Objective: To investigate the in vitro stability of(-)-gossypol in different physiological pH and biological sample. Method: (-)-Gossypol was incubated in different phosphate buffer solutions with pH of 1.2-8.0

artificial gastrointestinal fluid and isolated biological media.The concentration of(-)-gossypol was determined by HPLC to investigate the degradation kinetics and the enzymatic stabilities of(-)-gossypol. Result: (-)-Gossypol was stable in pH 1.2 dilute hydrochloric acid solution

artificial gastric juice and ingastric contents

after 12 h of incubation

degradation rate of(-)-gossypol was less than 10%.(-)-Gossypol was unstable in phosphate buffer solutions at pH 6.8

7.4 and 8.0 after 12 h of incubation.The degradation rates of(-)-gossypol in small intestinal contents

large intestine contents and liver homogenates were 81.3%

96.9%and 97.3%after 8 h

degradation profiles of(-)-gossypol in gastric contents

small intestinal contents

large intestine contents and liver homogenates were similar to that in the aqueous buffer. Conclusion: (-)-Gossypol is stable in acid environment

but it is unstable in phosphate buffer solutions at different pH.(-)-Gossypol is stable in gastric contents

but it is unstable in liver homogenate

small intestine and large intestine bacteria.