Cocculus hirsutus-Derived Phytopharmaceutical Drug Has Potent Anti-dengue Activity

Background Dengue is a serious public health concern worldwide, with ~3 billion people at risk of contracting dengue virus (DENV) infections. Currently, no effective vaccine or drug is available for the prevention or treatment of dengue, which leaves only anti-mosquito strategies to combat this disease. The present study was initiated to determine the in-vitro and in vivo protective effects of a plant-derived phytopharmaceutical drug for the treatment of dengue. Methodology/Principal Findings In our previous report, we had identified methanolic extract of the aerial parts of Cissampelos pareira to exhibit in vitro and in vivo anti-dengue activity against all the four DENV serotypes. In the current study, we have identified another Indian medicinal plant, Cocculus hirsutus, which has a more potent anti-dengue activity than C. pareira. The activity has been evaluated through flow-cytometry-based virus inhibition assay. Interestingly, the stem of C. hirsutus was found to be more potent than the aerial part irrespective of the extraction solvent used viz., denatured spirit, hydro-alcohol (50:50) and water. Hence, the aqueous extract of stem of C. hirsutus (AQCH) was further advanced for investigations because of greater regulatory acceptance. The AQCH exhibited dose-dependent inhibition of release of DENV and its secretory antigen, NS1. Five chemical markers viz. Sinococuline, 20-Hydroxyecdysone, Makisterone-A, Magnoflorine and Coniferyl alcohol were identified as the major chemical ingredients of the AQCH extract. These chemicals were subsequently used for extract standardisation. Importantly, AQCH completely protected AG129 mice at 25 mg/kg/dose body weight when fed 4 times a day post-infection with a lethal dose of DENV-2 S221 strain. Because of its potential as an effective phytopharmaceutical drug against dengue, AQCH, has been formulated into tablets for further pre-clinical and clinical developments. Conclusions/Significance We provide evidence of the pan anti-dengue potential of C. hirsutus-based phytopharmaceutical drug as determined through in vitro and in vivo experiments. We have also characterized five chemical entities in the drug substance, which provides means for standardization of drug substance and drug product. Based on these findings, a program to develop a safe and effective C. hirsutus-derived phytopharmaceutical drug for the treatment of dengue has been initiated. Author summary There is an urgent need to develop a safe and effective drug against dengue, which is a rapidly expanding mosquito-borne viral disease. Half of the world’s population has been estimated to be at risk of contracting this disease and the situation remains grim due to lack of an approved drug. We aimed to develop an ethnopharmacological drug against dengue by exploring traditional Indian medicinal science, Ayurveda. This led us to identify a creeper, Cocculus hirsutus, as a more potent anti-dengue plant than Cissampelos pareira, reported in our earlier published study. The stem part of C. hirsutus was found to be more efficacious in inhibiting the propagation of dengue viruses (DENVs) in cell culture than its aerial part. Hence, we chose to advance aqueous extract of stem of C. hirsutus (AQCH) for further studies. Importantly, AQCH also protected immune-compromised mice from lethal DENV infection, which is suggestive of its potential clinical relevance. We have identified five chemical marker compounds in AQCH to gauge the quality and consistency of extract preparation and its formulation into stable tablets. Based on the findings of this study, we have undertaken the development of a safe and effective C. hirsutus-derived phytopharmaceutical drug for the treatment of dengue.