COVID-19, caused by the coronavirus SARS-CoV-2, emerged in late December 2019 in Wuhan, China. As of 8 April 2022, the virus has caused a global pandemic, resulting in 494,587,638 infections leading to 6,170,283 deaths around the world. Although several vaccines have received emergency authorization from USA and UK drug authorities and two more in Russia and China, it is too early to comment on the prolonged effectiveness of the vaccines, their availability, and affordability for the developing countries of the world, and the daunting task to vaccinate 7 billion people of the world with two doses of the vaccine with additional booster doses. As a result, it is still worthwhile to search for drugs and several promising leads have been found, mainly through in silico studies. In this study, we have examined the binding energies of several alkaloids and anthocyanin derivatives from the Solanaceae family, a family which contains common consumable vegetables and fruit items such as eggplant, pepper, and tomatoes. Our study demonstrates that Solanaceae family alkaloids such as incanumine and solaradixine, as well as anthocyanins and anthocyanidins, have very high predicted binding energies for the 3C-like protease of SARS-CoV-2 (also known as Mpro). Since Mpro is vital for SARS-CoV-2 replication, the compounds merit potential for further antiviral research towards the objective of obtaining affordable drugs.

Cells must continuously adjust metabolic output to maintain homeostasis under changing environmental conditions, yet the mechanisms that enable rapid and reversible control of pathway activity remain largely unknown. The methylerythritol phosphate (MEP) pathway, of bacterial origin and conserved in plastid-bearing eukaryotes, including plants and apicomplexan parasites, produces isoprenoid precursors essential for growth and stress adaptation. Here, we identify methylerythritol cyclodiphosphate (MEcPP) as a dual-function metabolite that serves both as a biosynthetic intermediate and a direct modulator of enzyme activity. Genetic perturbations and high light stress revealed step-specific MEcPP accumulation independent of transcriptional regulation. Biochemical and protease-protection assays showed that MEcPP destabilizes and inhibits methylerythritol cytidylyltransferase (MCT) while modestly stabilizing hydroxymethylbutenyl diphosphate synthase (HDS). Molecular docking analyses indicate that MEcPP interacts directly with the MCT catalytic site, displacing the natural substrate and thereby attenuating enzyme activity, suggesting a competitive, feedback-like mechanism of metabolic control. These results define MEcPP as a metabolic feedback signal that translates stress-induced changes into targeted enzymatic control. This mechanism illustrates how pathway intermediates dynamically coordinate biosynthetic activity with environmental cues, representing a broadly conserved strategy for metabolite-driven control of cellular metabolism.

This study investigates the relationship between secondary metabolites and stress tolerance in moss species, with a specific emphasis on comparing Antarctic and Korean mosses. Analyses of total phenolic content (TPC) and total flavonoid content (TFC) revealed that Antarctic mosses contain these compounds at significantly higher levels compared to the Korean mosses. These findings are consistent with greater antioxidant activities observed in Antarctic mosses through DPPH and ABTS^•+ radical scavenging assays. In this study, a total of 620 metabolites were identified from the moss samples. The results showed that Antarctic mosses exhibited a high number and diversity of compounds including terpenoids, flavonoids, lipids, and other classes. Additionally, Antarctic mosses had fewer lipids with carbon chain lengths below 18 and a higher content of unsaturated lipids, indicating adaptations to maintain membrane fluidity under cold stress. The phylogenetic relationships suggested a correlation between metabolite profiles and genetic adaptations between these species. This research highlights the complex biochemical strategies that mosses, particularly those in Antarctic regions, employ to adapt the environmental stressors. The high abundance of secondary metabolites in Antarctic mosses not only serves as a defense mechanism against oxidative stress but also suggests their potential applications in various biotechnological aspects. This study reveals new avenues for exploring the ecological roles and potential uses of these resilient plant species.