Quantitation of the Flavonols Quercetin and Kaempferol in the Leaves ofTrigonella foenum-graecumby High-Performance Liquid Chromatography – Diode Array Detection

Abstract

Trigonella foenum-graecum is known for the strong hypoglycemic effects of the seed extract and for its significant allelopathic effects. The leaf extract however has not been studied thoroughly up-to-date and no data are available regarding the quantitative content of the plant's leaves. The purpose of this study was to quantify the flavonoid content and to assess the flavonoid seasonal variation in the leaves of the plant during the three developmental stages, vegetative, flowering, and fruiting. An HPLC method has been developed and validated employing a reversed phase C18 column and Diode Array Detection. Sample pre-treatment was performed by methanol:water (80:20 v:v) extraction and glucoside hydrolysis with HCl. The method allowed the reliable determination of the aforementioned substances in the Trigonella's leaves revealing the highest amount of flavonoids during the flowering stage.