Chemical composition and biological aktivities of Rhododendron essential oil and extracts

Free radicals are formed in the organisms as a result of normal metabolism or because of various factors including pesticides, aromatic hydrocarbons, txins, stres, and radiation. Antioxidants scavenge these free radicals. Many compounds with antioxidant activity are known today. Some of these are made by our body as a defense system against free radicals, and some are obtained by diet from plants. In the current study, acetonitrile extracts of Rhododendron luteum and Rhododendron ponticum are investigated for chemical composition determination as well as bioactivity evaluation. Not very well known in public, the plants are collected in Trabzon. Acetonitrile extracts of leaves and flowers were investigated for antioxidant activity with DPPH scavenging, ferric reducing/antioxidant power (FRAP) and total phenolic content determinations comparatively with standart antioxidants BHT, vitamin C and Trolox, and carbonic anhydrase inhibitory activity was measured in comparison with acetazolamide. The samples were also tested for antimicrobial activity. The extracts showed high antioxidant and antimicrobial activity compared to the standards. Gram (-) bacteria were specifically susceptible to the extracts. High CA inhibitory activity was observed in alll the extracts. The extracts contained the phenolic acids gallic acid, protocatechuic acid, protocatechaldehyde, p-OH-benzoic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid and synapic acid. Essential oils obtained with normal and acidified methods showed changes with respect to both chemical composition and biological activity. Carbonic anhydrase inhibitory components of these plants deserve further study.