Tannin fraction of pistachio green hull extract with pancreatic lipase inhibitory and antioxidant activity.

Polyphenolic compounds (present in different parts of the plant) have beneficial properties such as antioxidant and inhibition of key enzymes. In this research, antioxidant and anti-lipase activity of pistachio green hull (PGH) extract was investigated. Fractionation of PGH on Sephadex LH-20 furnished a tannin enriched fraction with higher antioxidant activity respect to that of the extract and of the non-tannin fraction. UHPL/MS² analyses showed the presence of phenolic compounds including galloyl-O-hexoside, galloyl-shikimic acid, galloylquinic acid, and gallic acid in tannin fraction. PGH-extract was an un-competitive inhibitor against porcine pancreatic lipase so that its IC₅₀ value was 2.26 mg/ml. In the same phenol amount (490 µg), anti-lipase activity of the tannin fraction was also more than non-tannin fraction and crude PGH-extract. This is probably due to the presence of some active polyphenolic compounds such as gallic acid. PRACTICAL APPLICATIONS: Pistachio is native to the arid regions of Central and West Asia including Iran. The green hull is main by-product of pistachio industry that has numerous phenolic compounds. Our results showed that the pistachio green hull extract has antioxidant and anti-lipase activity and these activities in its tannin fraction were higher than non-tannin fraction. Therefore, the PGH extract and its tannin fraction can be used as potential substitutes of anti-obesity drugs. This allows the use of pistachio processing waste and reduces the amount of waste.