Design and Synthesis of C-8 spiro-isoxazoline analogues of 14-Deoxy-11,12-didehydroandrographolide (14-DDA) for dual targeting of CDK4 and BCL2 mediated anticancer activity

14-Deoxy-11,12-didehydroandrographolide (14-DDA, 3), a secondary metabolite found in Andrographis paniculata nees, has been synthetically modified into a new series of C-8 spiro-isoxazoline derivatives. Andrographolide and its derivatives were well reported for the anticancer activity so herein we have synthesised C-8 spiro-isoxazoline derivatives (4a-l) and screened for in vitro studies against four human cancer cell lines: breast (MCF-7), lung (A549), pancreatic (MiaPaCa-2), and prostate (PC-3). Most of the synthesized compounds exhibited better anti-cancer activities than the parent natural products andrographolide (1) and 14-deoxy-11,12-didehydroandrographolide (3) for different human cancer lines. Among all compounds, compound 4k displayed most potent cytotoxicity (IC₅₀ =3 μM) in breast cancer cells (MCF-7). Further, mechanistic studies revealed that compound 4k affected the nuclear morphology of MCF-7 cells, increased the production of cellular and mitochondrial ROS, decreased the mitochondrial membrane potential (MMP), and inhibited the colony formation. The compound 4k also induced apoptosis in MCF-7 by attenuating the BCl2 expression in a dose dependent manner. The expression of Cdk-4 was also downregulated by 4k. The overall findings of this study indicate that the compound 4k exhibited significant anticancer activity with reduced toxicity in-vitro and might thus be a promising anti-cancer lead candidate.