Antifungal Activity on the Strain of Lasiodiplodia theobromae and Phytochemical Study of Ageratum conyzoides and Newbouldia laevis from the Kisangani Region / DR Congo
J. T. K. Kwembe
Department of Chemistry, Faculty of Sciences, University of Kisangani, B.P. 2012 Kisangani, R D Congo.
J. P. Mbula
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.
G. Haesaert
Department of Plants and Crops, Faculty of Engineering Biosciences, Ghent of University, Ghent 9000, Belgium.
*Author to whom correspondence should be addressed.
Abstract
Aims: To extract, identify and evaluate in vitro the antifungal activity of the phytochemical groups of Ageratum conyzoides and Newbouldia laevis on the strain of Lasiodiplodia theobromae.
Study Design: Exploitation of medicinal plants to combat the growth of L. theobromae, responsible for the decline of cocoa cultivation.
Location and Duration of Studies: Faculty of Sciences, University of Kisangani, between April 2017 and February 2018.
Methodology: The crude extracts of the dry leaves of A. conyzoides and N. laevis were tested (at 100 mg/mL). Potato dextrose agar was used as the culture medium. After chemical screening, abundant phytochemical groups were isolated and tested.
Results: The aqueous, 95% ethanolic and ethereal crude extracts of A. conyzoides are more antifungal (respective percentages of inhibition PI: 80.74; 84.10 and 85.64%) than those of N. laevis (63.28; 72.64 and 75.23%). The minimum inhibitory concentration (MIC) of the aqueous crude extract of A. conyzoides is lower (25 mg/mL) than that of the ethanolic extract (50 mg/mL). Tannins are very abundant in A. conyzoides and in N. laevis. Saponins, sterols and terpenes are abundant in both plants. The extraction yields of tannins and saponins are respectively 20.67 and 2.43% in A. conyzoides and 10.47 and 2.38% in N. laevis. A. conyzoides contains the gallic tannins while N. laevis, the condensates and catechics. The saponins and tannins of A. conyzoides are more antifungal (respective PI: 84.40 and 54.44%) than those of N. laevis (PI: 75.56 and 32.96%).
Discussion: The saponins of A. conyzoides and N. laevis are more active on the strain of L. theobromae than the tannins. Saponins are surfactants that can destabilize membrane structure of microorganisms including fungi.
Conclusion: The saponins of the two plants have shown a very interesting antifungal power on the strain of L. theobromae. The identification of their active molecules is ongoing.
Keywords: Antifungal, Lasiodiplodia theobromae, Ageratum conyzoides, Newbouldia laevis, phytochemical.