Suppression of cytokine production by newly isolated flavonoids from pepper

Abstract

New flavonoid glycoside, kaempferol 3-O-α-[(6-P-coumaroyl galactopyranosyl-O-β-(→4)-O-α-rhamnopyranosyl-(1→4)]-O-α-rhamnopyranoside 1, in addition to five known flavonoid glycosides (2–6) kaempferol 3-O-[α-rhamnopyranosyl-(1→4)-O-α-rhamnopyranosyl-(1→6)-O]-β-galactopyranoside (kaempferol 3-O-β-isorhamninoside) 2, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1 → 6)-β-galactopyranoside 3, quercetin 3-O-[(2,4-diacetyl-α-rhamnopyranosyl)-(1 → 6)]-3,4-diacetyl-β-galactopyranoside 4, quercetin 3-O-[(2,4-diacetyl-α-rhamnopyranosyl)-(1→6)]-2,4-diacetyl-β-galactopyranoside 5, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1 → 6)-3-acetyl-β-galactopyranoside 6 were isolated from bell pepper (Capsicum annum L.) fruits and tested for both anti-inflammatory activity through cytokine production (TNF-α and IL-1β) and antioxidant activity through scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Compounds 1–3 significantly suppressed production of TNF-α / IL-1β in cultured THP-1 cells previously co-stimulated by LPS in a dose-dependent manner (10.2/49.1, 28.1/55.7, and 35.2/57.5 μM respectively) whereas compounds 4–6 have relatively weaker inhibitory activity. (45.3/73.5, 48.2/65.6, and 42.2/67.4 μM respectively). All compounds 1–6 showed no cytotoxic activity against the growth of THP-1where the percentage of cell viability was (127.4, 108.5, 105.4, 103.9, 103.4, and 104.2 μM respectively). All isolated compounds exhibited higher radical scavenging activity than ascorbic acid in (DPPH) assay. These results indicated that bell pepper fruits could be an effective candidate for ameliorating inflammatory-associated complications.