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Extractable and Non-Extractable Polyphenols from Apples: Potential Anti-inflammatory Agents

With diet being such a huge factor in the development of diseases, emerging research has supported that apple consumption is a promising candidate for disease prevention due to the high phenolic content it possesses. These polyphenols can be found in two forms: extractable polyphenols (EP) and non-extractable polyphenols (NEP). Polyphenols have been shown to have strong anti-inflammatory and anti-oxidant properties, but up until this point, most researchers focus on EP fractions, while NEP are neglected. After the EP extraction using acetone and acetic acid (99:1) from the Apple Boost powder, three additional extraction methods were conducted on the remaining powder residue to extract the NEP. These extractions put the residue in three different environments for hydrolysis to compare their extraction abilities: enzyme, alkaline, and acid. After analyzing the EP and NEP total phenolic content (TPC) levels, oxygen radical absorbance capacity (ORAC) assay was conducted to measure anti-oxidation capacity of each extraction, and in vitro anti-inflammatory assay was performed to evaluate the anti-inflammation capacity of each extraction where inflammation was induced by LPS. The results showed that the NEP obtained from acid hydrolysis had the highest readings in both the TPC and ORAC assay, but did not show any anti-inflammatory effects in vitro. The EP extraction had the second highest readings in the TPC, ORAC and anti-inflammatory assays. The NEP enzyme extraction had the second lowest TPC and ORAC assay performance, but highest performance in the anti-inflammatory assay. The NEP alkaline extraction had the lowest TPC and performed poorly in both the anti-inflammatory assay and ORAC assay.