A library of six novel phenylhydrazones were synthesized and evaluated for their in vitro antimicrobial and resistance modulating activity against a panel of Gram-positive, Gram-negative, and fungal species. The compounds were produced in good yields of 60–92% w/w and characterized using melting point, UV-visible spectroscopy, infrared, and nuclear magnetic resonance (1H, 13C, and DEPT-Q) techniques. Mass spectroscopy was used to confirm the identity of one of the most active compounds, 5 [SA5]. The phenylhydrazones showed activity against all the six selected microorganisms with minimum inhibitory concentration (MIC) values of the most active compounds, 1 [BP1] and 5 [SA5], at 138 µM (Klebsiella pneumoniae) and 165 µM (Streptococcus pneumoniae), respectively. Compound 1 [BP1] further demonstrated a high resistance modulatory activity at 1.078 µM against Streptococcus pneumoniae and Klebsiella pneumoniae.
The most common diseases that affect low-income countries are helminthosis and trypanosomosis. In Ghana, and in many other African countries, herbal treatment of various diseases is still common. In the present study, we sought to determine the antitrypanosomal and anthelminthic activities of Carica papaya and Ceiba pentandra. The ethanol extracts of Carica papaya stem bark (PPSe) and leaves (PPLe) and ethanol extracts of Ceiba pentandra stem bark (CPSe) and leaves (CPLe) were screened against Trypanosoma brucei brucei and Pheretima posthuma worms in vitro. CPSe exhibited strong antitrypanosomal activity, while the other extracts exhibited moderate activity against T. b. brucei. All the extracts showed weak selective indices (SI) when tested on Jurkat cell lines, which is indicative of a potential toxic effect. When the extracts were screened against P. posthuma worms, only PPSe and CPSe were able to kill the worms after the exposure time at concentrations of 2.5, 5, and 10 mg/mL. PPSe was again the only extract that potentiated the anthelminthic activity of albendazole against P. posthuma worms. Preliminary phytochemical screening and GC-MS analysis revealed the presence of compounds with antitrypanosomal and anthelminthic properties. The results confirmed the potential of C. papaya and C. pentandra as remedies for trypanosomosis and helminthosis and also gives credence to their folkloric use.
Resistance modulatory activities of natural products on traditional antibiotics have gained scientific interest in recent years. This is aimed at maximizing antimicrobial potency with major strides in curbing microbial resistance and leading to potential drug discovery. The antimicrobial activity of vernolide, a compound isolated from Vernonia colorata was investigated following its forklore use as antibiotic. The compound Vernolide was isolated from the leaves of Vernonia colorata and the identity was confirmed by appearance, melting point, 1H and 13C NMR as well as UV-Vis and IR spectroscopy. The antimicrobial activity of the isolate was evaluated with MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay using micro broth dilution and 96 well microtiter plates against standardized bacteria suspensions of selected inoculum. Vernolide showed activity against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis with minimum inhibitory concentrations (MICs) of 0.3, 0.3 and 0.4 mg/ml respectively. The MIC of the selected antibiotics, namely on ciprofloxacin, amoxicillin, tetracycline and erythromycin were subsequently determined as a range between 0.1µg/ml to 16 µg/ml. Modulation studies between vernolide and the selected antibiotics showed that all antibiotics were able to prevent growth of the microorganisms at a concentration of 0.2 mg/mL vernolide and varying concentrations of the standard antibiotics in the range of 4.00 µg/ml to 0.0005 µg/ml which are far well below their observed MICs. Vernolide has therefore been shown to possess strong resistance modulatory activity on ciprofloxacin, amoxicillin, tetracycline and erythromycin against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis
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