The clinical success of Escherichia colil-asparaginase II (EcAII) as a front line chemotherapeutic agent for acute lymphoblastic leukemia (ALL) is often compromised because of its silent inactivation by neutralizing antibodies. Timely detection of silent immune response can rely on immobilizing EcAII, to capture and detect anti-EcAII antibodies. Having recently reported the use of a portable surface plasmon resonance (SPR) sensing device to detect anti-EcAII antibodies in undiluted serum from children undergoing therapy for ALL (Aubé et al., ACS Sensors2016, 1 (11), 1358-1365), here we investigate the impact of the quaternary structure and the mode of immobilization of EcAII onto low-fouling SPR sensor chips on the sensitivity and reproducibility of immunosensing. We show that the native tetrameric structure of EcAII, while being essential for activity, is not required for antibody recognition because monomeric EcAII is equally antigenic. By modulating the mode of immobilization, we observed that low-density surface coverage obtained upon covalent immobilization allowed each tetrameric EcAII to bind up to two antibody molecules, whereas high-density surface coverage arising from metal chelation by N- or C-terminal histidine-tag reduced the sensing efficiency to less than one antibody molecule per tetramer. Nonetheless, immobilization of EcAII by metal chelation procured up to 10-fold greater surface coverage, thus resulting in increased SPR sensitivity and allowing reliable detection of lower analyte concentrations. Importantly, only metal chelation achieved highly reproducible immobilization of EcAII, providing the sensing reproducibility that is required for plasmonic sensing in clinical samples. This report sheds light on the impact of multiple factors that need to be considered to optimize the practical applications of plasmonic sensors.

Agricultural wastes such as the peels of onion and garlic were used as a supplement along with l-asparagine for the very first time to produce increased yield of l-asparaginase by Pseudomonas plecoglossicida RS1. Statistical optimization strategies such as response surface methodology were used to generate a medium composition containing extracts of 0.9 (v/v) of garlic peel waste and 0.5% (v/v) onion peel waste along with 0.2% (w/w) l-asparagine, which yielded a twofold increase in the enzyme activity compared to the unsupplemented minimal (M-9) medium. The presence of l-asparagine content in the peel extract was confirmed by high-performance liquid chromatography. Further, l-asparaginase was purified to homogeneity, and identity was confirmed by matrix-assisted laser desorption ionization time-of-flight analysis. The application of the purified l-asparaginase as a therapeutic was studied in HeLa cells which showed a p53-mediated G2 cell cycle arrest. Moreover, the purified l-asparaginase showed effective acrylamide mitigation in vitro, at 6 IU, and its effective degradation was also demonstrated by the effect on chemotactic index of Caenorhabditis elegans and the restoration of the cognitive abilities of C. elegans which was coexposed to acrylamide and l-asparaginase compared to that exposed to acrylamide alone. Thus, l-asparaginase, with multipotent applications, was produced by effective waste utilization for economical commercial production.

The essential oil (EO) composition of the aerial parts of Erigeron multiradiatus (Lindl.ex DC.) Benth growing wild in the central Himalayan region of Uttarakhand, India, was analyzed by capillary gas chromatography with a flame ionization detector and gas chromatography-mass spectrometry. A sum of 12 constituents was identified, representing 97.81% of the oil composition. The oil was composed mainly of oxygenated monoterpenes (88.95%), sesquiterpene hydrocarbons (5.61%), oxygenated sesquiterpenes (3.05%), and monoterpene hydrocarbons (0.20%). Major constituents identified were trans-2-cis-8-matricaria-ester (77.79%), cis-lachnophyllum ester (11.04%), zingiberene (4.43%), and spathulenol (1.59%). Further, the leishmanicidal effect of EO and the purified compound trans-2-cis-8-matricaria-ester has been investigated against Leishmania donovani promastigotes and intracellular amastigotes. EO and trans-2-cis-8-matricaria-ester were safer for the hamster peritoneal macrophage and lethal to promastigotes and intracellular amastigotes at different concentrations. Further, using an in silico approach, these four compounds were tested against 10 major proteins of L. donovani associated with its virulence. Out of them, only trans-2-cis-8-matricaria-ester was found to be effective against the four target proteins, namely, l-asparaginase-1-like protein, metacaspase 2, metacaspase 1, and DNA topoisomerase II of L. donovani. The results indicate that EO contains trans-2-cis-8-matricaria-ester as a major component and showed antileishmanial activity which may facilitate discovery of new lead molecules for developing herbal medicines against visceral leishmaniasis.