Proteins and peptides are the most diverse biomolecules found in nature and make our interest due to their wide applications in food and pharmaceutical industry. Angiotensin Converting Enzyme (ACE) plays a major role in controlling blood pressure. The inhibition of ACE with peptides is a main target in the regulation of hypertension. The objective of the present study was to investigate the therapeutic potential of soy bean. This was accomplished by isolation of ACE inhibitory peptides using response surface methodology (RSM) and characterization of these bioactive peptides by mass spectrometry. 31 hydrolyzed fractions were isolated and evaluated for their ACE inhibition potential. Hydrolyzed fraction having highest ACE inhibitory activity was characterized by liquid chromatography-mass spectrometry (LC-MS) technique. RSM results showed maximum ACE inhibition potential (64%) by hydrolyzate was obtained at 45 ºC temperature, pH 8.0, E/S 0.2 in 2 hours hydrolysis time. Results of LC-MS analysis revealed Ser-Gly, Ser-Pro, Met-Ala, His-Ala, Lys-Pro, Phe-Thr, Met-Leu, Pro-Arg, Ala-Pro-Val, Pro-Ala-Leu, Val-Met-Gly, Pro-Leu-Val, Pro-Pro-Gln, His-Arg-Gly, Ser-Phe-Val-Leu, Ala-Val-His-Try, Arg-Thr-Val-Arg, His-His-Tyr-Leu-Val, Asp-Gly-Ala-Cys-Ser-Ala-Asn and MetVal-Thr-Gly-Pro-Gly-Cys-His bioactive peptides in hydrolyzed fraction of soy bean. Our data provide evidence that response surface methodology is a good approach for isolation of antihypertensive bioactive peptides with more potent activity as nutraceuticals or pharmaceuticals. Therefore soy bean can be use for industrial production of pharmaceutical grade natural medicines for handling high blood pressure.

Major objective of this study was to appraise the variation of antioxidant activity, total phenols, total flavonoids and individual phenolic acids among fruit peels from five species of Citrus namely C. sinensis 'Valancia' (Mausami), C. sinensis 'Maltaise Sanguine' (Red blood), C. reticulata (Kinnow), C. reticulata Blanco 'Merisol' (Fruiter), and C. paradisi 'Macfadyen' (Grapefruit) as function of extraction solvents. The extract yield from the fruit peels of the selected Citrus species by using four solvents varied significantly (p<0.05) 17.56-49.13 g/100g in relation to the extraction media and type of peel. The highest extraction yield was obtained with 100% methanol from Red blood (C. sinensis 'Maltaise Sanguine') peel while the least with 100% ethanol from Fruiter (C. reticulata Blanco 'Merisol') peel. The total phenolic contents (TPC), total flavonoid contents (TFC), DPPH radical scavenging activity (IC50) and reducing power [FRAP (EC50)] for peel extracts ranged from 13.69 to 66.10 GAE mg/g of dry weight (DW), 9.34 to 28.99 CE mg/g DW, 0.33 to 2.32 mg/mL and 2.05 to 6.76 mg/mL, respectively. According to HPLC analysis of peel extracts, gallic acid and protocatechuic acid with contribution 11.96-96.08 and 109.18-578.59mg/kg of extract, respectively, were detected to be the main phenolic acids among others. Total amount of individual phenolic acids (TPAs) in the tested peels varied over 18.37 to 1015.99 mg/kg of extract. The highest amount of TPAs was extracted in Red blood (C. sinensis 'Maltaise Sanguine') with 80% methanol while the least in Grapefruit (C. paradisi 'Macfadyen') with 100% methanol. It can be concluded from the present data that both the species and extraction solvents have notable effect on the antioxidant attributes and phenolics of citrus peels. Overall, the results of this study showed that extracts from peel of Red blood (C. sinensis 'Maltaise Sanguine'), among others, possessed superior antioxidant activity and greater amount of phenolic acids.

Aqueous and acidified methanol extracts from C. limonum fruit residues (CLFR) were evaluated for their total phenolic contents, antioxidant and antimutagenic activities. Total phenolic contents (TPC) of aqueous (30% and 70%) and acidified (0.5 N and 1.0 N) methanol extracts from CLFR were estimated by Folin-Ciocalteu reagent method whereas in-vitro antioxidant activity was assessed calorimetrically by measuring DPPH* scavenging capacity and inhibition of linoleic acid peroxidation. Anti-mutagenic potential of the extracts was appraised by Ames bacterial reverse mutation test. TPC, DPPH° scavenging capacity and inhibition of linoleic acid peroxidation were varied from 27.75-126.35 mg gallic acid equivalent (GAE)/g DW, 46-91%, and 34-83%, respectively. All the tested extracts of CLFR noticeably hunted mutagens (16.47-55.69 %) whereas none of these caused mutagenesis. Overall, acidified methanol extracts from CLFR exhibited higher extraction yields, TPC, inhibition of peroxidation and DPPH radical scavenging activity among others indicating a significant (p<0.05) variation of these attributes in relation to residue samples and extraction media. The results support that CLFR (peel and pulp biomass) being a rich source of phenolic antimutagens, can be explored as a potential candidate for the development of natural chemo-preventive drugs and nutracueticals.