Didactic approach recounting advances and limitations in novel glutathione and cysteine detection (reduced GSH probe) with mixed coumarin, aldehyde, and phenyl-selenium chemistry.

We describe the pertinent research steps and analysis, many of which are chemical, to achieve a novel molecular probe for glutathione (GSH) which has been published and patented based on two recent articles: "Exceptional time response, stability and selectivity in doubly-activated phenyl selenium-based glutathione-selective platform" and "Enhanced Doubly Activated Dual Emission Fluorescent Probes for Selective Imaging of Glutathione or Cysteine in Living Systems" (Kim et al., 2015; Mulay et al., 2018). The papers involve coumarin probes. Reaction/detection unfolds with aminothiol attack at an electrophilic ring carbon position. An adjacent -CHO group is heavily involved in resonance aspects of the C-Se position, as well as the binding of the pendant N-group; the coumarin lactone carbonyl also allows for resonance to be achieved (vide infra). The leaving group, -SePh, while precedented in some systems, depends on electronic tuning (Fig. 1). For 1, the response times with GSH was ~100ms; a 100-fold fluorescence increase is observed (Compound 1). The probe also reacts with cysteine (Cys) and homocysteine (Hcy), albeit differently. For glutathione probing, the greater wavelength maxima (1: 550nm, DACP-1: 555nm, DACP-2: 590nm) enabled eventual cell studies (confocal microscopy) and animal studies. The limits of detection (LOD, 1: 270nM DACP-1: 10.1nM DACP-2: 17.0nM), as measured using the 3σ/k method. We provide a didactic presentation from probe conception to probe in vivo testing, etc., with additional considerations presented; a variety of factors/issues (2.1-2.28) help maintain a realistic sequence, a flow from wider to narrower, of the factors that go into developing medical, biological and neurodegenerative disease-related probes, meant to help other researchers follow our intention, gain perspective, and overcome current limitations.

Anticancer activity of Sasa borealis leaf extract-mediated gold nanoparticles.

Advancements in metal nanoparticle synthesis using plant extracts and their anticancer activity have received significant attention in recent years. The green approach for the synthesis of gold nanoparticles (AuNPs) using leaf extract of Sasa borealis is reported in this study. Synthesis of AuNPs was performed at 50 °C, and nanoparticle formation was observed after 20 min incubation. AuNPs formation was confirmed by the UV-visible spectrum peak at 542 nm. The synthesized AuNPs were oval, spherical with sizes around 10-30 nm observed using the transmission electron microscope. Energy dispersive X-ray analysis was utilized for the detection of elemental compound. The face centered cubic structure was confirmed by X-ray diffraction pattern. The reduction of tetrachloroauric acid into AuNPs by the phytochemical compounds of S. borealis extract was determined by Fourier transform infrared spectroscopy and the presence of biomolecules was studied by GC-MS. The synthesized AuNPs was tested for toxic effect on HEK293 cells and anticancer activity on AGS cells by WST-1® assay. Condensation or fragmentation is a characteristics of apoptosis, which was confirmed by 4,6-diamidino-2-pheynylindole dihydrochoride (DAPI) staining. The S. borealis-mediated AuNPs have good activity as an anticancer agent and it will be beneficial in cancer therapeutics.