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Bovine skin gelatin was hydrolyzed with sequential protease treatments in the order of Alcalase, Pronase E, and collagenase using a three-step ultrafiltration membrane reactor. The molecular weight distributions of the first, second, and third hydrolysates were 4.8-6.6, 3.4-6.6, and 0.9-1.9 kDa, respectively. The angiotensin I converting enzyme (ACE) inhibitory activity of the third hydrolysate (IC(50) = 0.689 mg/mL) was higher than that of the first and second hydrolysates. Two different peptides showing strong ACE inhibitory activity were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography, ion-exchange chromatography, and reversed-phase high-performance liquid chromatography. The isolated peptides were composed of Gly-Pro-Leu and Gly-Pro-Val and showed IC(50) values of 2.55 and 4.67 microM, respectively.

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Alaska pollack frame protein, which is normally discarded as an industrial byproduct in the processing of fish in plants, was hydrolyzed with pepsin. This was fractionated into five major types of Alaska pollack frame protein hydrolysates (APH-I, 10-30 kDa; APH-II, 5-10 kDa; APH-III, 3-5 kDa; APH-IV, 1-3 kDa; and APH-V, below 1 kDa) using an ultrafiltration membrane bioreactor system. Angiotensin I converting enzyme (ACE) inhibitory activities of the fractionated hydrolysates were investigated, and the fraction that exhibited the highest ACE inhibitory activity was further purified using consecutive chromatographic methods on SP-Sephadex C-25 column, Sephadex G-25 column, and high-performance liquid chromatography (HPLC) on an octadecylsilane column. Finally, we purified a novel ACE inhibitory peptide with an IC50 value of 14.7 microM, and the sequence of the peptide was Phe-Gly-Ala-Ser-Thr-Arg-Gly-Ala. In addition, the ACE inhibition pattern of the peptide was found to be noncompetitive.

BACKGROUND: Diabetes mellitus (DM) is a chronic metabolic disorder characterized by defects in insulin secretion and action, which can lead to damaged blood vessels and nerves. With respect to effective therapeutic approaches to treatment of DM, much effort has being made to investigate potential inhibitors against α-glucosidase and α-amylase from natural products. The edible marine brown alga Ecklonia cava has been reported to possess various interesting bioactivities, which are studied here.

Inhibition of apoptosis leads to activation of cell survival factors (e.g., AKT) causes continuous cell proliferation in cancer. Apoptosis, the major form of cellular suicide, is central to various physiological processes and the maintenance of homeostasis in multicellular organisms. A number of discoveries have clarified the molecular mechanism of apoptosis, thus clarifying the link between apoptosis and cell survival factors, which has a therapeutic outcome. Induction of apoptosis and inhibition of cell survival by anticancer agents has been shown to correlate with tumor response. Cellular damage induces growth arrest and tumor suppression by inducing apoptosis, necrosis and senescence; the mechanism of cell death depends on the magnitude of DNA damage following exposure to various anticancer agents. Apoptosis is mainly regulated by cell survival and proliferating signaling molecules. As a new therapeutic strategy, alternative types of cell death might be exploited to control and eradicate cancer cells. This review discusses the signaling of apoptosis and cell survival, as well as the potential contribution of marine bioactive compounds, suggesting that new therapeutic strategies might follow.