**Abstract**

Fenugreek (*Trigonella foenum-graecum*) is an annual medicinal plant with trifoliate leaves, a branched stem, white flowers, rooted tubers, and golden yellow seed belonging to Fabaceae family. Fenugreek is used in different industries such as pharmaceutical, nutraceutical and food industries as an ancient crop plant. Fenugreek is grown as a medicinal herb in many countries and has antioxidant, hypoglycemic, hypercholesterolemia, stomach protective, chemopreventive, laxative and appetite stimulating properties. In recent years, many important studies have been conducted on the biological activities and therapeutic properties of fenugreek mainly secondary metabolites such as alkaloids, flavonoids, steroids and saponins. These compounds are used for multipurpose uses in different industries and also appreciated by scientists. Based on these several health usefulness as discussed in review, fenugreek might be a good candidate for a herbal drug and used for preparation of new drugs. In this review, secondary metabolites used in different industries of fenugreek will be discussed and general benefits of them will be expressed within the all significant aspect of fenugreek as clearly. This review also highlights the traditional uses and nutraceutical properties (antioxidant activity, antibacterial, antifungal, anticancer hypoglemic effects and anti-inflammatory and immunological activity) of fenugreek. These uses and effect properties of fenugreek have been discussed and researchable areas were implied to depending on the previous studies. In the future, studies on fenugreek are needed some important applications to increasing the popularity of fenugreek. In this context, researchers should be focused on secondary and primary metabolite studies in fenugreek seeds and leaves. In addition to these, fenugreek germplasm should be collected and subjected to intensive selection via modern breeding programs and new fenugreek genotypes with desired properties should be obtained.

**Keywords:** Fenugreek, *Trigonella foenum-graecum* L., ancestor plant, multipurpose uses, secondary metabolite

## **1. Introduction**

Fenugreek (*Trigonella foenum-graecum* L.) is commonly grown in many parts of the world for both culinary purposes and health benefits. Fenugreek is rich in minerals, protein, vitamin A and C, and contains several bioactive compounds including proteins, protease inhibitors. Its seeds contain 23–43% protein, up to 58% carbohydrate, nearly 10–13% moisture, 5–6% lipid and less than 1% minerals. In particular, the plant is rich in soluble fiber, mucilage and galactomannan which decrease the uptake of bile salts and starch absorption [1].

The main secondary metabolites and seed contents of fenugreek were given in **Figure 1** [2–4].

Polyphenol compounds *viz.* rhaponticin and isovitexin were noted as major bioactive compounds in seeds of fenugreek [5]. In addition, fenugreek seed extracts have a number of phenolic constituents similar to beta-D-glucopyranoside, methyl, alpha-d-mannopyranoside, methyl, and diethyl phthalate. Fenugreek also represents a significant source of antioxidants [6].

A wide range of beneficial effects of fenugreek seeds has been reported by a number of researchers. In addition to antidiabetic effects, seeds have significant antiatherosclerotic [7], anti-inflammatory [8], antinociceptive [9], and antiulcerogenic activities [10] which are essential for cure of diabetes and cancer disease. Antioxidant property helps in anti-aging. The phenolic antioxidants present in the extract of fenugreek show free radical scavenging activity which reduce oxidative stress in the body. This reduced oxidative stress reduces frequency of age-related disorders [11].

It was reported that fenugreek seeds had low amount essential oil and fatty oil [12]. According to the essential oil compounds findings; olfactometry diacetyl, 1-Octen-3-one, sotolone, acetic acid; 3-Isobutyl-2-methoxypyrazine, butanoic acid, isovaleric acid, 3-isopropyl2-methoxypyrazine, caproic acid, eugenol, 3-Amino-4,5-dimethyl-3, linalool, (Z)-1,5-Octadiene-3-one, 4-dihydro-2(5H)-furanone were determined as the main components [13]. It has been noted that sotolone is mostly found in fenugreek (5 s)-enantiomeric form (95%) among these essential oil components.

A study on human sweat was conducted by Meghwal and Goswami [3] and regarding essential oil components; pinene,3-octen-2-one, 2,5-dimethylpyrazine, b-camphor; terpinen-4-ol, 4-isopropylbenzaldehyde were found as the odor in sweat, while neryl acetate and b-caryophylene, 2,5-dimethylpyrazine has been observed to be the main component responsible for the compound contributing to sweat odor.

Many studies have been conducted on the therapeutic applications of various plant species on different diseases such as fungal, viral and bacterial contamination. Therefore, approximately one third of the world's population uses traditional/therapeutic plants and their extracts in their treatments [14]. A drug with both antidiabetic and antioxidant activity is much more beneficial in the treatment of diabetes. In addition, herbal medicines are more preferred due to the undesirable side effects of the existing antidiabetic medicine. As can be seen from the above explanations, fenugreek has the potential to be a versatile herbal medicine. Therefore, further studies are needed to provide detailed information

**Figure 1.** *Main secondary metabolites and seed context of fenugreek.*

about the effects of fenugreek. So, in this review, it was aimed to inform about the studies conducted with the effects of fenugreek.

Generally, this study revealed the importance of focusing on the antioxidant, hypoglycemic, hypercholesterolemia, anticancer, antibacterial and antifungal properties, as well as on its medicinal properties, phytochemical and nutrient contents. In case, fenugreek is grown for bioactive secondary metabolites, concentrating on different activities such as polyphenol compounds, anti-inflammatory, antimicrobial properties.
