Effect of Sauropus androgynus L. Merr. on dengue virus-2: An in vitro and in silico study

Sauropus androgynus L. Merr. (Euphorbiaceae) commonly known as "multigreen" and "multivitamin" is consumed as a vegetable and used in traditional medicine to relieve fever.

This in vitro study is aimed to explore the activities of the lipophilic fraction of the leaves of S. androgynus (LFSA) against dengue (DENV), chikungunya (CHIKV) viruses and malaria (P. falciparum strain 3D7) parasite.

The LFSA was analyzed by using GC-FID and GC-MS. The antiviral activity of LFSA was studied using the Vero CCL-81 cell line. The cytotoxicity assay was performed using 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). Focus forming unit (FFU), cell-based immunofluorescence (IFA) assays, and quantitative RT-PCR, were used to determine and confirm antiviral activity against DENV and CHIKV. The antiparasitic activity of LFSA was carried out against P. falciparum strain 3D7 grown in fresh O+ human erythrocytes culture.

Twelve compounds were identified in LFSA using GC/MS. The most abundant compound was squalene (36.9%), followed by vitamin E (12.5%) and linolenic acid (10.2%). Significant reduction in DENV titre was observed under pre- and post-infection treatment conditions at a concentration of 31.25 μg/ml, but no anti-malarial and anti-CHIKV activity was observed. The Autodock-Vina-based in-silico docking study revealed that β-sitosterol could form a strong interaction with the DENV E glycoprotein.

Our findings suggest that LFSA can inhibit DENV infection and might act as a potent prophylactic/therapeutic agent against DENV-2. In-silico results suggested that β-sitosterol may block the viral entry by inhibiting the fusion process.