Antioxidant and antihypertensive effects of garlic protein and its hydrolysates and the related mechanism.

Garlic protein (GP) was enzymatically hydrolyzed using pepsin and trypsin followed by the evaluation of antioxidant and angiotensin-converting enzyme (ACE) inhibitory activities of GP and its hydrolysates. The antihypertensive effects of GP and its hydrolysates were determined in vivo. The results showed that GP and its hydrolysates namely GPH-P (pepsin) and GPH-T (trypsin) possessed appreciable antioxidant and ACE inhibitory activities. The ACE inhibitory activity of GP, GPH-T, and GPH-P was in consistent with their antioxidant activities. GP and its hydrolysates offered significant protective effects against H2 O2 -induced oxidative damage (p < .05). In addition, the administration of GP, GPH-T, and GPH-P reduced the blood pressure in hypertensive rats. The mechanism might be to reduce blood pressure by inhibiting the activity of ACE, reducing the formation of ACEII, and protecting the activity of bradykinin. This study suggested that GP might be utilized as a promising functional food as antioxidant and antihypertensive agents. PRACTICAL APPLICATIONS: Garlic (Allium sativum L.) is one of the oldest cultivated plants that belongs to the Liliaceae family and it has been used in cooking and medicinal applications. Large quantities of garlic residuals were produced with the development of the garlic essential oil industry. These residuals are highly rich in proteins and they can be used for the preparation of protein hydrolysates. Generally, hydrolysates are considered as a promising food supplement due to the enrichment of amino acids present in it. In this study, garlic proteins (GPs) and its hydrolysates retain effective antioxidant effects. They were found to reduce  the blood pressure and prevent oxidative stress induced by H2 O2 . The information from this study could be used to develop a new nutritional supplement from GP and its hydrolysates to treat hypertension as well as prevent oxidative damage.

Identification and antimicrobial activity evaluation of three peptides from laba garlic and the related mechanism.

Laba garlic is a traditional Chinese processed garlic (Allium sativum L.) with multiple health benefits. This study was aimed at isolating and identifying three antimicrobial peptide fractions from laba garlic using Sephadex chromatography, pre-HPLC and LC-MS/MS and investigating the potential antimicrobial mechanism. The sequences of the three peptides were demonstrated to be Tyr-Asn-His-Asn-Phe (YNHNF, F3-3-a), Trp-Pro-Thr-Ser-Phe-Thr (WPTSFT, F3-3-b) and Ala-Val-Asp-Arg-Ala-Val (AVDRAV, F3-3-c), respectively. F3-3-c showed the strongest anti-microbial effects among these three fractions and it could inhibit the mycelial growth of E. coli and S. aureus in vitro with a minimum inhibitory concentration (MIC) of 100 µM and exhibited negligible hemolytic activity. F3-3-c showed amphipathic properties with the presence of α-helix (25.8 ± 0.56%), ß-strands (19.7 ± 0.45%), turns (21.2 ± 0.78%) and unordered conformation (33.3 ± 1.09%). Treatment of F3-3-c resulted in a change in the morphology of the hyphae and the disruption of membrane integrity as shown by SEM and TEM analyses. These results suggested that the laba garlic peptide F3-3-c might be a promising candidate for antibiotics and related functional foods.

Effects of N-trans-feruloyltyramine isolated from laba garlic on antioxidant, cytotoxic activities and H2O2-induced oxidative damage in HepG2 and L02 cells.

Laba garlic is a kind of processed garlic products, it is the traditional Chinese food with a long history. In this study, the antitumor, antioxidant and cytotoxic properties of the blue pigment (BP) from Laba garlic were investigated. N-trans-feruloyltyramine (FLA) was isolated and identified from BP. The protective effects of FLA against H2O2-induced oxidative damages in L02 cells were also assessed. The apoptotic effects of FLA were detected by using flow cytometry analysis. Results showed that the tumor growth was significantly suppressed by BP (P<0.05). BP and FLA exhibited remarkable antioxidant activities. L02 cells pretreatment with FLA could significantly fight against the oxidative damage induced by H2O2, inhibit the morphological changes of mitochondria and maintain the integrity of mitochondria. FLA showed proliferation inhibition on HepG2 cells with IC50 value of 194 ±â€¯0.894 µM. After treatment of FLA (320 µM), the results of MTT assay on HepG2 and L02 cells indicated that FLA had selective cytotoxic effects. It suggested a new way of prevention and treatment of tumors and FLA might be a promising candidate in cancer therapy and functional foods.

