Chemical Diversity of Lippia multiflora Essential Oils from West Africa

Abstract

The essential oil content, composition and the physicochemical properties of Lippia multiflora leaves from twelve different regions in Ghana were characterized in this study. The Ghanaian oils showed a significant variability in their chemical composition and five chemotypes were identified. The oil from Aframso Bridge was yellow with a refractive index (RI) of 1.4853, density (DE) of 0.894 and was dominated by linalool (29%) and germacrene D (28%) with fresh, and slightly medicinal and spicy aroma. Ghanaian samples from Seikwa, Buem Nsuta and Golokwati were characterized by high levels of sesquiterpenes (45–70%). The aroma was medicinal/herbaceous and the color was typically yellow, except the oil from Seikwa which was dark orange-yellow, RI ranging from 1.4920 to 1.5043 and DE 0.893 to 0.93 D. The oils from Nyankpala, Sari, Amantin, Atebubu and Kobre contained high levels of aromatic monoterpenes (p-cymene 14–19%, thymol 30–40%, and thymyl acetate 14–17%). The oils were characterized as spicy and the color ranged from dark yellow (Nyankpala, Sari and Kobre) to yellow (Atebubu and Amantin) (RI 1.4969 to 1.5020, DE 0.9207 to 0.9344). The oil from Ho showed lower levels of aromatic monoterpenes and higher levels of farnesol, the oil was yellow and aroma woody/camphoraceous (1.492 RI, 0.893 D). In contrast, oils from Nsawkaw and Kofiase-Kubesiase were composed of high amounts of 1,8-cineole (43–47%), sabinene (12–15%, respectively), and were light yellow (RI 1.4695 to 1.4712, DE 0.8995 to 0.9002). A cluster analysis was performed for comparison and characterization of L. multiflora oils from Ghana other 33 oils from 10 African countries. The oils from Ghana with these five chemotypes appeared to be the most diverse oils in Sub-Saharan Africa.