cyclohexane (C₂₆H₅₀) [66]. It has various therapeutic impacts on several conditions such as gynaecologic, digestive, neurologic, and respiratory disorders and against stored-product insects [67,68,69]. It is predominately grown for its fruits, commercially called “seeds” that are presently used for flavouring [70,71]. It has been reported that hot water extracts of the seeds have been consumed in folk medicine for their laxative and diuretic effect, expectorant and anti-spasmodic action, and their capability to ease intestinal colic and flatulence [72]. The methods of hydrodistillation (HD), solvent extraction, steam distillation, press, Ohmic-assisted hydrodistillation (OH), ohmic heating, ultrasound, microwave extraction and supercritical fluid can be considered as advanced and usual extraction methods [73]. Balbino et al. [74] showed that pressurized liquid extraction can be a useful tool for modulating the content and composition of bioactive molecules in lipid extracts from Apiaceae seeds. The water extracts of anise seeds showed greater antioxidant capacity than that of ethanol [13]. Lee [75] reported that anisaldehyde, estragole, anethole, and myrcene derived from anise seeds are appropriate as a lead compound to development new factors for selective control of the stored food mite (Tyrophagus putrescentiae). Yazdi et al. [76] found that dietary inclusion of 10 g anise/kg can be used as alternatives to in-feed antibiotics for broiler diets. Foliar applications of aniseed essential oil at concentrations of 0.2% and 0.4% (0.1 and 0.2 mL, respectively) to lettuce plants infested with homogeneous populations of Nasonovia ribisnigri decreased the number of insects in comparison with the control in the greenhouse and laboratory trials [77]. In traditional medicine, its seeds recommended for its central tranquilizing action, but on the basis of experiment, it failed to support and have significant roles in anxiety-related central action [78]. Iannarelli et al. [63] reported that aniseed essential oil indicated a significant anti-inflammatory impacts on both HTEpC and HBEpC cells together with mucus hypersecretion. The main points about anise seeds are presented in Table 1. The most important health benefits of anise seeds are shown in Figure 1.

3. Basil (Ocimum basilicum L.)

Basil seed is rich in fiber, nutrients and health benefits [79,80,81,82,83]. The seeds are high in dietary fiber and, thus, have significant potential as a functional ingredients, the mucilage obtained from basil seeds has been extensively studies, and has notable emulsifying, thickening, foaming, viscosity, stabilizing, and gelling properties [84,85,86,87,88]. Basil seeds are not normally utilized as a food, despite the literature indicating that its consumption stands for both its nutritious value and for its significant health advantages, such as antimicrobial, antidiabetic, antioxidant, and anticancer characteristics [89,90]. Basil has also been extensively applied in traditional medicine in the treatment of headaches, constipation, coughs, warts, diarrhea, kidney problems and worms [91]. Carbohydrate (hemicellulose, cellulose, and ligning) (60.8%), lipid (13.8%) and crude protein (13.7%) are the principle constituents of basil seed and the residue is mainly ash and moisture. Its black seeds are oval, the length, width and thickness are 3.22 ± 0.33 mm, 1.84 ± 0.24 mm and 1.37 ± 0.15 mm, respectively, and the main composition of the basil seed includes carbohydrate, protein and lipid [92,93,94]. The physical characteristics of basil seeds in Iran are 1.82 mm width, 3.11 mm length, 1.34 mm thickness [95], 1.84 mm width, 3.22 mm length, 1.37 mm thickness [96], the seeds from Serbia have 1.30-1.54 mm width, 2.31-2.64 mm length, and 0.99-1.14 mm thickness, and the seeds from India have 1.06 mm width and 1.97 mm length [84]. The basil plant seeds are small (2-3 mm), egg-shaped, elongated and black-colored and are generally applied in most desserts, and the seed also contain several traditional medicinal importance as it is useful in the treatment of various medical ailments such as ulcer, diarrhea, piles, dyspepsia, etc [97]. It can be categorized into different types such as the large leaf robust type, tall slender type, compact types, dwarf types which are small and short leafed, purple types, purpurascens, and citriodorum types.

