Abstract Andrographolide, a diterpene lactone from Andrographis paniculata, is a promising anticancer lead due to its versatile scaffold. Its hydroxy groups (C-3, C-14, C-19), α-alkylidene-γ-butyrolactone, and reactive C12–C13 and C-17 double bonds allow diverse semisynthetic modifications. Structure–activity relationship studies identify C-19 as a key potency-enhancing site, where bulky and lipophilic substituents, particularly silicon-containing groups that markedly improve cytotoxicity. In addition, C-14 modification primarily influences selectivity to provide the α-alkylidene-γ-butyrolactone and 8,17-epoxide moieties remain intact. Functionalization at C12–C13 further expands anticancer activity, while retention of the 8,17-epoxide is essential for maximal cytotoxicity and targeting of human DNA topoisomerase IIα. These findings highlight critical pharmacological hotspots and support rational multi-site design of next-generation andrographolide-based anticancer agents.
Silalai et al. (Tue,) studied this question.