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Nsuala, B., Kamatou, G.P.P., Sandasi, M., Enslin, G., Viljoen, A.M. 2017. Variation in essential oil composition of Leonotis leonurus, an important medicinal plant in South Africa. Biochemical Systematics and Ecology 70: 155-161.
Leonotis leonurus has been widely used by traditional
healers in southern Africa for treatment of various ailments and is well known
for its reported psychoactive properties. The present study was undertaken to
investigate the variation in essential oil composition between geographically
distinct populations of L. leonurusin South Africa using gas chromatography. Plant material (n = 50) was collected from three provinces of South Africa. Essential
oils of the aerial parts were obtained by hydrodistillation and analysed using
one and two dimensional gas chromatography. Twenty-six compounds accounted for
more than 80% of the total composition of the oil. Eight major constituents in
the oil, representing about 50% of the total oil composition, were identified by
both GC–MS–FID and GCxGC–ToF–MS. These major
compounds were trans-?-ocimene (0.1-5.0%),cis-?-ocimene (0.1-31.5%), ?-caryophyllene
(0.3-15.0%), caryophyllene oxide (0.1-5.0%), ?-humulene (0.4-18.2%), ?-elemene
(0.4-10.6%), ?-cubebene (0.2-12.0%) and germacrene D (0.1-22.1%). The study
showed marked similarities in the essential oil composition between populations
and revealed mostly quantitative differences using the GC–MS–FID method, while
data revealed both quantitative and qualitative differences in the essential
For the holistic assessment
of chemical patterns within the data, untargeted multivariate analysis was
performed using SIMCA-P+ 14.0. PCA and OPLS-DA methods identified two distinct clusters,
where inland samples separated from coastal collections.