Effect of harvest date on the yield and chemical composition of Croton gratissimus leaf essential oil

Abstract

Essential oils are sensitive and complex mixtures which are composed of volatile secondary metabolites. The chemical profile of essential oils harvested from a particular plant vary with different parameters such as climate, soil type, methods of extraction, geographical origin, plant part and harvest conditions. As such, it is of paramount necessity to profile the essential oils extracted under different conditions as this can determine their potential applications. This study explored for the first time, the chemical composition of Croton gratissimus essential oil extracted by hydrodistillation from fresh leaves harvested on different dates. There was no difference in the essential oil yields obtained from the leaves harvested on different dates. The chemical profiling using gas chromatography mass spectrometry showed that the most dominant component in the essential oils extracted from the leaves harvested on different dates was cis-muurola-4(15),5-diene although its percentage abundance varied significantly. The essential oil extracted from the leaves harvested on different days also showed significant variation in the percentage composition of other major compounds such as camphor, germacrene D, β-himachalene, caryophyllene, α-muurolol and aromadendrene. The most abundant class of secondary metabolites for the essential oils harvested on all dates studied was the sesquiterpenes which also varied significantly in its percentage composition. These results point to a significant variation in the chemical profile of essential oils harvested from the same plant on different dates. Consequently, it is important to determine the chemical profile of the leaves of Croton gratissimus as it can vary depending on the conditions.