Cardiovascular diseases and diabetes are the biggest causes of death globally. Therefore, prevention of these diseases is a focus of pharmaceuticals and functional food manufacturers. This review summarizes recent research trends and scientific knowledge in seaweed protein-derived peptides with particular emphasis on production, isolation and potential health impacts in prevention of hypertension, diabetes and oxidative stress. The current status and future prospects of bioactive peptides are also discussed. Bioactive peptides have strong potential for use in therapeutic drug and functional food formulation in health management strategy, especially cardiovascular disease and diabetes. Seaweeds can be used as sustainable protein sources in the production of these peptide-based drugs and functional foods for preventing such diseases. Many studies have reported that peptides showing angiotensin converting enzyme inhibition, antihypertensive, antioxidative and antidiabetics activities, have been successfully isolated from seaweed. However, further research is needed in large-scale production of these peptides, efficient isolation methods, interactions with functional foods and other pharmaceuticals, and their ease to digestion in in vivo studies and safety to validate the health benefits of these peptides.

Fish has been widely used as an excellent source of animal protein and other nutrients. It functions to prevent human beings from variety of diseases all over the world. Through different processing methods, it is possible to achieve the keeping of quality and securing fish availability round the year. This paper reviews up-to-date research on effect of processing methods on nutritional and physico-chemical composition of fish. Additionally, effects of different fish processing methods (such as drying, smoking, freezing, cooking and canning) on chemical, physical and nutritional composition are presented. The most compositional constituents of fish which can be affected through processing methods are proteins, fats, vitamins, minerals and the sensory attributes such as color, flavor, texture and general appearance. Changes of chemical composition resulted from processing methods can mainly be expressed as denaturation, coagulation, reduction of protein digestibility, oxidation and loss of vitamins. Heating protein fish can cause loss of nutritional value through amino acids destruction, protein denaturation and maillard reaction. Smoking is one of the processing methods which has an impact on fish protein denaturation that leads to changes in physical and chemical structure of protein and a reduction in the biological availability of protein. The major physical changes which occur on fish due to processing are changing texture (becomes hard and firm), change in color (the major first judgment detrimental factor) and yields. The extent of these changes depends on the temperature and time of treatment. All these changes (chemical, physical and nutritional) affect the final quality of fish and fishery products.

Inhibition of α-amylase enzyme is one therapeutic approach in lowering glucose level in the blood to manage diabetes mellitus. In this study α-amylase inhibitory peptides were identified from proteolytic enzymes hydrolysates of red seaweed laver ( Porphyra species) using consecutive chromatographic techniques. In the resultant fractions from RP-HPLC (D-), D inhibited α-amylase activity (88.67 ± 1.05%) significantly ( p ≤ 0.5) at 1 mg/mL protein concentration. A mass spectrometry (ESI-Q-TOF- MS) analysis was used to identify peptides from this fraction. Two novel peptides were identified as Gly-Gly-Ser-Lys and Glu-Leu-Ser. To validate their α-amylase inhibitory activity, these peptides were synthesized chemically. The peptides were demonstrated inhibitory activity at IC value: 2.58 ± 0.08 mM (Gly-Gly-Ser-Lys) and 2.62 ± 0.05 mM (Glu-Leu-Ser). The inhibitory kinetics revealed that these peptides exhibited noncompetitive binding mode. Thus, laver can be a potential source of novel ingredients in food and pharmaceuticals in diabetes mellitus management.