Extracts of Thesium chinense inhibit SARS-CoV-2 and inflammation in vitro.

CONTEXT: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still spreading rapidly. Relevant research based on the antiviral effects of Thesium chinense Turcz (Santalaceae) was not found. OBJECTIVE: To investigate the antiviral and anti-inflammatory effects of extracts of T. chinense. MATERIALS AND METHODS: To investigate the anti-entry and replication effect of the ethanol extract of T. chinense (drug concentration 80, 160, 320, 640, 960 µg/mL) against the SARS-CoV-2. Remdesivir (20.74 µM) was used as positive control, and Vero cells were used as host cells to detect the expression level of nucleocapsid protein (NP) in the virus by real-time quantitative polymerase chain reaction (RT-PCR) and Western blotting. RAW264.7 cells were used as an anti-inflammatory experimental model under lipopolysaccharide (LPS) induction, and the expression levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: The ethanol extract of T. chinense significantly inhibited the replication (half maximal effective concentration, EC50: 259.3 µg/mL) and entry (EC50: 359.1 µg/mL) of SARS-CoV-2 into Vero cells, and significantly reduced the levels of IL-6 and TNF-α produced by LPS-stimulated RAW264.7 cells. Petroleum ether (EC50: 163.6 µg/mL), ethyl acetate (EC50: 22.92 µg/mL) and n-butanol (EC50: 56.8 µg/mL) extracts showed weak inhibition of SARS-CoV-2 replication in Vero cells, and reduced the levels of IL-6 and TNF-α produced by LPS-stimulated RAW264.7 cells. CONCLUSION: T. chinense can be a potential candidate to fight SARS-CoV-2, and is becoming a traditional Chinese medicine candidate for treating COVID-19.

[Evaluation of the influence of humidity and temperature on the drug stability by initial average rate experiment].

OBJECTIVE: To evaluate the influence of temperature and humidity on the drug stability by initial average rate experiment, and to obtained the kinetic parameters. METHODS: The effect of concentration error, drug degradation extent, humidity and temperature numbers, humidity and temperature range, and average humidity and temperature on the accuracy and precision of kinetic parameters in the initial average rate experiment was explored. The stability of vitamin C, as a solid state model, was investigated by an initial average rate experiment. RESULTS: Under the same experimental conditions, the kinetic parameters obtained from this proposed method were comparable to those from classical isothermal experiment at constant humidity. The estimates were more accurate and precise by controlling the extent of drug degradation, changing humidity and temperature range, or by setting the average temperature closer to room temperature. CONCLUSION: Compared with isothermal experiments at constant humidity, our proposed method saves time, labor, and materials.

[Synthesis and characterization of PEG-b-(PG-g-PEI) for gene delivery].

OBJECTIVE: To synthesize a biodegradable non-viral gene carrier with a high transfection efficiency and a low cytotoxicity. METHODS: Poly(ethylene glycol)-block-(poly(L-glutamic acid)-graft-polyethylenimine) was prepared via ammonolysis of poly(ethylene glycol)-block-poly (γ-benzyl L-glutamate) with the low-molecular-mass polyethylenimine (600 Da). The synthesized copolymer was characterized by 1H nuclear magnetic resonance spectroscopy and gel permeation chromatography. The polyplex micelle from PEG-b-(PG-g-PEI) and plasmid DNA (pDNA) was studied using dynamic light scattering, zeta-potential measurements, and gel retardation assay. The in vitro cytotoxicity and transfection efficiency of PEG-b-(PG-g-PEI) were tested by MTT assay and luciferase assay in HEK 293T cells using PEI (25 kDa) as the control. RESULTS: PEG-b-(PG-g-PEI) could efficiently condense DNA into nanosized particles with positive surface charges when the N/P ratio of polymer and DNA was above 5:1. The zeta potential of the polyplexes was about 25 mV, and the particle size was 120 nm at a N/P ratio of 10. The cell toxicity and gene transfection evaluations showed a lower cytotoxicity and a higher gene transfection efficiency of the copolymer than PEI 25000 in HEK 293T cells. CONCLUSIONS: The polymer can be used as a potential non-viral gene carrier for gene therapy.