Graphical abstract

The study evaluates the toxic effects of acute and sub-acute oral administration of methanol extracts of Geophila obvallata in rats. During acute study, a dose of 1600, 2900 and 5000 mg/kg bw of extract was orally administered to rats. Rats were observed for signs of toxicity for two weeks. During sub-acute study (28 days), the extract, at doses of 100, 500 and 1000 mg/kg bw were administered orally to rats while control rats were given only tap water. At the end of the study, samples were collected for analyses. In acute toxicity studies, the extract did not induce death after single dose administration. Hence, the LD50 was estimated above 5000mg/kg. The results of sub-acute toxicity study show that no significant changes were observed in the body weights, organ weights, kidney function and organ histology. There were significant changes in hematology and biochemical indices investigated at elevated doses of 500 and 1000 mg/kg bw compared to the control. GOE may be considered non-toxic at a dose of 100 mg/kg with promising applications in drug therapy.

Background: The increase in synthetic drug resistance by pathogenic microbes has led to the development of plant-based antimicrobial drugs that are more reliable and non-lethal to human health at increased dosage. Methods: The antibacterial and antifungal potential of Geophila obvallata extracts were tested on clinical isolates (Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, Streptococcus pyogenes, Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus) using standard techniques. Results: The zones of inhibition were shown to increase with increasing concentrations of the extracts. Inhibition was higher in Gram positive bacteria (9.10 to 31.00mm in 40mg/mL concentration) than Gram negative bacteria (3.50 to 27.00mm in 40mg/mL concentration), while the fungal isolates had the least zones of inhibition (2.83 to 25.00mm in 40mg/ml concentration). The minimum inhibitory concentrations (MIC) were lowest in the methanol extract than aqueous extract. Simillarly, MIC for bacteria (Bacillus subtilis) and fungi (Aspergillus fumigatus) were 0.3 and 2.0mg/mL respectively. Methanol extract had higher antibacterial and antifungal effect than aqueous extract. Ciprofloxacin, used as control for bacteria had the highest inhibitory activity (33.67mm) when compared to that of the highest concentration of plant extracts administered. Also, ketoconazole gave the highest zones of inhibition (32.33mm) on the fungi isolates compared to those of the extracts. The performance of the methanol extract of 40mg/mL of Geophila obvallata in the inhibition of Bacillus subtilis was not significantly different from that of Ciprofloxacin. Conclusion: The findings in this study therefore validate the antimicrobial effect of Geophila obvallata leaf extracts as well as its possible application in medicine.

The increase in synthetic drug resistance by pathogenic microbes has led to the development of plant-based antimicrobial drugs that are more reliable and non-lethal to human health at increased dosage. The antibacterial and antifungal potential of Geophila obvallata extracts were tested on clinical isolates (Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis,Streptococcus pyogenes, Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus) using standard techniques. The zones of inhibition were shown to increase with increasing concentrations of the extracts. Inhibition was higher in Gram positive bacteria (9.10 to 31.00mm in 40mg/mL concentration) than Gram negative bacteria (3.50 to 27.00mm in 40mg/mL concentration), while the fungal isolates had the least zones of inhibition (2.83 to 25.00mm in 40mg/ml concentration). The minimum inhibitory concentrations (MIC) were lowest in the methanol extract than aqueous extract. Simillarly, MIC for bacteria (Bacillus subtilis) and fungi (Aspergillus fumigatus) were 0.3 and 2.0mg/mL respectively. Methanol extract had higher antibacterial and antifungal effect than aqueous extract. Ciprofloxacin, used as control for bacteria had the highest inhibitory activity (33.67mm) when compared to that of the highest concentration of plant extracts administered. Also, ketoconazole gave the highest zones of inhibition (32.33mm) on the fungi isolates compared to those of the extracts. The performance of the methanol extract of 40mg/mL of Geophila obvallata in the inhibition of Bacillus subtilis was not significantly different from that of Ciprofloxacin. The findings in this study therefore validate the antimicrobial effect of Geophila obvallata leaf extracts as well as its possible application in medicine.

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