Bioactivity guided isolation of analgesic and anti-inflammatory constituents of Cnestis ferruginea Vahl ex DC (Connaraceae) root

Ethnopharmacological relevance

Cnestis ferruginea (CF) Vahl ex DC (Connaraceae) is a shrub widely used in Traditional African Medicine (TAM) for the treatment of various painful and inflammatory conditions.

Aim of the study

To isolate the active pharmacological constituents responsible for the anti-inflammatory and antinociceptive properties of the methanolic root extract of C. ferruginea.

Materials and methods

The crude methanolic root extract of CF was sequentially fractionated into four sub extracts (chloroform, ethylacetate, n-butanol and the remaining aqueous fraction). The aqueous–butanol fractions, having showed significant inhibition of inflammation and pain, were subjected to fractionation through successive column chromatography on silica gel 60–120 mesh, eluted with a gradient of CHCl₃–MeOH.Sixty five fractions were collected; fractions with similar TLC profiles were grouped into seven major fractions (1–7). Fraction 4 being the most active in bioassay was rechromatographed to obtain CF-2. Analgesic activity was evaluated using the acetic acid-induced writhing and hot plate tests in mice while carrageenan induced paw oedema test was used to investigate the anti-inflammatory actions of the fractions obtained.

Result

Amentoflavone (CF-2) was isolated from the aqueous/n-butanol fraction. CF-2 (12.5, 25 and 100 mg/kg; p.o) produced significant (P<0.05) dose dependent inhibition of pain response elicited by acetic acid and increased nociceptive reaction latency in hot plate test. In addition it produced significant (P<0.05) dose-dependent inhibition of oedema in the carrageenan-induced inflammation.

Conclusion

This study showed that amentoflavone is responsible for the analgesic and anti-inflammatory activity of Cnestis ferruginea.