2. Anise (Pimpinella anisum L.)
Pimpinella anisum L. belongs to the Apiaceae (Umbelliferae) family, and it is an annual herb and a grassy plant with small green to yellow seeds and white flowers that grows in Iran, Turkey, Egypt, India, and many other warm parts of the world
[59,60][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][61][62][63][64][65]. Anise seeds are small, measuring about 3.5 mm in length, and they are teardrop-shaped seeds that are most often used dried. Fresh Anise seeds have a sage green coloring that transitions into a grey-brown hue as they dry, and the seeds are slightly hairy, with five distinct dorsal ridges running lengthwise along the surface. The seeds are brown in colour, and they have a characteristic sweet smell and a pleasant aromatic taste. The molecular formula of anise methanolic extract comprises anethole (C
10H
12O), Eicosane (C
20H
42), Varidiflorene (C
15H
24), Docosane (C
22H
46), Pentadecane (C
15H
32), Nonadecane (C
19H
40), Butanoic acid (C
15H
20O
3), Octacosane (C
28H
58), Heneicosane (C
21H
44), Hexadecane (C
20H
42) and Cyclohexane (C
26H
50)
[66]. It has various therapeutic impacts on several conditions, such as gynaecologic, digestive, neurologic, and respiratory disorders, and also against stored-product insects
[67,68,69][67][68][69]. It is predominately grown for its fruit and commercially named “seeds”, which are presently used for flavouring
[70,71][70][71]. It has been reported that hot water extracts of the seeds have been consumed in folk medicine for their laxative and diuretic effects, their 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].
3. Basil (Ocimum basilicum L.)
Basil seed is rich in fiber, nutrients, and health benefits
[79,80,81,82,83][74][75][76][77][78]. The seeds are high in dietary fiber and thus have significant potential as a functional ingredients, and the mucilage obtained from basil seeds has been extensively studied and has notable emulsifying, thickening, foaming, viscosity, stabilizing, and gelling properties
[84,85,86,87,88][79][80][81][82][83]. Basil seeds are not normally utilized as a food, despite the literature indicating that its consumption provides both nutritional value and significant health advantages, such as antimicrobial, antidiabetic, antioxidant, and anticancer ones
[89,90][84][85]. Basil has also been extensively applied in traditional medicine in the treatment of headaches, constipation, coughs, warts, diarrhea, kidney problems, and worms
[91][86]. Carbohydrate (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][87][88][89]. The physical characteristics of basil seeds in Iran are 1.82 mm width, 3.11 mm length, 1.34 mm thickness
[95][90], 1.84 mm width, 3.22 mm length, and 1.37 mm thickness
[96][91]. 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][79]. The basil plant seeds are small (2–3 mm), egg-shaped, elongated, black-colored, and generally applied in most desserts, and the seeds also contain several traditional characteristics of medicinal importance that are useful in the treatment of various medical ailments, such as ulcers, diarrhea, piles, dyspepsia, etc.
[97][92].
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][93]. The mineral components of basil seeds are Fe (2.27 mg/100 g), Mn (1.01 mg/100 g), Zn (1.58 mg/100 g), Mg (31.55 mg/100 g), Na, K, and Ca
[99][94]. Basil seed gum is the mucopolysaccharide obtained from basil seed, and it shows a fibrillar structure connected with many globules and suggests different practical usages, including as an emulsifier, a stabilizer, a fat replacer, and a thickener
[100,101,102][95][96][97]. Basil seed gum is a plant-derived hydrocolloid, and its high molecular weight (Mw) (2320 kDa) imparts high pseudoplastic and viscous behaviour
[100][95]. It is identified as an anionic heteropolysaccharide, including glucomannan, and is composed of two main fractions with different molecular weights and monosaccharides units: PERBSG fraction (6000 kDa) and SUPER-BSG (1045 kDa)
[103,104][98][99]. Basil seed gum has demonstrated a high flexible chain, which makes it liable to change structure by adding sugar solutions, and it has indicated random coil-to-rod conformation and no molecular entanglement at the various conditions
[105,106][100][101]. Basil seed mucilage demonstrates significant chemical and physical properties, such as high water absorbing capacity as well as stabilizing and emulsifying properties
[107,108,109][102][103][104]. The
Ocimum basilicum mucilage (OBM) contains carbohydrates such as D-Galactose, D-Glucose, D-Mannose, glucomannan, L-Rhamnose, pectins, and hemicellulose materials, as well as a small amount of non-polysaccharides, such as fat, minerals, and protein
[110,111,112][105][106][107].
