Endocytic Transport as a Drug Target in Infectious Diseases.

Components of the extracellular environment can be transported into cells by molecular mechanisms collectively termed endocytosis. Cells typically use a multitude of such internalization pathways. These endocytic transport pathways have a wide range of implications for physiological regulation as well as pathological processes. Many infectious diseases, for example, involve internalization of the pathogen into the cell as part of the infection process. Selective interference with the endocytic transport of a microbe, thus, represents a therapeutic strategy that may prevent infections or decrease the rate of their progression. Herein, we provide a brief review of strategies for discovery of novel anti-infection drugs and their pharmacological implications.

Activities of apocynin in cytotoxicity assays of potential pathological relevance.

Low levels of some reactive oxygen and nitrogen species (ROS, RNS) are of physiological importance; but high levels result in oxidative stress and can perturb many cell functions including signal transduction and transport, and contribute to aging and chronic diseases. Apocynin (1-(4-hydroxy-3-methoxyphenyl)ethanone) is a phytochemical with reported antioxidant activities in some experimental models of human disease. The major objectives of the current study were to test the antioxidant capacity of apocynin in a hemin-peroxide assay, and test its capacity to moderate pro-oxidant-dependent inhibition of a cell function-endocytic transport. Apocynin, tested at concentrations up to 20µM, did not exhibit statistically significant antioxidant activity (94.3±7.8% relative to controls, p>0.05) in the oxidation assay. When tested against the inhibition of endocytic transport by hydrogen peroxide, apocynin treatment did not significantly rescue such inhibition in the cell types tested (p>0.05, relative to peroxide alone). When cells were treated with a cytotoxic protein aggregate that increased both ROS and RNS, apocynin treatment only inhibited production of the latter (30.0±3.6% inhibition relative to controls without apocynin, p<0.05). The results provide evidence that apocynin, unlike other phytochemicals such as curcumin, does not exhibit antioxidant activity in the heme-peroxide assay. The results also provide the first evidence that apocynin does not rescue hydrogen peroxide-mediated inhibition of endocytic transport, nor prevent hydrogen peroxide production by a cytotoxic protein aggregate. In the latter toxicity assay, however, apocynin could moderate oxidative stress by decreasing cellular levels of RNS.