Abstract 314: Highly polymeric grape seed proanthocyanidins: A call for establishing the safe dose

Abstract Introduction: Proanthocyanidins (PC) are the oligomers and polymers of flavan-3-ols, especially catechin and epicatechin. PC in general are proven to be beneficial against cancers and widely available as over the counter (OTC) supplements. However, role of highly polymeric PC (HP-PC) on human cancer prevention remain unknown. Therefore, the effects of HP-PC supplementation on hepatic pathology in the context of hepatocellular carcinoma (HCC) were evaluated. HP-PC supplementation on mice gut microbiota was also evaluated considering the association of dysbiosis-mediated inflammation with HCC. Methodology: Crude PC was extracted from grape seeds (GS) using 70% acetone (in water) as the extraction solvent. PC mixture was purified and fractionated by flash chromatography. Monomeric and oligomeric PC was eluted with 100% ethanol and the HP-PC was collected by eluting with 70% acetone. C57BL/6 mice (49 - 56 days old) were supplemented with HP-PC (200 mg/kg body weight per day) for 14 days and sacrificed to collect livers and blood serum. Feces samples were collected from mice colon to evaluate the composition of gut microbiota using the 16S rRNA sequencing technology. Mice liver histopathology was examined by staining with hematoxylin and eosin. The level of alanine aminotransferase (ALT) in mice blood serum was measured as a marker of liver damage. Results: Evaluation of liver histopathology revealed signs of steatosis in the mice supplemented with HP-PC. Interestingly, rare foci of monocytic lobular inflammation was visible in the hepatic tissues of the mice supplemented with HP-PC. The alpha diversity of the mice gut microbiome was evaluated in terms of Shannon Index, Pielou's evenness, Faith's phylogenic diversity, and observed operational taxonomic units. A significant difference was not observed for the alpha diversity between the HP-PC supplemented and control group mice gut microbiota. The levels of ALT in the mice blood serum were not significantly different between HP-PC supplemented and control group mice. Conclusions: The preliminary experimental data suggests the potential of HP-PC to promote steatosis and hepatic inflammation. However, further studies must be conducted to understand potential harmful effect of HP-PC (if any) in hepatic toxicity and safer dose to use for potential health benefits. Furthermore, the results of this study emphasize the critical importance of establishing the safe dose of HP-PC or any OTC supplements. Citation Format: Wasitha Thilakarathna, H.P. Vasantha Rupasinghe. Highly polymeric grape seed proanthocyanidins: A call for establishing the safe dose [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 314.