Revista de nefrología y terapéutica

In vitro anti-influenza virus activity of Rooibos tea

Abstract

Mona Timan Idriss Gassab

Background:  Influenza virus is a major public health and its control continues to be a challenge. One of the possible sources of anti-influenza active agents might be Rooibos teas (RT), with various pharmacological actions.

Methods: We searched for anti-influenza activity using standard in vitro antiviral assays such as Inhibition of virus induced cytopathic effect (CPE) assay, inhibition of viral plaques, and hemagglutination assay. Time-of-addition assay was performed to target an event in the virus life cycle.

Results: RT crude extract showed anti-influenza activity and the 50% effective inhibitory concentration (CC50) was 4%, while IC50 for A/WSN/33 was 0.13%, when they were measured with both Crystal violet and Water-soluble tetrazolium salt (WST-1) assays. The virus-induced cytopathic effects were thus significantly reduced.  Plaque assays demonstrated that RT extracts reduced virus infectivity markedly in dose dependent manner, when the viruses were treated with RT extract before exposure and post exposure to MDCK cells. In contrast, pretreatment of MDCK cells with RT extracts before influenza virus infection did not affect virus infectivity. The inhibitory effect of RT extract was observed against influenza A/PR/8/34 (H1N1), A/WSN/33 and A/HK/8/68 (H3N2) and influenza B. Our results suggest that RT extract contains anti-influenza virus substances that directly affects influenza virus particles and disrupts the function of virus adsorption to host cells.

Conclusions: These results have exposed the capability of the extracted RT for strongly inhibit influenza virus replication and offers an opportunity for the development of a new anti-influenza virus agent.