Traditional Triphala (three fruits), consisting of Phyllanthus emblica, Terminalia chebula, and Terminalia bellirica, presents a broad range of biological activities. However, its ability to inhibit dengue virus (DENV) infection has not been reported yet. Herein, the authors investigated the efficiency of three different Triphala formulations and its individual extract constituents to inhibit DENV infection. Treatment with T. bellirica extract or Triphala formulated with a high ratio of T. bellirica extract showed remarkable efficiency in significantly lowering DENV infection in Vero cells. Their effects were further studied in Huh7 cells, to address its potential ability in human cells. Treatment with 100 μg/mL of T. bellirica extract or Triphala resulted in an approximate 3000-fold or 1000-fold lowering of virus production, respectively. Furthermore, the treatment diminished IL-6 and CXCL-10 expressions, which are the hallmark of the cytokine storm phenomenon in DENV infection. The HPLC profiling demonstrated gallic acid as a major compound, the treatment by which showed its ability to effectively inhibit DENV infection after virus entry. Molecular docking demonstrated that gallic acid was able to interact with DENV NS5 protein, which could be one of Triphala's antiviral mechanism. This study offers Triphala formulation and its ingredient, T. bellirica extract, as a natural based pharmaceutical to be used in DENV infection treatment.
Keywords: Terminalia bellirica extract; Triphala; anti-dengue virus activity; cytokine storm; gallic acid.