Phytochemical contents, antioxidant effects, and inhibitory activities of key enzymes associated with Alzheimer's disease, ulcer, and skin disorders of Sideritis albiflora and Sideritis leptoclada.

In this study, urease, tyrosinase, cholinesterase inhibitory, and antioxidant activities of various extracts of Sideritis albiflora and Sideritis leptoclada were determined together with the phytochemical contents. In addition, the fatty acid compositions and phenolic compounds were investigated by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography-diode array detector (HPLC-DAD). Rosmarinic acid and caffeic acid in both Sideritis species were identified as the most abundant phenolic compounds whereas palmitic acid was found as a major fatty acid. The acetone extract of S. leptoclada indicated the highest antioxidant activity in ß-carotene-linoleic acid (IC50 : 17.23 ± 0.11 µg/ml), DPPH• (IC50 : 28.14 ± 0.05 µg/ml) and ABTS•+ (IC50 : 15.18 ± 0.02 µg/ml) assays. The acetone extract of S. albiflora (A0.50 : 32.71 ± 0.44 µg/ml) was found as the best reductant in cupric reducing antioxidant capacity (CUPRAC) assay. Against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), only the hexane extracts of Sideritis species showed moderate inhibitory activity. Moreover, all extracts of S. albiflora and the hexane extract of S. leptoclada exhibited significantly higher urease inhibitory activity than that of thiourea. Further, in vivo activity studies on extracts and isolated constituents obtained from these species are needed to understand the activity in biological systems. PRACTICAL APPLICATIONS: Multiple pharmacological studies have proven that Sideritis species is precious with significant bioactive properties. This is the first comprehensive research to determine the enzyme inhibitory and antioxidant activities of various extracts of S. albiflora and S. leptoclada with phytochemical contents. Both Sideritis species were found to be rich in rosmarinic and caffeic acids. The acetone extracts showed the highest activity in terms of antioxidant activity, while the hexane extracts exhibited superior urease inhibitory activity. These results show that Sideritis species could be used as urease inhibitors' agents and source of antioxidants in food, pharmaceutical, and cosmetic industries.

Optimization of Regeneration Conditions and In Vitro Propagation of Sideritis Stricta Boiss & Heldr.

In this study the micropropagation of endemic species Sideritis stricta was investigated. Leaf segments and shoot explants (hypocotyl, single node and shoot tips) taken from in vitro growing plantlets and cultured on MS and B5 media containing different growth regulators combinations BAP (0.0, 1.0, 2.0 and 3.0mg/l) and NAA (0.0, 0.1 and 0.5mg/l). MS and B5 media supplemented with BAP (1.0, 2.0 and 3.0mg/l) and NAA (0.1mg/l) combinations or only BAP and kinetin (2.0 and 3.0mg/l) were used at the subculture experiments of shoots and MS and B5 media supplemented with different concentrations of IBA (0.0, 1.5, 3.0, 4.5 and 10.mg/l) were used at the rooting experiments. S. stricta seeds germinated at the rate of 100% when the seed coat was removed and endoperm with embryo part cultured on B5 medium. The single node explants taken from in vitro germinated and grown 30-40 days plantlets on B5 medium have been determined as the most successful explant at all used hormone combinations. B5 medium supplemented with 1.0mg/l BAP+0.1mg/l NAA and 2.0mg/l BAP+0.5mg/l NAA was determined as the most effective medium on shoot formation. At the first and second subculture, the highest shoot formation was maintained on medium supplemented with 1.0mg/l BAP+0.1mg/l NAA and the number of shoots per explant were 4 and 2.11, respectively. The highest multiplication rate has been determined as 33.76 at the end of second subculture. The best rooting was achieved on B5 medium supplemented with 4.5mg/l IBA. The rooted shoots were successfully acclimatized to outdoor conditions and survival rate was determined as 90%.