α-Amylase Inhibitor Peptides Derived from Goat Casein Tryptic Hydrolysate

Antioxidative activity and functional properties of protein hydrolysate of yellow stripe trevally ( Selaroides leptolepis) as influenced by the degree of hydrolysis and enzyme type

Poly(vinyl alcohol) (PVOH) is widely used in various industrial applications. However, its water solubility reduces film performance, which is important in PVAc-based wood adhesives. In this sector, AlCl3 is often used as a complexing agent for PVOH. In this work, the effect of heating and aluminium addition on the structure and viscoelastic properties of PVOH with different degrees of hydrolysis (DH), 88%, 92% and 99%, was studied. Products treated with either HCl or acetic acid were also considered. The polymer properties were evaluated by infrared spectroscopy and dynamic mechanical analysis, and the mass loss of the polymers on heating was also evaluated to explain the observed differences. The measurements showed that the peaks of the tanδ curves occurred at slightly lower temperatures as the DH increased, although higher crystallinity was observed at the end of the DMA tests for higher DHs. This is due to the increasing affinity of highly hydrolysed PVOH for water molecules. However, as the temperature increased, the storage modulus was higher for higher DHs due to the better mutual interaction of OH groups that develops during the tests in highly hydrolysed polymers. The addition of aluminium caused a slight increase in Tg, the magnitude of which was inversely proportional to the DH. However, as the temperature increased, the storage modulus decreased more at lower DHs than at higher DHs. This effect was related to a combination of factors: the lower presence of crystallites in products with lower DH and the formation of conjugated polyenes, which was also more pronounced in products with lower DH. Both mechanisms were due to the action of aluminium. Thus, both heat and the addition of aluminium had a determining effect on the properties of PVOH films, although the degree of importance depended on the degree of hydrolysis of the polymer.

O objetivo deste trabalho foi produzir filmes biodegradáveis à base de álcool polivinílico (PVA) e, também avaliar o efeito dos diferentes graus de hidrólise (DH) e graus de polimerização (DP) do PVA nas propriedades desses filmes. Quatro tipos diferentes de PVA com DH variando de 88,0 a 98,4% e DP variando de 150 a 2000 foram utilizados para produzir os filmes por casting, e o glicerol foi usado como plastificante. Os filmes formulados com PVA com menor DH (SelvolTM 540 e 203) apresentaram maior solubilidade, permeabilidade ao vapor de água e capacidade de absorção de água, além de serem menos rígidos e apresentarem menores temperaturas de transição vítrea e de fusão quando comparados aos filmes obtidos com PVA com maior DH (SelvolTM 325 e 107). O DP afetou a solubilidade dos filmes, o filme produzido com PVA com maior DP (SelvolTM 325 - DP = 1000????1500) apresentou menor valor de solubilidade. Os filmes formulados com PVA com maior DP (SelvolTM 540 e 325) apresentaram maiores valores de elongação na ruptura. Tanto o DH quanto o DP afetaram as propriedades dos filmes de PVA, resultando em materiais com diferentes possibilidades de aplicação, no entanto, observou-se que o efeito do DH foi mais importante para as propriedades dos filmes de PVA do que o efeito DP.

Influence of different degrees of hydrolysis of poly(vinyl alcohol) membrane on transport properties in pervaporation of IPA/water mixture

ABSTRACTThe functional and in vitro antioxidant properties of common kilka fish protein hydrolysates with different degree of hydrolysis (DH) obtained by kiwifruit protease (KP) and ginger protease (GP) were evaluated. The electrophoretic patterns of hydrolysates showed the presence of one major band in different DHs with a molecular weight of less than 25 kDa. Protein solubility was positively correlated with DH, and the solubility of KP and GP hydrolysates (HKP and HGP, respectively) at 15% DH was higher than other DHs (p ≤ 0.05). Higher emulsifying and foaming properties were observed in HKP over a pH range of 2–10 (p ≤ 0.05), and in vitro antioxidant activity was higher in HKP at 15% DH as seen from 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric-reducing power. Thus, the results reveal that DH and enzyme type affects functional properties and antioxidant activity of the hydrolysates.

