Antimicrobial and toxicity studies of erythrophleum ivorense (Leguminoseae) and parquetina nigrescens (Ascelpiadaceae)

Erythrophleum ivorense and Parquetina nigrescens are plants found in the tropical regions and they are used in African traditional medicine to treat various ailments including wounds, boils and anaemic conditions. Some species of plant in the Erythrophleum genus are also known to be poisonous and toxic to several livestock. However, there is no information on the toxicity of E. ivorense and P. nigrescens has been reported to possess cardiotoxicity. This study is to determine the antimicrobial, cytotoxicity and subchronic toxicity properties of methanol leaf extract (EIML) and methanol stem barks extract (EIMB) of E. ivorense and methanol leaf and other aerial part extract of P. nigrescens (PNML). Agar well diffusion and micro-dilution methods were used to assess the antimicrobial activity of the methanol extracts against two Gram-positive and Gram-negative bacteria and a fungus. In the subchronic toxicity studies, rats were administered with 100, 300 and 1000 mg/kg body weight of the extracts (EIML, EIMB and PNML) for 35 days. Concentrations from 0.1 to 100 μg/mL of the extracts were used to determine the influence of the extracts on viability, proliferation and release of lactate dehydrogenase (LDH) on HaCaT keratinocytes. The extracts (EIML, EIMB and PNML) showed antimicrobial activity against Staphylococcus aureus ATCC 25923, Bacillus subtilis NTCC 10073, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 4853 and clinical strain of Candida albicans at concentrations of 12.5 to 100 mg/mL with mean zones of inhibition ranging from 10 to 23 mm. The MICs of EIML, EIMB and PNML extracts ranged between 2.0 to 6.0 mg/mL against Gram-positive bacteria, 3.0 to 8.0 mg/mL against the Gram-negative bacteria and 2.0 to 4.0 mg/mL against C. albicans. Phytochemical screening of EIML, EIMB and PNML extracts revealed the presence of alkaloids, tannins, flavonoids, sterols, cardiac glycosides and terpenoids. HPLC finger-printing of the extracts (EIML, EIMB and PNML) showed chromatograms with peaks appearing after different retention times from 1 to 13 min for EIML, 1 to 5 min for EIMB and 1 to 9 min for PNML extracts and these can be used for quality ix control purposes. In the sub-chronic toxicity studies, tissues from the kidney and liver of the rats treated with lower doses (100 to 300 mg/kg body weight) of EIML extract showed highly vascularized kidneys with numerous glomerular tufts, healthy hepatocytes and sinusoids in liver. However, there were persistent renal tissue inflammation and glomerular degeneration in kidney, and increased inflammatory infiltrates with few vacuolations, scarrings in liver in rats treated with higher extract dose of 1000 mg/kg body weight of rat. The rats treated with EIMB extract showed persistent renal and hepatocyte inflammations with glomerular and hepatocyte necrosis at all administered doses (100, 300 and 1000 mg/kg body weight) which are indications of renal and hepatic toxicities. Though rats administered with 100 and 300 mg/kg of PNML extract showed renal haemorrhage and inflammation and hepatic inflammation, the rats administered with 1000 mg/kg body weight showed restoring glomerular tufts and improved vasculature and liver with reduced inflammatory infiltrates with healthy hepatocytes. All extracts decreased the viability and proliferation of the HaCaT keratinocytes significantly (p<0.05) within concentrations of 10 to 100 μg/mL. There was also release of LDH from the HaCaT keratinocytes within 0.1 to 100 μg/mL but not statistically significant (p>0.05). Methanol extracts of E. ivorense and P. nigrescens exhibited toxic effects on kidney and liver cells of rats treated with extract doses of 100, 300 and 1000 mg/kg body weight for 35 days.

Source: KNUST