Sudden exposure to solar UV-B radiation reduces net CO(2) uptake and photosystem I efficiency in shade-acclimated tropical tree seedlings. (1/17)

Tree seedlings developing in the understory of the tropical forest have to endure short periods of high-light stress when tree-fall gaps are formed, and direct solar radiation, including substantial UV light, reaches the leaves. In experiments simulating the opening of a tree-fall gap, the response of photosynthesis in leaves of shade-acclimated seedlings (Anacardium excelsum, Virola surinamensis, and Calophyllum longifolium) to exposure to direct sunlight (for 20-50 min) was investigated in Panama (9 degrees N). To assess the effects of solar UV-B radiation (280-320 nm), the sunlight was filtered through plastic films that selectively absorbed UV-B or transmitted the complete spectrum. The results document a strong inhibition of CO(2) assimilation by sun exposure. Light-limited and light-saturated rates of photosynthetic CO(2) uptake by the leaves were affected, which apparently occurred independently of a simultaneous inhibition of potential photosystem (PS) II efficiency. The ambient UV-B light substantially contributed to these effects. The photochemical capacity of PSI, measured as absorbance change at 810 nm in saturating far-red light, was not significantly affected by sun exposure of the seedlings. However, a decrease in the efficiency of P700 photooxidation by far-red light was observed, which was strongly promoted by solar UV-B radiation. The decrease in PSI efficiency may result from enhanced charge recombination in the reaction center, which might represent an incipient inactivation of PSI, but contributes to thermal dissipation of excessive light energy and thereby to photoprotection.  (+info)

Inocalophyllins A, B and their methyl esters from the seeds of Calophyllum inophyllum. (2/17)

Fractionation of the ethanolic extract of the seeds of Calophyllum inophyllum L. has resulted in the isolation of four novel pyranocoumarin derivatives, designated as inocalophyllins A (1), B (2) and their methyl esters (3, 4) in addition to the known calophyllolide. The structures of these compounds have been determined on the basis of spectroscopic analysis including MS, heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and two dimensional incredible natural abundance double quantum transfer experiment (2D-INADEQUATE). Two new methylated products, 5 and 6 were also prepared by methylation of compounds 1 and 2, respectively.  (+info)

Trypanocidal constituents in plants 3. Leaves of Garcinia intermedia and heartwood of Calophyllum brasiliense. (3/17)

The constituents of the leaves of Garcinia intermedia and heartwood of Calophyllum brasiliense were investigated based on their trypanocidal activity against epimastigotes of Trypanosoma cruzi, the etiologic agent of Chagas' disease. As the active components, the polyisoprenylated benzophenone derivative guttiferone A and the xanthone 8-desoxygartanin were isolated along with the biflavonoids podocarpusflavone A and amentoflavone, and friedelin from the former. Three xanthones, jacareubin, 6-deoxyjacareubin, and 1,3,5,6-tetrahydroxy-2-(3-methyl-2-butenyl)xanthone from the latter showed activity. The trypanocidal activity of these compounds against trypomastigotes, an infectious form of T. cruzi, was examined as well as gossypol, berberine chloride, and harmine for comparison.  (+info)

Chromanones and dihydrocoumarins from Calophyllum blancoi. (4/17)

Chromatographic fractionation of the acetone extract of the seeds of Calophyllum blancoi yielded six pyranochromanone derivatives; apetalic acid (1), isoapetalic acid (2), apetalic acid methyl ester (3), apetalic acid 5-O-acetate (4), isoapetalic methyl ester (5), and isoapetalic acid 5-O-acetate (6). In addition, one new dihydrocoumarin derivative, isorecedensolide (7), was also isolated together with recedensolide (8). The structures of the isolated compounds were established through analysis of NMR spectral data including 2D techniques as well as other physical and spectroscopic methods. Compounds 3, 4, 5, 7, and 8 showed mild activity against KB (human oral epidermoid carcinoma) and Hela (human cervical epitheloid carcinoma) tumor cell lines.  (+info)

HIV-1 inhibitory compounds from Calophyllum brasiliense leaves. (5/17)

The hexane, acetone and methanol extracts of Calophyllum brasiliense leaves were fractionated following a three bioassay guide: high HIV-1 RT inhibition, low cytotoxicity on MT2 cells and high inhibition of HIV-1 IIIb/LAV replication. This led to the isolation of three anti HIV-1 dipyranocoumarins: calanolides A and B and soulattrolide. In contrast, other isolated compounds such as apetalic acid, isoapetalic acid, a structural isomer of isoapetalic acid, friedelin, canophyllol and amentoflavone were devoid of HIV-1 RT inhibitory activity. Calanolide C was also obtained as a natural product and showed moderate inhibitory properties.  (+info)

Bioactive pyranoxanthones from the roots of Calophyllum blancoi. (6/17)

Phytochemical investigation of the roots of Calophyllum blancoi growing in Taiwan resulted in the isolation of three new pyranoxanthones, blancoxanthone (1), acetyl blancoxanthone (2) and 3-hydroxyblancoxanthone (3), in addition to two known pyranoxanthones, pyranojacaeubin (4) and caloxanthone (5). Structural characterization of the isolated compounds was determined by spectral analyses especially 2-D NMR. Biological study of the isolated xanthones revealed that blancoxanthone (1) exhibited significant anti-coronavirus activity.  (+info)

Evaluation of the relaxant action of some Brazilian medicinal plants in isolated guinea-pig ileum and rat duodenum. (7/17)

PURPOSE: The present study aimed to evaluate the possible antispasmodic activity in vitro of methanolic extracts (ME) of six Brazilian medicinal plants. METHODS: The extracts were evaluated on isolated guinea-pig ileum and rat duodenum preparations. RESULTS: Rubus imperialis, Maytenus robusta, Ipomoea pes caprae and Epidendrum mosenii did not inhibit the contractile response elicited by acetylcholine on guinea-pig ileum. On the other hand, ME from Calophyllum brasiliense and Cynara scolymus exhibited significant inhibitory activity for the contractile response elicited by acetylcholine on guinea-pig ileum and on rat duodenum in a noncompetitive and concentration-dependent manner. CONCLUSIONS: The current study suggests that, of the six medicinal plants evaluated, only the ME of Calophyllum brasiliense and Cynara scolymus show probable antispasmodic activity, confirming and justifying their use in folk medicine for the treatment of intestinal disorders.  (+info)

Caloxanthones O and P: two new prenylated xanthones from Calophyllum inophyllum. (8/17)

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