Fenugreek: A Miraculous Medicinal Herb

Saponins are amphipathic glycosides having hydrophilic glycoside moieties combined with a lipophilic triterpene derivative. The glycoside free (aglycone) portion of the saponin is termed as sapogenins. There are different sources of saponins and one of the chief source is fenugreek. Fenugreek contains approximately 4 to 8% saponins and about 1% alkaloids. The main steroidal sapogenins obtained from fenugreek seeds are diosgenin and yamogenin which are used as steroid intermediates in the pharmaceutical industry. The occurrence of diosgenin [(25R)-spirost-5-en-3β-ol] in the seeds of fenugreek has been well expected for over 50 years [15]. Other saponins and steroidal saponins present in fenugreek include fenugrin B, fenugreekine, trigofoenosides A-G, tigogenin, neotigogenin, gitogenin, neogitogenin, yuccagenin and saponaretin [16]. The plant alkaloid Trigonelline (0.3-0.4%) was first isolated from the seeds of fenugreek. it is a pyridine alkaloid, known for its hypoglycaemic and hypocholesterolemic activity. Trigonelline (N-methylnicotinic acid) is derived from nicotinic acid and the reaction is catalysed by S-adenosyl-L-methionine (SAM)dependent nicotinate enzyme N-methyltransferase. Nicotinamide and nicotinic acid, the products of pyridine nucleotide cycle (PNC) give rise to trigonelline. The synthesis of trigonelline from nicotinamide mononucleotide (NaMN) is shown in the Figure 2. Other alkaloids present n fenugreek include Choline, Gentianine, Carpaine and Betain [16-18].