Potential Photochemopreventive Effect of Fatty Acids and Terpenoid Rich Leaf Extract of Canarium odontophyllum Miq. on UVB-induced Immortalized Human Keratinocytes (HaCaT) Skin Cancer Model.

Abstract

Keratinocyte carcinoma is found in skin areas which are often exposed to the sun and a variety of natural products has been developed as a chemoprevention agent. One example is the Canarium odontophyllum Miq, or “Dabai”, which is an indigenous plant to Borneo, Sarawak. Fatty acids & terpenoid-rich extract from the leaf were obtained via extraction using hexane. FRAP assay showed antioxidant capacity for both 500 & 1000 µg/ml extract but not significantly different between doses. Untreated and treated immortalized human keratinocytes (HaCaT) were irradiated with UVB for 6 passages to a cumulative of 180 mJ/cm2 UVB. Findings showed 1000 ug/ml of TRCO significantly reduced p53 expression compared to the untreated group. Both 500 & 1000 µg/ml of TRCO significantly reduced the expression of Ki67 compared to the untreated group. Antioxidant and oxidative stress markers measurement revealed 500 µg/ml of TRCO significantly increased superoxide dismutase activity compared to the untreated group, both 500 & 1000 µg/ml TRCO significantly reduced catalase, glutathione peroxidase, glutathione S-transferase, and protein carbonyls compared to the untreated group. Reduced glutathione peroxidase activity is potentially due to depletion in glutathione by the UVB and extract. In vitro evaluations of TRCO on UVB-induced HaCaT skin cancer model revealed photochemopreventive properties. These promising findings validate further evaluation of C. odontophyllum Miq leaf extract as a potential therapeutic agent