Antiviral effects and possible mechanisms of action of constituents from Brazilian propolis and related compounds

Abstract

Propolis is a well-known medicinal bee hive product amongst others due to its antiviral properties. Human rhinoviruses (HRVs) are recognized to be responsible for more than 50% of common colds worldwide. This study was performed to determine if kaempferol (KF) and p-coumaric acid (p-CA) extracted from Brazilian propolis and another eight previously known compounds of propolis had antiviral activity toward human rhinovirus (HRV)-2, HRV-3, and HRV-4 in HeLa cells and to determine their mechanism of action using sulforhodamine B assay and real-time reverse transcription polymerase chain reaction. Results were compared with those of a positive control ribavirin. Based on IC₅₀ values, KF, quercetin, chrysin, and luteolin were more pronounced in antiviral activity toward HRV-2 (7.3–37.4 μM), HRV-3 (11.9–20.4 μM), and HRV-4 (12.9–24.4 μM) than a drug reference ribavirin (270.1–323.9 μM). The 35 μM KF and 610 μM p-CA did not interact with the HRV-3 particles. KF and p-CA inhibited HRV-3 infection when added during the early stages (0–4 h) after virus inoculation. These constituents remarkably reduced the RNA replication levels of HRV-3 in the HeLa cell cultures. These findings suggest that KF and p-CA may block or reduce the entrance of the viruses into the cells to protect the cells from the virus destruction and abate virus replication, which may play a crucial role in interfering with expressions of intercellular adhesion molecule-1 and interleukin-6. Further studies about the possible applications of propolis-derived materials as potential products to prevent or treat HRV infection are warranted.

Keywords:

• propolis
• human rhinovirus
• p-coumaric acid
• kaempferol
• mechanism of action
• natural antiviral agent

Disclosure Statement

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ010487) from the Rural Development Administration (RDA) of the Republic of Korea and by the Brain Korea 21 PLUS Program through the National Research Foundation of Korea funded by the Ministry of Education of the Korean Government to Y.-J. Ahn.