In vitro evaluation of antifungal activity of Ageratum conyzoides, Basella alba and Mitracarpus villosus on the strain of Lasiodiplodia theobromae in the Kisangani Region / D R Congo

ABSTRACTFollowing our previous investigations relating to the in vitro evaluation of antifungal activity, this study focused on the demonstration of the inhibitory power of extracts of fresh and dry leaves of Ageratum conyzoides, Basella alba and Mitracarpus villosus on the strain of Lasiodiplodia theobromae, fungus responsible for brown rot of cocoa pod in the Kisangani region. In six repetitions on the Patato dextrose agar medium, the strain of L. theobromae was inhibited up to 68.1% by the aqueous extract of B. alba; 60.0% by the ethanolic extract of A. conyzoides and 55.2% by the ethanolic extract of M. villosus (all obtained from dry leaves). Only the fresh leaves of the aqueous (56.7%) and ethereal (51.1%) extracts of A. conyzoides showed high inhibition percentages compared to those of the extracts of the fresh leaves of B. alba and M. villosus. The extracts of the dry leaves showed high inhibition percentages followed by those of the fresh leaves and finally those of crude extracts after two days of incubation. Thus, in addition to the expected results, the plants studied are all active. These inhibitory powers could be very high for the secondary metabolites of the respective plants.

Download Full-text

Antifungal Activity on the Strain of Lasiodiplodia theobromae and Phytochemical Study of Ageratum conyzoides and Newbouldia laevis from the Kisangani Region / DR Congo

International Journal of Pathogen Research ◽

10.9734/ijpr/2020/v5i430138 ◽

2020 ◽

pp. 1-10

Author(s):

J. T. K. Kwembe ◽

J. P. Mbula ◽

O. Onautshu ◽

P. T. Mpiana ◽

G. Haesaert

Keyword(s):

Antifungal Activity ◽

Culture Medium ◽

Inhibitory Concentration ◽

Ethanolic Extract ◽

Ageratum Conyzoides ◽

Phytochemical Study ◽

Lasiodiplodia Theobromae ◽

Chemical Screening ◽

Crude Extracts

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.

Download Full-text

Chemical Composition of Essential Oil of Ageratum conyzoides with Antifungal Activity on the Lasiodiplodia theobromae Strain in the Region of Kisangani and DR Congo

Archives of Current Research International ◽

10.9734/acri/2021/v21i130222 ◽

2021 ◽

pp. 12-23

Author(s):

J. T. K. Kwembe ◽

O. Onautshu ◽

P. T. Mpiana ◽

Pieter Vermeir ◽

G. Haesaert

Keyword(s):

Chemical Composition ◽

Antifungal Activity ◽

Essential Oil ◽

Democratic Republic Of Congo ◽

Ageratum Conyzoides ◽

Lasiodiplodia Theobromae ◽

Inhibitory Power ◽

Separate Molecule ◽

Very High

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.

Download Full-text