Functional food components of Antigonon leptopus tea

The tubers and flowers of Antigonon leptopus, belonging to the family Polygonaceae, are consumed as food in several parts of the world. The aerial portion, including flowers, is used in the preparation of tea used as a cold remedy. This prompted us to investigate its functional food qualities and found that the methanol extract of the aerial parts of A. leptopus, inhibited lipid peroxidation (LPO) by 89% and cyclooxygenase enzymes, COX-1 and COX-2 by 50.4% and 72.5%, respectively, at 250 μg/ml. Purification of the methanolic extract yielded n-hentriacontane (1), ferulic acid (2), 4-hydroxycinnamic acid (3), quercetin-3-rhamnoside (4), and kaempherol-3-glucoside (5) along with β-sitosterol, β-sitosterol-glucoside and d-mannitol. Compounds 3, 4 and 5 inhibited LPO by 19.5%, 41.0%, and 60.5%, respectively, at 5 μg/ml. Similarly, compounds 3, 4 and 5 inhibited COX-1 enzyme by 64.7%, 16.9%, and 38.5% and COX-2 enzyme by 87.4%, 88.8%, and 90.2%, respectively, at 25 μg/ml. Compounds 3, 4 and 5 showed 50% inhibition (IC50) at 17.4%, 68.9% and 36.3 μg/ml, against COX-1 and 8.57%, 7.86% and 6.78 μg/ml for COX-2, respectively. This is the first report of the isolation of compounds 2–5 from A. leptopus and their LPO and COX inhibitory activities.