Endemik bir bitki olan astragalus Gymnolobus Fischer'ın in vitro rejenerasyonu, biyolojik aktiviteleri ve fenolik bileşimi

Astragalus is a large genus covering about 3000 species belonging to Fabaceae family. Astragalus species have been used as antibacterial, antiviral, antifungal, antioxidant, anticancer, hepatoprotective, wound healing, anti-diabetic and diuretic in folk medicine. Astragalus gymnolobus Fischer (milkvetch weed) is an endemic dwarf cushion-forming shrub. An efficient plant regeneration system was developed for A. gymnolobus. Two different explants (leaf and petiole) were cultured on MS (Murashige and Skoog) medium with various plant growth regulator combinations. Leaf explants formed more shoots than petiole explants. The best shoot formation was obtained from leaf explants with 0.5 mg/l TDZ (thidiazuron). The best callus formation was obtained with 3.0 mg/l BA (benzyladenine) and 0.5 mg/l 2,4-D (2,4-dichlorophenoxyacetic acid) with leaf explant. Regenerated shoots were put on medium containing different concentrations of IAA (indole-3-acetic acid), IBA (indole-3-butyric acid), 2,4-D or NAA (naphthalene acetic acid). However, rooting was not observed with regenerated shoots. Collected calluses were used for biological activity studies of A. gymnolobus. Antibacterial and antioxidant activities, total phenol and flavonoid content, and HPLC (high performance liquid chromatograph) analysis of phenolic constituents of field-grown leaves and in vitro-grown callus parts of A. gymnolobus were evaluated. Antibacterial activity of water and methanol extracts of A. gymnolobus was determined with Kirby-Bauer disk diffusion assay. Generally, field-grown leaves showed better antibacterial activities than in vitro-grown callus. The free radical scavenging potency of methanol extracts of A. gymnolobus was determined with DPPH (2,2-diphenyl-1-picrylhydrazil) method. The best antioxidant activity was obtained with methanol extract of field-grown leaves at 25 μg/ml concentrations (91.47 %). Total phenolic content by using Folin-Ciocaltaeu method and the total flavonoid content by using aluminum chloride (AlCl3) colorimetric method were determined. Methanol extract of field-grown leaves contained more phenols and flavonoid than in vitro-grown callus. Concentrations of phenolic compounds in field-grown leaves were found higher than the in vitro-grown callus with HPLC analysis.