An estimated quantitative lateral flow immunoassay for determination of artesunate using monoclonal antibody

There have been reports of fake artesunate (ART), which has led to deaths from untreated malaria in South East Asia. To rapidly screen for fake and adulterated ART products in the drug market, a lateral flow immunoassay (LFIA) based on a colloidal gold–monoclonal antibody probe for detection of ART within samples was developed. With this method, the calibration curve for ART was determined by the intensity ratio of the test and control bands at various ART concentrations. The linearity range was 12.5–200 μg/ml of ART. Samples were tested by the developed LFIA and can be calculated for ART contents. The levels of ART in the samples were also confirmed by enzyme-linked immunosorbent assay. The results of the two methods were in good conformance. The proposed LFIA was demonstrated to be a simple and rapid analytical method for detecting ART in the pharmaceutical formulation.     

ESR Spin Trapping of the Reaction Between Urate and Peroxynitrite: the Hydrogen Adduct

Under basic conditions, the hydrogen adduct of the spin traps N-t-butyl-phenylnitrone (PBN) and α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN) is formed as a major product in the reaction between the urate anion or dianion and peroxynitrite. It shows a characteristic nine-line spectrum with an intensity pattern of (1:2:1:1:2:1:1:2:1) and hyperfine splitting constants of a(H) = 10.68 G (two magnetically equivalent protons) and a(N) = 16.64 G. The hydrogen adduct of PBN also forms in the absence of urate. In this case, its formation is proposed to follow the non-traditional “inverted spin trapping” mechanism, followed by electron transfer between spin traps and the PBN–OH (or POBN–OH) adduct or one of its decomposition products. The H adduct formation is amplified when uric acid and peroxynitrite are present. Different yields of H adducts obtained from various spin traps supported the inverted spin trapping mechanism and can be rationalized by the relative redox potential of the spin traps.