4. Borage (Borago officinalis L.)
Borage is one of the most important medicinal and nutritional plants due to the occurrence of high levels of γ-linolenic acid (GLA) in its seed oil
[123,124,125,126][108][109][110][111]. It is a notable garden herb of the plant family Boraginaceae, and it is freshly consumed in salads
[127,128][112][113]. In addition, its 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][111]. Its seed oil is a highly emollient oil that hydrates, protects, and nourishes the skin
[126,127,128][111][112][113]. The seed is 4–5 mm in length, and the borage seedling produces a pair of rounded, wavy-edged cotyledons, and the first true leaves are hairy with a rougher texture. It is a dark coloured seed, varying from brown to black, with a coarse and rough texture. 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 required for this process
[129][114]. Due to its potential market for gamma linolenic acid (GLA), it has been the subject of increasing agricultural interest and different fatty acids obtained from the seeds
[130][115]. In addition to GLA, borage seeds contain stearic, erucic, linoleic, palmitic, oleic, α-linolenic, and erucic acids
[131,132,133,134][116][117][118][119]. GLA is an omega-6 essential fatty acid that has been considered as having many positive therapeutic impacts, such as the treatment of diabetes, arthritis, heart disease, atopic eczema, cyclic mastalgia, and multiple sclerosis
[135,136][120][121]. Oil from plant seeds mostly includes triglycerides consisting of C16–C20 fatty acids, and triglycerides are sufficiently soluble in SC-CO
2, but they are much more so in
n-alkane, such as propane
[137][122]. Borage seed oil is mostly obtained by organic solvent extraction (mainly hexane), extrusion procedures such as cold pressing and hot expelling, or a mixture of extrusion processes and solvent extraction
[138][123].
5. Coriander (Cilantro) (Coriandrum sativum L.)
Coriander is an annual herb that belongs to family Apiaceae, and the coriander 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][124][125][126]. All parts of the plant are edible, with dried seeds and fresh leaves usually used as culinary ingredients
[144,145][127][128]. It is probably one of the first species used by humanity
[146,147,148][129][130][131]. Principle constituents in coriander are aldehydes (82.6%) followed by alcohols (16.6%). Coriander is also an appropriate source of essential fatty acids
[149,150][132][133]. α-linolenic acid and Linoleic acid are found in high concentration, and both are essential fatty acids and are precursors of omega-6 fatty acids and omega-3 fatty acids, respectively
[151][134]. The major monoterpenes of coriander are linalool followed by camphor, geraniol, and limonene
[152][135]. The essential oils found in coriander leaves and seeds have become increasingly popular as functional foods and as 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 due to its distinctive pungent, aldehydic, and fatty aroma
[153][136]. The major aromatic compounds are aliphatic aldehydes (mainly C
10–C
16 aldehydes), with a fetid-like aroma in the fresh herb oil
[154][137]. The oil composition of the seeds can be influenced by several parameters, such as genetic structure, plant and soil macronutrient and micronutrient contents, climatic conditions, and agronomical practices
[155,156,157][138][139][140].
The seeds of coriander are ovate globular, the length of the seed is 3–5 mm, there are many longitudinal ridges on the surface, and, when dried, the seeds are generally brown but may be green, straw-colored, or off white. The seed is usually sold sun dried and is made accessible for both whole and ground coriander, and coriander seeds have a sweet, mild, slight pungent, citrus-like flavor with a hint of sage
[158][141]. There are three main extraction processes used to obtain vegetable oil (VO) and essential oil (EO) from coriander seeds, which are organic solvent extraction (Soxhlet), steam distillation, and supercritical fluid extraction
[159][142]. The most cited compounds are (
E)-2-decenal, decanal, (
E)-2-dodecenal, (
E)-2-tridecenal, dodecanal, and tetradecenal
[160,161][143][144].
