The cell growth and cell cycle inhibitory properties of the bacterial metabolites kinamycin A and kinamycin C were investigated in an attempt to determine their mechanism of action and to develop these or their analogs as anticancer agents. Both kinamycin A and kinamycin C have a highly unusual and potentially reactive diazo group. Even with short incubations, both the kinamycins were shown to have very potent cell growth inhibitory effects on either Chinese hamster ovary or K562 cells. Kinamycin C induced a rapid apoptotic response in K562 cells. The cell cycle analysis results in synchronized Chinese hamster ovary cells treated with kinamycin A revealed that they only displayed a G1/S phase block upon entry to the second cycle. Both kinamycins inhibited the catalytic decatenation activity of DNA topoisomerase IIalpha, but neither kinamycin acted as a topoisomerase II poison. Their inhibition of catalytic activity was not correlated with cell growth inhibitory effects. Pretreatment of the kinamycins with dithiothreitol protected the topoisomerase IIalpha activity, which suggested that they may be targeting critical protein sulfhydryl groups, either through reaction with the quinone or with an activated electrophilic diazo group. Neither kinamycin A nor kinamycin C intercalated into DNA, nor were they able to cross-link DNA. Although the cellular target(s) of the kinamycins has yet to be identified, the cluster map analysis, and the cell cycle and proapoptotic effects suggest that kinamycin C has a target different than other established anticancer compounds.
The bacterial metabolite kinamycin F, which is being investigated as a potent antitumor agent, contains an unusual and potentially reactive diazo group as well as a paraquinone and a phenol functional group. Kinamycin F reacted with glutathione (GSH) in a complex series of reactions which suggested that kinamycin F may have its cytotoxicity modulated by GSH. Consistent with this idea 2-oxo-4-thiazolidinecarboxylic acid treatment to increase cellular GSH levels and buthionine sulfoximine treatment to decrease GSH levels resulted in decreased and increased kinamycin F cytotoxicity, respectively, in K562 leukemia cells. Kinamycin F weakly bound to DNA and induced DNA damage in K562 cells that was independent of GSH levels. The GSH-promoted DNA nicking induced by kinamycin F in vitro was attenuated by deferoxamine, dimethyl sulfoxide, and by catalase, which indicated that DNA damage initiated by this agent occurred in an iron-, hydrogen peroxideand hydroxyl radical-dependent manner. Electron paramagnetic resonance spectroscopy experiments showed that the GSH/kinamycin F system produced a semiquinone free radical and that the hydrogen peroxide/peroxidase/kinamycin F system generated a phenoxyl free radical. In conclusion, the results indicated that kinamycin F cytotoxicity may be due to reductive and/or peroxidative activation to produce DNA-and protein-damaging species.
Phytochemistry and antibacterial potency of some crude and partially purified fractions of Senna alata flower was examined against 22 bacterial strains. The crude plant extracts, containing steroids, anthraquinone glycosides, volatile oils and tannins, exhibited a high minimum inhibitory concentration of 500 mg/mL against Staphylococcus aureus, Streptococcus faecalis, Micrococcus luteus, Bacillus subtilis and Pseudomonas putida, but was generally inactive against Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens, and Pseudomonas fluorescens (above 1000 mg/mL). However, the partially purified plant extract was bacteriostatic at a low concentration of 100 mg/mL, with a minimum bactericidal concentration of 500 mg/mL, primarily against the Gram positive organisms. At a concentration slightly above the minimum inhibitory concentration, the purified extract was nearly as potent as standard antibiotics, exhibiting zones of bacterial growth inhibition ranging from 10 to 25 mm, even against multiple antibiotic resistant local isolates that were not susceptible to methicillin, penicillin and streptomycin.
