Potential Complementary Therapy for Adverse Drug Reactions to Sulfonamides: Chemoprotection Against Oxidative and Nitrosative Stress by TCM Constituents and Defined Mixtures.

PURPOSE: Our working hypothesis is that bioactive phytochemicals that are important constituents of Traditional Chinese Medicine and their defined mixtures have potential as complementary therapy for chemoprotection against adverse drug reactions whose toxicity is not related to the pharmacological action of the drug but where oxidative and nitrosative stress are causative factors. METHODS: In this investigation we measured cytotoxicity, lipid peroxidation, protein carbonylation and ROS/NOS-mediated changes in the disulfide proteome of Jurkat E6.1 cells resulting from exposure to sulfamethoxazole N-hydroxylamine with or without pre-treatment with low µM concentrations of baicalein, crocetin, resveratrol and schisanhenol alone and in defined mixtures to compare the ability of these treatment regimens to protect against ROS/RNS toxicity to Jurkat E6.1 cells in culture. RESULTS: Each of the Traditional Chinese Medicine constituents and defined mixtures tested had significant chemoprotective effects against the toxicity of ROS/RNS formed by exposure of Jurkat E6.1 cells to reactive metabolites of sulfamethoxazole implicated as the causative factors in adverse drug reactions to sulfa drugs used for therapy. At equimolar concentrations, the defined mixtures tended to be more effective chemoprotectants overall than any of the single constituents against ROS/RNs toxicity in this context. CONCLUSIONS: At low µM concentrations, defined mixtures of TCM constituents that contain ingredients with varied structures and multiple mechanisms for chemoprotection have excellent potential for complementary therapy with sulfa drugs to attenuate adverse effects caused by oxidative/nitrosative stress. Typically, such mixtures will have a combination of immediate activity due to short in vivo half-lives of some ingredients cleared rapidly following metabolism by phase 2 conjugation enzymes; and some ingredients with more prolonged half-lives and activity reliant on phase 1 oxidation enzymes for their metabolic clearance. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Attenuation of Oxidative Stress in HEK 293 Cells by the TCM Constituents Schisanhenol, Baicalein, Resveratrol or Crocetin and Two Defined Mixtures.

PURPOSE: Our working hypothesis is that single bioactive phytochemicals with antioxidant properties that are important constituents of Traditional Chinese Medicine (TCM) and their defined mixtures have potential as chemoprotective agents for chronic conditions characterized by oxidative and nitrosative stress, including Alzheimer's. Here we evaluate the ability of baicalein, crocetin, trans-resveratrol or schisanhenol and two defined mixtures of these TCM phytochemicals to attenuate the toxicity resulting from exposure to cell permeant t-butyl hydroperoxide (tBPH) in wild-type and bioengineered (to express choline acetyltransferase) HEK 293 cells. METHODS: Endpoints of tBHP-initiated oxidative and nitrosative stress in both types of HEK 293 cells and its attenuation by TCM constituents and mixtures included cytotoxicity (LDH release); depletion of intracellular glutathione (GSH); formation of S-glutathionylated proteins; oxidative changes to the disulfide proteome; and real-time changes in intracellular redox status. RESULTS: At low µM concentrations, each of the TCM constituents and mixtures effectively attenuated intracellular toxicity due to exposure of HEK 293 cells to 50 or 250 µM tBHP for 30 min to 3 h. Confocal microscopy of HEK 293 cells transfected with mutated green fluorescent protein (roGFP2) showed effective attenuation of tBHP oxidation by baicalein in real time. Three redox-regulated proteins prominent in the disulfide proteome of HEK 293 cells were identified by MALDI-TOF mass spectrometry. CONCLUSIONS: We conclude that single TCM chemicals and their simple mixtures have potential for use in adjunct chemoprotective therapy. Advantages of mixtures compared to single TCM constituents include the ability to combine compounds with varying molecular mechanisms of cytoprotection for enhanced biological activity; and to combine chemicals with complementary pharmacokinetic properties to increase half-life and prolong activity in vivo. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.