Evaluation of Antioxidant, Antiglycant and ACE-Inhibitory Activity in Enzymatic Hydrolysates of <i>α</i>-Lactalbumin

Whey proteins are known for their high nutritional value and bioactivity, notably great potential is found on α-lactalbumin. The objective of this study was to evaluate antioxidant, antiglycant and ACE (angiotensin converting enzyme)-inhibitory activity of α-lactalbumin peptides obtained from enzymatic hydrolysis with Alcalase through different hydrolysis conditions. The optimization of enzymatic hydrolysis was studied by response surface methodology variating enzyme:substrate ratio (0.0050%, 0.0525% and 0.1000% w/w) and time (0, 30 and 60 minutes) measuring antioxidant activity by ABTS and ORAC-FL (response variables), founding an augment of this activity with time. Characterization of seven samples showed increasing hydrolysis with time. Hydrolysate obtained with 0.1000% w/w and 60 minutes demonstrated higher antioxidant activity related to greater hydrolysis. This hydrolysate did not show antiglycant activity but promoted advanced glycation end products formation with methylglyoxal and glucose. In contrast, this sample showed 30% of ACE inhibition when compared to Captopril, having great potential by enhancing hydrolysis.

Antiglycating effects of citrus flavonoids and associated mechanisms

Glycation of proteins and DNA forms advanced glycation end products(AGEs)causing cell and tissue dysfunction and subsequent various chronic diseases,in particular,metabolic and age-related diseases.Targeted AGE inhibition includes scavengers of reactive carbonyl species(RCS)such as methylglyoxal(MG),glyoxalase-1 enhancers,Nrf2/ARE pathway activators,AGE/RAGE formation inhibitors and other antiglycatng agents.Citrus flavonoids have demonstrated antioxidant and anti-inflammatory effects and are also found to be effective antiglycating agents.Herein,we reviewed the up to date progress of the antiglycation effects of citrus flavonoids and associated mechanisms.Major citrus flavonoids,hesperedin and its aglycone,hesperetin,inhibited glycation by scavenging MG forming mono-or di-flavonoid adducts with MG,enhanced the activity of glyoxase-1,activated Akt/Nrf2 signal pathway while inhibiting AGE/RAGE/NF-κB pathway,reduced the formation of Nε-(carboxylmethyl)lysine(CML)and pentosidine,inhibited aldol reductase activity and decreased the levels of fructosamine.The antiglycating activity and mechanisms of other flavonoids was also summarized in this review.In conclusion,citrus flavonoids possess effective antiglycating activity via different mechanisms,yet there are many challenging questions remaining to be studied in the near future such as in vivo testing and human study of citrus flavonoids for efficacy,effectiveness and adverse effects of citrus flavonoids as a functional food in managing high levels of AGEs and controlling AGE-induced chronic diseases,diabetic complications in particular.

Antioxidant and antiglycation properties of different solvent extracts from Chinese olive(Canarium album L.) fruit

Objective:To evaluate the antioxidant activity,antiglycation property,and bioactivc components content of different solvent extracts from Chinese olive(Canarium album L.) fruit.Methods:The dry powder of Chinese olive fruit was extracted with different solvents,i.e.,water,water/ethanol(1/1,v/v),ethanol,methanol,acetone and ethyl acetate.The total phenolic,total flavonoids and total triterpenoids contents of various extracts were determined by spectrophotometric methods.Phenolic compounds were identified by high performance liquid chromatography.The assayed antioxidant activity was determined in vitro models such as antioxidant capacity by radical scavenging activity using 2,2'-azino-bLs(3-ethylbenzthiazoline-6-sulfonic acid)(ABTS),l,l-diphenyl-2-picryl- hydrazyl(DPPH) and nitrite oxide methods,chelating activity on metal ions,lipid and protein peroxidation methods.In vitro glucosebovine serum albumin assay was used to evaluate the antiglycation of various extracts.Results:The water/ethanol extracts of Chinese olive fruit exerted significant scavenging effects on free radicals and strong inhibitory effects on advanced glycation end products formation.The Chinese olive fruit extracts were rich in phenolic compounds and triterpenoids.Gallic acid,ferulic acid and rutin were identified from the water/ethanol extracts.Correlation analysis indicated that there was a linear relationship between the antioxidant potency,free radical scavenging ability and phenolic compounds content of the Chinese olive fruit extracts.Conclusions:Chinese olive fruit could be a natural candidate for studies of dietary complement to diabetes treatment since it combines antioxidant and antiglycation activities.

