Antiviral activity of 5-aminolevulinic acid against variants of severe acute respiratory syndrome coronavirus 2

Background Genetic variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began to emerge in 2020 and have been spreading globally during the coronavirus disease 2019 (COVID-19) pandemic. Despite the presence of different COVID-19 vaccines, the discovery of effective antiviral therapeutics for the treatment of patients infected with SARS-CoV-2 are still urgently needed. A natural amino acid, 5-aminolevulinic acid (5-ALA), has exhibited both antiviral and anti-inflammatory activities. In a previous study, we demonstrated an in vitro antiviral effect of 5-ALA against SARS-CoV-2 infection without significant cytotoxicity. In the present study, we sought to investigate whether 5-ALA with or without sodium ferrous citrate (SFC) can inhibit in vitro both the original SARS-CoV-2 Wuhan strain and its variants, including the Alpha, Beta, Gamma and Delta strains. Methods The antiviral activity of ALA with or without SFC was determined in Vero-E6 cell. The virus inhibition was quantified by real time RT-PCR. Results Co-administration of 5-ALA and SFC inhibited the Wuhan, Alpha and Delta variants of SARS-CoV-2 with IC50 values of 235, 173 and 397 µM, respectively, and the Beta and Gamma variants with IC50 values of 1311 and 1516 µM. Conclusion Our study suggests that 5-ALA with SFC warrants accelerated clinical evaluation as an antiviral drug candidate for treating patients infected with SARS-CoV-2 variants.

Safety Assessment of Oral 5-aminolevulinic Acid and Ferrous iron in Healthy Human Subjects: A Non-randomized, Open-label, Non-placebo-controlled Trial

The combination of 5-aminolevulinic acid (5-ALA) phosphate and sodium ferrous citrate (SFC) has been approved as an ingredient of food supplement in several countries because of its wide applicability to healthcare areas. We aimed to assess the safety of 5-ALA phosphate and SFC in healthy adult subjects at the dose several times higher than that available on market. This was an open, non-randomized, non-placebo-controlled trial that included 11 men and 11 women. Doses of 250 mg 5-ALA phosphate and 143.4 mg SFC (15 mg as Fe) per day were orally administered for 28 days. Blood and urine analyses and interviews were conducted to assess the safety. No test compound-related adverse events or abnormal values were observed, except for elevated serum iron levels, which were mild to moderate and transient. Combined administration of 5-ALA phosphate and SFC to healthy adults is well-tolerated and safe at the dose and duration investigated in this study.

CYB561A3 is the Key Lysosomal Iron Reductase Required for Burkitt B-cell Growth and Survival

Epstein-Barr virus (EBV) causes endemic Burkitt lymphoma, the leading childhood cancer in sub-Saharan Africa. Burkitt cells retain aspects of germinal center B-cell physiology with MYC-driven B-cell hyperproliferation, yet little is presently known about their iron metabolism. CRISPR/Cas9 analysis highlighted the little studied ferrireductase CYB561A3 as critical for Burkitt proliferation, but not for that of closely related EBV-transformed lymphoblastoid cells or nearly all other Cancer Dependency Map cell lines. Burkitt CYB561A3 knockout induced profound iron starvation, despite ferritinophagy and plasma membrane transferrin upregulation. Elevated concentrations of ascorbic acid, a key CYB561 family electron donor or the labile iron source ferrous citrate rescued Burkitt CYB561A3 deficiency. CYB561A3 knockout caused catastrophic lysosomal and mitochondrial damage and impaired mitochondrial respiration. By contrast, lymphoblastoid B-cells with the transforming EBV latency III program were instead dependent on the STEAP3 ferrireductase. These results highlight CYB561A3 it as an attractive therapeutic Burkitt lymphoma target.