Phytochemical characterization, antioxidant capacity and in vitro inhibition of adipogenesis and inflammation of phenolic extracts in Vaccinium floribundum and Aristotelia chilensis

Abstract

Interest in berries from South America has increased due to their potential health benefits. The objective of this study was to characterize the anthocyanins and proanthocyanidins total phenolics and antioxidant capacity (AC) of V. floribundum and A. chilensis, and evaluate, in vitro, the ability of their phenolic extracts to reduce adipogenesis, and lipid accumulation in 3T3-L1 adipocytes. The anti-inflammatory properties of these extracts on RAW 264.7 macrophages was also investigated. The berry of A. chilensis contained 45.7 mg/g DW (cyanidin-3-glucososide (C3G) equivalents) total anthocyanins. Seven main anthocyanin structures were identified in this berry of which delphinidin-3-glucoside was the main anthocyanin component in this berry. The berry and the commercial powder of V. floribundum contained 10.6 mg/g DW and 2.4 mg/g (C3G equivalents) respectively of total anthocyanins. Five main anthocyanin structures where identified of which delphinidin-3- arabinose and cyanidin-3-arabinose were the main anthocyanins present in the berry and in the commercial powder of V. floribundum. The berry of A. chilensis contained 4.0 mg/g DW (epicatechin equivalents) of total proanthocyanidins, while the berries and commercial powder from V. floribundum had a slightly higher concentration of 5.2 and 4.8 mg/g DW (epicatechin equivalents) respectively. A. chilensis contained mainly proanthocyanidin dimers (56%) and trimers (14%). V. floribundum contained trimers (68%) and in less proportion pentamers (16%) and hexamers (8%). The commercial powder contained a larger percentage of dimers (34%) and trimers (23%). The berries of A. chilensis and V. floribundum showed similar values of total phenolics; however, AC was higher in the berries of A. chilensis. The commercial powder of V. floribundum had a lower phenolic content and AC than the freeze dried berry. Total phenolics and AC were highly correlated for A. chilensis and both the berries and the commercial powder of V. floribundum with R2 values of 0.90, 0.86 and 0.78, respectively. Anthocyanins were more highly correlated with AC than proanthocyanins. Phenolic extracts of the two berries and the commercial powder inhibited lipid accumulation by 4.0 to 10.8% when adipocytes were treated at maturity and by 5.9 to 37.9% when treated throughout differentiation. Furthermore, a proanthocyanidin-enriched-fraction from V. floribundum significantly induced Pref-1 expression in preadipocytes. Phenolic extracts decreased the production of nitric oxide (3.7 - 25.5%) and prostaglandin E2 (9.1 - 89.1%) and the expression of inducible nitric oxide synthase (9.8 - 61.8 %) and cycloxygenase-2 (16.6 - 62.0%) in lipopolysaccharide-stimulated RAW 264.7 macrophages. V. floribundum and A. chilensis phytochemicals limit adipogenesis and inflammatory pathways in vitro, warranting further in vivo studies