Identification of Phytochemicals in Muscadine Pomace and Their Anti‐inflammatory Activities on RAW 264.7 Murine Macrophages

Abstract

Southern muscadine grapes are known to contain a variety of health‐promoting polyphenolic compounds. About 98% of these nutraceutical compounds in muscadine grapes are found in the skins and seeds. They are often discarded in the form of pomace after winemaking. The objective this study was to identify phytochemicals in muscadine pomace and determine their anti‐inflammatory activities. Muscadine wine pomace of three cultivars (Noble, Welder, and Carlos) was separated into skin and seeds. Part of the seeds was processed on a single‐screw press at 90°C to obtain seed oil and partially defatted seeds. This step reduced the fat content in seeds from about 13% to 5% (w/w). All samples were ground into powders and extracted using methanol/water/acetic acid (85:15:0.5; v/v/v). The resultant crude extracts were subject to acid hydrolysis and water/ethyl acetate partition. HPLC‐MS analyses showed that the major compounds in seeds and skins were ellagic acid, epicatechin and gallic acid. Welder seed extract contains the highest amount of ellagic acid (230 μg/mg extract), epicatechin (122 μg/mg extract) and gallic acid (107 μg/mg extract). RAW 264.7 macrophages were pretreated with extracts and stimulated with lipopolysaccharides to induce inflammatory responses. RT‐PCR results show that IL‐1 and IL‐6 gene expression were reduced by muscadine extracts while TNF‐α expression remained the same or slightly increased. Overall, the grape pomace contained several types of polyphenols and showed anti‐inflammation activities in vitro.Support or Funding InformationThis research is supported in part by Florida Viticulture Council and Florida Specialty Crop Block Grant