Iranian basil seed is oval in shape and black in color with mean dimensions of 3.11 ± 0.29 mm (length), 1.34 ± 0.19 mm (height) and 1.82 ± 0.26 mm (width) [98]. The mineral components of basil seeds are Fe (2.27 mg/100 g), Mn (1.01 mg/100g), Zn (1.58 mg/100 g), Mg (31.55 mg/100 g), Na, K and Ca [99]. Basil seed gum is the mucopolysaccharide obtained from basil seed and it shows a fibrillar structure connected with many globules and suggests different practical use as emulsifier, stabilizer, fat replacer, and thickener [100,101,102]. Basil seed gum is a plant-derived hydrocolloid which its high molecular weight (Mw) (2320 kDa) imparts high pseudoplastic and viscous behaviour [100]. It is identified as an anionic heteropolysaccharide including glucomannan, which is composed of two main fractions with different molecular weights and monosaccharides units: PERBSG fraction (6000 kDa) and SUPER-BSG (1045 kDa) [103,104]. Basil seed gum demonstrated high flexible chain which makes it liable to change structure by adding sugar solutions, and it indicated random coil to rod conformation and no molecular entanglement at the various conditions [105,106]. Basil seed mucilage demonstrates significant chemical and physical properties like high water absorbing capacity, stabilizing and emulsifying properties [107,108,109]. The Ocimum basilicum mucilage (OBM) contains carbohydrates like D-Galactose, D-Glucose, D-Mannose, glucomannan, L-Rhamnose, pectins, hemicellulose materials, and little amount of non-polysaccharides like fat, minerals and protein [110,111,112].

The amino acid components of basil seeds are aspartic acid, glutamic acid, serine, glycine, arginine, alanine, histidine, threonine, tyrosine, proline, valine, leucine, cysteic acid, isoleucine, lysine, phenylalanine, methionine sulfone and tryptophan [113]. Basil seeds have a specific content of gum (generally ranging from 10% to 20% on the basis of the treating methods) with surprising functional characteristics which is comparable with some other commercial gums like xanthan [114]. Calcined basil seed indicated the adsorption capability of herbicides [115]. Rectal administration of combination of basil seeds plus gum arabic after induction of colitis, showed anti-inflammatory and antioxidant impacts, and accelerates the healing of the colon in experimental colitis increased by acetic acid [116]. Peptides from its seeds revealing anti-oxidant, α-amylase and α-glucosidase inhibitory activity using in-vitro models [117]. The hydrocolloids from seeds can be utilized in food formulations because of their availability, affordable price, and functionality [118,119]. Generally, the basil seeds have appropriate antioxidant potential, which is higher than other seeds, such as red seeds or sesame, and could be utilized to develop new natural antioxidants or be included as ingredients to prevent oxidative deterioration in foods [120,121]. Basil seeds are traditionally applied as a natural treatment for indigestion, ulcers, sore throats, diarrhea, and kidney disorders [121,122], and they have been used as a diuretic, aphrodisiac, antipyretic, and anti-dysenteric [121]. Key points about basil seeds are presented in Table 2. Fascinating health benefits of basil seeds are shown in Figure 2.

4. Borage (Borago officinalis L.)

Borage is on of the most important medicinal and nutritional plant because of the occurrence of high levels of γ-linolenic acid (GLA) in its seed oil [123,124,125,126]. It is a notable garden herb of the plant family Boraginaceae, and it is freshly consumed in salads [127,128]. In addition, this oil consists of more than 60% of polyunsaturated fatty acids (PUFA), and the high PUFA amount of borage oil makes it susceptible to oxidation [126]. Its seed oil is a highly emollient oil that hydrates, protects and nourishes the skin. The plant is a culinary and traditional medicinal herb native to the Mediterranean area, which is self-incompatible, and therefore pollinating insects are needed to transfer pollen between different plants with at least two honey bee hives per hectare [129]. Due to its potential market for gamma linolenic acid (GLA), it has been the subject of increasing agricultural interest and different fatty acid obtained from the seeds [130]. In addition to GLA, borage seeds contain stearic, erucic, linoleic, palmitic, oleic,α-linolenic, and erucic acids [131,132,133,134]. GLA is an omega-6 essential fatty acid which has been considered as having many positive therapeutic impacts such as treatment of diabetes, arthritis, heart disease, atopic eczema, cyclic mastalgia, and multiple sclerosis [135,136]. Oil from plant seeds includes mostly of triglycerides consisting of C16-C20 fatty acids, triglycerides are sufficiently soluble in SC-CO₂, but much more so in n-alkane, like propane [137]. Borage seed oil is mostly obtained by organic solvent extraction (mainly hexane), extrusion procedure such as cold pressing and hot expelling or a mixture of extrusion processes and solvent extraction [138]. Borage extracts showed remarkable antioxidant properties and these impacts were related to their phenolic components [139]. HPLC analysis allowed to recognize nine phenolic acids during seed maturation with the performance of rosmarinic, sinapic and syringic acids [140]. Key points about borage seeds are presented in Table 3. The most impressive health benefits of borage are presented in Figure 3.

