Gymnema

Gymnema is a perennial woody vine native to Asia, including the Arabian Peninsula, to Africa and to Australia. It is also called Australian cowplant and periploca of the woods, and the Hindi name gurmar means sugar destroyer. It is a climber with soft hairs on the upper surface of its elongated-oval leaves, and it bears a small yellow umbel of flowers throughout the year. The page says it has been used in Ayurvedic medicine and has a long history in herbal medicine. The leaves contain gymnemic acids, triterpenoid saponins that interact with taste receptors on the tongue and temporarily suppress the taste of sweetness. The page says this effect lasts from 15 to 50 minutes, and sometimes several hours, and does not affect bitter, salty or sour taste. It also says the antidiabetic properties were not confirmed in rats.