Dengue virus (DENV) infection, which causes dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is a severe global health problem in tropical and subtropical areas. There is no effective vaccine or drug against DENV infection. Thus, the development of anti-DENV agents is imperative. This study aimed to assess the anti-DENV activity of (E)-guggulsterone using a DENV infectious system. A specific inhibitor targeting signal molecules was used to evaluate the molecular mechanisms of action. Western blotting and qRT-PCR were used to determine DENV protein expression and RNA replication, respectively. Finally, an ICR suckling mouse model was used to examine the anti-DENV activity of (E)-guggulsterone in vivo. A dose-dependent inhibitory effect of (E)-guggulsterone on DENV protein synthesis and RNA replication without cytotoxicity was observed. The mechanistic studied revealed that (E)-guggulsterone stimulates Nrf2-mediated heme oxygenase-1 (HO-1) expression, which increases the antiviral interferon responses and downstream antiviral gene expression by blocking DENV NS2B/3B protease activity. Moreover, (E)-guggulsterone protected ICR suckling mice from life-threatening DENV infection. These results suggest that (E)-guggulsterone can be a potential supplement for controlling DENV replication.

Dengue virus (DENV) infection is a serious global health issue as it causes severe dengue hemorrhagic fever and dengue shock syndrome. Since no approved therapies are available to treat DENV infection, it is necessary to develop new agents or supplements that can do this. In this study, grape seed proanthocyanidins extract (GSPE), which is widely consumed as a dietary supplement, dose-dependently suppressed the replication of four DENV serotypes. The inhibitory mechanism demonstrated that GSPE downregulated DENV-induced aberrant cyclooxygenase-2 (COX-2) expression, revealing that the inhibitory effect of the GSPE on DENV replication involved targeting DENV-induced COX-2 expression. Mechanistic studies on signaling regulation have demonstrated that GSPE significantly reduced COX-2 expression by inactivating NF-κB and ERK/P38 MAPK signaling activities. Administrating GSPE to DENV-infected suckling mice reduced virus replication, mortality, and monocyte infiltration of the brain. In addition, GSPE substantially reduced the expression of DENV-induced inflammatory cytokines associated with severe dengue disease, including tumor necrosis factor-α, nitric oxide synthase, interleukin (IL)-1, IL-6, and IL-8, suggesting that GSPE has potential as a dietary supplement to attenuate DENV infection and severe dengue.