5-amino levulinic acid inhibits SARS-CoV-2 infection in vitro.

The current COVID-19 pandemic requires urgent development of effective therapeutics. 5-amino levulinic acid (5-ALA) is a naturally synthesized amino acid and has been used for multiple purposes including as an anticancer therapy and as a dietary supplement due to its high bioavailability. In this study, we demonstrated that 5-ALA treatment potently inhibited infection of SARS-CoV-2, a causative agent of COVID-19, in cell culture. The antiviral effects could be detected in both human and non-human cells, without significant cytotoxicity. Therefore, 5-ALA is worth to be further investigated as an antiviral drug candidate for COVID-19.

FR227673 and FR190293, novel antifungal lipopeptides from Chalara sp. No. 22210 and tolypocladium parasiticum No. 16616.

Novel antifungal lipopeptides, FR227673 and FR190293, were isolated from the fermentation broths of fungal strains Chalara sp. No. 22210 and Tolypocladium parasiticum No. 16616, respectively. These compounds have the same cyclic peptide nuclear structure as FR901379, with different side chains, and showed antifungal activity against Aspergillus fumigatus and Candida albicans attributed to inhibition of 1,3-beta-glucan synthesis.

Suppressive effect of antibiotic siomycin on antibody production.

The antibiotic thiazole compound siomycin, which we have found from the culture broth of Actinomycetes (strain No.806097) in search of antibody production inhibitor, showed the in vitro immunosuppressive property against B-cells stimulated with T-cell independent antigen DNP-LPS (dinitrophenyl-lipopolysaccharide) while it also showed inhibitory effect against T-cell proliferation. Its inhibitory mechanism was considered to be different from that of FK506, the representative of T-cell immunosuppressant. Moreover, siomycin showed inhibitory effect in both T-cell dependent and independent murine antibody production models and decreased the severity in murine collagen arthritis model. Therefore, siomycin is a unique immunosuppressant which has potential for the treatment of some antibody-mediated diseases.

FR252921, a novel immunosuppressive agent isolated from Pseudomonas fluorescens no. 408813. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities of FR252921, FR252922 and FR256523.

Novel immunosuppressive agents, FR252921, FR252922 and FR256523 were isolated from the cultured broth of a bacterial strain No. 408813. The strain was identified Pseudomonas fluorescens from morphological and physiological characteristics. FR252921, FR252922 and FR256523, novel compounds containing macrolactone ring, showed immunosuppressive activity against murine splenocyte proliferation stimulated with lipopolysaccharide (LPS) or anti-CD3 mAb in vitro.

FR252921, a novel immunosuppressive agent isolated from Pseudomonas fluorescens no. 408813 II. In vitro property and mode of action.

A novel immunosuppressive agent, FR252921 was isolated from the cultured broth of a species of Pseudomonas fluorescens. We have shown that FR252921 inhibited splenic proliferation stimulated with LPS, insensitive to calcinuerin inhibitor. In this study, FR252921 was found to inhibit IL-2 and IL-12 production as well as proliferaion of splenocyte. Analysis of transcription activity revealed that FR252921 inhibited activating protein-1 (AP-1). Exposures of antigen presenting cells (APC) to FR252921 attenuated proliferation supplemented by naïve T cells. Further, FR252921 strongly suppressed splenic dendritic cell proliferation stimulated with LPS and anti-CD40 mAb, while it did not inhibit purified T cell activation, including CD154 expression and IL-2 production. These results suggest that APC is dominant target cell population.

FR252921, a novel immunosuppressive agent isolated from Pseudomonas fluorescens no. 408813 III. In vivo activities.

A novel immunosuppressive agent, FR252921 was isolated from the cultured broth of a species of Pseudomonas fluorescens. We have shown that FR252921 inhibit activating protein-1 (AP-1) transcription activity and act dominantly against antigen presenting cells comparing to T cell. Possibility of FR252921 as concomitant drug of FK506, T-cell specific inhibitor was evaluated. FR252921 showed synergy with FK506 in immunosuppressive activity both in splenic proliferation and in murine skin transplantation.