Novel Anticancer Dimeric Napthoquiones from Diospyros lotus Having Anti-Tumor, Anti-Inflammatory and Multidrug Resistance Reversal Potential: In Vitro, In Vivo and In Silico Evidence

Background: Cancer being a genetically heterogenous and complex disease and the available therapies are not very effective, rendering them the predominant cause of mortality across the world. The discovery of new anticancer drugs with higher efficacy and milder side effects is a great challenge for health professionals. Objective: The current study focused on anticancer potential of two known dimeric napthoquiones, diospyrin (1) and 8-hydroxydiospyrin (2) isolated from the roots of Diospyros lotus. Method: In-vitro Epstein-Barr-Virus (EVA) early antigen activation assay was used to evaluate the antitumor potential of test compounds followed by two-stage carcinogenesis assay on mouse skin for anti-carcinogenic effect. Compounds were also assessed for their multidrug resistance reversal potential. The in-vitro heat induced protein denaturation assay was used for the anti-inflammatory effect of the test compounds. Results: Both compounds evoked marked cytotoxic activity with IC50 of 47.40 and 36.91 ppm, respectively. In Epstein-Barr-Virus (EVA) early antigen activation assay compounds 1 and 2 showed IC50 values of 426 ppm and 412 ppm, respectively. The tested compounds showed 60% survival rate of the lymphoblastoid Raji cells at a concentration of 1000 (mol / ratio 32 pmol TPA). In two-stage carcinogenesis assay on mouse skin, both compounds significantly delayed the formation of papillomas on mouse skin. Compound 1 showed 50% effect at 14th weeks, whereas compound 2 exerted the same effect at 13th weeks, while both provoked 100% effect at 20th weeks. Both compounds significantly attenuated thermal induced protein denaturation with EC50 values of 298 and 264 µg/mL, respectively. The dimeric napthoquiones were evaluated for their effects on the reversion of multidrug resistant (MDR) cell lines mediated by P-glycoprotein using rhodamine 123 dye-based exclusion screening test on human mdr1 gene transfected thymic lymphoma L5178 cell line. The compounds 1 and 2 exhibited promising MDR reversal effect in a dose-dependent manner against mouse Tlymphoma cell line. Docking results also showed that both compounds have good docking statistics as compared with standard. Conclusions: Both the compounds demonstrated marked anti-tumor, anti-carcinogenic, and MDR reversal effects with significant attenuation of thermal induced denaturation of protein. These compounds may explain the traditional uses of D. lotus and might be effective anticancer agents.