In-vitro antiviral activity of Carica papaya formulations against dengue virus type 2 and chikungunya virus

Dengue and chikungunya are diseases of global health significance and currently, no antivirals are available to treat these arboviral diseases. Carica papaya leaves extract is traditionally used to treat thrombocytopenia in patients infected with the dengue virus. The current study was undertaken to study the antiviral activity of commercially available Carica papaya leaves extract (CPLE) based products and CPLE prepared in four formulations against dengue virus type 2 (DENV-2) and chikungunya virus (CHIKV). Maximum nontoxic concentrations of the commercially available CPLE based products and CPLE based formulations (Carica papaya leaves in powder form, Carica papaya leaves in lyophilized form, Carica papaya leaves based silver nanoparticles and supercritical fluid extract of Carica papaya leaves) were used for screening the antiviral activity. The antiviral activity against DENV-2 and CHIKV were assessed post infection using focus forming unit assay. Effective formulations were tested under different conditions i.e. pretreatment, cotreatment and posttreatment. The virus output after treatment was assessed by real-time RT-PCR, immunofluorescence assay and focus forming unit assay. The results revealed Carica papaya leaves based silver nanoparticles and supercritical fluid extract of Carica papaya leaves formulations showed significant inhibition in case of DENV while papaya leaves in powder form showed significant reduction in case of CHIKV. This study demonstrates the antiviral activity of CPLE formulations against DENV-2 and CHIKV infection in in-vitro system and needs further validation in in-vivo models.