Selected traditional medicinal plants exhibit therapeutic effects in coronavirus disease (Covid-19) patients. This review aims to identify the phytochemicals from five traditional medicinal plants (Glycyrrhiza glabra, Nigella sativa, Curcuma longa, Tinospora cordifolia and Withania somnifera) with high potential in modulating the main protease (Mpro) activity and cytokine storm in Covid-19 infection. The Mpro binding affinity of 13 plant phytochemicals were in the following order: Withanoside II>withanoside IV>withaferin A>α-hederin>withanoside V>sitoindoside IX>glabridin>liquiritigenin, nigellidine>curcumin>glycyrrhizin>tinocordiside>berberine. Among these phytochemicals, glycyrrhizin, withaferin A, curcumin, nigellidine and cordifolioside A suppressed SARS-CoV-2 replication and showed stronger anti-inflammatory activities than standard Covid-19 drugs. Both preclinical and clinical evidences supported the development of plant bioactive compounds as Mpro inhibitors.
Pluripotent stem cells may serve as an alternative source of beta-like cells for replacement therapy of type 1 diabetes; however, the beta-like cells generated in many differentiation protocols are immature. The maturation of endogenous beta cells involves an increase in insulin expression starting in late gestation and a gradual acquisition of the abilities to sense glucose and secrete insulin by week 2 after birth in mice; however, what molecules regulate these maturation processes are incompletely known. In this study, we aim to identify small molecules that affect immature beta cells. A cell-based assay, using pancreatic beta-like cells derived from murine embryonic stem (ES) cells harboring a transgene containing an insulin 1-promoter driven enhanced green fluorescent protein reporter, was used to screen a compound library (NIH Clinical Collection-003). Cortisone, a glucocorticoid, was among five positive hit compounds. Quantitative reverse transcription-polymerase chain reaction analysis revealed that glucocorticoids enhance the gene expression of not only insulin 1 but also glucose transporter-2 (Glut2; Slc2a2) and glucokinase (Gck), two molecules important for glucose sensing. Mifepristone, a pharmacological inhibitor of glucocorticoid receptor (GR) signaling, reduced the effects of glucocorticoids on Glut2 and Gck expression. The effects of glucocorticoids on ES-derived cells were further validated in immature primary islets. Isolated islets from 1-week-old mice had an increased Glut2 and Gck expression in response to a 4-day treatment of exogenous hydrocortisone in vitro. Gene deletion of GR in beta cells using rat insulin 2 promoter-driven Cre crossed with GRflox/flox mice resulted in a reduced gene expression of Glut2, but not Gck, and an abrogation of insulin secretion when islets were incubated in 0.5 mM d-glucose and stimulated by 17 mM d-glucose in vitro. These results demonstrate that glucocorticoids positively regulate glucose sensors in immature murine beta-like cells.