Are there medicinal plants that can maintain immunity?

At present the Corona positive cases are increasing in number. Amid the Covid-19 pandemic, it is very important to stay healthy so that the body is able to defend itself from disease. Various efforts can be made such as consumption of healthy foods, consumption of vitamins, and supplements. Another thing that can be done is to consume traditional medicine which is efficacious to increase endurance (immunostimulant). Indonesia has a lot of natural wealth, especially medicinal plants which are useful as immunostimulant.

BPOM RI itself has mentioned in the "Buku Saku Obat Tradisional Untuk Memelihara Daya Tahan Tubuh " that there are some traditional medicinal plants that have the efficacy of maintaining immunity. Some of the plants recommended by BPOM are bitter (Andrographis paniculata (Burm.f)), turmeric (Curcuma longa L.), guava (Psidium guava L.), meniran (Phyllanthus niruri), curcuma (Curcuma xanthorhiza Roxb), guava (Psidium guava L.), meniran (Phyllanthus niruri), ginger (Zingiber officinale Roscoe). This plant empirically and tests on test animals show efficacy can increase endurance (BPOM, 2020).

On the other hand, it turns out that some of these herbs are able to prevent the infection of the SARS-CoV-2 virus (the cause of COVID19) is a close relative of SARS-CoV (the cause of SARS) in silico, in-vitro and in-vivo. It is known that SARS-CoV-2 infects humans in a way very similar to its relative SARS-CoV that interacts with ACE2 receptors. ACE2 is a receptor identified as the entry point for the SARS-CoV-2 virus to infect humans. These receptors are widely expressed in the lungs. In addition to the ACE2 receptor, the presence of S protein on the surface of the virus that binds to the ACE2 receptor. Next will be the activation of the serine protease enzyme by TMPRSS2 (a transmembrane glycoprotein) which allows the virus to fuse and enter the target cell.

Here are some studies that support the ability of these herbs in preventing SARS-CoV-2 virus infection. Computationally tested in silico, andrographolide compounds in bitter (Andrographis paniculata (Burm.f)) were able to inhibit the activation of the serine protease enzyme (Sukanth et al., 2020). Curcumin contained in turmeric (Curcuma longa L.) is able to inhibit the interaction of ACE2 receptors (Pang et al., 2015) in test mice. 6-gingerol, in silico, which is contained in the ginger rhizome (Zingiber officinale Roscoe) is able to inhibit the interaction of ACE2 receptors (Sivaraman and Pradeep, 2020). Of course this study is still very much needed an in vitro test, preclinical test or clinical test to ensure its efficacy in preventing SARS-CoV-2 virus infection. So that it still requires a fairly long stage in ensuring the efficacy of this herb in preventing infection of the SARS-CoV-2 virus.