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe

The aim of this work was to hydrolyze kidney bean (Phaseolus vulgaris L.) protein isolate (KBPI) using pepsin (P7000) to obtain kidney bean protein hydrolysates (KBPH) with different degrees of hydrolysis (DH). Antioxidant and antibacterial activities of KBPH against selected pathogenic and spoilage bacteria were evaluated. In addition, applying KBPH as a potential preservative in minced beef during cold storage was studied. The extent of protein degradation by pepsin was determined by measuring DH and SDS-PAGE. KBPH obtained after 6 h of hydrolysis had the highest DH (33.7%), while KBPH obtained after 1, 2, 3, 4 and 5 h had DH values of 11.6, 15, 20.7, 25.6, and 30, respectively. The highest antiradical activity of KBPH (85% for DPPH· and 80% for ABTS+ assay) was recorded after 6 h of hydrolysis. The hydrolyzate with the highest antibacterial activity (DH = 33.7%) was selected for the antibacterial evaluation in situ and in vitro. The antibacterial activity of KBPH (100 mg/mL) with a different degree of hydrolysis on bacterial growth was evaluated using the disc-diffusion method. KBPH reduced the growth of gram-positive bacteria by 70–75% and the bacterial growth of gram-negative bacteria by about 78–80%. Total viable, psychrotrophic bacterial and coliform bacterial counts were determined in beef samples enriched with KBPH (100 and 200 µg/g) during storage at 4 °C for 15 days. Samples supplemented with 200 µg/g KBPH kept the level of the total viable count at 5.7 and 6.55 log after 12 and 15 days of storage, which increased the secured storage time to be 14 or 15 days instead of 7 or 8 days in the case of the control sample. The results could be useful to formulate functional peptides from KBPI that could be applied in novel foods and nutraceuticals.

Diabetes mellitus is a growing global health concern, and α-amylase inhibitors have been recognized as promising therapeutic agents for its treatment. This study aimed to design, synthesize and evaluate 1,3,4-oxadiazole derivatives as potential α-amylase inhibitors. A series of 1,3,4-oxadiazole derivatives were designed and subjected to in silico ADMET, Lipinski's Rule of Five, and drug-likeness analysis. The most promising compounds, SC2 and SC8, were synthesized and their α-amylase inhibitory activity was assessed in vitro. The interactions with the human α-amylase (PDB ID: 6Z8L) which is a target protein, was analyzed through molecular docking studies. The designed compounds complied with Lipinski's Rule of Five and exhibited favourable drug-likeness properties. In silico ADMET analysis predicted good absorption and distribution profiles. SC2 and SC8 demonstrated potent α-amylase inhibitory activity with IC50 values of 36.5±1.5 µg/mL and 45.2±2.1 µg/mL, respectively, compared to acarbose (68.9±3.2 µg/mL). Molecular docking revealed that both compounds formed crucial interactions with key amino acid residues in the enzyme’s active site. The binding affinities of SC2 and SC8 were -10.1 kcal/mol and -9.1 kcal/mol, respectively. The 1,3,4-oxadiazole derivatives, particularly SC2 and SC8, demonstrated potential as α-amylase inhibitors with favorable ADMET properties. These findings provide a basis for further optimization and development of these compounds as novel antidiabetic agents.

Functional properties, antioxidant, and angiotensin-I converting enzyme (ACE) inhibitory activities of egg white protein hydrolysate (EWPH) prepared with trypsin at different degree of hydrolysis (DH) were investigated. The DPPH radical scavenging activity, reducing power, lipid peroxidation inhibitory activity, and ACE inhibitory activity increased with DH at first and then decreased gradually. Hydrolysates with 12.4% DH had the highest antioxidant and ACE inhibitory activities. As DH increased, the solubility of EWPH increased while the emulsifying and foaming properties decreased. The functional properties of EWPH were also controlled by pH. Ultrafiltration of the hydrolysate with 12.4% DH revealed that the fractions of molecular weight lower than 3 kDa exhibited the highest antioxidant and ACE inhibitory activities. The results indicated that EWPH with different DH have different bioactive and functional properties and EWPH by controlled hydrolysis may be useful ingredients in food and nutraceutical applications with potential bioactive properties.

Characterization of structural and functional properties of fish protein hydrolysates from surimi processing by-products

Protein hydrolysates (PH) from splendid squid fins (Loligo formosana) (SFPH) with different degrees of hydrolysis (DH) (10-40%) were prepared using alcalase and characterized. The yield of SFPH was increased with increasing DH (p<0.05). All SFPHs showed high protein content but low fat and ash contents. The lightness of SFPH was reduced with augmenting DH as advocated by increasing redness and yellowness (p<0.05). All SFPH samples having DH above 10% exhibited relative solubility higher than 90% (p<0.05). Foaming properties of SFPH were also improved with increasing DH. In general, antioxidant activities upsurged with increasing DH, except metal chelating activity and DPPH radical scavenging activity, which were decreased at higher DHs. Molecular weight (MW) of peptides was lowered with increasing DH as measured by size exclusion chromatography and SFPH having DH 40% (SFPH-40) possessed a higher proportion of peptides with smaller MW. SFPH-40 was rich in aspartic acid/asparagine and glutamic acid/glutamine. SFPH-40 had bitterness, especially at high concentrations. SFPH-40 contained a high number of volatile compounds associated with squid flavor. Thus, hydrolysates from squid fin could serve as an alternative nutrient with flavoring characteristics and antioxidant properties for food applications.

