Isothymusin, a Potential Inhibitor of Cancer Cell Proliferation: An In Silico and In Vitro Investigation

Background: Since centuries plant-based compounds are known for the treatment of cancer in both traditional and contemporary medicine. The problems like target non-specificity and toxicity are well-known regarding anticancer drugs. Therefore, target specific search of novel entities is constant. Isothymusin is a dimethoxy, trihydroxy flavone present in plants like Ocimum sanctum, and Limnophilla geoffrayi. There are limited reports available on the anticancer potential of isothymusin. Objectives: The effects of isothymusin on redox status, cell cytotoxicity, and targets involved in the promotion and progression of the cancer cells have been investigated. Methods: Antiproliferative efficacy was evaluated by MTT, Neutral Red Uptake, and Sulforhodamine-B assays. The spectrophotometric methods were adopted to study the effect against selected targets. Redox activity was assessed by in vitro antioxidant assays and the interaction study, ADMET profiling, and toxicity assessments were done in silico. Results: Isothymusin scavenges the radicals, i.e., DPPH and nitric oxide with moderate ferric reducing potential. It affected the proliferation of leukemia, colon, skin, and breast cancer cell lines by more than 50% but moderately affected prostate, kidney, lung, hepatic, and breast adenocarcinoma (up to 48%). Isothymusin inhibited the enzymes associated with the promotion stage of cancer, including cycloxygenase- 2 and lipoxygenase-5. Additionally, it also inhibited the activity of proliferation markers like cathepsin- D, dihydrofolate reductase, hyaluronidase, and ornithine-decarboxylase. Besides, in silico studies supported the in vitro enzyme inhibition assays outcome. Toxicity studies showed promising results of chemical descriptors and non-skin-irritant, moderate ocular-irritancy, and in vitro Ames test confirmed non-mutagenic nature. Conclusion: Isothymusin showed radical scavenging and anti-proliferative activities, which may be taken up as a phytochemical lead for the synthesis of analogues possessing enhanced anticancer potential.