Relationship between native and exotic plant species at multiple savannah sites

We tested whether the recently proposed two‐part measure of degree of invasion (DI) of a community relating exotic proportion of cover to exotic proportion of richness can characterize patterns of plant invasions at multiple savannah sites in Southern Africa. Regression analysis was performed on transformed data to assess how this two‐part measure of DI compares to other metrics of community invasibility. The results indicate that at the plot level, the absolute cover of exotics was not significantly related to native cover for three sites out of four assessed (R² ≤ 0.17; P > 0.05). Also, at all four sites, no significant relationships were detected between native and exotic plant richness at both the 1‐m² and 400‐m² plot scales. By contrast, significant (P < 0.05) positive linear relationships were observed between exotic proportion of richness and exotic proportion of cover at all sites (R² was as high as 0.67 and 0.97 for two sites). Our results indicate that the new two‐part measure of DI is able to characterize patterns of plant invasions across plant communities in African savannahs.     

Regulation of growth,nutritive, phytochemical and antioxidant potential of cultivated <Emphasis Type="Italic">Drimiopsis maculata</Emphasis> in response to biostimulant (vermicompost leachate,VCL) application

The effect of vermicompost leachate (VCL, low-cost biostimulant) on the growth, elemental (macro and micro-nutrients) and phytochemical content as well as the antioxidant potential of Drimiopsis maculata was evaluated. Three dilutions (1:5; 1:10 and 1:20) of VCL were tested and the cultivation lasted for 3 months. In addition to the recorded growth parameters, dried and ground plant materials (leaves and bulbs) were evaluated for nutrients, phenolic acids and antioxidant capacity. Vermicompost leachate application enhanced the growth of D. maculata, particularly, the leaves (VCL 1:10) and bulbs (VCL 1:20) which were significantly bigger than the controls. Apart from the concentration of phosphorus which was significantly lower in the leaves of VCL (1:20)-treated plants, the quantity of all four macro-nutrients analysed were similar with and without VCL. Similar observations were also demonstrated in the majority of quantified micro-nutrients in D. maculata. Relative to the control, VCL-treated plants had higher concentrations of the 10 phenolic acids quantified in the leaves. However, the majority of the quantified phenolic acids were not significantly enhanced in bulbs. Antioxidant activity of D. maculata extracts was generally higher in leaves than in the bulbs. The leaf extract from VCL (1:10 and 1:20)-treated plants exhibited lower oxygen radical absorbance capacity (ORAC) when compared to the control. However, bulbs from VCL (1:5) treatment had significantly higher ORAC than the control. From a conservational perspective, the current findings provided insight on viable approaches useful for mitigating challenges associated with over-harvesting of highly utilized but slow-growing plant species.     

Changes in certain hematological and physiological variables following single gallium arsenide exposure in rats

Gallium arsenide (GaAs), a group III-VA intermetallic semiconductor, possesses superior electronic and optical properties and has a wide application in electronic industry. Exposure to GaAs in the semiconductor industries could be a possible occupational risk. The aim of the present study was to determine the dose-dependent effect of single oral exposure to GaAs (500, 1000, or 2000 mg/kg) on some biochemical variables in heme synthesis pathway and few selected physiological variables at d 1, 7, and 15 following administration. The results indicate that GaAs produced a significant effect on the activity of δ-aminolevulinic acid dehydratase (ALAD) in blood and heart (particularly at d 7) following exposure to 2000 mg/kg, whereas urinary δ-aminolevulinic acid (ALA) excretion was elevated only at d 7. No marked influence of GaAs on blood hemoglobin, zinc protoporphyrin, and packed cell volume was noticed. Blood glutathione (GSH) was significantly reduced at d 7, but remained unchanged at two other time intervals. On the other hand, heart GSH contents remained uninfluenced on GaAs exposure. Most of the physiological variables, viz. blood pressure, heart and respiration rate, and twitch response, remained unchanged, except for some minor alterations observed at d 7 and 15 following exposure to GaAs at a dose of 2000 mg/kg. Blood gallium concentration was not detectable in normal animals and rats exposed to 500 mg/kg GaAs. Blood arsenic concentration was, however, detectable even at the a lower dose level and increased in a dose-dependent manner. All these changes showed a recovery pattern at d 21, indicating that the alterations are reversible.     

Peganine hydrochloride dihydrate an orally active antileishmanial agent

Protozoic infections caused by genus Leishmania pose an enormous public health threat in developing countries, compounded by the toxicity and resistance to current therapies. Under the aegis of our ongoing program on drug discovery and development on antileishmanial agents from plants, we carried out bioassay guided fractionation on Peganum harmala seeds which resulted in the isolation of 1 as an antileishmanial agent. 2D-NMR spectral data and single crystal X-ray crystallography data indicated 1 as peganine hydrochloride in dihydrated form. The compound 1 exhibited in-vitro activity against both extracellular promastigotes as well as intracellular amastigotes residing within murine macrophages in Leishmania donovani. Furthermore, 1 also exhibited in-vivo activity, 79.6 (±8.07)% against established VL in hamsters at a dose of 100 mg/kg b.wt.