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51.
Cui‐Ying Ma Sebisubi Fred Musoke Ghee Teng Tan Kongmany Sydara Somsanith Bouamanivong Bounhoong Southavong D. Doel Soejarto Harry H. S. Fong Hong‐Jie Zhang 《化学与生物多样性》2008,5(11):2442-2448
Bioassay‐directed fractionation led to the isolation of seven compounds from a sample of the dried leaves, twigs, and branches of Diospyros quaesita Thw . (Ebenaceae). One of the isolates, betulinic acid 3‐caffeate ( 1 ), showed in vitro antimalarial activity against Plasmodium falciparum clones D6 (chloroquine‐sensitive) and W2 (chloroquine‐resistant) with IC50 values of 1.40 and 0.98 μM , respectively. Evaluation of compound 1 in the human oral epidermoid (KB) cancer cell line revealed cytotoxicity at ED50 of 4.0 μM . In an attempt to reduce the cytotoxicity of 1 , the acetylated derivative 1a and betulinic acid ( 1b ) were prepared. Of the seven isolates, diospyrosin ( 2 ) was determined to be a new neolignan. In addition to 1 , other known compounds isolated in this study were pinoresinol, lariciresinol, N‐benzoyl‐L ‐phenylalaninol, scopoletin, and poriferast‐5‐en‐3β,7α‐diol. The structure of 2 was elucidated based on spectroscopic data analysis including 1D‐ and 2D‐NMR, and HR‐ESI‐MS. 相似文献
52.
Pectin is a group of carbohydrate polymers constructing the primary cell walls and the middle lamella of terrestrial plants. Herein, we demonstrated the structure and immunomodulatory activity of the major pectic polysaccharide DL‐3B2 isolated from the leaves of Diospyros kaki. Based on composition analysis, methylation analysis, two‐step acid hydrolysis, lithium‐mediated selective degradation, 13C NMR spectroscopy, and electrospray ionization mass spectrometry, DL‐3B2 was found to contain an α‐1, 4‐linked galacturonic acid (GalA) backbone with some insertions of α‐1, 2‐linked rhamnose residues. The arabinan‐ and arabinogalactan‐side chains were attached to O‐4 of the rhamnose residues, whereas the linear arabinoxylan was probably linked to O‐3 of the GalA residues. Immunological tests in vitro showed that DL‐3B2 could help stimulate lipopolysaccharide‐induced B lymphocyte proliferation, but not ConA‐induced T lymphocyte proliferation, and that the arabinose residues play a role in maintaining this immunological activity. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 649–656, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com 相似文献