A Natural Quinazoline Derivative from Marine Sponge Hyrtios erectus Induces Apoptosis of Breast Cancer Cells via ROS Production and Intrinsic or Extrinsic Apoptosis Pathways.

Here, we report the therapeutic potential of a natural quinazoline derivative (2-chloro-6-phenyl-8H-quinazolino[4,3-b]quinazolin-8-one) isolated from marine sponge Hyrtios erectus against human breast cancer. The cytotoxicity of the compound was investigated on a human breast carcinoma cell line (MCF-7). Antiproliferative activity of the compound was estimated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. MTT assay showed significant inhibition of MCF-7 cells viability with the IC50 value of 13.04 ± 1.03 µg/mL after 48 h. The compound induced down-regulation of anti-apoptotic Bcl-2 protein and increase in the pro-apoptotic Bax/Bcl-2 ratio in MCF-7 cells. The compound activated the expression of Caspases-9 and stimulated downstream signal transducer Caspase-7. In addition, Caspase-8 showed remarkable up-regulation in MCF-7 cells treated with the compound. Moreover, the compound was found to promote oxidative stress in MCF-7 cells that led to cell death. In conclusion, the compound could induce apoptosis of breast carcinoma cells via a mechanism that involves ROS production and either extrinsic or intrinsic apoptosis pathways. The systemic toxic potential of the compound was evaluated in an in vivo mouse model, and it was found non-toxic to the major organs.

Effect of Sodium Hypochlorite on Biofilm-Forming Ability of Histamine-Producing Bacteria Isolated from Fish.

Histamine poisoning occurs when temperature-abused marine fish containing elevated levels of histamine are consumed. Histamine-producing bacteria found in fish can colonize processing surfaces and form biofilms. In this study, the biofilm-forming abilities of histamine-producing bacteria from Indian mackerel (Rastrelliger kanagurta) and the effect of hypochlorite treatment on biofilm formation were studied. The isolates of this study produced histamine in the range of 471 to 2,126 ppm. The histidine decarboxylase gene hdc was detected in all isolates producing histamine except in one strain each of Psychrobacter pulmonis and Proteus vulgaris. All isolates tested in this study produced moderate biofilms under control conditions, whereas exposure to 1 and 3 ppm of sodium hypochlorite significantly enhanced biofilm formation. However, exposure to 5 ppm of sodium hypochlorite showed an inhibitory effect on biofilm formation by all the isolates except Klebsiella variicola. The results of this study suggest that histamine-producing bacteria can form stable biofilms and that this activity may be enhanced by the application of low levels of sodium hypochlorite, a phenomenon that might influence the persistence of histamine-producing bacteria in fish processing areas.