Antibacterial activity of the roots, stems and leaves of Alchornea floribunda

ETHNOPHARMACOLOGICAL RELEVANCE

Alchornea floribunda Müll. Arg. is used in traditional medicine across Africa for the treatment of bacterial, fungal, parasitic and inflammatory disorders.

AIM OF THE STUDY

To evaluate the antibacterial activity of the crude extracts of different plant parts in order to provide a scientific rationale for the proposed broad efficacy of Alchornea floribunda in the treatment of bacterial infections.

MATERIALS AND METHODS

Extracts of roots, stems and leaves were prepared using solvents of various polarities in order to extract a wide range of phytochemicals. The antibacterial activity of these crude extracts was evaluated by micro-dilution assay, against Gram-positive (i.e. Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus saprophyticus) as well as Gram-negative (i.e. Escherichia coli, Klebsiella pneumoniae, Moraxella catarrhalis and Proteus mirabilis) bacteria.

RESULTS

Generally, the ethanol (EtOH), methanol (MeOH), ethyl acetate (EtOAc) and chloroform (CHCl3) extracts demonstrated the best activities, with the leaves exhibiting the highest average activity for six of the eight pathogens. Of these, the ethanolic leaf extract was the most active against Staphylococcus aureus with an MIC value of 50µg/mL. Some other notable activity was observed for the ethyl acetate and chloroform root extracts against Staphylococcus aureus (50µg/mL), and for selected stem extracts against Staphylococcus aureus (50µg/mL), Klebsiella pneumoniae (63µg/mL) and Staphylococcus saprophyticus (63µg/mL).

CONCLUSION

This study demonstrates the promising antibacterial activity of Alchornea floribunda against both Gram-positive and Gram-negative bacteria responsible for gastrointestinal, skin, respiratory and urinary ailments, and validates its use in the ethnopharmacology of the region.

Assessment of trace element concentrations in soil and plants from cropland irrigated with wastewater

Samples of soil and food plants were collected from wastewater-irrigated fields in the vicinity of Gaziantep, in southeast Turkey, and analyzed for several trace elements (TEs). The concentrations of Co, Mo and Zn in edible portions of corn, mint and vegetables (eggplant, pepper and tomato) were 0.03-0.66, 0.1-3.2 and 8-148 mg kg⁻¹, respectively. In the edible portions of corn and mint, Cd, Cr, Cu, Ni and Pb concentrations in all samples were <0.01-0.05, 2.0-5.5, 6-47, 0.6-6.7 and 0.2-3.5 mg kg⁻¹, respectively. No single plant species had consistently high concentrations of all metals. For example, corn had the highest concentration of Zn (89 mg kg⁻¹), but the lowest concentration of Cd (<0.01 mg kg⁻¹). The maximum concentrations of some TEs in some crop samples, as well as soil samples, exceeded certain threshold values set in Turkey and other countries. For some TEs there was little difference between wastewater-irrigated and control soil concentrations. Transfer factors (TFs; plant concentration/soil concentration) were high for Cu, Zn and Mo, in comparison with the other TEs (Cd, Co, Cr, Ni and Pb). Higher uptake of certain metals may be associated with the dominant form of the element in the soil matrix. The uptake of chemicals to plant tissues is influenced by the chemical and physical characteristics of the soil and species-specific factors. Although the geochemistry of the region plays a significant role in the levels of TEs in soil and plants, bioaccumulation of metals and subsequent toxicity to plants and animals can be exacerbated by higher environmental concentrations caused by wastewater irrigation and other anthropogenic factors.

Huang-Lian-Jie-Du-Decotion induced protective autophagy against the injury of cerebral ischemia/reperfusion via MAPK-mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du-Decotion (HLJDD, Hwangryun-Hae-Dok-Decotion in Japan), an ancient antipyretic and detoxifying traditional Chinese medicine formula, was reported to have protective effect on ischemic stroke.

AIM OF THE RESEARCH

To investigate the therapeutic effect of HLJDD on ischemic stroke and explore its mode of action.

MATERIAL AND METHODS

A model of ischemic stroke in the rat was established after transient middle cerebral artery occlusion (MCAO) followed by reperfusion. Rats were assigned randomly to groups of control, sham, transient ischemia/reperfusion (I/R), and three treatment groups by HLJDD at 2.5, 5.0, 10.0mg/kg. The neurological deficit, the cerebral infarct size, morphology abnormality, biochemical parameters were examined, and the levels of relevant proteins were determined by immunoblotting analysis to evaluate the protective effects of HLJDD on ischemic stroke and explore the underlying mechanism.

RESULTS

Compared with I/R group, HLJDD significantly ameliorated neurological deficit and histopathology changes, decreased infarct area, and restored the levels of biochemical indicators including nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), glutathione disulfide (GSSG), total superoxide dismutase (T-SOD), Cu/Zn-SOD, Mn-SOD and glutathione peroxidase (GSH-PX). HLJDD also notably elevated the levels of microtubule-associated protein 1 light chain 3 (LC3), Beclin-1, and other autophagy related genes (Atgs), promoted the activation of extracellular signal-regulated kinases (ERK), protein kinase B (Akt), 3-phosphoinositide-dependent kinase (PDK1), and inhibited the activation of mammalian target of rapamycin (mTOR), c-Jun N-terminal protein kinases (JNK), p38, phosphatase and tensin homolog (PTEN).

CONCLUSION

HLJDD showed neuroprotective effects on ischemic stroke, at least in part to the induced protective autophagy via the regulation of mitogen-activated protein kinase (MAPK) signals. This Akt-independent protective autophagy is favorable in the treatment of stroke, avoiding unfavorable side-effects associated with the inactivation of Akt. The efficacy of HLJDD on ischemic stroke and its safety warranted by its long-term clinical use in traditional Chinese medicine favored further study to develop HLJDD as an effective therapeutic agent to treat ischemic stroke.

Hydroxypropyl-β-cyclodextrin impacts renal and systemic hemodynamics in the anesthetized dog

Hydroxypropyl-β-cyclodextrin (HPβCD) is a complexation agent used to enhance drug solubilization and formulation stability. Although its toxicity is well characterized, its cardiovascular effects are less known. To investigate them, HPβCD was infused intravenously over 10 min in anesthetized dogs (10-40% (w/v, i.e. 200-800 mg/kg) in non-denervated animals and at 40% in denervated animals). HPβCD increased renal arteriolar resistance and decreased renal blood flow at all doses, almost immediately after infusion start, more drastically in females. A less pronounced increase in total peripheral resistance occurred in females only due to sex difference in sympathetic tone. Pulmonary hemodynamic parameters remained unaffected, suggesting that the renal effect was rather selective. As a consequence of the increased systemic blood pressure, heart rate decreased in normal animals without direct effect on cardiac conductance. This effect was abolished in denervated animals. This suggests that autonomous nervous feedback loops are functional in normal animals and that HPβCD has no direct chronotropic effect. In conclusion, systemic and renal hemodynamic changes should be considered as potential background effects at 200-400 mg/kg. At higher doses (800 mg/kg), changes are more pronounced and could mask/exacerbate hemodynamic response of drug candidate; such doses should be avoided in nonclinical safety studies.