Traditionally used aqueous herbal extracts for respiratory ailments exhibit anti-inflammatory activity

Background: Phytoconstituents from plants provide a huge array of medicinal properties and have been used for many centuries as household medicines in India to treat respiratory illnesses. There are limited studies on comprehensive evaluations of these plant extracts to understand their healing properties.\r\n\r\nAim: To evaluate the antimicrobial and immunomodulatory properties of the 10 commonly used medicinal plants to treat respiratory illnesses in a comprehensive manner.\r\n\r\nMaterials and Methods: The acetone, ethanol and aqueous extracts from the 10 plants were evaluated for antiviral, antifungal and antibacterial activity. Additionally, the aqueous extracts were also evaluated for immunomodulatory properties.\r\n\r\nResults: None of the extracts exhibited antiviral activity against the four influenza viruses, antifungal activity against Candida albicans or antibacterial activity against Gram negative bacilli. Eight acetone extracts, nine ethanol extracts and one aqueous extract (NSAq) exhibited antibacterial activity at concentrations below 1mg/ml against S. pyogenes and/or S. pneumoniae. All the aqueous extracts exhibited dose-dependent anti-inflammatory activity against the innate immunity cytokines, TNF-α and IL-1β, and the Th1 cytokine, IFN-γ, but not against the Th2 cytokine, IL-4.\r\n\r\nConclusions: Overall the study elucidates that the acetone and ethanol extracts exhibit antibacterial activity, while the commonly consumed aqueous extracts ameliorate respiratory illnesses through immune modulation.