Rice Husk Derived Activated Carbon-Catalyzed Synthesis of Coumarin Derivatives: Study of Anti-Cancer Activity

Herein, we report the fabrication of biomass rice husk-derived chemically activated carbon (RCAC) sheets which are self-assembled to 2D hollow porous materials and demonstrated their catalytic efficiency in the domino Knoevenagel-Michael addition reaction for the synthesis of various bio-active coumarin derivatives in excellent yields under metal-free conditions mild reaction conditions. Particularly, we have illustrated a facile, eco-friendly, economical, and sustainable method for the synthesis of bis-(4-hydroxycoumarin)methanes, bis-dimedones, and 4-hydroxy-3-thiomethylcoumarins, via three-component reactions of 4-hydroxy coumarin/demedone, aldehydes and or thiophenols. Moreover, the Michael addition of 4-hydroxy coumarin and chalcone derivatives leading to the synthesis of warfarin derivatives has also been demonstrated using RCAC as a catalyst. The cytotoxicity potential has been performed against human liver cancer cell line Hep-G2 cancer cells for all the synthesized products by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The cytotoxicity study against Hep-G2 results indicates that all compounds are capable of killing the liver cancer cell line. The most potent anti-proliferative activity was observed in compounds 3 g, 5 b, 5 c, 5 a, and 9 b against liver cancer cells. Synthesis of 4-hydroxy-3-thiomethylcoumarins, bis-(4-hydroxycoumarin)methanes, bis-dimedones, and warfarins via domino Knoevenagel-Michael addition has been demonstrated using rice husk derived chemically activated carbon as mild catalyst. The anti-proliferative activity of few synthesized molecules was studied against Hep-G2 cells. image