Chemical composition, antioxidant and anti-inflammatory properties of pistachio hull extracts

Phytochemical and bioactivity analyses of pistachio hulls revealed the presence of anacardic acids (3198 mg/100 g), fatty acids (1500 mg/100 g), and phytosterols (192 mg/100 g) as major components. Carotenoids (4.93 mg/100 g), chlorophylls (10.27 mg/100 g), tocopherols (8.83 mg/100 g), and three triterpene acids (mangiferolic, isomangiferolic and mangiferonic acids) were characterized. A polar (P) extract contained quercetin-3-O-glucoside (6.27 mg/g), together with smaller concentrations of quercetin, myricetin and luteolin flavonoids, accounting for 5.53 mg/g. Gallotannins and other phenolic compounds esterified with a gallic acid moiety characterized the P extract. P extract potently inhibited the release of nitric oxide (NO) and reactive oxygen species (ROS) in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. The mRNA expression levels of the anti-inflammatory cytokine COX-2 were significantly inhibited by fractions P2-P5, while IL-6 was only inhibited by fraction P3. Moreover, the P extract significantly decreased the non-mitochondrial oxidative burst associated with inflammatory response in macrophages.