In vitro anti-inflammatory property of a Quercetin-3-O-diglucoside-7-O-glucoside characterized from fresh leaves of Trigonella foenum-graecum L

Trigonella foenum-graecum L. (fenugreek) leaves are nutritionally rich green leafy vegetables consumed in South-East Asian and Middle-Eastern countries. Scientific data suggests properties including anti-inflammatory, antipyretic, anti-nociception, and hepatoprotective. However, the molecules responsible for these properties are yet to be identified. In the present study, we have isolated and characterized an anti-inflammatory nutraceutical molecule based on bioassay from the fresh leaves of fenugreek. The lipoxygenase inhibition assay revealed 79.9 +/- 1.1% and 69.0 +/- 2.9% inhibition in ethanolic and aqueous extracts, respectively. The ethanolic extract purified on a semi-prep HPLC column yielded a nutraceutical molecule quercetin glycoside (QG) having potent inhibition of lipoxygenase (75.3 +/- 1.6%) at 10 mM and hyaluronidase (67.4 +/- 4.0%) at 2 mM, respectively. The QG structure was elucidated by spectroscopic data, including FTIR, UHPLC-MS/MS, and 1D and 2D NMR as Quercetin-3-O-diglucoside-7-O-glucoside. QG also suppressed ROS, NO, and IL-6 production in LPS stimulated RAW264.7 cells. Radical scavenging assays of DPPH and ABTS revealed the potent antioxidant activity of QG with an EC50 of 245.5 and 68.8 mu M, respectively. Our results demonstrate that newly characterized quercetin glycoside from fresh leaves of fenugreek possesses potential anti-inflammatory and antioxidant activities.