In Vitro Inhibition of Alphaviruses by Lycorine.

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus. As an emerging virus, CHIKV imposes a threat to public health. Currently, there are no vaccines or antivirals available for the prevention of CHIKV infection. Lycorine, an alkaloid from Amaryllidaceae plants, has antiviral activity against a number of viruses such as coronavirus, flavivirus and enterovirus. In this study, we found that lycorine could inhibit CHIKV in cell culture at a concentration of 10 µmol/L without apparent cytotoxicity. In addition, it exhibited broad-spectrum anti-alphavirus activity, including Sindbis virus (SINV), Semliki Forest virus (SFV), and Venezuelan equine encephalomyelitis virus (VEEV). The time of addition studies indicated that lycorine functions at an early post-entry stage of CHIKV life cycle. The results based on two different CHIKV replicons provided further evidence that lycorine exerts its antiviral activity mainly by inhibiting CHIKV translation. Overall, our study extends the antiviral spectrum of lycorine.

Insights into SARS-CoV-2: Medicinal Chemistry Approaches to Combat Its Structural and Functional Biology.

Coronavirus disease 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still a pandemic around the world. Currently, specific antiviral drugs to control the epidemic remain deficient. Understanding the details of SARS-CoV-2 structural biology is extremely important for development of antiviral agents that will enable regulation of its life cycle. This review focuses on the structural biology and medicinal chemistry of various key proteins (Spike, ACE2, TMPRSS2, RdRp and Mpro) in the life cycle of SARS-CoV-2, as well as their inhibitors/drug candidates. Representative broad-spectrum antiviral drugs, especially those against the homologous virus SARS-CoV, are summarized with the expectation they will drive the development of effective, broad-spectrum inhibitors against coronaviruses. We are hopeful that this review will be a useful aid for discovery of novel, potent anti-SARS-CoV-2 drugs with excellent therapeutic results in the near future.

Biosynthesis of Taxadiene in Saccharomyces cerevisiae : selection of geranylgeranyl diphosphate synthase directed by a computer-aided docking strategy.

Identification of efficient key enzymes in biosynthesis pathway and optimization of the fitness between functional modules and chassis are important for improving the production of target compounds. In this study, the taxadiene biosynthesis pathway was firstly constructed in yeast by transforming ts gene and overexpressing erg20 and thmgr. Then, the catalytic capabilities of six different geranylgeranyl diphosphate synthases (GGPPS), the key enzyme in mevalonic acid (MVA) pathway catalyzing famesyl diphosphate (FPP) to geranylgeranyl diphosphate (GGPP), were predicted using enzyme-substrate docking strategy. GGPPSs from Taxus baccata x Taxus cuspidate (GGPPSbc), Erwinia herbicola (GGPPSeh), and S. cerevisiae (GGPPSsc) which ranked 1st, 4th and 6th in docking with FPP were selected for construction. The experimental results were consistent with the computer prediction that the engineered yeast with GGPPSbc exhibited the highest production. In addition, two chassis YSG50 and W303-1A were chosen, and the titer of taxadiene reached 72.8 mg/L in chassis YSG50 with GGPPSbc. Metabolomic study revealed that the contents of tricarboxylic acid cycle (TCA) intermediates and their precursor amino acids in chassis YSG50 was lower than those in W303-1A, indicating less carbon flux was divided into TCA cycle. Furthermore, the levels of TCA intermediates in the taxadiene producing yeasts were lower than those in chassis YSG50. Thus, it may result in more carbon flux in MVA pathway in chassis YSG50, which suggested that YSG50 was more suitable for engineering the taxadiene producing yeast. These results indicated that computer-aided protein modeling directed isoenzyme selection strategy and metabolomic study could guide the rational design of terpenes biosynthetic cells.

Anti-dengue-virus activity and structure-activity relationship studies of lycorine derivatives.

Dengue is a systemic viral infection that is transmitted to humans by Aedes mosquitoes. No vaccines or specific therapeutics are currently available for dengue. Lycorine, which is a natural plant alkaloid, has been shown to possess antiviral activities against flaviviruses. In this study, a series of novel lycorine derivatives were synthesized and assayed for their inhibition of dengue virus (DENV) in cell cultures. Among the lycorine analogues, 1-acetyllycorine exhibited the most potent anti-DENV activity (EC50 =0.4 µM) with a reduced cytotoxicity (CC50 >300 µM), which resulted in a selectivity index (CC50 /EC50 ) of more than 750. The ketones 1-acetyl-2-oxolycorine (EC50 =1.8 µM) and 2-oxolycorine (EC50 =0.5 µM) also exhibited excellent antiviral activities with low cytotoxicity. Structure-activity relationships for the lycorine derivatives against DENV are discussed. A three-dimensional quantitative structure-activity relationship model was established by using a comparative molecular-field analysis protocol in order to rationalize the experimental results. Further modifications of the hydroxy group at the C1 position with retention of a ketone at the C2 position could potentially lead to inhibitors with improved overall properties.

Novel lycorine derivatives as anticancer agents: synthesis and in vitro biological evaluation.

Lycorine, which is the most abundant alkaloid isolated from the Amaryllidaceae family of plants, reportedly exhibits promising anticancer activities. Herein, a series of novel lycorine derivatives were synthesized and evaluated for their in vitro inhibitory activities against seven different cancer cell lines, including A549, HCT116, SK-OV-3, NCI-H460, K562, MCF-7 and HL-60. The results indicated that compounds bearing diverse amine substituents at the C-2 position demonstrated good anticancer activities. The selectivity towards different cancer cell lines of the synthesized derivatives is discussed.

P-glycoprotein ATPase activating effect of opioid analgesics and their P-glycoprotein-dependent antinociception in mice.

It is well known that opioid analgesics exert central antinociceptive actions. However, in vivo and in vitro studies have shown that some opioid analgesics given systemically have limited access to the central nervous system because of the blood-brain barrier (BBB). P-glycoprotein (P-gp), an ATP-dependent drug efflux transporter, is one component of the BBB. In this report, we assessed the antinociceptive effect of morphine, fentanyl, and meperidine in P-gp deficient (mdr1a KO) mice, and compared these effects with those in wild type (WT) mice. The antinociceptive effects of morphine and fentanyl in mdr1a KO mice were significantly greater than those in WT mice. However, there was no clear difference in the antinociceptive effects of meperidine in the two genotypes. In addition, we determined the effect of opioid analgesics on P-gp ATPase activity, which is requisite for drug transport, using mouse brain capillary endothelial cells. In our observations, morphine and fentanyl, but not meperidine, significantly increased P-gp ATPase activity, and the drugs' concentration-response curves were bell-shaped, reaching a peak at a concentration of 1 muM. These results suggest that P-gp ATPase activity may be, at least in part, involved in the antinociceptive potencies of those opioid analgesics that are substrates for P-gp.