LAUSR

Twenty of the 41 Aethionema species in Turkish Flora are endemic to the country [1]. Various new taxa have since been included, including A. alanyae, A. dumanii, A. acarii, and A. karamanicum [2]. The species described in the present paper raises the total of known Turkish Aethionema species to 42. This makes Anatolia an important center for the genus [1]. Until now, the antioxidant and antimicrobial activities, and the volatile components of A.diastrophis have not been studied. The aims of the present study are to evaluate the volatile components, phenolic composition, and antioxidant, antibacterial, and antifungal activities of A. diastrophis, in addition to assessing its potential for use in the food industry and medicine. Samples of A. diastrophis were collected from Artvin, Turkey, in May 2014. A voucher specimen was deposited in the Herbarium of the Faculty of Forestry, Karadeniz Technical University, Trabzon (KATO 17115). Antioxidant capacity was assessed by ferric-reducing antioxidant power (FRAP) [3], cupric-reducing antioxidant capacity (CUPRAC) [4], and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay [5]. In addition to the methanolic extract, the water extract of A. diastrophis was also tested to determine antimicrobial activity. The agar-well diffusion method [6] was employed with modifications [7] for susceptibility screening. The compositions of the essential oils were characterized by SPME and GC-FID/MS. Reverse-phase high-performance liquid chromatography (RP-HPLC) DAD (Diode Array Detector) and UV spectral analysis (200–400 nm) were also applied to the methanolic extracts. Protocatechuic aldehyde (29.4%), chlorogenic acid (14.3%), and benzoic acid (56.3%) were detected by comparison with 16 phenolic acid standards based on retention time and UV spectra. The total phenolic contents of A. diastrophis were 551 2.12 mg GAE/g in methanolic extract and 882 2.48 mg GAE/g in aqueous extract using the Folin–Ciocalteu method. Total antioxidant activities as FRAP values for A. diastrophis were 160 1.15 mol Trolox per gram of sample in methanolic extract and 508 2.02 mol Trolox per gram of sample in aqueous extract. The DPPH scavenging activities of methanolic and aqueous extracts of A. diastrophis, expressed in terms of SC50, were 1.036 0.008 mg/mL and 0.764 0.003, respectively. The radical-scavenging activity of extracts was lower than that of BHT (0.013 0.001 mg/mL), a commonly used synthetic antioxidant in the food industry. The cupric-reducing powers of methanolic and aqueous extracts of A. diastrophis, expressed as TEAC values, were 122.8 1.02 and 223.5 1.25 mol Trolox/g sample, respectively. The methanolic and aqueous extracts were tested for antimicrobial activity against six bacterial and two yeast strains using disc diffusion. The results were assessed on the basis of inhibition zone diameters. Ampicillin, streptomycin, and fluconazole were employed as positive controls. The control drug activity findings were Ampicillin against E. coli: 10 mm, Y. pseudotuberculosis: 10 mm, P. aeruginosa: 18 mm, S. aureus: 10 mm, E. faecalis: 35 mm, B. cereus: 15 mm; streptomycin against M. smegmatis: 35 mm; fluconazole against C. albicans: 25 mm, S. cerevisiae > 25 mm. The methanolic extract exhibited particular efficacy against Mycobacterium smegmatis ATCC®607, Yersinia pseudotuberculosis ATCC®911, and Escherichia coli ATCC®35218, Staphylococcus aureus ATCC 25923, Candida albicans ATCC 60193, and Saccharomyces cerevisiae RSKK 251.