Hemostatic action of lotus leaf charcoal is probably due to transformation of flavonol aglycons from flavonol glycosides in traditional Chinses medicine

Nelumbo nucifera Gaertn (lotus) leaves were empirically carbonized to enhance the hemostatic effect in traditional Chinese medicines. The mechanism of this application remains unclear.The present study aims at exploring the transformation of phytochemical compounds in lotus leaves after heating and figuring out the phytochemical mechanism of the application of charcoal hemostatic styptics.Raw lotus leaves were heated at 150 °C and 220 °C, respectively, and the transformation of the phytochemicals was studied. Flavonol glycosides in raw lotus leaves were found to be degraded to their corresponding aglycons in 150 °C lotus leaf charcoals (LLC) and the subsequent degradation products of aglycons in 220 °C LLC. 150 °C LLC exhibited the most desirable hemostatic effect in mice on reducing both bleeding time (BT) and clotting time (CT) by more than 30% as compared to the untreated group (P < 0.05). The extracts of 150 °C LLC were further separated by using different solvents. Ethyl acetate fraction which contained much flavonol aglycons displayed the most desirable hemostatic effect. On the contrary, petroleum ether fraction contains poor flavonoid and much alkaloid thus prolonged BT and CT. N-butanol extracts which contained only flavonol glycoside failed to shorten CT. In rats, quercetin (aglycon) standard promoted blood coagulation by shortening APTT (activated partial thromboplastin time) and increasing fibrinogen (P < 0.05). Hyperoside (glycoside) increased fibrinogen and platelet count (P < 0.05). Nuciferine was shown to prolong APTT and TT (thrombin time) and decrease fibrinogen (P > 0.05).Degradation of flavonoids and alkaloids in lotus leaves was suggested to enhance the hemostatic effect of LLC. Flavonol aglycons were found to be more effective on blood clotting compared with their corresponding glycosides. Nuciferine, a typical alkaloid in lotus leaves which was degraded in LLC showed anticoagulation effect in rats. The content of flavonoid aglycon can be regarded as a criterion to qualify LLC.