A rice bran polyphenol, cycloartenyl ferulate, elicits apoptosis in human colorectal adenocarcinoma SW480 and sensitizes metastatic SW620 cells to TRAIL-induced apoptosis.

High intake of whole grain food has been suggested as an important factor for reducing the risk of colon cancer, owing to the abundance of indigestible fibers. Our findings demonstrated that, among various rice bran phenolic compounds tested, cycloartenyl ferulate (CF) showed the most prominent in vitro growth inhibition on human colorectal adenocarcinoma SW480, but had low toxicity on normal colon CCD-18-Co cells. The anticancer activity of CF was further illustrated by its ability to induce significant regression of SW480 xenograft in nude mice. CF elevated the death receptors DR4 and DR5 and triggered both the death receptor and the mitochondrial apoptosis pathways. Depletion of anti-apoptotic Bcl-2 and up-regulation of pro-apoptotic Bak were observed, accompanied by dissipation of the mitochondrial membrane potential and release of cyto c and SMAC/DIABLO from mitochondria into the cytosol. Bid was found to be cleaved by caspase-8, so that the death receptor pathway might be exaggerated by the mitochondrial pathway. Strikingly, we showed for the first time that CF also sensitized the metastatic and resistant colon cancer SW620 to TRAIL-induced apoptosis and the mechanisms involved at least enhanced activation of caspase-8 and -3. This study provides a clear evidence that the health-beneficial properties of whole grain consumption are not only limited by the presence of dietary fibers but also other molecules that can either act as a chemopreventive agent to directly induce tumor regression or as a sensitizer to enhance TRAIL-induced apoptosis in metastatic cancer cells.

Ethyl acetate extract of Chinese medicinal herb Sarcandra glabra induces growth inhibition on human leukemic HL-60 cells, associated with cell cycle arrest and up-regulation of pro-apoptotic Bax/Bcl-2 ratio.

Sarcandra glabra (Thunb.) Nakai, colloquially known as Caoshanhu, is a Chinese medicinal herb with reported anti-tumor, anti-inflammatory, anti-viral and non-specific immunoenhancing properties. Although the plant has been clinically used for treating a variety of diseases, its bioactive ingredients are largely unknown and its mode of action has never been investigated. In this study, the anti-tumor property of ethyl acetate (EA) extract of S. glabra was investigated by determining its in vitro growth-inhibitory effects on a panel of human cancer cell lines of different histotypes. Growth inhibition of the EA extract on the cancer cells seemed to be selective, and the leukemic HL-60 was found to be the most responsive after 48 h of treatment (IC50=58 microg/ml). Flow cytometric studies further illustrated that the extract might interfere with DNA replication and thus arrested the cell cycle at S phase in the leukemic cells, followed by DNA fragmentation and loss of phospholipid asymmetry in the plasma membrane after 72 h of treatment. Concurrently, the pro-apoptotic Bax/Bcl-2 ratio was also up-regulated by more than 178% of the control level. All these findings suggested that the extract had initiated apoptosis to kill the leukemic cells. Results from this pioneer study help to establish a scientific foundation for future research and development of the bioactive ingredients in EA extract of S. glabra as efficacious anti-cancer agents.

In vitro antiviral activities of Chinese medicinal herbs against duck hepatitis B virus.

Fifty-six different Chinese medicinal herbs from 29 families were evaluated for their antiviral activities against duck hepatitis B virus (DHBV) in vitro. The DHBV DNA level in primary duck hepatocyte cultures was monitored by dot blot hybridization and the cytotoxicity was evaluated by MTT assay. Anti-DHBV activities were found more strongly in the aqueous extracts of Ardisia chinensis and Pithecellobium clypearia with selective indices of 2.6 and >2.7, respectively, which were comparable to that of 2',3'-dideoxycytidine. Further research on the isolation of the active antiviral phytochemicals from these herbs may provide alternative options for the treatment of chronic hepatitis B.