An in vitro and in silico study of anti-dermatophytic activity of gossypol from fruits of Thespesia populnea (L.) Sol. ex Correa

Objective: To isolate, purify, and characterize gossypol from the fruits of Thespesia populnea (L) Sol. ex Correa, test its anti- dermatophytic activity, identify its targets on the dermatophyte, and confirm the binding of gossypol with the fungal target by molecular docking study. Methods: Gossypol from Thespesia populnea was characterized by high performance liquid chromatography, liquid chromatograph- mass spectrometry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The anti-dermatophytic activity of gossypol was tested against four different dermatophytes, viz. Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis, and Microsporum gypseum. Trichophyton mentagrophytes was selected for further studies. The inhibitory mode of action of gossypol on Trichophyton mentagrophytes was determined by analyzing the modulation of gene expression in various pathways of the dermatophyte. Results: Gossypol inhibited all the dermatophytes. The minimum inhibitory concentrations were 12.5 μg/mL for Trichophyton mentagrophytes and Microsporum canis and 25 μg/mL for Trichophyton rubrum and Microsporum gypseum. The minimum fungicidal concentrations were 50 μg/mL for Trichophyton mentagrophytes, 100 μg/mL for Microsporum canis and Trichophyton rubrum, and 200 μg/mL for Microsporum gypseum. Gossypol inhibited the mRNA expression of metalloprotease (MEP4) and isocitrate lyase (ICL). The binding of gossypol with the enzymes was confirmed by molecular docking studies. The best docking poses were found and the low binding energies were recorded with the two target enzymes. Conclusions: Gossypol is a potential antifungal agent and can be further explored as an anti-dermatophytic drug.

Salt mediated changes in some enzymes of carbohydrate metabolism in halotolerant Cladosporium sphaerospermum.

Cladosporium sphaerospermum, isolated from salt pans was halotolerant. When grown in the presence of salt, the activities of invertase, isocitrate lyase, fructose-1,6 diphosphate aldolase and malate dehydrogenase were found to be increased and that of amylase decreased. Both, enzyme activation as well as an increase in de novo synthesis of enzymes were found to be some of the mechanisms of salt mediated changes. This may be one of the adaptive mechanisms, in halotolerant Cladosporium sphaerospermum.

Embryonic control of isocitrate lyase activity in cotyledons of germinating soybean.

The activity of isocitrate lyase (EC 4.1.3.1) in the cotyledons of germinating soybean is controlled by the embryonic axis. Plant growth regulators like gibberellic acid, indole acetic acid and 2,4 dichlorophenoxy acetic acid are able to increase the enzyme activity in cotyledons of whole seedlings but not in dissected cotyledons. The control of induction of the enzyme activity during germination by the embryo could be mediated by the elaboration of kinetin.