Anti-inflammatory and anti-nociceptive activities of essential oil of Waltheria indica

This paper reports for the first time volatile compounds, anti-nociceptive and anti-inflammatory activities of essential oils from the leaves of Waltheria indica L. (Stericullaceae) growing in Nigeria. The essential oil was hydro-distilled and characterized by gas chromatography-flame ionization detection (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS) analyses. The anti-inflammatory activity was evaluated on carrageenan induced rat paw edema while the anti-nociceptive test was based on hot plate model. The hydro-distillation afforded 0.41% (dry weight basis) of light green oil. Forty compounds representing 99.8% were identified in the oil. The main constituents of the oil were limonene (34.7%), sabinene (21.2%) and citronellal (9.7%). The anti-nociceptive property of the essential oils statically inhibited edema development (p<0.001) at a dose of 200 and 400 mg/kg independent of time of exposure. However, the 100 mg/kg Waltheria indica essential oils (WIEO) displayed a relatively low inhibition (p<0.01-p>0.5) which declines as exposure time increases. The anti-inflammatory activities shows a steady rate and non-dose dependent activity (p<0.001) up to the 3rd h of inflammation study. Conversely, a sharp reduction at the rate of p<0.5, 0.1 and 0.01 for the 100, 200 and 400 mg/kg WIEO doses respectively. Overall, the results presented sustain and establish the anti-nociceptive and anti-inflammatory properties and justifies the need for further evaluation and development of the essential oils from this plant.