Antiviral activity of Andrographolide against Ebola virus, Dengue fever and SARS coronavirus

Abstract Andrographolide (1) a bitter, diterpenes lactone is the most biologically active constituent from Andrographis paniculata. Andrographolide showed in vitro inhibition of the growth of Ebola virus (Zaire) with EC50 activity of 10 µM which is twenty-five-fold the activity of the control Favipiravir (EC50 = 250µM) in the Crystal violet (Plaque reduction/ Neutral red (Toxicity) assay. It also showed significant activity against Dengue fever virus with EC50 value of 0.56 µg/ml in the Visual (Cytopathic effect/ Toxicity) Assay and EC50 of 0.58 µg/ml in the Neutral Red (Cytopathic effect/ Toxicity) Assay (comparable to the values obtained with 6-Azauridine as the positive control EC50 = 0.32 µg/ml and 0.38 µg/ml in the respective bioassays; and against SARS Coronavirus. Andrographolide had an EC50 of 1.2 µg/ml in the Visual (cytopathic effect/toxicity) assay and 1.1 µg/ml in the Neutral Red (cytopathic effect/toxicity) assay. The compound exerts several immunomodulatory properties. In experimental models, it effectively reduced the levels of proinflammatory cytokines such as IL-1/3, IL-6, GMCSF, and TNF-a. The compound has a good pharmacokinetics profile and relatively non-toxic even at high doses making it an experimental drug for the treatment of viral infections, with possible application in the control of the Novel Coronavirus, Covid – 19.