The methanol extract and chemical constituents of Lupinus arboreus leaf were investigated for antinociceptive and anti-inflammatory activities. The study was by experimental design. The extract was partitioned to yield hexane, ethylacetate, and methanol fractions. Phytochemical tests were done on the extract and fractions. Acute toxicity test (LD50) was carried out on crude methanol leaf extract (CME). Extract hexane fraction (HEF), ethylacetate fraction (EAF) and methanol fraction (MEF) were subjected to bioactivity guided fractionation using mice tail immersion, hot plate, acetic acid- induced tests and formaldehyde- and, egg albumin-induced rat paw oedema, as activity guide for antinociceptive and anti-inflammatory studies respectively. The active constituents were isolated by bioactivity-guided silica gel column chromatography eluted with gradient mixtures. The isolated active compounds were characterized using a combination of phytochemical analysis, m.p. determination, UV, IR, NMR and GC/MS spectral analyses.
The intraperitoneal (i.p) LD50 of the crude methanol extract was 84.85 mg/kg. Phytochemical analysis of the methanol extract indicated the presence of steroids, flavonoids, glycosides, terpenes and saponins. Tannin, resin, reducing sugar and protein were moderately present. The hexane fraction contained steroids and terpenes while ethylacetate fraction contained flavonoids and glycosides. Two active compounds AHF1 and AHF2 were obtained from the hexane fraction while AEF1 was obtained from the ethyl acetate fraction. The AHF1 contained steroids. while AHF2 contained terpenes; AEF1 contained flavonoids.
The crude methanol extract (CME) (30 and 60 mg/kg,) i.p produced dose-related resistance against thermal pain and significant (p 0.05). The oedema inhibition recorded by HEF and EAF were higher than the inhibition by aspirin (100 mg/kg).
The CME (30 and 60 mg/kg) significantly inhibited formaldehyde- induced arthritis, in a dose-related, manner over a period of 4 hours (p