Antiglycative activity of sulforaphane: a new avenue to counteract neurodegeneration?

Neurodegeneration is a key aspect of a large number of diseases that come under the umbrella of＂neurodegenerative diseases＂with the most notable being Parkinson＇s,Alzheimer＇s,and Huntington＇s diseases（AD,PD,HD）.They are all incurable and debilitating conditions that result in progressive degeneration and/or death of neurons and are the leading cause of disability in the elderly. The incidence of these diseases is on the rise and yet there is a paucity of effective therapies to treat them.

Antioxidant and antiglycation properties of two mango(Mangifera indica L.) cultivars from Senegal

Objective: To evaluate the total phenolic contents, antioxidant and antiglycation activities of leaves, barks, roots and kernels from two cultivars of Mangifera indica(Anacardiaceae). Methods: Total phenolic contents were determined by using Folin-Ciocalteu's method. The antioxidant activities were assessed by three different protocols including DPPH, oxygen radical absorbance capacity and iron(Ⅱ) chelation assays. In addition, in vitro bovine serum albumin/D-ribose assay was chosen to evaluate the antiglycation properties of the extracts. Results: All the investigated extracts were found to contain high level of total phenols as well as potent antioxidant activities. Kernel extracts showed the highest total phenol contents and DPPH radical scavenging activities whereas higher oxygen radical absorbance capacity values were observed for leave, root and bark extracts. Besides, extracts from leaves, roots and barks from both cultivars exhibited potent inhibitory effects against the formation of advanced glycation end products, with IC_(50) values lower than the standard positive control aminoguanidine. Conclusions: The potent antiglycation and antioxidative activities of these two Mangifera indica cultivars suggest a possible role in targeting aging, diabetic complications and oxidative stress related diseases.

Isolation and evaluation of antiglycation potential of polyalthic acid(furano-terpene)from Daniella oliveri

A furano-diterpene（polyalthic acid） was isolated as a major stable compound for the first time from the oleoresin of the Daniella oliveri of the family Caesalpiniacea through column chromatography fractionation.Polyalthic acid was characterized using data obtained from EIMS,HREIMS,ESI-MS,MALDI-MS as well as 1D and 2D NMR and it was evaluated for its potential to inhibit the formation of advanced glycation end-products（AGEs） using a standard in vitro antiglycation procedure.Polyalthic acid indicated a negative antiglycation potential compared to standard inhibitor that has 85%inhibition,which is an indication that polyalthic acid may not contribute to the antiglycation activity of the plant as acclaimed in folkloric medicine.The negative antiglycation observed could indicate that the polyalthic acid could trigger glycation,thereby subjecting users to various degrees of complications.The bioactivity evaluation on molinspiration evaluator indicated that polyalthic acid could be a potential drug candidate.The biological and chemical insights gained on polyalthic acid provide a good basis for future research.

Antiglycation and antioxidation properties of juglans regia and calendula officinalis:possible role in reducing diabetic complications and slowing down ageing

OBJECTIVE:Accumulation of advanced glycation end products(AGEs) in the body due to the non-enzymatic glycation of proteins and oxidation is associated with aging and diabetes mellitus.In this study we wanted to investigate the antiglycation and antioxidation potential of two medicinal plants:Juglans regia and Calendula officinalis.METHODS:In-vitro investigation was carried out to discover the antiglycation and antioxidation potential of J.regia and C.officinalis.Using an Ultraviolet Double-beam Spectrophotometer,we evaluated the antiglycation property of the crude methanolic extracts of J.regia and C.officinalis by assessing their ability to inhibit the Maillard reaction.Employing the same instrument we also measured the antioxidation potential of these plant extracts using the nitric oxide(NO) free radical-scavenging assay.RESULTS:J.regia had greater antiglycation ability,with a minimum inhibitory concentration(MIC 50) of 28 μg/mL as compared with that of C.officinalis(270 μg/mL).C.officinalis had greater antioxidation potential(26.10,22.07 and 16.06% at 0.5 mg,0.25 mg and 0.125 mg,respectively,as compared with 18.15,16.50 and 16.06% of J.regia,respectively).CONCLUSION:J.regia and C.officinalis inhibited the Maillard reaction and prevented oxidation in-vitro.Hence,the extracts of these plants could have therapeutic uses in curbing chronic diabetic complications and slowing down aging.

