Chem. Pharm. Bull., 51(1),24-26, January 2003

Regular Articles

Heat-Accelerated Degradation of Solid-State Andrographolide

Luelak LOMLIM,^a Noppong JIRAYUPONG,^a and Anuchit PLUBRUKARN^*,b

^a Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Prince of Songkla University; and ^b Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University; Hat-Yai, Songkhla 90112, Thailand. * To whom correspondence should be addressed. e-mail: planuchi@ratree.psu.ac.th

The stability of andrographolide, the major active diterpene lactone from Andrographis paniculata (BURM. f.) WALL. ex NEES., was determined to show that, while crystalline andrographolide was highly stable even at 70 °C (75% relative humidity) over a period of 3 months, its amorphous phase degraded promptly. Heat-accelerated conditions revealed second-order kinetics of the decomposition with the rate constant at 25 °C (k_25°C) predicted from the Arrhenius plot of 3.8×10⁻⁶ d⁻¹. The major decomposed product under elevated temperature (70 °C, 75% relative humidity) is 14-deoxy-11,12-didehydroandrographolide.

Key words andrographolide; Andrographis paniculata; 14-deoxy-11,12-didehydroandrographolide; stability