High-resolution bioguided screening of Ganoderma capense for P-GP modulating activity

Abstract

Ganoderma lucidum (Polyporaceae) is commonly used as a panacea e.g. in Traditional Chinese Medicine. Abundant research has shown its activity on several targets related to cancer, but no work assessed its modulating activity on P-gp transporter. We extracted metabolites from a clearly defined cultivated strain using petroleum ether, dichloromethane, acetonitrile, methanol and water. Water fraction was added ethanol to precipitate polysaccharides and separate them from supernatant. The 6 resulting fractions have been tested using three different cellular uptake-efflux tests (calceine, rhodamine and 3H- digoxine) in a 96-well format, using rat brain endothelium cells expressing P-gp exclusively. A systematic approach using multiple controls allowed us to record unequivocal data and gave evidence for the special procedure requirements for testing P-gp modulating activity of natural extracts. Triterpenes from the active dichloromethane fraction were isolated using a semi-preparative column and LC-MS monitoring. Compounds were tested at normalized doses, based on peaks areas detected by ELSD detection. Data are presented along with a literature review on P-gp modulating activity of plant triterpenes. Results give a rationale for the use of Ganoderma lucidum in the treatment of cancer and indicate potential pharmacokinetic interaction or potentiation of Ganoderma lucidum with other drug treatments.