Telomerase Inhibitory Effects of Red Pigment Rubropunctatin and Statin Monacolin L Isolated from Red Yeast Rice.

In addition to the cholesterol-lowering activity of red yeast rice (RYR), its anticancer activities have been frequently reported. However, the mechanism of action of the anticancer activity of RYR is not yet fully understood. The objective of the current study was to elucidate anticancer compositions and anticancer mechanism of actions of RYR. The isolated compounds from RYR were subjected to anti-proliferation assay, apoptosis assay via flow cytometry, and telomerase inhibitory assay via telomeric repeat amplification protocol-PCR (TRAP-PCR) assay, and Western blotting assay in an in vitro cell culture system. The results showed that a statin, monacolin L, and a red pigment, rubropunctatin, from RYR exhibited very strong cancer cell proliferation inhibitory effects; the rubropunctatin was comparable with anticancer drug -platinum, taxol, and 10-hydroxy-camptothecin (HCPT) in their IC values. Monacolin L and rubropunctatin exerted their anticancer activity via telomerase inhibitory effects. Monacolin L and rubropunctatin presented the similar telomerase inhibitory effects as the anticancer drug -platinum, while the anticancer drug HCPT presented a weak telomerase inhibitory effect in the TRAP-PCR assay. Meanwhile, rubropunctatin and -platinum did not present strong apoptosis induction activity as the momacolin L and HCPT did. These results indicate that the RYR may exert anticancer effects through the telomerase inhibitory effect of rubropunctatin and the apoptosis-induction effect of monacolin L.