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Oleander (Nerium oleander L., fam: Apocynaceae) is an evergreen shrub. Although it is known to be poisonous to humans, a large number of utilizations in folk medicine have been reported against diabetes, rheumatic pain and skin diseases. The present study aimed to investigate the cholinesterase inhibitory activities of oleander flower extracts and to isolate the active components responsible for the activity. The antidiabetic and skin care effects were also determined on some key enzymes (?-glucosidase, ?-amylase, tyrosinase). The flower extracts obtained with aqueous, polar and apolar organic solvents were evaluated for their phenolic contents and antioxidant capacities. The enzyme inhibitory activities (cholinesterase, ?-glucosidase, ?-amylase and tyrosinase) were examined by microtiter plate assays. Antioxidant properties were evaluated by DPPH, FRAP and CUPRAC assays. Total phenolic and flavonoid contents were determined using the Folin-Ciocalteu reagent and aluminum chloride, respectively. The structures of the isolates were elucidated by NMR and MS experiments.In the present study, cholinesterase inhibitory activity of the EtOH extract of the olaender flowers was investigated and ß-sitosterol and oleanolic acid were isolated as the active components. The less polar extracts (n-hexane) exerted better cholinesterase and ?-amylase inhibitory activities than those of the more polar extracts (R-H2O, EtOAc) which had better ?-glucosidase and tyrosinase activities. The highest antioxidant capacity values were obtained from EtOAc and EtOH extracts. The EtOH extract was found to contain the highest levels of total phenolic and flavonoid contents. The results suggest that the flowers of oleander could be a potential source for high value phytochemicals for developing novel drug leads. © 2017 Elsevier B.V.

WOS: 000390621600079 Daphne oleoides Schreb. subsp. oleoides is an evergreen shrub which is known for its folkloric usage against various ailments such as arthritic and infectious diseases. The aim of the present study was to comparatively investigate the in vitro anti-inflammatory (nitric oxide inhibitory effects), antioxidant (DPPH center dot,ABTS(center dot+) and FRAP tests) and antimicrobial activities of the extract/subextracts from the aerial parts of D. oleoides Schreb. subsp. oleoides (Thymelaeaceae). The powdered aerial parts were first extracted with methanol and then partitioned into five subextracts (n-hexane, dichloromethane (CH2Cl2), ethyl acetate (EtOAC), n-butanol and remaining water) by succesive solvent extractions. The chemical compositions of the extracts were compared with regard to their total phenolic, total flavonoid contents and fatty acid compositions. The CH2Cl2 and n-hexane extracts exerted the highest inhibitory effect on NO production (61.67 +/- 13.97% inhibition at 50 mu g/ml and 67.91 +/- 11.17% inhibition at 100 mu g/ml, respectively) of LPS-induced Raw 264.7 cells. The EtOAC subextract showed the highest antioxidant effect evaluated by DPPH center dot (IC50: 0.35 +/- 0.12 mg/ml) and FRAP (4.54 +/- 10.01 mM FeSO4/mg extract) tests. The CH2Cl2 subextract was shown to contain the highest levels of flavonoids (0.837 +/- 10.035 mg QUE/mg extract) and was also found to be rich in phenolics (1.063 +/- 10.011 mg GAE/mg extract). Fatty acid analysis of the n-hexane extract revealed hexadecahoic acid and 9,15-octodecadienoic acids to be the major components. The n-hexane and CH2Cl2 subextracts exerted the'highest antimicrobial potential.