Hyperkouytones A—O, New Polyprenylated Acylphloroglucinols from Hypericum kouytchense with Multidrug Resistance Reversal Activity

Given the lack of systematic polyprenylated acylphloroglucinols (PPAPs) research on traditional Chinese medicine of Hypericum kouytchense, this plant was applied for the phytochemical study, which led to fifteen new PPAPs (1—15, PPAPs), along with 36 known PPAP derivatives. Their structures and absolute configurations were established by comprehensive spectral analysis and theoretical ECD and NMR calculations. Structurally, compound 1 possesses a rare fused 6/6/6/5/5 pentacyclic ring system. Eleven compounds exhibited good multidrug resistance reversal activity (RF ranging from 5 to 53) in HepG2/ADR cells. Importantly, compound 34, the most potential MDR modulator, showed better reversal effect (RF: 53) than positive control, verapamil. The primary mechanistic study of compound 34, implied that this compound could prohibit the function of P-gp transport rather than its expression. The possible recognition mechanism between compound 34 and P-gp was predicted by molecular docking.