Targeting Natural Products for the Treatment of COVID-19 - An Updated Review.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is an ongoing, rapidly spreading pandemic caused by Severe Acute Respiratory Syndrome Coronavirus2 (SARS-CoV2). Among all the infected countries around the globe as of now (June 15, 2020), the total confirmed positive cases reported are 7,805,148, with the death of 431,192. At present, no specialized treatments evolved to cure COVID-19. Its treatment is symptomatic. Though huge efforts are being made to produce potential therapies to scuffle COVID-19, no drug has been discovered so far. OBJECTIVE: Natural products have been playing a significant role in disease control since ancient days. These products serve as templates for designing new anti-microbial agents with a different mechanism of action and also open a door for investigation of effective anti-viral drugs to combat COVID-19. By focusing on this, the authors have narrated the basic structure, infection, and pathogenesis of SARS-CoV2 virus in humans and also reported various natural products or plant-based extracts/bioactive compounds tested against coronaviruses like SARS and MERS, as these viruses are structurally similar to SARS-CoV2 and can be used in designing novel drug against this virus. CONCLUSION: The natural products having the potential to combat SARS, MERS, and other viruses reviewed in this review article might have anti-viral activities against the SARS-CoV2 virus and can be used directly for further preclinical studies. Therefore, all efforts should be focused on overcoming this serious problem to save many people's lives all over the world.

Stimulation of molt by RNA interference of the molt-inhibiting hormone in the crayfish Cherax quadricarinatus.

In crustaceans, molting is known to be under the control of neuropeptide hormones synthesized and secreted from the eyestalk ganglia. While the role of molt-inhibiting hormone (MIH) in regulating molting has been described in several species using classical methods, an in vivo specific MIH targeted manipulation has not been described yet. In the present study, an MIH cDNA was isolated and sequenced from the eyestalk ganglia of the Australian freshwater red claw crayfish Cherax quadricarinatus (Cq) by 5' and 3' RACE. We analyzed the putative Cq-MIH based on sequence homology, a three dimensional structure model and transcript's tissue specificity. We further examined the involvement of Cq-MIH in the control of molt in the crayfish through RNAi by in vivo injections of Cq-MIH double-stranded RNA, which resulted in, similarly to eyestalk ablation, acceleration of molt cycles. This acceleration was reflected by a significant reduction (up to 32%) in molt interval and an increased rate in molt mineralization index (MMI), which correlated with the induction of ecdysteroid hormones compared to control. Altogether, this study provides a proof of function for the involvement of the Cq-MIH gene in molt regulation in the crayfish.