In vitro antifungal activity of Dorstenia mannii leaf extracts (Moraceae)

Abstract

The leaves of Dorstenia mannii are used in traditional medicine in Cameroon and other African countries for the treatment of infectious diseases like malaria, skin rashes and stomach disorders. To substantiate this folkloric claim, the crude methanol extract and fractions from the leaves of D. mannii were investigated for their antifungal activity. The crude methanol extract was prepared from powdered dried leaves of the D. mannii. A portion was subjected to flash liquid chromatography on silica gel to afford test fractions. All test samples were screened for major groups of phytochemicals.Test samples and nystatin (reference) were evaluated for antifungal activity on ten yeasts using agar disc diffusion and broth microdilution methods. The qualitative analysis of crude methanol extract and fractions of D. mannii leaves revealed the presence of flavonoids, phenols, steroids and cardiac glycosides. In agar disc diffusion assay, seven of the ten pathogenic fungal strains were sensitive to the crude methanol extract (7/10), n-hexane ethyl-acetate (Hex-EA) (75%) (8/10) and ethyl-acetate (100%) (8/10). The minimum inhibitory concentrations (MICs) for the test samples varied from 80 to 1280 µg/ml. The crude extract and ethyl-acetate (100%) were the most active plant samples with both fungistatic and fungicidal effects (MIC/MFC values from 80 to 640 µg/ml) though not as the reference drug. Candida tropicalis was the least sensitive to the test samples. Some fractions exerted no fungicidal actions on Cryptococcus neoformans, Candida lusitaniae and Candida tropicalis. The present work shows that the crude methanol extract and fractions (n-hexane, ethyl acetate and residue) from the leaves of D. mannii possess growth inhibitory effect on pathogenic yeast. The active ingredients of this plant could be an addition to the antifungal arsenal to opportunistic fungal yeast pathogens.

Phytochemical and Pharmacological Studies on Species of Dorstenia Genus (2000-2016)

“…Other species have been marketed to be used as medicinal plants, such as D. ciliata, which yielded from the aerial parts two new prenylated flavones, ciliatins A (73) and B (85) [14], as well as isobavachalcone (44), stipulin 47 (42) were also found in the twigs of the Cameroonian D. turbinate [27]. Other three new prenylated chalcones were found in the twigs of D. angusticornis, which were named as angusticornin A (55), B (50), and C (91), plus stipulin (47), gancaonin Q (70), paratocarpin C (56), and paratocarpin F (79) [26,28].…”

“…Normally, the biological activity data are first obtained for the extracts analyzed in a panel of bioassays, and later the pure compounds isolated from those extracts are tested, but some studies directly describe the biological activity of pure compounds without previous research on the extracts. [27,[41][42][43][44][45][46].…”

“…Continuing on the microbicidal research, the report of Dzoyem et al (2013) showed the activity and mechanism of action of four prenylated flavonoids, 6,8-diprenyleriodictyol (68), yielded from the aerial parts of D. mannii, isobavachalcone (44) and 4-hydroxylonchocarpin (42), isolated from the twigs of D. barteri, and 6-prenylapigenin (64), from the twigs of D. dinklagei, against eight strains of MRSA (methicillinresistant Staphylococcus aureus). The results showed 6,8-diprenyleriodictyol (MIC = 0.5-4.0 μg/mL) to be more active, followed by isobavachalcone (MIC = 0.5-16.0 μg/mL) and 4-hydroxylonchocarpin (MIC = 1-8 μg/mL), while 6-prenylapigenin (MIC = 16-64 μg/mL) being the least active.…”

“…The CH2Cl2/CH3OH (1:1) extract from D. barteri var. multiradiata and their isolated flavonoids isobavachalcone (44), kanzonol C (46), 4-hydroxylonchocarpin (42), stipulin (47), and amentoflavone (89) were tested for antimycobacterial, antigonorrheal and anti-reverse transcriptase activities (anti-VIH). The antireverse transcriptase activity was significantly lower for all the samples analyzed than the reference compound doxorubicin, however, isobavachalcone did it well or even better in comparison to the reference drug used in the antimycobacterial (ciprofloxacin and isoniazid) and antigonorrheal (gentamycin) tests, with MIC's less than 10 μg/mL for all the strains tested [68].…”

“…The anticancer potential of secondary metabolites isolated from Dorstenia species has also been studied multiple times. The prenylated flavonoids kanzonol C (46), 4-hydroxylonchocarpin (42), isobavachalcone (44), paratocarpin C (56), stipulin (47) and dorsmanin A (41) of D. barteri var. multiradiata [71] and D. turbinata [72] showed that were even better than the two reference compounds (chlorogenic acid and epigallocatechin-3-gallate) to inhibit matrix metalloproteinase (MMP-2) from U87 glioblastoma cells.…”