Optimization of guggulsterone production in callus cultures of Commiphora wightii (Arnott.) Bhandari

Abstract

525-531Commiphora wightii (Arnott.) Bhandari is an endangered, slow growing medicinal tree. Its hypolipidemic and hypocholesterolemic activity is due to the presence of two closely related steroidal ketones guggulsterone-E and guggulsterone-Z in the resin. The callus cultures derived from zygotic embryos and leaf explants were exploited for the optimal production of these bioactive molecules. The production of guggulsterone in callus cultures was maximal during 35-d growth on modified MS medium. A correlation has been observed between guggulsterone yield in callus and in vivo in the plant. Guggulsterone content of callus was maximum during January to July, the period of gum exudation in nature. The cultures, which were grown on modified MS medium (950 mg/L KNO₃, 825 mg/L NH₄NO₃ and 220 mg/L CaCl₂.2H₂O) containing 2, 4, 5-T (0.25 mg/L) and kinetin (0.1 mg/L) (referred to as CM2 medium) accumulated ~15 µg/g guggulsterone. The optimal level of nitrogen [NH₄NO₃ (1650 mg/L), KNO₃ (475 mg/L)], CaCl₂ (110 mg/L) KH₂PO₄ (170 mg/L) in different media resulted in maximum accumulation of total guggulsterone up to 19 µg/g dry weight basis. The significant increase in total guggulsterone accumulation (59 µg/g) was recorded in the tissues grown on CM2 medium containing 40 g/L maltose. Significant increase in guggulsterone content was recorded in the tissues grown on the production medium with either sucrose or maltose alone (40 g/L) or glucose:sucrose ratio (20:20 g/L). Combination of all the optimal concentrations of salts and sugars did not further increase the guggulsterone accumulation. It appears that guggulsterone production reached to its maximum possible level (~3 fold increase) with medium salt manipulation containing 40 g/L maltose or glucose: sucrose (~60 μg/g dry weight) and further increase was not possible within these condition