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Abstract: Bioassay-directed phytochemical study of the Jerusalem artichoke (Helianthus tuberosus L.) leaves led to the isolation of a new sesquiterpene lactone of 3-Hydroxy-8β-tigloyloxy-1,10-dehydroariglovin (1), ten known sesquiterpene lactones (2–11) and two known flavones (12–13). Their chemical structures were elucidated on the basis of NMR (1D and 2D) and mass spectroscopic analysis. The cytotoxic activities of those compounds were subsequently tested against the MCF-7, A549 and HeLa cancer cells lines. The results indicated that sesquiterpene lactones 1–11 exhibited consistent cytotoxicity against all three cancer cell lines, while flavones 12 and 13 showed selective inhibitory activity against HeLa cell lines. Among them, compound 3 exhibited significant growth inhibitory activity against all three cell lines. The IC50 values of compound 3 against MCF-7, A549 and HeLa were 1.97±0.04, 7.79±0.44, 9.87±0.20μg/ml, respectively. In addition, some structure–activity relationships of these sesquiterpene lactones for cytotoxicity were explored and summarized in this study. [Copyright &y& Elsevier]

Abstract: The total phenolic content and radical scavenging activities of Jerusalem artichoke (Helianthus tuberosus L.) leaves were investigated. Results indicated that the ethyl acetate fraction contained the highest total phenolic content (266.69±2.51mgGAE/g dry extract) accompanied with strongest free radical scavenging abilities. Following an in vitro radical scavenging activity-guide fractionation procedure, six phenolic compounds which strongly quenched free radicals were separated from ethyl acetate fraction. Among them, 3-O-caffeoylquinic acid and 1,5-dicaffeoylquinic acid played a dominant role due to their strong free radical scavenging abilities and their high contents. The content of 3-O-caffeoylquinic acid in n-butanol fraction was 74.58±1.05mg/g, while 1,5-dicaffeoylquinic acid in ethyl acetate fraction was 104.51±2.86mg/g. The results imply that the leaves of Jerusalem artichoke might be a potential source of natural antioxidants. [Copyright &y& Elsevier]

There are two types of gas hydrate-bearing reservoirs in the permafrost area of Qilian Mountain. Most of the gas hydrates occur mainly in the fractured mudstone reservoirs and rarely in the pores of the sandstone reservoirs. In this study, for the acoustic velocity characterization of the fractured gas hydrate reservoirs of the Qilian Mountain permafrost area, some mudstone core samples were collected for physical rock experiments, such as the acoustic experiment and the porosity and permeability experiment. An acoustic velocity numerical simulation of gas hydrate reservoirs was performed according to the Biot theory and the differential effective medium theory, with the conditions of multiple gas hydrate occurrence models, including the suspension model, the semi-cementation model and the cementation model, and considering both infinite and penny-shaped cracks. Fracture porosity was added to the core samples that only contain matrix porosity. With fracture porosity ranging from 0.01% to 5%, the variation laws between acoustic velocity with fractured porosity and hydrate saturation are obtained: (1) In the case of an infinite crack, if the fractured porosity is 0.01%–1%, the P-wave velocity decreases rapidly in the case of the three occurrence models. If the fractured porosity is higher than 1%, the acoustic velocity decreases gradually. If the crack shape is a penny-shaped crack, the P-wave velocity decreases almost linearly with increasing fracture porosity. (2) If the hydrate occurrence model is the suspension model, the P-wave velocity increases slightly with increasing hydrate saturation. If the occurrence model is the semi-cementation model or the cementation model, when the gas hydrate saturation of the infinite crack ranges from 0 to 80%, the acoustic velocity increases approximately linearly, whereas when the gas hydrate saturation ranges from 80% to 100%, the velocity increases rapidly. If the crack is a penny-shaped crack, the velocity increases almost linearly with increasing gas hydrate saturation from 0 to 100%. (3) It is found that the fractured gas hydrate reservoirs of the Qilian Mountain permafrost area contain both penny-shaped and infinite cracks, of which the infinite crack is the main crack shape. The gas hydrate occurrence in the Qilian Mountain permafrost area mainly follows the suspension model. This has significance for the seismic exploration and log evaluation of gas hydrate-bearing fractured reservoirs in the permafrost area of the Qilian Mountain in studying the acoustic velocity characterization, the crack shapes and occurrence models of gas hydrate reservoirs in the study area. [ABSTRACT FROM AUTHOR]