Improvement of the alkali stability of Penicillium cyclopium lipase by error-prone PCR

BACKGROUND: Lipases are extensively exploited in lots of industrial fields; cold-adapted lipases with alkali-resistance are especially desired in detergent industry. Penicillium cyclopium lipase I (PCL) might be suitable for applications of detergent industry due to its high catalytic efficiency at low temperature and relatively good alkali stability. In this study, to better meet the requirements, the alkali stability of PCL was further improved via directed evolution with error-prone PCR. RESULTS: The mutant PCL (N157F) with an improved alkali stability was selected based on a high-throughput activity assay. After incubating at pH 11.0 for 120 min, N157F retained 70% of its initial activity, which was 23% higher than that of wild type PCL. Combined with the three-dimensional structure analysis, N157F exhibited an improved alkali stability under the high pH condition due to the interactions of hydrophilicity and ß-strand propensity. Conclusions: This work provided the theoretical foundation and preliminary data for improving alkali stability of PCL to meet the industrial requirements, which is also beneficial to improving alkali-tolerance ability of other industrial enzymes via molecular modification.

Inhibitory effect of epigallocatechin-3-O-gallate on α-glucosidase and its hypoglycemic effect via targeting PI3K/AKT signaling pathway in L6 skeletal muscle cells.

Epigallocatechin-3-O-gallate (EGCG), a tea polyphenol is renowned for its anti-diabetic properties, however limited studies elucidate its hypoglycemic mechanism from multi-perspectives. In the present study, the interaction between EGCG and α-glucosidase was investigated through kinetics analysis, fluorescence spectra, Fourier transform infrared (FT-IR) spectra and molecular docking studies. Additionally, the effect of EGCG on glucose uptake and its related signaling pathway in L6 muscle cells were also investigated. The results showed that the α-glucosidase inhibitory activity of EGCG (IC50 = 19.5 ±â€¯0.3 µM) was higher than that acarbose (IC50 = 278.7 ±â€¯1.1 µM). EGCG inhibited α-glucosidase in a reversible and non-competitive manner. EGCG quenched the fluorescence of α-glucosidase due to the complex formation between EGCG and α-glucosidase, where the hydrogen bonds played a critical role. Microenvironment and the secondary structure of α-glucosidase were highly influenced by EGCG. Molecular docking results indicated that the binding sites on α-glucosidase for EGCG were close to the active site pocket of the enzyme. EGCG was also found to enhance the glucose uptake and promote GLUT4 translocation to plasma membrane via PI3K/AKT signaling pathway in L6 skeletal muscle cells. Overall, these results revealed the possible hypoglycemic mechanism of EGCG.

Hypoglycemic effects of polysaccharides from corn silk (Maydis stigma) and their beneficial roles via regulating the PI3K/Akt signaling pathway in L6 skeletal muscle myotubes.

In the present study, the physicochemical properties of polysaccharides from corn silk (CSP) with different molecular weights were characterized and their inhibitory actions against α-glucosidase and α-amylase were evaluated. Then their effects on glucose uptake and mechanism of action in PI3K/Akt signaling pathway were also determined in L6 skeletal muscle cells. Results demonstrated that CSP could significantly inhibit α-amylase and α-glucosidase. CSP were non-toxic and they considerably increased the 2-NBDG uptake (P < 0.05) in L6 cells. Additionally, CSP regulated the PI3K/Akt signaling pathway and promoted the translocation of GLUT4 to the plasma membrane that would enhanced the glucose uptake in rat L6 skeletal muscle cells. Among the tested polysaccharides, CSP2 with the molecular weight of 62.16 kDa exerted appreciable hypoglycemic activity. Altogether it was suggested that CSP could be the promising candidate in the treatment of Type 2 Diabetes Mellitus (T2DM). The elucidation of the potential anti-diabetic mechanism of the polysaccharides from corn silk will facilitate their utilization in the functional food industries.

Physicochemical properties of polysaccharides from Lentinus edodes under high pressure cooking treatment and its enhanced anticancer effects.

This study was to investigate the physicochemical properties and anticancer effects of polysaccharides from Lentinus edodes extracted under high pressure cooking treatment (HPLPS) in vitro and in vivo. The extraction efficiency was improved. The main molecular weight of HPLPS was about 540 and about 227 kDa. And the inhibitory effects on HepG2 and HeLa cells of HPLPS were significantly increased (p < 0.05). The in vivo anticancer effect on H22 tumor bearing mice model was evaluated. The tumor growth inhibitory rate of HPLPS-H was 67.66%. The activities of ALT and AST were decreased. The activities of SOD, CAT, GSH-Px were notably increased. The expressions of IL-2 and TNF-α were increased while the expression of VEGF was decreased. These results suggested that high pressure-assisted extracted polysaccharides from Lentinus edodes might be effectively used for the treatment of hepatocellular carcinoma through its antioxidant and immunomodulatory effects.