Boswellia serrata oleo-gum-resin and β-boswellic acid inhibits HSV-1 infection in vitro through modulation of NF-кB and p38 MAP kinase signaling

BACKGROUND

Herpes Simplex Virus (HSV), a highly contagious pathogen, is responsible for causing lifelong oral to genital infection in human. Boswellia serrata oleo-gum-resin possesses a strong traditional background of treating diverse skin ailments including infection but its effect on HSV-1 has not been examined yet.

PURPOSE

To exploit its potential, we aimed to explore the antiviral activity of methanol extract of B. serrata oleo-gum-resin (BSE) and one of its major constituent β-boswellic acid (BA) against HSV-1 along with the underlying mechanism of action involved.

METHODS

BSE was subjected to RP-HPLC analysis to quantify the active constituent. Cytotoxicity (CC₅₀) and antiviral activity were evaluated by MTT and plaque reduction assay, followed by the determination of median effective concentration (EC₅₀). The mode of antiviral activity was assessed by time-of-addition assay and confirmed by reverse transcriptase-PCR (RT-PCR). Further, the expressions of various cytokines were measured by RT-PCR, while the proteins by Western blot.

RESULTS

BSE and BA potently inhibited wild-type and a clinical isolate of HSV-1 (EC₅₀ 5.2-6.2 and 12.1-14.63 μg/ml), with nearly-complete inhibition (EC₉₉) at 10 and 30 μg/ml, respectively. The inhibitory effect was significant at 1 h post-infection and effective up to 4 h. Based on target analysis we examined the inhibition of NF-κB, essential for virus replication, and observed significant down-regulation of NF-κB, and p38 MAP-kinase activation, with reduced expression of tumor necrosis factor (TNF)-α, Interleukin (IL)-1β and IL-6, involved in scheming NF-κB signaling.

CONCLUSION

Thus, our results support the ethnomedicinal use of BSE in skin infection by inhibiting HSV-1 through the modulation of NF-κB and p38 MAPK pathway.