Trigonella foenum graecum (fenugreek) is traditionally used to treat disorders such as diabetes, high cholesterol, wounds, inflammation, and gastrointestinal ailments. Recent studies suggest that fenugreek and its active constituents may possess anticarcinogenic potential. We evaluated the preventive efficacy of dietary fenugreek seed and its major steroidal saponin constituent, diosgenin, on azoxymethane-induced rat colon carcinogenesis during initiation and promotion stages. Preneoplastic colonic lesions or aberrant crypt foci (ACF) were chosen as end points. In addition, we assessed the mechanism of tumor growth inhibition of diosgenin in HT-29 human colon cancer cells. To evaluate the effect of the test agent during the initiation and postinitiation stages, 7-week-old male F344 rats were fed experimental diets containing 0% or 1% fenugreek seed powder (FSP) or 0.05% or 0.1% diosgenin for 1 week and were injected with azoxymethane (15 mg/kg body weight). Effects during the promotional stage were studied by feeding 1% FSP or 0.1% diosgenin 4 weeks after the azoxymethane injections. Rats were sacrificed 8 weeks after azoxymethane injection, and their colons were evaluated for ACF. We found that, by comparison with control, continuous feeding of 1% FSP and 0.05% and 0.1% diosgenin suppressed total colonic ACF up to 32%, 24%, and 42%, respectively (P < or = 0.001 to 0.0001). Dietary FSP at 1% and diosgenin at 0.1% fed only during the promotional stage also inhibited total ACF up to 33% (P < or = 0.001) and 39% (P < or = 0.0001), respectively. Importantly, continuous feeding of 1% FSP or 0.05% or 0.1% diosgenin reduced the number of multicrypt foci by 38%, 20%, and 36% by comparison with the control assay (P < or = 0.001). In addition, 1% FSP or 0.1% diosgenin fed during the promotional stage caused a significant reduction (P < or = 0.001) of multicrypt foci compared with control. Dietary diosgenin at 0.1% and 0.05% inhibited total colonic ACF and multicrypt foci formation in a dose-dependent manner. Results from the in vitro experiments indicated that diosgenin inhibits cell growth and induces apoptosis in the HT-29 human colon cancer cell line in a dose-dependent manner. Furthermore, diosgenin induced apoptosis in HT-29 cells at least in part by inhibition of bcl-2 and by induction of caspase-3 protein expression. On the basis of these findings, the fenugreek constituent diosgenin seems to have potential as a novel colon cancer preventive agent.

https://cebp.aacrjournals.org/content/cebp/13/8/1392.full.pdf

Diosgenin, a steroid saponin of Trigonella foenum graecum (Fenugreek), inhibits azoxymethane-induced aberrant crypt foci formation in F344 rats and induces apoptosis in HT-29 human colon cancer cells

Fenugreek (Trigonella foenum-graecum L.) is extensively used as a spice in India and the Mediterranean region and is known to possess a number of medicinal properties. Steroidal sapogenins and mucilaginous fibers present in the seed and leaves of this legume plant contribute to anti-diabetic and hypocholesterolaemic properties attributed to the plant. In recent years selected genotypes of this species have formed a niche crop that produces high yields of bloat-free forage that can increase both beef and milk production in semiarid regions of western Canada. Fenugreek genotypes tested in western Canada have demonstrated genetic variability for biomass production and nutraceutical properties indicating that there is much potential for enhancing the properties desired by agricultural and nutraceutical industries in this region. This paper reviews the history, culture and documented medicinal, agronomic and environmental value of fenugreek as well as discusses future potential of this crop for use in semiarid regions of North America.

Fenugreek, an Alternative Crop for Semiarid Regions of North America

The aroma and fragrance industry is a billion-dollar world market which grows annually. Essential oils comprise the majority of compounds used by these industries. These sets of metabolites are formed mainly by monoterpenes, which are products of the plants' secondary metabolism. Biosynthesized from mevalonate and methylerythitol phosphate, the essential oil production depends not only on genetic factors and the developmental stage of plants, but also on environmental factors which could result in biochemical and physiological alterations in plants modifying the quantity and quality of the essential oil. These modifications impair aromatic plant production aimed at essential oil by reducing their quality. It is desirable to develop techniques of agronomical management to improve essential oil products and their specific compounds. Among other factors influencing essential oil production are plant growth regulators or plant hormones. Endogenous levels as well exogenous application could affect essential oil production and chemical composition. In this review we will present research in which plant growth regulators or their synthetic analogs were used and their effects on essential oil production.

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Growth regulators and essential oil production

Fenugreek (Trigonella foenum-graecum L.) has a long and respected history of medicinal uses in Middle East and Persian medicine. The hypocholesterolaemic and hypoglycaemic effects of fenugreek were attributed to its major steroidal sapogenin, diosgenin and its major alkaloid, trigonelline. The knowledge of diosgenin and trigonelline biosynthesis is derived from studies of cholesterol and nicotinic acid production through acetyl-CoA→ mevalonate→ isopentenyl pyrophosphate→ squalene→ lanosterol→ cholesterol→ diosgenin and quinolinic acid→ nicotinamide adenine dinucleotide→ nicotinamide→ nicotinic acid→ trigonelline pathways, respectively. This paper reviews the secondary metabolites and metabolic pathways of diosgenin and trigonelline production in fenugreek as a medicinal plant and economical crop.

Bioengineering of important secondary metabolites and metabolic pathways in fenugreek (Trigonella foenum-graecum L.).

Sulfuric acid hydrolysis of steroidal glycosides of Amber fenugreek was studied by capillary gas chromatographic analysis of diosgenin [(25R)-spirost-5-en-3-ol] and isomeric spirostadiene artifacts from 100 mg samples of seed material. Following extraction with 80% ethanol, highest recoveries of diosgenin occurred when hydrolyses were conducted in sulfuric acid, prepared at 1 molar (M) concentration in water containing 60-80% 2-propanol. Compared to a previous method with aqueous hydrochloric acid, the selected conditions of hydrolysis at 100 degrees C for 2 h with sulfuric acid in 70% 2-propanol reduced diene formation but did not completely eliminate these artifacts. Extraction of steroidal saponins with various alcohol/water mixtures prior to sulfuric acid hydrolysis gave similar recoveries of diosgenin. Application of the quantitative method to experimental samples of Amber, Quatro, and ZT-5 fenugreek, using 10 mg subsamples of crushed seed that had been defatted with petroleum ether and dried at 60 degrees C, gave diosgenin levels of 0.55, 0.42, and 0.75%, respectively. Levels of smilagenin and sarsasapogenin were very low in hydrolyzed seed extracts from ZT-5, a Canadian breeder line of fenugreek.

R. Oncina

Papers

Bioproduction of diosgenin in callus cultures of Trigonella foenum-graecum L.

Distribution and changes of diosgenin during development of Trigonella foenum-graecum plants. Modulation by benzylaminopurine

Effect of ethylene on diosgenin accumulation in callus cultures of Trigonella foenum-graecum L

Regulation of the diosgenin expression in Trigonella foenum-graecum plants by different plant growth regulators