New antiglycation and enzyme inhibitors from Parmotrema cooperi

Lichens are unique individuals which have been widely used in traditional medicines. This study was focused on the bioassayguided phytochemical investigation, and bioactivity evaluation on a lichens species, Parmotrema cooperi. This first bioassaydirected chemical study on P. cooperi has led to the isolation of ethyl heamatomate （1）, atraric acid （2）, ethyl orsellinate （3）, orsellinic acid （4）, lecanoric acid （5）, gyrophoric acid （6）, and licanorin （7）. The structures of 1-7 were mainly elucidated from spectroscopic methods including 1D, and 2D NMR spectroscopy, and mass spectrometry. These compounds were evaluated for their antiglycation, urease, a-chymotrypsin, and β-glucoronidase inhibitory activities. Few of the phenolic compounds showed significant, while most of them showed good inhibition of protein glycation, and urease activities.

Evaluation of in vitro antioxidant, antiglycation and antimicrobial potential of indigenous Myanmar medicinal plants

Objective： Myanmar has a long history of using medicinal plants for treatment of various diseases. To the best of our knowledge there are no previous reports on antiglycation activities of medicinal plants from Myanmar. Therefore, this study was aimed to evaluate the antioxidant, antiglycation and antimicrobial properties of 20 ethanolic extracts from 17 medicinal plants indigenous to Myanmar. Methods： In vitro scavenging assays of 2,2-diphenyl-l-picrylhydrazyl （DPPH）, nitric oxide （NO）, superoxide （SO） radicals were used to determine the antioxidant activities. Folin-Ciocalteu＇s method was performed to determine the total phenolic content. Antiglycation and antimicrobial activities were detected by bovine serum albumin-fluorescent assay and agar well diffusion method. Results： Terminalia cbebula Retz. （Fruit）, containing the highest total phenolic content, showed high antioxidant activities with inhibition of 77.98% ± 0.92% 88.95% ± 2.42%, 88.56% ±1.87% and 70.74% ±2.57% for DPPH, NO, SO assays and antiglycation activity respectively. It also showed the antimicrobial activities against Staphylococcus aureus, Bacillus cereus, Escherichia coil, Pseudomonas aeruginosa and Candida albicans with inhibition zone of 19, 18, 17, 25 and 15 ram, respectively. Garcinia mangostana Linn. showed the strongest activities for SO and antiglycation assays with inhibition of 93.68% ± 2.63% and 82.37%± 1.78%. Bark of Melia sp. was the best NO radical scavenger with inhibition rate of 89.39%± 0.60%. Conclusion： The results suggest that these plants are potential sources of antioxidants with free radical-scavenging and antiglycation activities and could be useful for decreasing the oxidative stress and glycation end-product formation in glycation-related diseases.

Phytochemicals of six selected herbal plants and their inhibitory activities towards free radicals and glycation

In type 2 diabetes mellitus patients,hyperglycaemia speed up the production of advanced glycation end products(AGEs),leading to oxidative stress and various diabetic complications.In order to identify natural products with potential antioxidant and antiglycative properties,six herbal plants,namely Musa acuminata(flower buds),Bletilla striata(rhizomes),Amomum villosum(dried nuts),Moghania philippinensis(roots),Millettia speciosa(rhizomes),and Spatholobus suberectus(stems)were assessed for their antioxidant and antiglycative properties.Among all the selected samples,both water and ethanolic extracts of S.suberectus possessed the highest phenolic,flavonoid and triterpenoid contents,ranging from three to six-fold higher than other plant extracts.In consistent with its phytochemical content,S.suberectus also showed the highest antioxidant activities which are comparable,if not higher than the known antioxidants,butylated hydroxytoluene,gallic acid,rutin,quercetin and ursolic acid.Similarly,S.suberectus also displayed the highest antiglycative activities among the six herbal plants measured by two glycation assays using bovine serum albumin-glucose and bovine serum albumin-methylglyoxal as model systems.HPLC-QToF-MS/MS analysis identified 48 polyphenols and 76 terpenoids,from the water and ethanolic extracts of S.suberectus,where 12 polyphenols and 9 terpenoids are common in both extracts.The results also suggested that S.suberectus contains compounds such as quercetin,luteolin,apigenin and saponin derivatives,which were reported to exert high antioxidant and antiglycative properties.The high antioxidant and antiglycative properties suggest the great potential of S.suberectus in preventing the formation of AGEs and oxidative stress seen in type 2 diabetes.