5. Cilantro (Coriander) (Coriandrum sativum L.)

Cilantro is an annual herb which belongs to family Apiaceae, the cilantro plant yields two primary products that are applied for flavoring purposes, mature seeds as the spice coriander and immature fresh green herb [141,142,143]. All parts of the plant are edible with dried seeds and fresh leaves most usually used as culinary ingredients [144,145]. It is probably one of the first species used by humanity [146,147,148]. Principle constituents in cilantro are aldehydes (82.6%) followed by alcohols (16.6%). Cilantro is also an appropriate source of essential fatty acids [149,150]. α-linolenic acid and Linoleic acid are found in high concentration, are essential fatty acids and are precursors of omega-6 fatty acids and omega-3 fatty acids, respectively [151]. The major monoterpenes of coriander are linalool followed by camphor, geraniol, and limonene [152]. The essential oils found in cilantro leaves and seeds have become increasingly popular as as functional foods and substitute sources of natural preservative factors. Its essential oil has been utilized in the food industry for its flavor and aroma, or to mask displeasing odors of certain foods, because of its distinctive pungent, aldehydic and fatty aroma [153]. The major aromatic compounds are aliphatic aldehydes (mainly C₁₀-C₁₆ aldehydes) with a fetid-like aroma in the fresh herb oil [154]. The oil composition of seeds can be influenced by several parameters like genetic structure, plant and soil macro and micro nutrient contents, climatic conditions, and agronomical practices [155,156,157].

The seeds of coriander are ovate globular, the length of the seed is 3-5 mm and color and there are many longitudinal ridges on the surface, when dried, is generally brown, but may be green, straw-colored or off white; usually, the seed if sell sun dried and made accessible for both whole and ground, and coriander seeds have a sweet, mild, slight pungent, like citrus flavor with a hint of sage [158]. There are three main extraction processes used to obtain vegetal oil (VO) and essential oil (EO) from coriander seeds, which are organic solvent extraction (Soxhlet), steam distillation, and supercritical fluid extraction [159]. The most cited compounds are (E)-2-decenal, decanal, (E)-2-dodecenal, (E)-2-tridecenal, dodecanal and tetradecenal [160,161]. Lasram et al. [162] reported that seed essential oils of coriander proved to be a potential natural source of aflatoxin and antifungal inhibition agent against Aspergillus flavus. Seeds also have antimicrobial potential against various pathogen bacteria and yeasts, and both lipophilic and hydrophilic extracts of coriander have indicated significant antioxidant activities in in vivo and in vitro studies [163]. Mixing of fractions of eucalytpus, coriander, dill and cilantro resulted in synergistic, additive or antagonistic impacts against individual test microorganisms [164]. Chemical characterization of cilantro essential oil can be considered as a potential antifungal, methylglyoxal suppressor and antiaflatoxigenic [165]. The seeds are major accountable for the medical application of coriander and have bee utilized as a drug for indigestion, rheumatism, against worms and pain in the joints [166].

The coriander seeds have a satisfying flavour owing to the specific composition of the essential oil [166]. The high content of hydroxycinnamic acids was observed in ethanolic extracts achieved from exhausted coriander seeds with lowest mean particle size, consequently, coriander seeds, which have been identified for its rich essential oil content, could be applied for sequential production of polyphenolic-rich extracts with high antioxidant activity [167,168]. Coriander seeds antioxidant activity is primarily related to high levels of phospholipids, carotenoids and tocopherols. Coriander seed essential oil had a significant inhibitory impacts on Candida albicans [169]. Coriander seeds and leaves are nearly good sources of essential oil [170], and the content of essential oils is usually influenced by coriander cultivar, weather conditions, geographical location of the growth area and stage of maturity [171]. Coriander seeds essential oil had a very notable impacts on Candida albicans; Gram-positive bacteria were more sensitive to the essential oil of coriander seeds than Gram-negative bacteria [172]. Coriander seeds aqueous extract treatment increased exploratory activity in the animal models of anxiety, and restored monoamines and GABA levels to the respective baseline levels and it declined excitotoxic levels of glutamate in the hippocampus region [173]. Key points about cilantro seeds are presented in Table 4. The surprising health benefits of cilantro has presented in Figure 4.

