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We assessed the polyphenolic contents and antioxidant potential of the aqueous, ethanol and methanol stem bark extracts of Jatropha curcas. The total phenol, flavonoids, flavonols and proanthocyanidin contents of the extracts were evaluated to determine their effect on the antioxidant property of this plant, using standard phytochemical methods. The antioxidant and free radical scavenging activity of ethanol, methanol and aqueous extracts of the plant were also assessed against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing, nitric oxide (NO), superoxide anion, (O2−) and hydrogen peroxide (H2O2) using spectroscopic methods and results were compared with that of butylated hydroxyl toluene (BHT) and ascorbic acid as standards. The concentrations of different classes of phenolic compounds were higher in methanol and ethanol extracts compared to aqueous extracts. There was correlation between total phenol, total flavonoids, total flavonol and total proanthocyanidins (r = 0.996, 0.978, 0.908, and 0.985) respectively. There was correlations between the amount of phenolic compounds and percentage inhibition of DPPH radicals scavenging activity of the extract (r = 0.98). Findings from the present study indicated that J. curcas is a potential source of natural antioxidants and may be a good candidate for pharmaceutical plant based products.

Oxidative stress plays a significant role in the pathogenesis of metabolic syndrome including diabetes mellitus (DM). The inhibition of alpha-amylase is an important therapeutic target in the regulation of postprandial increase of blood glucose in diabetic patients. The present study investigated the alpha-amylase inhibitory and antioxidant potential of selected herbal drugs used in the treatment of DM by the traditional healers in Isiala Mbano and Ikwuano regions of southeastern Nigeria. Antioxidant activity was evaluated in terms of free radical scavenging, reducing power, and total phenolic (TPC) and flavonoid content (TFC) in consonance with the TLC profiling. The results showed that methanol crude extracts from Anacardium occidentale (AO) and Ceiba pentandra (CP) recorded higher TPC and TFC, potent free radical scavenging, and efficient reducing power (RP) as compared with other plant samples. All the plant extracts exhibited a relative alpha-amylase inhibition apart from Strophanthus hispidus (SH) extract with a negative effect. We discovered a mild to weak correlation between alpha-amylase inhibition or antioxidative capacity and the total phenol or flavonoid content. At least in part, the results obtained in this work support the traditional use of certain plant species in the treatment of patients with DM.

Our data suggest that S. latifolia extract has antibacterial and antioxidants activity and thus could be used as alternative therapy against antibiotic resistance bacteria and to prevent many radical related diseases.

The aqueous extract of the leaves of Leonotis leonurus (L.) R. Br. at the doses of 125, 250 and 500 mg/kg body weight was investigated for toxicity in male rats following administration on daily basis for 21 days. The extract did not significantly (p > .05) alter the levels of haemoglobin, packed cell volume, mean corpuscular volume, red cell distribution width, basophils, total protein, phosphorus, calcium and chloride ions of the animals. Whereas the levels of lymphocytes, eosinophils, monocytes, triacylglycerol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, atherogenic index, albumin as well as alkaline phosphatase and gamma glutamyl transferase activity were decreased by the extract, those of neutrophil, magnesium, total and conjugated bilirubin, alanine and aspartate aminotransferase as well as liver and kidney body weight ratios increased. There was decrease in the mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and cholesterol only at the 500 mg/kg body weight of the extract, whereas the large unstained cells, sodium ions, white blood cells and uric acid increased only at 250 and 500 mg/kg body weight of the extract, respectively. The urea, creatinine and potassium increased only at 125 mg/kg body weight of the extract while the globulin content was elevated only at 500 mg/kg body weight of the extract. The doses did not produce any definite pattern of effect on the red blood cells and platelets. These alterations by the aqueous extract of L. leonurus leaves on the haematological together with the liver and kidney functional indices suggests parameter and dose-selective effects of the extract and will have consequential effects on the normal functioning of the blood system, kidney and liver of the animals. The extract is also unlikely to predispose the animals to cardiovascular risk when repeatedly consumed on daily basis at the doses investigated for 21 days. Therefore, the aqueous extract of L. leonurus leaves may not be ‘safe’ as oral remedy in male rats.

Infection due to multidrug resistance pathogens is difficult to manage due to bacterial virulence factors and because of a relatively limited choice of antimicrobial agents. Thus, it is imperative to discover fresh antimicrobials or new practices that are effective for the treatment of infectious diseases caused by drug-resistant microorganisms. The objective of this experiment is to investigate for synergistic outcomes when crude methanolic extract of the stem bark of Afzelia africana and antibiotics were combined against a panel of antibiotic resistant bacterial strains that have been implicated in infections. Standard microbiological protocols were used to determine the minimum inhibitory concentrations (MICs) of the extract and antibiotics, as well as to investigate the effect of combinations of the methanolic extract of A. africana stem bark and selected antibiotics using the time-kill assay method. The extract of Afzelia africana exhibited antibacterial activities against both Gram-negative and Gram-positive bacteria made up of environmental and standard strains at a screening concentration of 5 mg/mL. The MICs of the crude extracts and the antibiotics varied between 1 μg/mL and 5.0 mg/mL. Overall, synergistic response constituted about 63.79% of all manner of combinations of extract and antibiotics against all test organisms; antagonism was not detected among the 176 tests carried out. The extract from A. africana stem bark showed potentials of synergy in combination with antibiotics against strains of pathogenic bacteria. The detection of synergy between the extract and antibiotics demonstrates the potential of this plant as a source of antibiotic resistance modulating compounds.