A study was conducted to assess the effectiveness of pulsed electric field (PEF) inactivation of a heterogeneous community of microbes. The aim was to assess the impact of process parameters on an indigenous population of microbes present in milk, rather than pure cultures used in other studies. Tests over an electric field strength range of 10 -40 kV/cm and 10 to 120 pulses per millilitre showed that high electric field strength and pulse number inactivated microbes by up to approximately 2 log. Inoculum size affected PEF effectiveness when only a few pulses were applied. A significant log-reduction was achieved against the indigenous microbes found in milk that were apparently recalcitrant to commercial pasteurization. Microbial inactivation was more extensive when E. coli was not added to the indigenous population, indicating that the added pure culture was more resistant than the indigenous microbes. The milk fat content had a significant negative effect on the extent of log-reduction for indigenous microbes, when 2% and 18% levels were compared.
Background: Black soap is a medicinal product that could be harnessed for economic purpose if properly packaged, and misconception about its traditional use by herbalists is thrown overboard.Aims: To promote the relevance of these soaps for economic development, this study compared the antibacterial activity of black soaps with medicated soaps widely used against bacterial infections.Methods: The antibacterial activities of these soap samples were determined by agar diffusion and macrobroth dilution methods.Results: In this study, the statistical analysis of the inhibition zones showed that black soaps were significantly (p < 0.05) more active than medicated soaps used against the test bacterial isolates. The black soaps inhibited and killed the isolates better than the medicated soaps at the different concentrations used. The minimum inhibitory concentration for Klebsiella pneumoniae and Enterococcus faecalis ranged between 0.125 mg/mL and 2 mg/mL, Staphylococcus aureus (0.25–4) mg/mL, Escherichia coli (0.125–4) mg/mL and Pseudomonas aeruginosa (1–4) mg/mL. The result showed that K. pneumoniae and E. faecalis were the most susceptible, followed by E. faecalis > E. coli > S. aureus > P. aeruginosa.Conclusion: As a valuable medicinal output derivable from organic waste product that could be converted to wealth, African black soap production, utilisation and commercialisation have tremendous economic potentials. These soaps showed significant antibacterial activity greater than those of the medicated soaps. Hence, their use could be a better option in place of commercially available medicated and antiseptic soaps because of the degree of antibacterial activities they exhibited.
Aqueous extract of the dormant fruits derived from Hyphaene thebaica was tested for in vitro antifungal activity using the agar dilution method. The extract was found to produce significant antifungal activity against a wide range of fungal isolates including Candida albicans, Microsporum gypseum, Trichophyton rubrum, Mucor sp., Fusarium solani and Aspergillus niger. The minimum inhibitory concentration of the extract ranged between 3.1 to 25% v/v. The dermatophytic fungi (Microsporum gypseum and Trichophyton rubrum) were more susceptible to the antifungal effects of the extract (MIC 3.1) while Candida albicans found to be least susceptible (MIC 25). The findings indicate that this material may have value in the treatment of fungal diseases, pending the results of further studies.
Antifungal activity of some components of Senna alata flower was examined against five fungi. The methanolic crude extract and the partially purified fractions were both active against standard strains of Aspergillus niger, Geotricum candidum, and Candida utilis, and local isolates of Aspergillus brevipes and Penicillium species, but at different concentrations. The minimum inhibitory concentration of the methanolic crude extract was low for all the fungal strains except Aspergillus niger with 5.0 mg/mL concentration, while the minimum inhibitory concentration of partially purified components (C and F) ranged between 0.312 mg/mL for extract F against Penicillium species and 2.5 mg/mL for extract C against Aspergillus niger, Penicillium species and Candida utilis. The minimum fungicidal concentration of the crude methanolic extract was generally higher than 5 mg/mL for most of the fungi but the partially purified extract exhibited fungicidal concentrations ranging from 2.5 mg/mL to 5.0 mg/mL. Antifungal properties against mycelial growth was also demonstrated by all the extracts against the tested strains, with the crude methanolic extract losing its activity after 48 hours. The partially purified Senna alata extracts exhibited a relatively high antifungal activity against mycelial growth with total suppression of sporulation for four days at a concentration of 2 mg/mL, while preventing fungal growth after the seventh day.Pharmaceutical Biology Downloaded from informahealthcare.com by Nanyang Technological University on 08/23/15For personal use only.
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