6. Chamomile (Matricaria chamomilla L.)

Chamomile belonging to the Asteraceae family and also called as German chamomile, is a medicinal plant of high economic importance in the world [174,175,176]. It is applied in perfumery, pharmaceutical, cosmetics, aromatherapy, food and flavor industries [177,178,179,180]. It is an aromatic annual herbaceous plant with capitulum inflorescence, and it is native to Western Asia and Eastern Europe [181]. Its seeds are one of the few seeds that need light to germinate, so establishing them by seed in a delicate process. Chamomile is classified mostly into five chemotypes, according to its content, of α-bisabolol, bisabolol oxide A and B, chamazulene, and bisabolone oxide in its essential oil [182]. The essential oil of chamomile has showed significant antioxidant, antibiotic, sedative, antifungal, anti-inflammatory and anti-allergic activities [183,184,185,186]. Chamomile could show potent antioxidant activity because of its content of flavanols, isoflavones, flavonoids, anthocyanin, flavones, isocatechins, tannins acid, and coumarin [187,188,189,190]. Chamomile is mainly used as infusion for anxiolytic and sedative purposes [191,192]. Utilizing chamomile in combination with Silver nanoparticles (AgNPs) may be an effective technique for efficacious treatment of lung cancer [193]. It has been reported that extracts of three essential oils of marjoram, chamomile, and Eucalyptus contain acaricidal activity against Tetranychus urticae [194]. Angelic, methacrylic acid esters, isobutyric and pinene were the main hydro-distilled essential oil volatiles [195,196,197]. It has been reported that chamomile seed based salvia substitute was effectual in relieving xerostomia signs [198]. Cicco et al. [199] showed that chamomile essential oils exerted their antioxidant and anti-inflammatory activity by regulating macrophages and CD4⁺ T cells-mediate immune response. Madadi et al. [200] concluded that 150 mg/L of chamomile shoot extract could be effective as a bioherbicide to sustainably control flixweed in wheat production. Chamomile extract is recommended in further decreasing the clinical traits and ameliorating the quality of life of Chronic Rhinosinusitis (CRS) patients [201]. Temperature, relative humidity, seed moisture content, and nature of the seeds impact the seed longevity during storage, and increment in temperature as well as moisture can lead to fungal growth which decreases seed viability [202,203,204,205,206,207]. Key points about chamomile seeds are presented in Table 5. Top health benefits of chamomile are shown in Figure 5.

7. Conclusion

Medicinal plant and herb seeds are seeds which have been standing in a special connection to humankind since the beginning of history. In these days, there is worldwide identification to the importance of medicinal and aromatic plants due to their uses in feed, food, pesticide and cosmetics industries as well as their preventive and curative characteristics, which is indicated by a growing demand for medicinal and aromatic products in the markets. Anise seeds are rich in nutrients, particularly its seeds are rich in iron, anise seed may help treat depression and reduce symptoms of it. Its seeds may help to prevent stomach ulcers and decrease unfavorable symptoms. Anethole which is an active component in anise seed, inhibits bacterial growth and other compounds possess potent antimicrobial properties. Anise seeds can help relieve menopause signs, balance blood sugar levels and decrease inflammation. The basil seeds are black colored and with oval shape, which has been used in traditional medicine such as antipyretic, antispasmodic, treatment of ulcer, stomachic, diarrhea and rich in plant compounds including flavonoids. In traditional medicine, borage used in herbal medicinal science, while commercially it is harvested as an oil seed. The seeds can decrease arthritis, relief from respiratory issues, having tremendous benefits to improve skin condition and cardiovascular health, important for treatment of allergies and diseases, recommended to relieve fever with anti-cancer activities. Chamomile plants are a member of the Asteraceae family, and two important common types of it are German chamomile and Roman chamomile. Terpenoid group like derivatives of acetylene and chamazulene are the main sources of antioxidants. It may help with depression and stress, improves digestion, appropriate to decrease pain and reduce inflammation. It has also strong anti-inflammatory and pain-reducing capabilities, anti-cancer activities, relieves congestion and promotes skin health. All these mentioned seeds of medicinal and aromatic plants which are also rich in many nutrients can boast a wide array of health benefits.