Slice of rhubarb pie on a bed of rhubarb leaves (which should not be eaten). The roots and stems of rhubarb are rich in anthraquinones, such as emodin and rhein. These substances are cathartic and laxative, explaining the sporadic use of rhubarb as a dieting aid. The anthraquinone compounds have been separated from powdered rhubarb root for medicinal purposes. The rhizomes contain stilbenoid compounds (including rhaponticin), which seem to lower blood glucose levels in diabetic mice. Rhubarb also contains the flavanol glucosides (+)-catechin-5-O-glucoside and (-)-catechin-7-O-glucoside. Rhubarb contains carbon-based quinone molecules which are capable of carrying an electrical charge. In 2014 a Harvard-based team of scientists published results describing the use of the quinone AQDS, almost identical to a form found in rhubarb, in flow-batteries.