Inhibitive efficacy of Nymphoides indica rhizome extract onα-glucosidase, and cross-link formation of advanced glycation end products

OBJECTIVE: To investigate the inhibitive efficacy of Nymphoides Indica(L.) Kuntze rhizome extract onα-glucosidase and on cross-link formation of advanced glycation end products(AGEs).METHODS: The plant extracts were prepared by cold maceration and fractionated in solvents of diverse polarity. The in vitro α-glucosidase inhibition assay, fluorescence spectrometry and SDS-PAGE analysis was performed for antiglycation assays.RESULTS: During α-glucosidase inhibition assay significant inhibition by chloroform(0.43 mg/mL)and methanol fractions(0.66 mg/mL) was noticed.During the AGEs inhibition assay, both oxidative(BSA-MGO) and non-oxidative(BSA-glucose)modes were employed. The inhibition of AGEs by total extract was considered moderate(IC_(50)0.10 mg/mL) as a result of non-oxidative mode, whereas in case of oxidative mode(BASA-MGO) no activity was recorded. Among fractions the methanolic fraction presented significant results both in oxidative(IC_(50)0.01 mg/mL) and non-oxidative modes(IC_(50) 0.3 mg/mL). Likewise the ethyl acetate fraction was more active in non-oxidative mode(IC_(50)0.04 mg/mL) compared to oxidative mode(IC_(50)0.32 mg/mL).During assay for inhibition of cross-link formation,the chloroform fraction significantly inhibited cross-link formation in a dose dependent mode.CONCLUSION: It was finally concluded that N. Indica rhizome extract possesses significant properties that inhibit α-glucosidase, and AGEs cross-link formation.

Potential for Pakistani traditional medicinal plants to combat diabetes

OBJECTIVE: To investigate the potential of medicinal plants used in traditional healing in Pakistan to inhibit the glycation process. This may be useful in combatting diabetes mellitus and its complications.METHODS: The in vitro antiglycation activity of 10 medicinal plants was examined by testing the ability of the extracts to inhibit the methyl-glyoxal-mediated development of fluorescence of bovine serumalbumin.RESULTS: Of the tested plants, Persicaria barbata,Geranium collinum and Berberis lyciumshowed significant inhibition of the formation of advanced glycation end products. The inhibitory capacity of these plants was 68.89%, 62.06% and 54.23%, respectively, compared with the positive control(rutin; 86%). All other plants inhibited AGE formation non-significantly.CONCLUSION:These findings will be helpful for further research into the use of traditional herbal medicines with antiglycation properties in the treatment of diabetes.

Inhibitory effect of a Chinese quince seed peptide on protein glycation:A mechanism study

Non-enzymatic glycation can cause the formation and accumulation of advanced glycation end products(AGEs),and it poses great threats to human health.It is urgent to search for safe and efficient inhibitors to prevent reducing sugar induced protein glycation.In this study,we inves-tigated the anti-glycation activity and mechanism of an identified peptide,Asparagine-Tyrosine-Arginine-Arginine-Glutamic acid(NYRRE)from Chinese quince seed protein hydrolysate,by mul-tispectroscopy,confocal imaging,and computational molecular simulation.Firstly,it was found that NYRRE could scavenge hydroxyl radicals and chelate Fe 2+.Besides,the NYRRE was effective in every stage of fructose induced bovine serum albumin(BSA)glycation.The NYRRE could re-duce the formation of fructosamine,carbonyl compounds,glycoxidation products and𝛽-amyloid structure.Meanwhile,NYRRE could protect thiol groups and stabilize the spatial conformation of BSA.The NYRRE presented strong inhibition in fluorescent AGEs,and 68.19%of total AGEs formation was prevented with NYRRE at 15 mmol/L.The results of molecular simulation indi-cated that NYRRE could insert into the hydrophobic pocket of BSA and interact with hot spots,including arginine and lysine residues.The mechanism of NYRRE inhibiting protein glycation could be due to its antioxidant activity,BSA structure stabilizing ability,and specific bond with glycation sites of BSA.These results provided a valuable reference for developing NYRRE as an efficient antiglycation agent in preventing glycation-mediated diseases.