Essential oils composition of Ocimum basilicum L. and Ocimum gratissimum L. from Kenya and their inhibitory effects on growth and fumonisin production by Fusarium verticillioides

This work investigated the constituents and the efficacy against Fusarium verticillioides infection and fumonisin production of essential oils of Ocimum basilicum L. and Ocimum gratissimum L. from different locations in Kenya. The oil of leaves and flowering tops of O. basilicum from Sagana contained mainly linalool (95%). The flowering tops and leaves from Yatta contained mainly camphor (32.6 and 31.0%, respectively) and linalool (28.2 and 29.3, respectively). Eugenol was the main constituent in the oil of O. gratissimum leaves from both Sagana (95.5%) and Yatta (70.1%). The oil of the flowering tops had significantly less eugenol. The main component of the oil of flowering tops from Yatta was Z-β-ocimene (34.1%). Oil from both species had some antifungal activity. The oils of O. basilicum and O. gratissimum from different locations showed chemical variation, antifungal activity, free radical scavenging capacity and antimycotoxicogenic property. These properties are attributed to the phenolic compound eugenol. Industrial relevance: This manuscript gives the chemical composition and some biological effects of essential oil of two Ocimum species in Kenya namely Ocimum basilicum L. and Ocimum gratissimum L. The work reveals that there are chemovarieties of these plants in different locations in the country. Of significance is the presence of very high amounts of linalool in one chemovariety of O. basilicum while geranial and neral are major in another. The third variety contains almost equal amounts of camphor and linalool. The first two containing high quantities of linalool, geranial and neral could be cultivated after agronomic studies to provide essential oils useful in perfumery, soap or food industry while that containing camphor and linalool may find use in medicine. Proper seed selection and good agricultural practice for O. gratissimum containing high amount of eugenol could serve as good substitute for cloves which grows best only in a few islands in East Africa. Clove oil due to its high eugenol content has many biological activities including those demonstrated in the present work, and many applications in medicine and commercial world. There is need for more research on these plants especially on cultivation and commercial exploitation of the herbs.