Isolation and Structural Elucidation of New Xanthone from Rot Bark of Cratoxylum sumatranum
Sumatranaxanthone A (1), a new xanthone, was isolated from the rot bark of Cratoxylum sumatranum. The structures were established based on spectroscopic studies, notably of the 1D and 2D NMR spectra. Preliminary results showed that 1 has antioxidative activity with inhibition 81% to fit with ascorbat acid standard.
In vitro Anti-Amebic Activity of Cage Xanthones from Cratoxylum sumatranum Stem Bark Against Entamoeba histolytica
The genus Cratoxylum consists of tropical plant within the Hypericaceae family which is widespread in tropical forests.1 Plant from the genus Cratoxylum been widely used for ethnomedicinal applications in South East Asia as a treatment of stomachache and diarrhea as well as for the prevention of gastric ulcers.2,3 Further work was able to isolate xanthone compounds from C. cochinchinense, which was reported to have bioactivity as an antioxidant, anticancer agent and protein inhibitor of tyrosine in diabetes.4-7 Preliminary research screening 22 species of plants from Balikpapan Botanical Gardens, Kalimantan Indonesia, demonstrated that dichloromethane extract from the stem bark of Cratoxylum sumatranum (Jack) Bl. has antiamebic activity against E. histolytica cells with an IC50 value of 22.07 μg/mL, CC50 of 29.69 μg/mL and a Selective Index (SI) of 1.34.8 Phytochemical studies of C. sumatranum obtained xanthone and anthraquinino-benzophenone such as cratoxyarborenones A-F; cratoxyarborequinones A-B; vismione B; 2,4,6-trihydroxybenzophenone 4-O-geranyl ether; δ-tocotrienol; betulinic acid,9 and sumatranaxanthone A.10 Other compounds that have also been isolated are cratosumatranone A-B; pruniflorone N; neriifolone B; isocudraniaxanthone B; 10-O-methylmacluraxanthone; macluraxanthone; 5-O-methyl-2deprenylrheediaxanthone B; pancixanthone B; pruniflorone M; 5′-demethoxycadensin G; 1,5-dihydroxy-8-methoxyxanthone; 1,5-dihydroxy6,7-dimethoxyxanthone; 1,3,6-trihydroxy-7methoxyxanthone; 1,3,5,6-tetrahydroxyxanthone; 1,2,8-trihydroxyxanthone; 2,8-dihydroxy1-methoxyxanthone; cratoxyarborenone F; 1,7-dihydroxyxanthone; trapezifolixanthone; cochinchinoxanthone; 5-O-methylisojacareubin; 2,4,6-trimethoxybenzophenone; 4-hydroxy-2,6dimethoxybenzophenone; and annulatomarin.11
Struggles for Visibility
This article addresses the ways in which terrorists are rendered visible in the news media. By studying images used in coverage of terrorists, the article focuses on the visual construction of this figure, which symbolizes the public’s notion of the “enemy”, in terms of specific attacks and the general threat thereof as well as terrorist actors, networks, and ideologies. The article takes its point of departure in the assumption that two visual forms are prevalent for representing terrorists in the news media, “surveillance representations” and “self-representations”. Based on this assumption, the article is guided by a principal research question, namely: How are terrorists made visible in the news media through surveillance representations and self-representations and what are the prevalent genres for visually representing terrorist actors? The article draws on a theoretical framework concerning the news media’s propensity to personalize the terrorist and the mediated visibility of terrorists. Empirically, the article is based on a quantitative content analysis of coverage of terrorism by Danish public service broadcasters DR and TV2 in 2016 to provide an overview of the proportions between surveillance representations and self-representations and develop a typology of the most widespread genres: ID photography, surveillance footage, selfies and similar, and private snapshots.