Natural molecules having anti-SARS-CoV activity - cannot they be effective against SARS-CoV-2?

In the current scenario, developing treatments, identifying cures and formulating intervention strategies to fight against the COVID-19 outbreak, have become the major concern for researchers globally. Several studies have confirmed the molecular pathway of COVID-19 virulence that involves activation of proteins like angiotensin-converting enzyme 2 (ACE2), angiotensin (AT) receptor which is mainly AT1, and transmembrane protease serine 2 (TMPRSS2). Since the virus needs the involvement of these proteins, over and above its spike protein, for activation and infecting the host, it is obvious that targeting or blocking the activation of these molecules may play a critical role in the development of therapeutics for the cure and management of COVID-19. Many studies have been reported and several are ongoing to find a cure using these molecules as a target. While initially COVID-19 was thought to be affecting the human respiratory system, recent shreds of evidence indicate that this infection can reach beyond the lungs. It can invade and rampage almost all the organs in the body, and 'cytokine storm' is considered to be responsible for this. The reason for disease severity is not what matters anymore now, everyone is hoping for a cure soon enough. Therefore, there is an urgent need to search for some novel drugs/chemicals. Towards this end, natural products can contribute immensely since they have a long history of usage for the cure and management of various ailments, including viral infections. Various natural products (mainly from plants) have structural similarities to the molecules which by AT has been shown to interact with targets used by COVID-19 during its infection. This is indeed a positive indication for the development of natural products-based therapeutics. This aspect, therefore, warrants serious consideration for the cure and management of the COVID-19 pandemic.