Anti-viral and Anti-inflammatory Isoflavonoids from Ukrainian Iris aphylla Rhizomes: Structure-Activity Relationship Coupled with ChemGPS-NP Analysis

Dried Iris rhizomes have been used in Chinese and European traditional medicine for the treatment of various diseases such as bacterial infections, cancer, and inflammation, as well as for being astringent, laxative, and diuretic agents. Eighteen phenolic compounds including some rare secondary metabolites, such as irisolidone, kikkalidone, irigenin, irisolone, germanaism B, kaempferol, and xanthone mangiferin, were isolated for the first time from Iris aphylla rhizomes. The hydroethanolic Iris aphylla extract and some of its isolated constituents showed protective effects against influenza H1N1 and enterovirus D68 and anti-inflammatory activity in human neutrophils. The promising anti-influenza effect of apigenin (13, almost 100% inhibition at 50 μM), kaempferol (14, 92%), and quercetin (15, 48%) were further confirmed by neuraminidase inhibitory assay. Irisolidone (1, almost 100% inhibition at 50 μM), kikkalidone (5, 93%), and kaempferol (14, 83%) showed promising anti-enterovirus D68 activity in vitro. The identified compounds were plotted using ChemGPS-NP to correlate the observed activity of the isolated phenolic compounds with the in-house database of anti-influenza and anti-enterovirus agents. Our results indicated that the hydroethanolic Iris aphylla extract and Iris phenolics hold the potential to be developed for the management of seasonal pandemics of influenza and enterovirus infections.