Inhibition of Anchorage-Independent Proliferation and G0/G1 Cell-Cycle Regulation in Human Colorectal Carcinoma Cells by 4,7-Dimethoxy-5-Methyl-l,3-Benzodioxole Isolated from the Fruiting Body of Antrodia camphorate

In this study, 4,7-dimethoxy-5-methyl-l,3-benzodioxole (SY-1) was isolated from three different sources of dried fruiting bodies of Antrodia camphorate (AC). AC is a medicinal mushroom that grows on the inner heartwood wall of Cinnamomum kanehirai Hay (Lauraceae), an endemic species that is used in Chinese medicine for its anti-tumor and immunomodulatory properties. In this study, we demonstrated that SY-1 profoundly decreased the proliferation of human colon cancer cells (COLO 205) through G0/G1 cell-cycle arrest (50–150 μM) and induction of apoptosis (>150 μM). Cell-cycle arrest induced by SY-1 was associated with a significant increase in levels of p53, p21/Cip1 and p27/Kip1, and a decrease in cyclins D1, D3 and A. In contrast, SY-1 treatment did not induce significant changes in G0/G1 phase cell-cycle regulatory proteins in normal human colonic epithelial cells (FHC). The cells were cultured in soft agar to evaluate anchorage-independent colony formation, and we found that the number of transformed colonies was significantly reduced in the SY-1-treated COLO 205 cells. These findings demonstrate for the first time that SY-1 inhibits human colon cancer cell proliferation through inhibition of cell growth and anchorage-independent colony formation in soft agar. However, the detailed mechanisms of these processes remain unclear and will require further investigation

Coherent imaging using laser feedback interferometry with pulsed-mode terahertz quantum cascade lasers

We report a coherent terahertz (THz) imaging system that utilises a quantum cascade laser (QCL) operating in pulsed-mode as both the source and detector. The realisation of a short-pulsed THz QCL feedback interferometer permits both high peak powers and improved thermal efficiency, which enables the cryogen-free operation of the system. In this work, we demonstrated pulsed-mode swept-frequency laser feedback interferometry experimentally. Our interferometric detection scheme not only permits the simultaneous creation of both amplitude and phase images, but inherently suppresses unwanted background radiation. We demonstrate that the proposed system utilising microsecond pulses has the potential to achieve 0.25 mega-pixel per second acquisition rates, paving the pathway to video frame rate THz imaging

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation

Visible Light Photoredox Catalysis: Synthesis of Indazolo[2,3‑<i>a</i>]quinolines from 2‑(2-Nitrophenyl)-1,2,3,4-tetrahydroquinolines

The synthesis of indazolo[2,3-<i>a</i>]quinoline derivatives in moderate to good yields from 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinolines via visible light photoredox catalysis is reported. The reaction involves a novel ruthenium-catalyzed intramolecular formation of the N–N bond of the indazole ring

Photochromism of <i>o</i>‑Nitrophenyl-Substituted Oxazabicycles

The <i>o</i>-nitrophenyl-substituted oxazabicycle <b>1</b> was prepared via a one-pot tandem multicomponent reaction. Upon exposure to UV light in CH₂Cl₂, it turned purple and reverted back to its original color while being heated. The in situ trapping of the photogenerated product with trimethylsilyl cyanide yielded the adduct <b>4</b>, which confirmed the formation of the ring-opened zwitterionic species <b>2</b>. The EPR spectroscopic data, PBN spin-trapping experiments, and spectroelectrochemical studies of the model compound <b>7</b> provided evidence to support that the photochromism of <b>1</b> involved the zwitterionic biradical intermediate <b>5</b>, generated by photoinduced intramolecular electron transfer from the amine moiety to the nearby <i>o</i>-nitrophenyl group. Further, two photogenerated side products responsible for the photofatigue of <b>1</b> were isolated and characterized, and a possible mechanism for their formation was proposed

Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation