Chemical composition, anti-nociceptive and anti-inflammatory activities of essential oil of Bougainvillea glabra

Ethnopharmacological relevance: Bougainvillea glabra is widely used in Nigeria for the treatment of inflammatory-related conditions, and as remedy for pain ailments. Aim of the study: Considering the lack of scientific studies focused on chemical constituents and pharmacological activity of B. glabra essential oil, this work was designed to characterize the volatile compounds and evaluate the anti-inflammatory and anti-nociceptive properties ascribed to this plant species. Materials and methods: The essential oil was extracted from the leaf of B. glabra by hydrodistillation in an all glass Clevenger-type apparatus and characterized by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS) on HP-5 column. The anti-inflammatory property of the essential was established by measurement of carrageenan induced rat paw edema while the anti-nociceptive activity was determined by hot plate test, according to established procedures. Results: The essential oil was obtained in a yield of 0.08% (v/w) calculated on dry weight basis. A total of 11 compounds representing 96.2% of the oil contents were identified by GC/MS. The main constituents of the essential oil were (E)-nerolidol (31.4%), (E)-beta-ionone (10.3%) and linalool (10.1%). The anti-nociceptive property of the essential oil was statistically significant p < 0.001 at all doses of when compared to the control while exhibiting an activity in tandem with the standard drug. For the 1st and 2nd h, at doses of 100 and 200 mg/kg, the anti-inflammatory activity was statistically very significant (p < 0.001), while at 3rd h the activity declined (p < 0.01) at a dose of 200 mg. The activity was non-significant at the 4th h experimental duration. Conclusions: This is first report on the chemical constituents and biological activity of essential oil of B. glabra from Nigeria. Overall, the results herein presented sustain and strengthen the anti-nociceptive and anti-inflammatory properties traditionally ascribed to B. glabra.