Background: Diabetes mellitus is the most occurring non-communicable disease resulting in a high blood glucose level. There has been an immense interest in the development of alternative medicines for diabetes treatment, specifically screening functional foods for phytochemicals with the capability of delaying or preventing glucose absorption through digestive enzymes (e.g. α-amylase) inhibition. So, the development of α-amylase inhibitors derived from natural food products is an alternative way to prevent diabetes mellitus. Objective: In this study, organic solvent extracts of the Arachis hypogaea (Peanut) and Cinnamomum tamala (Indian bay leaf/Tejpata) were used to investigate their potential α-amylase inhibition and cytotoxic activities through α-amylase inhibition assay and brine shrimp lethality bioassay respectively. Methods: The α-amylase inhibition assay was performed using the 3,5-dinitrosalicylic acid method for different concentrations of plant extracts. The optical density (OD) of the solutions were measured to determine the inhibition activity at 540 nm using a spectrophotometer. The cytotoxicity of the plant extracts was measured using brine shrimp (Artemia salina) lethality bioassay. Results: Among the different organic solvent extracts, peanut seed ethanol extract showed the highest α-amylase inhibition activity (67.68±8.67%) at 1.25 μg/mL concentration with an IC50 value of 0.61 μg/mL which is very close to standard α-amylase inhibitor Acarbose (72.34±4.23%) with an IC50 value of 0.32 μg/mL while acetone extract of Indian bay leaf exhibited the lowest inhibition activity (47.75±1.63%) with an IC50 value of 1.42 μg/mL at the same concentration. Besides, the maximum cytotoxic activity was found in acetone extract of peanut shell with an LC50 value of 57.87 μg/mL, whereas ethanol extract of peanut seed showed the lowest cytotoxicity with an LC50 value of 413.90 μg/mL. Conclusion: The result of the present work clearly indicates the potentiality of peanut seed ethanol extract to be used in the management of hyperglycemia as it significantly inhibits α-amylase activity while showing less cytotoxic activities.

An effective polyvinyl alcohol for the solubilization of poorly water-soluble drugs in solid dispersion formulations

The aqueous‐phase size exclusion chromatography (SEC) represents a suitable method for the analysis of molecular weight distribution (MWD) of polyvinylalcohols (PVOHs) of different degree of hydrolysis ranging from 72 to 98 mol‐% applying the Suprema columns. Eluents of different composition were used consisting of either a mixture of water and acetonitrile for the lower degrees of hydrolysis (72 ‐ 88 mol‐%) or 0.1 M LiNO3 solution for the higher degrees of hydrolysis (88 ‐ 98 mol‐%). By knowing the M̄w̄ values of commercially available PVOHs samples of a given degree of hydrolysis and using the commercial water soluble narrow distribution standards, a principle of the constant hydrodynamic equivalence ratios was applied to obtain the absolute values of the molecular weights of PVOHs of different degree of hydrolysis. The effect of a various number of extrusion cycles on MWD of different PVOHs was used to demonstrate the sensitivity of the selected SEC conditions.

Enzymatic hydrolysis of sodium caseinate (NaCas) may lead to the development of bitterness. Careful selection of hydrolysis conditions (i.e. enzyme preparation and duration) yielding different degrees of hydrolysis (DH) may aid in the development of low bitterness. Eighteen NaCas hydrolysates were generated with four enzyme preparations (Alcalase 2.4L, Prolyve 1000, FlavorPro Whey and pepsin) to different DH values. Hydrolysate bitterness score, assessed using a trained panel (ten assessors), generally increased at higher DH values for Alcalase, Prolyve and pepsin hydrolysates. However, all FlavorPro Whey hydrolysates (DH 0.38-10.62%) displayed low bitterness score values (<26.0%) comparable to that of intact NaCas (13.8 ± 2.0%, P > 0.05). Enzyme preparation and DH affect the bitterness of NaCas hydrolysates. The results are relevant for the generation of NaCas hydrolysates with reduced bitterness. © 2017 Society of Chemical Industry.