Chemical composition, biological activities, and molecular mechanism of Inula viscosa (L.) bioactive compounds: a review.

Inula viscosa is an herbaceous plant mainly found in Mediterranean regions, predominantly, used in developing countries as a folk remedy for treating numerous diseases using different traditional methods of preparation that includes infusion, decoction, and external application. Researchers have been interested in studying the antioxidant, anti-inflammatory, antifungal, antibacterial, antidiabetic, and antitumor effects of I. viscosa extracts, due to its high countenance of bioactive molecules. The chemical studies of ethanol, methanol, chloroform, aqueous, petroleum ether, dichloromethane, and ethyl acetate extracts from different parts of I. viscosa, growing around the world, and analyzed by different analytical techniques allowed to isolate and identify a great number of secondary metabolites from terpenes, flavonoids, phenylpropanoids, and polyketides, and complementary in vitro and in vivo studies indicated the pharmacological activities of an isolated compound, a mixture, or the crude extract. I. viscosa extracts had a great in vivo potential reducing mice paw, ear, and the severity of pulmonary edema, and the occurrence of skin carcinoma growing; in vitro recent study results showed, in addition, the high antioxidant, α-glucosidase, and α-amylase inhibitory activity, and neuroprotectivity effects; a correlation with the in vivo studies confirming the anti-inflammatory and antitumor proprieties, elucidating some molecular mechanisms: showing that tomentosin reduced pro-inflammatory cytokine secretion (IFNγ, IL-1, IL-2, TNF-α, and IL-6) via the suppression of transcription factor NF-κB and MAP kinase (p38/JNK) activation, and that the two phenolic compounds banaxanthone E and paxanthone inhibited the antiapoptotic protein BCL-2, activating the apoptotic process leading to the antiproliferative effect.