Antioxidant rich Morus alba leaf extract induces apoptosis in human colon and breast cancer cells by the downregulation of nitric oxide produced by inducible nitric oxide synthase.

Morus species had been used widely in the traditional medicines for various diseases. In this study we report the in vitro antiproliferative activity of the methanol extract of Morus alba. The extract is capable of inducing cytotoxicity in human colon cancer (HCT-15) cells (IC(50) = 13.8 µg/ml) and breast cancer (MCF-7) cells (IC(50) = 9.2 µg/ml), resulted in significant morphological changes of the cells, fragmentation of DNA, and caspase-3 activation- characteristics of apoptosis. It downregulated the amount of nitric oxide (NO) produced as a result of inducible nitric oxide (iNOS) activation. The HPLC analysis of the extract showed epicatechin (20%), myricetin (10%), quercetin hydrate (12%), luteolin (12%), and kaempferol (6%) as the major active components and ascorbic acid, gallic acid, pelargonidine, and p-coumaric acid as the minor components. To the best of our knowledge, this is the first report showing the downregulation of iNOS and induction of apoptosis by M. alba extract.

Purified mulberry leaf lectin (MLL) induces apoptosis and cell cycle arrest in human breast cancer and colon cancer cells.

Medicinal values of mulberry are known to humans from ancient ages. The white mulberry, Morus alba L. is a rich source of many bioactive phytochemicals. Earlier investigations in our laboratory lead to the purification and characterization of an anti-proliferative lectin (MLL) from the leaves of this plant. Further to that, here we have investigated the mechanism of cell death induction by MLL on human breast cancer (MCF-7) and colon cancer (HCT-15) cells. Cells were treated with GI(50) concentration (concentration of lectin required for 50% inhibition of cell growth) of MLL (8.5 µg/ml for MCF-7 and 16 µg/ml for HCT-15) for 24 h to induce cell death. The induction of apoptosis was studied by morphological analysis, DNA fragmentation, apoptotic cell staining and caspase 3 activity assay. Apoptotic cells in sub G0-G1 phase were monitored using flow cytometry. MLL induced significant morphological changes and DNA fragmentation associated with apoptosis in MCF-7 and HCT-15 cells. Positive annexin V and acridine orange/ethidium bromide stained cells indicated apoptosis induction by MLL. Up-regulation of caspase 3 activity was also found in cells treated with MLL. Flow cytometry analysis showed an increase in the percentage of cells in sub G0-G1 phase confirming the MLL induced apoptosis. In conclusion, MLL induced apoptosis in MCF-7 and HCT-15 cells in a caspase dependent manner.

Purification and characterization of a novel anti-proliferative lectin from Morus alba L. leaves.

A novel anti-proliferative lectin was purified from Morus alba L. (Mulberry) leaves by a two step chromatographic procedure namely, immobilized metal ion affinity chromatography (IMAC) and convective interaction media (CIM) based anion exchange chromatography. The purified mulberry leaf lectin (MLL) was specific to galactose, galactosamine and N-acetyl galactosamine (GalNAc). MLL was homogenous with a molecular weight of ~56kDa in silver stained SDS-PAGE. The lectin showed RBC agglutination activity up to 40°C and was independent of pH above pH 6. Haemagglutination activity of purified MLL was not dependent on any metal ions. However, with high concentration of trivalent metal ions, Fe3+ and Al3+ and the divalent metal ion Fe2+, a three fold increase in agglutination activity was observed. The purified MLL showed an anti-proliferative activity towards human breast cancer cells (MCF-7) and colon cancer cells (HCT-15) with a higher potency towards MCF-7 cells. This is the first report on the anti-proliferative activity of a GalNAc specific lectin from M. alba.