Quantitative analysis of proanthocyanidins in cocoa using cysteamine-induced thiolysis and reversed-phase UPLC

A novel thiolysis-HPLC method for the determination of proanthocyanidins in grape seeds

A novel thiolysis-HPLC method for quantitative determination of total proanthocyanidins and mean degree of polymerization in grape seeds has been developed. Following thiolysis with formic acid and benzyl mercaptan, reaction products were separated and purified. Three proanthocyanidin monomers and three derivatives were obtained and their structures were identified by LC-MS, fourier transform infrared spectroscopy, and NMR. A decomposition model of the thiolysis products and a correction formula for proanthocyanidins concentration were established. This thiolysis-HPLC method displayed good calibration linearity (R² > 0.999 over the concentration range 0.01 to 10 mg/mL), and excellent accuracy (recoveries of 97.9-99.6%) and precision (repeatability relative standard deviations of 0.45-0.75%). This method is suitable for the quantitative analysis of proanthocyanidins in grape seed products. This article is protected by copyright. All rights reserved.

Evolution of cocoa flavanol analytics: impact on reporting and cross-study comparison

Cocoa flavanols (CF) are a group of dietary bioactives that have been studied for their potential health benefits for over two decades. In this time, multiple methods for CF testing have evolved, introducing the potential for differences in reported CF content. The reliable characterization of CF content in food and test materials used in clinical studies is critical to comparisons of research studies over time, as well as critical to enabling the systematic reviews and meta-analyses required to support dietary recommendations of bioactives. In this work, we compared two analytical methods that have been widely applied to characterize materials used in clinical research and a method newly recognized by AOAC as the official method for CF analysis. Differences in accuracy of -36% to +20% were observed when comparing CF contents determined with these methods, supporting the notion that CF values determined across methods are not directly comparable. To address differences, a linear regression model was developed to predict CF values. This approach was cross-validated and directly applied to the conversion of CF values published in key scientific papers on the benefits of CF. This work provides a valid tool to compare CF values reported across these different methods and enables comparisons and interpretation of studies investigating the bioactivity of CF.

Antidiabetic, Antimicrobial, and Molecular Profiling of Selected Medicinal Plants

Natural products have been the center of attraction ever since they were discovered. Among them, plant-based natural products were popular as analgesics, anti-inflammatory, antidiabetic, and cosmetics and possess widespread biotechnological applications. The use of plant products as cosmetics and therapeutics is deep-rooted in Nepalese society. Although there are few ethnobotanical studies conducted, extensive research of these valuable medicinal plants has not been a priority due to the limitation of technology and infrastructure. Here, we selected 4 traditionally used medicinal plants to examine their bioactive properties and their enzyme inhibition potential. α-Glucosidase and α-amylase inhibitory activities were investigated using an in vitro model followed up by antioxidant and antimicrobial activities. The present study shows that ethyl acetate fraction of Melastoma melabathrium (IC₅₀ 9.1 ± 0.3 µg/mL) and water fraction Acacia catechu (IC₅₀ 9.0 ± 0.6 µg/mL) exhibit strong α-glucosidase inhibition. Likewise, the highest α-amylase inhibition was shown by crude extracts of Ficus religiosa (IC₅₀ 29.2 ± 1.2 µg/mL) and ethyl acetate fractions of Shorea robusta (IC₅₀ 69.3 ± 1.1 µg/mL), and the highest radical scavenging activity was shown by F. religiosa with an IC₅₀ 67.4 ± 0.6 µg/mL. Furthermore, to identify the metabolites within the fractions, we employed high-resolution mass spectrometry (LC-HRMS) and annotated 17 known metabolites which justify our assumption on activity. Of 4 medicinal plants examined, ethyl acetate fraction of S. robusta, ethyl acetate fraction of M. melabathrium, and water or ethyl acetate fraction of A. catechu extracts illustrated the best activities. With our study, we set up a foundation that provides authentic evidence to the community for use of these traditional plants. The annotated metabolites in this study support earlier experimental evidence towards the inhibition of enzymes. Further study is necessary to explore the clinical efficacy of these secondary molecules, which might be alternatives for the treatment of diabetes and pathogens.