Chemical Composition of Essential Oil of Ageratum conyzoides with Antifungal Activity on the Lasiodiplodia theobromae Strain in the Region of Kisangani and DR Congo
J. T. K. Kwembe
Department of Chemistry, Faculty of Sciences, University of Kisangani, B. P. 2012 Kisangani, R D Congo.
O. Onautshu
Department of Biotechnological Sciences, Faculty of Sciences, Kisangani of University, B. P. 2012 Kisangani, R D Congo.
P. T. Mpiana *
Department of Chemistry, Faculty of Sciences, University of Kinshasa, B. P. 190 Kinshasa XI, R D Congo.
Pieter Vermeir
Department of Green Chemistry and Technolog, Faculty of Bioscience Engineering, Ghent of University, Ghent 9000, Belgium.
G. Haesaert
Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent of University, Ghent 9000, Belgium.
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine the chemical composition of essential oil of Ageratum conyzoides with antifungal activity on the strain of Lasiodiplodia theobromae in the Kisangani region.
Location and Duration of Studies: Faculty of Sciences of University of Kisangani (Democratic Republic of Congo) and Faculty of Biosciences Engineering of University of Ghent (Belgium), between May to November 2019.
Methodology: The essential oil from the leaves of A. conyzoides was extracted by hydrodistillation. Potato dextrose agar (PDA) was used as a culture medium. In vitro evaluation of its antifungal activity was performed on PDA medium and expressed as percentage of inhibition (PI).
Results: The extracted essential oil (with a yield of 0.63%) showed a PI of 91.63% on the strain of L. theobromae after two days of incubation. It consists of at least 23 compounds, of which seven are in the majority (abundances greater than 1.5% and represent 92.05%), namely Precocene I (38.33%), Beta-caryophyllene (26.51%), Beta-sesquiphellandrene (8.63%), Beta-cubebene (7.91%), Alpha-muurolene (4.95%), 1.5.9.9-Tetramethyl-1.4.7-cycloundecatriene (3.04%), Cis-beta-farnesene (2.99%). The hydrocarbon sesquiterpenes are the most frequent compounds (58.95%).
Discussion: Compared to the A. conyzoides saponins the PI obtained from the essential oil is higher. The essential oil chemotype obtained from the leaves of A. conyzoides is of the Precocene I type, similar to the oils from the stems and flowers of the same plant in West Africa.
Conclusion: The essential oil of A. conyzoides has a very high inhibitory power on L. theobromae. It mainly contains the Precocene and the hydrocarbon sesquiterpenes. Assessment of the antifungal activity of each separate molecule should be considered.
Keywords: Ageratum conyzoides, Lasiodiplodia theobromae, Essential oil, Antifungal activity, Chemotype.