Antiglycation and antioxidant potential of coumaric acid isomers: a comparative in-vitro study

Advanced glycation end products (AGEs) are the product of non-enzymatic glycation of serum proteins. AGEs increase reactive oxygen species (ROS) formation, which leads to diabetic complications. Phytochemicals exhibit lesser side effects as compared to conventional therapy. In this study, three isomers of coumaric acid (ortho, meta, para) were used to deduce the better one in terms of reducing diabetic complications. For this purpose, human serum albumin (HSA) was incubated with glucose in the absence and presence of isomers for 28 days. To avoid any growth, NaN3 was added and temperature was kept constant throughout the incubation period. Studies like fluorescence, circular dichroism spectroscopy, fructosamine analysis, free lysine estimation, free thiol group estimation were done. To investigate the ROS production, fluorescence microscopy of isolated lymphocytes using DAPI and dichloro-dihydro-fluorescein diacetate were performed. Molecular docking and molecular dynamic simulations (root-mean-square deviation, root-mean-square fluctuations, radius of gyration and solvent-accessible surface area) of HSA and peroxisome proliferator activated receptor (PPAR) alpha and gamma were also done. It was observed that in glycated protein samples, the level of absorbance, fluorescence, fructosamine and carbonyl group increased along with the loss of secondary structure, free lysine and thiol group. These parameters were found gradually recovered in treated samples. ROS production and apoptosis were found to be reduced in lymphocytes treated with p-Coumaric acid (pCA)-treated protein samples as compared to lymphocyte treated with glycated protein. Computational modelling suggested a stable complex formation of HSA and PPARs with pCA. Results with pCA at 200 µM were consistently better than other two isomers. Our next step is to evaluate this study in rats.Communicated by Ramaswamy H. Sarma.

A Pilot Study for Metabolic Profiling of Obesity-Associated Microbial Gut Dysbiosis in Male Wistar Rats

Obesity is one of the most incident and concerning disease worldwide. Definite strategies to prevent obesity and related complications remain elusive. Among the risk factors of the onset of obesity, gut microbiota might play an important role in the pathogenesis of the disease, and it has received extensive attention because it affects the host metabolism. In this study, we aimed to define a metabolic profile of the segregated obesity-associated gut dysbiosis risk factor. The study of the metabolome, in an obesity-associated gut dysbiosis model, provides a relevant way for the discrimination on the different biomarkers in the obesity onset. Thus, we developed a model of this obesity risk factors through the transference of gut microbiota from obese to non-obese male Wistar rats and performed a subsequent metabolic analysis in the receptor rats. Our results showed alterations in the lipid metabolism in plasma and in the phenylalanine metabolism in urine. In consequence, we have identified metabolic changes characterized by: (1) an increase in DG:34:2 in plasma, a decrease in hippurate, (2) an increase in 3-HPPA, and (3) an increase in o-coumaric acid. Hereby, we propose these metabolites as a metabolic profile associated to a segregated dysbiosis state related to obesity disease.

Identification of phenolic compounds that suppress the virulence of Xanthomonas oryzae on rice via the type III secretion system

The targeting of bacterial type III secretion systems (T3SSs), which are critical virulence factors in most Gram-negative pathogens, is regarded as an alternative strategy for the development of novel anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc) are two of the most important bacterial pathogens on rice, which cause leaf blight and leaf streak diseases, respectively. To identify potential anti-virulence drugs against these two pathogens, we screened a library of plant phenolic compounds and derivatives for their effects on the Xoo T3SS. Ten of 56 compounds significantly inhibited the promoter activity of a harpin gene, hpa1. These inhibitors were further tested for their impact on the hypersensitive response (HR) caused by Xoo on non-host tobacco plants. The results showed that pretreatment of Xoo with TS006 (o-coumaric acid, OCA), TS010, TS015 and TS018 resulted in significantly attenuated HR without affecting bacterial growth or survival. In addition, Cya translocation assays demonstrated that the translocation of two T3 effectors was suppressed by the four inhibitors. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that mRNA levels of representative genes in the hrp (hypersensitive response and pathogenicity) cluster, as well as the regulatory genes hrpG and hrpX, were reduced by treatment with the four inhibitors, suggesting that expression of the Xoo T3SS was suppressed. The expression of other virulence factors was not suppressed, which indicated possible T3SS-specific inhibition. Finally, we demonstrated that these inhibitors reduced the disease symptoms of Xoo and Xoc on the rice cultivar (Oryza sativa) IR24 to varying extents.