Bioactivity-guided isolation of cytotoxic secondary metabolites from the roots of Glycyrrhiza glabra and elucidation of their mechanisms of action

Çevik, D. | Burçin Yılmazgöz, Ş. | Kan, Y. | Akhan Güzelcan, E. | Durmaz, I. | Çetin-Atalay, R. | Kırmızıbekmez, H.

Article | 2018 | Industrial Crops and Products124 , pp.389 - 396

Licorice (Glycyrrhiza glabra L.) is one of the most widely used plants worldwide for its various pharmacological activities. The aim of this study was to isolate the potential cytotoxic secondary metabolites from the MeOH extract prepared from the roots of Glycyrrhiza glabra through bioactivity-guided isolation procedure and to elucidate their mechanisms of action. The crude MeOH extract as well as CHCl3 and EtOAc subextracts significantly inhibited cell proliferation on hepatocelullar (Huh7), breast (MCF7) and colorectal (HCT116) cancer cell lines with IC50 values in the range of 5.6 to 33.6 µg/mL. Chromatographic seperations of th . . .e CHCl3 and EtOAc subextracts yielded 13 secondary metabolites. Structures were characterized based on NMR and MS data. Amongst isolates, glabridin (1), 4'-O-methylglabridin (2), ß-amyrin (3), kanzonol U (4), glabrene (7) and tetrahydroxymethoxychalcone (10) were established to be responsible for in vitro cytotoxicity of G. glabra, exerting the best activity particularly against Huh7 cells. Further mechanistic studies demonstrated that 2 and 7 induced caspase-dependent apoptosis by increasing cytochrome C release and subsequently cleaved caspase-9 level in Huh7 cells. Moreover, both compounds decreased pRb and p21 levels and thus induced the accumulation of Huh-7 cells in subG1 and G2/M phases. Compound 10 which displayed the most potent activity in Hoechst staining and cell cycle assays through G2/M arrest, caused cell death by apoptosis in Huh7 cells. © 2018 Elsevier B.V Daha fazlası Daha az

Enzyme inhibitory and antioxidant activities of Nerium oleander L. flower extracts and activity guided isolation of the active components

Atay Balkan, İ. | Doğan, H.T. | Zengin, G. | Colak, N. | Ayaz, F.A. | Gören, A.C. | Yeşilada, E.

Article | 2018 | Industrial Crops and Products112 , pp.24 - 31

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 pheno . . .lic 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 Daha fazlası Daha az

Assessment of potential bioavailability of major phenolic compounds in Lavandula stoechas L. ssp. stoechas

Celep, E. | Akyüz, S. | İnan, Y. | Yeşilada, Erdem

Article | 2018 | Industrial Crops and Products118 , pp.111 - 117

Despite the countless number of studies on phenolic compounds from herbal resources and their related bioactivities, their bioavailability factors are generally disregarded. The present study was performed in order to assess the potential bioavailability of major phenolics found in the aerial parts of Lavandula stoechas L. ssp. stoechas. To that end, a simulated human digestion method consisting of both gastric and intestinal phases was conducted. The total phenolic, phenolic acid and flavonoid contents were appraised together with high performance thin layer chromatography analysis of the two phenolic acids (rosmarinic acid and chl . . .orogenic acid) and two flavone glycosides (apigenin 7-glucoside and luteolin-7-O-ß-glucoside). On the other hand, antioxidant potentials of the samples were investigated using assays with different mechanisms such as free radical scavenging tests and metal-related activity tests. According to the results, flavone glycosides had lower bioavailability than phenolic acids, and antioxidant activities were altered due to in vitro gastrointestinal digestion. © 2018 Elsevier B.V Daha fazlası Daha az

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