In vitro stability and metabolism of salvinorin A in rat plasma

Abstract

Salvinorin A is the main active psychoactive ingredient in Salvia divinorum, a Mexican plant that has been widely available as a hallucinogen in recent years. The aims of this study were to investigate the stability of salvinorin A in rat plasma, esterases responsible for its degradation, and estimation of the degradation products.The apparent first-order rate constants of salvinorin A at 37°C, 25°C, and 4°C were 3.8 × 10−1, 1.1 × 10−1, and < 6.0 × 10−3 h−1, respectively.Salvinorin A degradation was markedly inhibited by the addition of sodium fluoride, an esterase inhibitor. Moreover, phenylmethylsulfonyl fluoride (serine esterase inhibitor) and bis-p-nitrophenyl phosphate (carboxylesterase inhibitor) also inhibited salvinorin A degradation. In contrast, little or no suppression of the degradation was seen with 5,5´-dithiobis-2-nitrobenzoic acid (arylesterase inhibitor), ethopropazine (butyrylcholinesterase inhibitor), and BW284c51 (acetylcholineseterase inhibitor). These findings indicated that carboxylesterase was mainly involved in the salvinorin A hydrolysis in rat plasma.The degradation products of salvinorin A estimated by liquid chromatography-mass spectrometry included the deacetylated form (salvinorin B) and the lactone-ring-open forms of salvinorin A and salvinorin B. This lactone-ring-opening reactions were involved in calcium-dependent lactonase.