Anti-Human Papillomavirus (HPV) 16 E6 Activity of Ling Zhi or Reishi Medicinal Mushroom, Ganoderma lucidum (W. Curt.: Fr.) P. Karst. (Aphyllophoromycetideae) Extracts

Cancer of the cervix ranks second in the demographics of cancers affecting women worldwide. Human papillomavirus (HPV) type 16 is one of the major causative agents for cervical cancer. The E6 region of the HPV 16 genome encodes for an oncoprotein responsible for the pathogenesis of the disease. The E6 oncoprotein is abundant in cervical cancer and cervical cancer-derived cell lines. Mushrooms of the genus Ganoderma have long been used traditionally as an immunomodulating and antitumor agent, with recent studies validating its use in chemotherapeutics. Due to the importance of the E6 oncoprotein in the carcinogenesis of cervical cancer, this study was undertaken to screen the crude dichloromethane, ethanol, water, and polysaccharide extracts of Ganoderma lucidum for the ability to suppress the expression of HPV 16 E6 and to evaluate secondary metabolite classes present in the active crude extract. CaSki cells were treated with the crude extracts and were then subjected to immunocytochemistry protocols. All crude extracts of G. lucidum presented HPV 16 E6 suppression, with the dichloromethane extract being the most active compared to the other crude extracts. The crude dichloromethane extract was then subjected to thin-layer chromatography to evaluate the secondary metabolite classes present. The present study shows that the crude dichloromethane extract of G. lucidum possesses flavonoids, terpenoids, phenolics, and alkaloids. Further isolation work on the dichloromethane extract of G. lucidum could direct us to lead compounds with promising anti-HPV 16 E6 activity.