Inhibition of pro-inflammatory responses and antioxidant capacity of mexican blackberry (Rubus spp.) extracts

Total polyphenolic and anthocyanin- and proanthocyanidin-rich fractions from wild blackberry genotypes (WB-3, WB-7, WB-10, and WB-11), a domesticated noncommercial breeding line (UM-601), and a commercial cultivar (Tupy) were evaluated for inhibition of pro-inflammatory responses [nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression, cyclooxygenase-2 (COX-2) expression, and prostaglandin E₂ (PGE₂)] in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). At 50 μM [cyanidin-3-O-glucoside (C3G) or catechin equivalent], most fractions significantly (P < 0.05) inhibited all markers. The anthocyanin-rich fraction from WB-10 and the proanthocyanidin-rich fraction from UM-601 exhibited the highest NO inhibitory activities (IC₅₀ = 16.1 and 15.1 μM, respectively). Proanthocyanidin-rich fractions from the wild WB-10 showed the highest inhibition of iNOS expression (IC₅₀ = 8.3 μM). Polyphenolic-rich fractions from WB-7 and UM-601 were potent inhibitors of COX-2 expression (IC₅₀ = 19.1 and 19.3 μM C3G equivalent, respectively). For most of the extracts, antioxidant capacity was significantly correlated with NO inhibition. Wild genotypes of Mexican blackberries, as rich sources of polyphenolics that have both antioxidant and anti-inflammatory properties, showed particular promise for inclusion in plant improvement programs designed to develop new varieties with nutraceutical potential.