Purpose-Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is a naturally occurring polyphenol with a broad range of possible health benefits, including anti-cancer activity. However, the biological activity of resveratrol may be limited by poor absorption and first-pass metabolism: only low plasma concentrations of resveratrol are seen following oral administration, and metabolism to glucuronide and sulfate conjugates is rapid. Methylated polyphenol analogs (such as pterostilbene [3,5-dimethoxy-4′-hydroxy-trans-stilbene], the dimethylether analog of resveratrol) may overcome these limitations to pharmacologic efficacy. The present study was designed to compare the bioavailability, pharmacokinetics, and metabolism of resveratrol and pterostilbene following equimolar oral dosing in rats.Methods-The agents were administered orally via gavage for 14 consecutive days at 50 or 150 mg/kg/day for resveratrol and 56 or 168 mg/kg/day for pterostilbene. Two additional groups were dosed once intravenously with 10 and 11.2 mg/kg for resveratrol and pterostilbene, respectively. Plasma concentrations of agents and metabolites were measured using a high-pressure liquid chromatograph-tandem mass spectrometer system. Noncompartmental analysis was used to derive pharmacokinetic parameters.Results-Resveratrol and pterostilbene were approximately 20 and 80% bioavailable, respectively. Following oral dosing, plasma levels of pterostilbene and pterostilbene sulfate were markedly greater than were plasma levels of resveratrol and resveratrol sulfate. Although plasma levels of resveratrol glucuronide exceeded those of pterostilbene glucuronide, those differences were smaller than those of the parent drugs and sulfate metabolites.Conclusions-When administered orally, pterostilbene demonstrates greater bioavailability and total plasma levels of both the parent compound and metabolites than does resveratrol. These differences in agent pharmacokinetics suggest that the in vivo biological activity of equimolar doses of pterostilbene may be greater than that of resveratrol.

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As coronavirus disease 2019 (COVID-19) outbreak, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), started in China in January, 2020, repurposing approved drugs is emerging as important therapeutic options. We reported here the first clinical study using hepatitis C virus (HCV) protease inhibitor, danoprevir, to treat COVID-19 patients. Danoprevir (Ganovo) is a potent HCV protease (NS3/4A) inhibitor (IC50 = 0.29 nM), which was approved and marketed in China since 2018 to treat chronic hepatitis C patients. Ritonavir is a CYP3A4 inhibitor to enhance plasma concentration of danoprevir while it also acts as a human immunodeficiency virus (HIV) protease inhibitor at high doses. The chymotrypsin-like protease of SARS-CoV-2 shares structure similarity with HCV and HIV proteases. In the current clinical study (NCT04291729) conducted at the Nineth Hospital of Nanchang, we evaluated therapeutic effects of danoprevir, boosted by ritonavir, on treatment naive and experienced COVID-19 patients. The data from this small-sample clinical study showed that danoprevir boosted by ritonavir is safe and well tolerated in all patients. After 4 to 12-day treatment of danoprevir boosted by ritonavir, all eleven patients enrolled, two naive and nine experienced, were discharged from the hospital as they met all four conditions as follows: (1) normal body temperature for at least 3 days; (2) significantly improved respiratory symptoms; (3) lung imaging shows obvious absorption and recovery of acute exudative lesion; and (4) two consecutive RT-PCR negative tests of SARS-CoV-2 nucleotide acid (respiratory track sampling with interval at least one day). Our findings suggest that repurposing danoprevir for COVID-19 is a promising therapeutic option.

An analytical approach for the determination of trans-resveratrol (3,5,4′-trihydroxy-trans-stilbene) and its glucuronide and sulfate conjugates in dog plasma by LC-MS/MS (without enzymatic hydrolysis of the conjugates) was validated to support pre-clinical toxicological and pharmacological studies. The approach required two independent sample extractions and consequent instrument runs. Samples for resveratrol determination were prepared by protein precipitation with acetonitrile; acetonitrile-methanol was used instead for resveratrol metabolites. Chromatographic separation was performed using a C18 column (30 × 2.0 mm) at a flow rate of 0.25 mL/min. For resveratrol the mobile phase consisted of A: 5 mM ammonium acetate in water-isopropanol (98:2, v/v) and B: methanol-isopropanol (98:2, v/v) and for metabolites the mobile phase was modified as follows: A: 0.1% (v/v) formic acid in water and B: 0.1% (v/v) formic acid in acetonitrile. Total run time was 12 min for each run with retention times of about 4-5 min for all analytes. A turbo ion spray source was used operating in negative mode for resveratrol and resveratrol sulfate and in positive mode for resveratrol glucuronide. Calibration curves were linear from 5 to 1000 ng/mL for resveratrol and its glucuronide, and 10 to 2000 ng/mL for resveratrol sulfate. Linearity was assessed using the internal standard method for resveratrol and the external standard method for the metabolites. Method accuracy was 90 to 112% of the true value for all analytes with precision of 9 %RSD or less for all validation experiments. The validated method was applied to a preclinical toxicology study in dogs after oral administration (200 to 1200 mg/kg) of the agent. Peak plasma resveratrol concentration (Cmax) for most animals was observed within 1 to 5 h of dosing, with group mean values in the 1.7 to 9.9 μg/mL (7.5 to 43 μM) range. Area under the plasma concentration-time curve (AUC) mean values for resveratrol ranged from 3.6 to 44 h*μg/mL for all study groups and were generally proportional to the dose, with no consistent statistically significant changes observed for gender or number of doses. Mean molecular-weight adjusted ratios of resveratrol metabolites to resveratrol for AUC ranged from 1 to 9 for resveratrol glucuronide and from 2 to 11 for resveratrol sulfate.