In this study, a detailed phytochemical analysis of the medicinal herb Inula viscosa leaves was performed. Furthermore, in vitro antioxidant and antifungal properties of its methanolic extract were evaluated and compared with the corresponding phenolic profile obtained by high-performance liquid chromatography and mass spectrometry. Data obtained underscore the high amount of total lipids (6.14%) in leaves. Chromatographic analysis revealed its high content of unsaturated fatty acids (UFAs) with the essential ones α-linolenic and linoleic acids being the main compounds. It also showed good nutritional quality because of its high UFA/saturated fatty acid ratio and the lower values of atherogenic and thrombogenic indices. The volatile oil analyzed by gas chromatography-mass spectrometry showed the abundance of nonterpenic compounds, namely aliphatic alkanes. The total phenol content (TPC) and total flavonoid content (TFC) were higher in I. viscosa leaves (103 mg GAE/g dw and 99 mg CE/g dw for TPC and TFC, respectively). The use of HPLC-PDA-ESI-MS/MS allowed the identification of 17 components with hydroxycinnamic acids, namely mono-and dicaffeoylquinic acids being the most prominent components. The presence of these phenolic compound conferred strong free radical scavenging and antifungal properties to the methanol extract. Therefore, I. viscosa leaves could be considered as an excellent source of food functional ingredients with high nutritional value and health benefits.

ABSTRACT:The secondary metabolite composition, antioxidant activities, and microbial inhibition properties of leaves of two Cistus species; C. monspeliensis and C. salvifolius were investigated using three solvent extracts (ethanol, hexane and distilled water). Ethanol extracts were most efficient at extracting phenolics, flavonoids and condensed tannins compared to hexane and distilled water for both Cistus species. A total antioxidant test (TAA) and two radical scavenging tests (DPPH and ABTS) indicated that the 70% ethanolic extract from C. salvifolius leaves had stronger antioxidant activity compared to the C. monspeliensis 70% ethanol extract, while the aqueous extract of C. monspeliensis was much stronger than the aqueous extract or the 70% ethanol extract of C. salvifolius. Overall, the polar extracts were more active in both species than the non-polar extracts. Thus aqueous ethanol extracts of the leaves of each Cistus species were tested for their ability to inhibit seven pathogenic microbial strains, including Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, and Candida albicans. Leaf ethanol extracts from both species were active against each microbial species, but the C. monspeliensis leaf ethanolic extract was much more active against several microbial species than that of C. salvifolius. For example, the C. salvifolius 70% ethanol extract showed its highest antimicrobial activity against P. aeruginosa and A. niger (MIC 3.1 mg/ml and MBC 6.3 mg/ml for both), while the C. monspeliensis extract showed much higher overall activity against E. coli, P. aeruginosa and C. albicana. (MIC 6.25 mg/ml and MBC 12.5 mg/ml for all three). In conclusion, maceration with 70% ethanol was the most efficient method for extracting total polyphenols, flavonoids, and condensed tannins from the two Cistus species, and the aqueous-ethanol extracts displayed the highest antioxidant and antimicrobial activities. Hence, the aqueousethanolic extracts of both species may be considered as potential sources of natural antioxidants and antimicrobial agents.

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