The effect of 6-deoxyclitoriacetal from Clitoria macrophylla Wall. on rat liver mitochondrial respiration and ATPase activity

A Thai plant Clitoria macrophylla Wall. was claimed to possess some pharmacological activities. The phytochemical studies reported a rotenoid compound, 6-deoxyclitoriacetal, which exhibits the cytotoxic effect in several cell line experiments. This report was to study the effect of 6-deoxyclitoriacetal on rat liver mitochondria, which may associated to its cytotoxic phenomena. Mitochondrial suspension was prepared from male Wistar rat liver by standard method (Hogeboom, 1955). The mitochondrial functions were demonstrated by measuring the oxygen consumption by standard polarographic method. The ATPase activity was measured from the amount of inorganic phosphate released from ATP hydrolysis. Protein content was measured by the method of Lowry et. al. (1951) 6-Deoxyclitoriacetal inhibited the oxygen consumption and oxidative phosphorylation with NAD+-linked substrates (glutamate+malate, ?-ketoglutarate and ?-hydroxybutyrate) but not with succinate. The compound also inhibited the NADH oxidation in osmotic-shocked mitochondria. These suggested that 6-deoxyclitoriacetal act as a mitochondrial electron transport inhibitor by inhibiting the complex I. In addition, 6-deoxyclitoriacetal activated the mitochondrial ATPase and led to decrease mitochondria ATP synthesis. 6-Deoxyclitoiacetal, a new rotenoid isolated from Clitoria macrophylla Wall. demonstrated its inhibitory effect on site I mitochondrial respiratory chain and stimulate APTase activity which may partly explain its cytotoxic effect.