Anti-inflammatory and antioxidant activities of the root and bark extracts of Vitex grandifolia (Verbanaceae)

Abstract

Medicinal plants form the basis for many medical treatments and a precursor for most drugs. This study examined the anti-inflammatory and antioxidant properties of the root and bark extracts of Vitex grandifolia. Soxhlet extraction was used to obtain the crude extracts. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide and phosphomolybdenum (PM) assays were used to evaluate antioxidant properties. Total phenolic content determination was by the Folin Ciocalteu method. The carrageenan-induced paw edema model in day-old chicks was used to evaluate anti-inflammatory activity. The root and bark ethanolic extracts displayed similar antioxidant activities in the DPPH and PM assays. The bark extract was a better anti-oxidant than the root extract in the hydrogen peroxide assay with an inhibition concentration of 218.90 µg/mL. Both extracts showed similar levels of phenolic compounds, with values of 5.72 ± 1.96 and 5.09 ± 2.25 g/100g gallic acid equivalent (GAE) for root and bark extracts respectively. For anti-inflammatory action, the bark extract, with a half maximal effective dose (ED50) of 34.48 ± 6.00 mg/kg, proved superior to root extract (ED50 of 76.90 ± 7.76 mg/kg). The bark extract which gave the best anti-inflammatory activity was fractionated using butanol, ethyl acetate and hexane to identify the fraction in which the anti-inflammatory principles were concentrated. The ED50 for the fractions were in the order ethyl acetate < hexane < butanol. The results obtained showed that both root and bark extracts were potent anti-inflammatory and anti-oxidant agents and validates their use in folkloric medicine for treating inflammation-related diseases.