Effect of Sublethal Concentration of Heavy Metal Contamination on Soil Physicochemical Properties, Catalase and Dehydrogenase Activities.

The effect of sublethal contaminations (100 g/dm3) of heavy metals such as mercury (Hg), lead (Pb) and cadmium (Cd) on soil enzyme and physicochemical properties was investigated after one hundred and twenty days. Soil sample without heavy metal contamination served as the control. Results indicate that Hg, Pb and Cd at 100 g/dm3 concentration caused a significant (P<0.05) change in the soil pH and electrical conductivity relative to the control. There was no significant (P>0.05) difference in these soil physicochemical properties: moisture, phosphate, sulphate, chloride, calcium carbonate, total nitrogen and organic carbon when compared to the control. There were significant (P<0.05) decrease in soil dehydrogenase and catalase activities in all the metalcontaminated soil samples when compared to the control, indicating that these heavy metals increased soil acidity and electrical conductivity at this concentration and period of exposure.

Antioxidant Content and Free Radical Scavenging Activity of Honeys of Apis mellifera of Obudu Cattle Ranch.

Honey is a naturally sweet and viscous fluid produced by honeybees (Apis mellifera) from the nectar of flowers. Proline, free amino acid, tannins, phenols and flavonoids content were determined in eight samples of Obudu cattle ranch honeys. Antioxidant content (ascorbic acid equivalent, quercetin equivalents, tocopherol content) and free radical scavenging activity of Obudu ranch honeys were determined by standard methods. The relationship existing between proline and antioxidant content with free radical scavenging activity was assessed by mathematical modelling using Levenberg Marquardt algorithm. Results of our study showed that Obudu ranch honey was of high quality having comparable total free amino acid, proline, phytochemical and antioxidant content with good quality honeys found elsewhere. α-Tocopherol content was 16.50 ± 1.40 μg/100 g, quercetin equivalent antioxidant content (QEAC) was 9.43 ± 0.9 mg/100 g, ascorbic acid equivalent antioxidant content (AEAC) was 18.56 ± 1.78 mg/100 g, while the mean inhibitory concentration (IC50) of the honey samples against the 2,2-diphenyl-1- picrylhydrazyl (DPPH) radicals (RSA: IC50) was evaluated to be 12.74 ± 0.71mg/ml. Proline content, AEAC, QEAC and α-tocopherol were logistically related (r2 = 0.726, 0.971, 0.960 and 0.888 respectively) to the radical scavenging activity. The results obtained from the present study showed that Obudu ranch honeys were of high quality and possessed antioxidant and free radical scavenging property. Since proline content of the tested honey samples were comparable to proline content of unadulterated honey samples elsewhere, the commercial samples may not be adulterated Results showed that traditional usage of the honey for various medicinal usages may be related to its chemical content and radical scavenging property.