Biophysical, Biochemical, and Molecular Docking Investigations of Anti-Glycating, Antioxidant, and Protein Structural Stability Potential of Garlic.

Garlic has been reported to inhibit protein glycation, a process that underlies several disease processes, including chronic complications of diabetes mellitus. Biophysical, biochemical, and molecular docking investigations were conducted to assess anti-glycating, antioxidant, and protein structural protection activities of garlic. Results from spectral (UV and fluorescence) and circular dichroism (CD) analysis helped ascertain protein conformation and secondary structure protection against glycation to a significant extent. Further, garlic showed heat-induced protein denaturation inhibition activity (52.17%). It also inhibited glycation, advanced glycation end products (AGEs) formation as well as lent human serum albumin (HSA) protein structural stability, as revealed by reduction in browning intensity (65.23%), decrease in protein aggregation index (67.77%), and overall reduction in cross amyloid structure formation (33.26%) compared with positive controls (100%). The significant antioxidant nature of garlic was revealed by FRAP assay (58.23%) and DPPH assay (66.18%). Using molecular docking analysis, some of the important garlic metabolites were investigated for their interactions with the HSA molecule. Molecular docking analysis showed quercetin, a phenolic compound present in garlic, appears to be the most promising inhibitor of glucose interaction with the HSA molecule. Our findings show that garlic can prevent oxidative stress and glycation-induced biomolecular damage and that it can potentially be used in the treatment of several health conditions, including diabetes and other inflammatory diseases.

Glycation and Oxidative Stress Increase Autoantibodies in the Elderly.

Aging causes gradual changes in free radicals, antioxidants, and immune-imbalance in the elderly. This study aims to understand links among aging, gluco-oxidative stress, and autoantibodies in asymptomatic individuals. In vitro glycation of human serum albumin (Gly-HSA) induces appreciable biochemical changes. Significant inhibition of advanced glycation end products (AGEs) formation was achieved using garlic extract (53.75%) and epigallocatechin-3-gallate from green tea (72.5%). Increased amounts of serum carbonyl content (2.42 ± 0.5) and pentosidine (0.0321 ± 0.0029) were detected in IV-S (S represent smokers) vs. IV group individuals. Direct binding ELISA results exhibited significantly high autoantibodies against Gly-HSA in group IV-S (0.55 ± 0.054; p < 0.001) and III-S (0.40 ± 0.044; p < 0.01) individuals as compared to the age matched subjects who were non-smokers (group IV and III). Moreover, high average percent inhibition (51.3 ± 4.1%) was obtained against Gly-HSA in IV-S group individuals. Apparent association constant was found to be high for serum immunoglobulin-G (IgG) from group IV-S (1.18 × 10-6 M) vs. serum IgG from IV group (3.32 × 10-7 M). Aging induced gluco-oxidative stress and AGEs formation may generate neo-epitopes on blood-proteins, contributing to production of autoantibodies in the elderly, especially smokers. Use of anti-glycation natural products may reduce age-related pathophysiological changes.