Enhanced recovery of antitumor ganoderic acid T from Ganoderma lucidum mycelia by novel chemical conversion strategy

Abstract

The removal of analog impurities with a very small sample size presents a major challenge in the purification of high-valued biochemicals such as those derived from fermentation or herbs. Ganoderic acid T (GA-T), an antitumor drug candidate, is very difficult to purify from the mycelia of medicinal mushroom Ganoderma lucidum due to co-purifying analog impurities. A novel pretreatment process with three consecutive chemical conversion steps, namely hydrolysis-acetylation-hydrolysis, was developed to convert two key analog impurities (7-O-ethyl GA-O and GA-Mk) to GA-T. It increased the GA-T amount in the 100 g dried mycelia from the initial 0.444 g to 1.621 g after the pretreatment, representing an apparent yield of 365% for the pretreatment. If the yield basis were the initial GA-T amount plus the GA-T amount from 100% conversion of 7-O-ethyl GA-O and GA-Mk in the crude extract, the yield, termed adjusted yield for the pretreatment in this work, would still reach 90.8%. Furthermore, the subsequent RP-HPLC purification was considerably enhanced due to the conversion of the analog impurities. This game-changer strategy achieved a daily GA-T throughput of 2.9 g with 95% purity (mass based). Even at the laboratory scale, it is now possible to produce a sufficient amount of GA-T for small-scale pharmacological and clinical evaluations. The approach of converting analog impurities that are otherwise difficult to remove to the product in a bioseparation process may be useful to achieve enhanced recovery of other medicinally useful natural products.

From 2000years of Ganoderma lucidum to recent developments in nutraceuticals

“…More specifically, it was found that using hydrolysis and acetylation, the amount of GA-T (4) can be increased 4-fold by converting the GA-T analogues to GA-T (4) (Wang et al, 2012a).…”

“…Overexpression of 3-hydroxy-3-methylglutaryl CoA reductase, a key enzyme in GA synthesis, has led to a 2-fold increase in total GA produced ). In addition, the level of specific GAs can be increased using additional chemical conversion processes to convert the analogue impurities to the desired compound (Wang et al, 2012a).…”

Preparative isolation of ganoderic acid S, ganoderic acid T and ganoderol B from Ganoderma lucidum mycelia by high‐speed counter‐current chromatography

“…After employing the recycling elution mode of HSCCC, ganoderic acid T and ganoderic acid S could be purified successfully. Although the yield of ganoderic acid T (0.32 g ganoderic acid T was obtained from 100 g dried mycelia) was lower than that reported in the literature (Wang, Gu, & Zhong, ), this might be due to the different strains origin of Ganoderma .…”

Enhanced production of individual ganoderic acids by integrating Vitreoscilla haemoglobin expression and calcium ion induction in liquid static cultures of Ganoderma lingzhi

“…GA‐O, GA‐T, GA‐Me, GA‐S and GA‐Mk were detected as major GA components from G. lingzhi mycelia (Xu et al ., ; Wang et al ., ). The time profiles of GA‐O, GA‐Mk, GA‐T, GA‐S and GA‐Me accumulation in both WT and VHb cultures are shown in Fig.…”