Chemical Investigation and Therapeutic Significance of Essential Oils of Nigerian Plumeria acuminata Ait.

Adekemi Alade, Sherifat Aboaba, Prabodh Satyal, Olusegun Ekundayo and William Setzer

Background and Objective: Plumeria acuminata has a long history of use in traditional medicine which includes treatment of rheumatism, pruritic skin lesion, toothache, asthma, cracks on the feet sole crack, heart stroke, dysentery and diarrhoea. This study was designed to extract essential oils from the leaf, flower and root of P. acuminata, analyse the oils and evaluate their cytotoxicity and antimicrobial and antioxidant activities. Materials and Methods: Essential oils obtained from leaf, flower and root of P. acuminata by hydrodistillation were analyzed using the Gas Chromatography-Mass Spectrometry technique. The toxicity, antimicrobial and antioxidant activities of the oils were evaluated via brine shrimp lethality, agar well-diffusion and DPPH free radical-scavenging assays, respectively. Results: A total of 26, 85 and 12 constituents were identified in the leaf, flower and root oils corresponding to 70.0, 99.8 and 97.4% of the whole oils, respectively. The major components were β-eudesmol, 43.0% (root), nonanal, 20.0% (flower), palmitic acid, 27.6% (root) and linalool, 16.1% (leaf). The oils exhibited high toxicity with LC₅₀ less than 100 ppm, indicating they are biologically active. They also showed potent antimicrobial activities with an inhibition zone range of 1.7±0.2-22.1±0.1 mm when compared with the activities of standard drugs: Gentamycin (8.0±0.0-12.5±0.1 mm) and ketoconazole (10.3±0.4-21.0±1.4 mm). However, low antioxidant activities were demonstrated by the oils (IC₅₀ = 441-695 μg mL^–1) concerning the positive control, α-tocopherol (81.58 μg mL^–1) and butylated hydroxyanisole (45.11 μg mL^–1). Conclusion: The findings from this study suggest that P. acuminata essential oils are biologically active and could be natural sources of antibiotics.

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