Channel activity of SARS-CoV-2 viroporin ORF3a inhibited by adamantanes and phenolic plant metabolites.

SARS-CoV-2 has been responsible for the major worldwide pandemic of COVID-19. Despite the enormous success of vaccination campaigns, virus infections are still prevalent and effective antiviral therapies are urgently needed. Viroporins are essential for virus replication and release, and are thus promising therapeutic targets. Here, we studied the expression and function of recombinant ORF3a viroporin of SARS-CoV-2 using a combination of cell viability assays and patch-clamp electrophysiology. ORF3a was expressed in HEK293 cells and transport to the plasma membrane verified by a dot blot assay. Incorporation of a membrane-directing signal peptide increased plasma membrane expression. Cell viability tests were carried out to measure cell damage associated with ORF3a activity, and voltage-clamp recordings verified its channel activity. The classical viroporin inhibitors amantadine and rimantadine inhibited ORF3a channels. A series of ten flavonoids and polyphenolics were studied. Kaempferol, quercetin, epigallocatechin gallate, nobiletin, resveratrol and curcumin were ORF3a inhibitors, with IC50 values ranging between 1 and 6 µM, while 6-gingerol, apigenin, naringenin and genistein were inactive. For flavonoids, inhibitory activity could be related to the pattern of OH groups on the chromone ring system. Thus, the ORF3a viroporin of SARS-CoV-2 may indeed be a promising target for antiviral drugs.

Contribution of CYP27B1 and CYP24A1 genetic variations to the incidence of acute coronary syndrome and to vitamin D serum level.

Cardiovascular diseases remain a major public health burden worldwide. It was reported that vitamin D protects the cardiovascular system through several mechanisms mainly by hindering atherosclerosis development. Genetic variations in vitamin D metabolic pathway were found to affect vitamin D levels. This study aimed at investigating the association between single nucleotide polymorphisms in genes involved in vitamin D metabolism, CYP27B and CYP24A1; 25-hydroxyvitamin D (25(OH)D) levels; and susceptibility to acute coronary syndrome (ACS). One hundred and eighty-five patients and 138 healthy controls were recruited. CYP24A1 rs2762939 was genotyped using fast real-time PCR, while CYP24A1 rs4809960 and CYP27B1 rs703842 were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP). 25(OH)D3 and 25(OH)D2 levels were measured using ultra-performance liquid chromatography tandem mass spectrum. Vitamin D level was significantly lower in patients than controls (p < 0.05). The GG genotype of rs2762939 was significantly associated with the risk of ACS development, but not correlated to the vitamin D level. rs4809960 and rs703842 genetic variations were not associated with ACS nor with 25(OH)D level. The genetic variant rs2762939 of CYP24A1 is remarkably associated with ACS. Meanwhile, the variants rs4809960 and rs703842 are not associated with ACS incidence.