The coriander seeds have a satisfying flavour owing to the specific composition of the essential oil
[166][145]. The high content of hydroxycinnamic acids was observed in ethanolic extracts achieved from exhausted coriander seeds with lowest mean particle size, and, consequently, coriander seeds, which have been identified for their rich essential oil content, could be applied for sequential production of polyphenolic-rich extracts with high antioxidant activity
[167,168][146][147]. The antioxidant activity of coriander seeds is primarily related to high levels of phospholipids, carotenoids, and tocopherols
[167,168,169][146][147][148]. Coriander seed essential oil has a significant inhibitory impact on the fungus
Candida albicans [169][148]. The content of the essential oil of the seeds is usually influenced by coriander cultivar, weather conditions, the geographical location of the growth area, and the stage of maturity
[170,171,172][149][150][151].
6. Chamomile (Matricaria chamomilla L.)
Chamomile belonging to the Asteraceae family, and also called German chamomile, is a medicinal plant of high economic importance in the world
[174,175,176][152][153][154]. It is applied in perfumery, pharmaceutical, cosmetics, aromatherapy, and food and flavor industries
[177,178,179,180,181][155][156][157][158][159]. Its seeds are one of the few types of seed that need light in order to germinate, so establishing by seed is a delicate process. Chamomile is classified mostly into five chemotypes according to the content of α-bisabolol, bisabolol oxide A and B, chamazulene, and bisabolone oxide in its essential oil
[182][160]. The essential oil of chamomile has showed significant antioxidant, antibiotic, sedative, antifungal, anti-inflammatory, and anti-allergic activities
[183,184,185,186][161][162][163][164]. 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][165][166][167][168]. Chamomile is mainly used as an infusion for anxiolytic and sedative purposes
[191,192][169][170]. Utilizing chamomile in combination with Silver nanoparticles (AgNPs) may be an effective technique for efficacious treatment of lung cancer
[193][171]. It has been reported that extracts of the three essential oils of marjoram, chamomile, and Eucalyptus contain acaricidal activity against Tetranychus urticae
[194][172]. Angelic, methacrylic acid esters, isobutyric, and pinene were the main hydro-distilled essential oil volatiles
[195,196,197][173][174][175]. It has been reported that chamomile seed-based salvia substitute was effectual in relieving xerostomia signs
[198][176].
7. Conclusions
Medicinal plant and herb seeds are seeds that have had a special connection to humankind since the beginning of history. In today’s world, there is worldwide identification of the importance of medicinal and aromatic plants due to their uses in the feed, food, pesticide, and cosmetics industries as well as due to their preventive and curative characteristics, which are indicated by a growing demand for medicinal and aromatic products in the markets. Anise seeds are rich in nutrients and its seeds are particularly rich in iron, and anise seed may help treat depression and reduce its symptoms. Its seeds may also 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 have an oval shape, and they have been used in traditional medicine, such as antipyretic, antispasmodic, stomachic, diarrhea, as well as the treatment of ulcers, and they are rich in plant compounds, including flavonoids. In traditional medicine, borage is used in herbal medicinal science, while it is harvested as an oil seed commercially. The seeds can decrease arthritis, provide relief from respiratory issues, have tremendous benefits on improving both skin condition and cardiovascular health, are important for treatment of allergies and diseases, and are recommended to help relieve fever with anti-cancer activities. Chamomile plants are a member of the Asteraceae family, and two important common types are German chamomile and Roman chamomile. The terpenoid group, such as derivatives of acetylene and chamazulene, is the main source of antioxidants. This may help with depression and stress, improve digestion, and help to decrease pain and reduce inflammation. Chamomile also possesses strong anti-inflammatory and pain-reducing capabilities and anti-cancer activities, and, in addition, it relieves congestion and promotes skin health.