Lantadenes are pentacyclic triterpenoids present in the leaves of the plant Lantana camara. In the present study, in vitro antioxidant activity and free radical scavenging capacity of lantadene A was evaluated using established in vitro models such as ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH•), hydroxyl radical (OH•), nitric oxide radical (NO•), superoxide anion scavenging activities and ferrous ion chelating assay. Interestingly, lantadene A showed considerable in vitro antioxidant, free radical scavenging capacity activities in a dose dependant manner when compared with the standard antioxidant in nitric oxide scavenging, superoxide anion radical scavenging and ferrous ion chelating assay. These findings show that the lantadene A possesses antioxidant activity with different mechanism of actions towards the different free radicals tested. Since lantadene A is a very popular drug in modern medicine, it is a promising candidate for use as an antioxidant and hepatoprotective agent.
The endophytic fungi isolated from leaves of Ocimum sanctum Linn. of different ages were examined for antimicrobial activity. The agar plug diffusion assay was used for primary screening. A total of 148 fungal endophytes were successfully isolated and cultured but only 134 of them (90.5%) exhibited inhibitory activity towards at least one test microorganisms. Moreover, the colonization rate indicated that the old leaves were frequently and densely colonized by endophytes. The results suggested that healthy leaves at older stages of growth can be a potential source for the isolation of endophytic fungi with antimicrobial properties. The ethyl acetate extract prepared from the fermentative broth exhibited better antimicrobial activity and it suggested the antimicrobial activity of the isolates was affected by the culture medium. A better antimicrobial activity was observed in the yeast extract sucrose broth as compared to malt extract broth. Significant improvements in the antimicrobial activity of the crude extract were observed after addition of water extract of the host plant in the culture medium.
Introduction: Foodborne disease is a serious public health problem worldwide and most of the disease is related to food spoilage by bacteria. Thus, there is a need for the discovery of a natural antibiotic to inhibit these foodborne bacteria. Materials and Methods: Disk diffusion and broth microdilution assays were performed to access the antibacterial activity of the fungal extracts against test bacteria. Meanwhile, the scanning electron microscope (SEM) was employed to study the structural degeneration of bacterial cells exposed to the extracts. Results: The ethyl acetate extract of Lasiodiplodia pseudotheobromae IBRL OS-64 demonstrated favorable antibacterial activity towards all test bacteria with inhibition zone ranged from 15.0 mm to 26.0 mm. All test bacteria were resistant to hexane and butanolic extracts. Minimum inhibition concentration (MIC) values of the ethyl acetate extract between 62.5 µg/mL to 500 µg/mL whereas minimum bactericidal concentration (MBC) was in the range of 125 µg/mL to 2000 µg/mL. The SEM micrographs exhibited major abnormalities that occurred on the bacterial cells after exposure to the extract with alteration in their morphology and cell death beyond repair. Conclusion: The extracts of L. pseudotheobromae IBRL OS-64 may be an effective antibacterial agent to treat foodborne bacteria.
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