Anti-nociceptive Property, Anti-inflammatory Activity and Constituents of Essential Oils from the Leaves and Stem Bark of Turnera diffusa Wild (Passifloraceae) Growing in Nigeria

Abstract

Because of the need to source biologically active products from plants, this paper reports the chemical compounds, anti-nociceptive and anti-inflammatory activities of essential oils hydrodistilled from the leaves and stem bark of Turnera diffusa Wild (Passifloraceae). The essential oils were separately isolated using hydrodistillation of the pulverized (360 g of leaf and 316 g of stem bark) materials in an all-glass Clevenger- type apparatus and characterized by GC-FID and GC-MS. The hot plate method was used to determine the anti- nociceptive property while the anti-inflammatory activity was established using the Carrageenan induced paw edema model. The yields of the essential oils were 0.19% (v/w, yellow, leaf) and 0.28% (v/w, colorless, stem bark), calculated on a dry weight basis. The leaf oil consists mainly of β-caryophyllene (43.7%) and germacrene B (21.3%) while geranial (50.7%) and neral (33.6%) were the main constituents of the stem bark oil. In our study, we found that the essential oils of T. diffusa (100, 200, and 400 mg/kg) exhibited an anti-nociceptive effect at all observation periods at a significance of p<0.001 for both the leaves and stem bark. The essential oil from the stem bark showed high anti-inflammatory activity (p<0.001) at the 1st to the 4th h for all the essential oil doses while the leaves of T. diffusa inhibited inflammation up to the 3rd h post-treatment, but were non-significant at the 4th h for all doses. The results indicate the potential of the essential oils in pain-relieving activities.