Morphology and anatomy of developing fruits and seeds of Mammea americana L. (Clusiaceae). (1/44)

Morphological, structural and developmental features of fruits and seeds of Mammea americana L. are here studied, with the purpose to give a proper classification of their fruit and embryo type and to contribute to future taxonomical and ecological studies. The fruit is a berry and the "rind" consists of the exocarp, represented by a periderm with lenticels, and by the parenchymatic mesocarp, with branched secretory ducts and vascular bundles. The edible pulpy is formed by the endocarp, destituted of secretory ducts, and derived from the activity of a ventral meristem, which emerges early in the fruit development. The inner endocarp cell layers undergo a radial elongation and become firmly attached to the testal outer layers. At maturation the endocarp may be released from the rest of the pericarp. The ovules are unitegmic and they turn into unitegmic and exalbuminous seeds. The multiseriate testa consists of thick-walled cells and sclerenchymatous fibers. This last features have carried out to a wrong interpretation that the fruit of this species is a drupe. The embryo is pseudo-conferruminate, with two massive foodstoring cotyledons, rich in starch, firmly attached.  (+info)

High light-induced switch from C(3)-photosynthesis to Crassulacean acid metabolism is mediated by UV-A/blue light. (2/44)

The high light-induced switch in Clusia minor from C(3)-photosynthesis to Crassulacean acid metabolism (CAM) is fast (within a few days) and reversible. Although this C(3)/CAM transition has been studied intensively, the nature of the photoreceptor at the beginning of the CAM-induction signal chain is still unknown. Using optical filters that only transmit selected wavelengths, the CAM light induction of single leaves was tested. As controls the opposite leaf of the same leaf pair was studied in which CAM was induced by high unfiltered radiation (c. 2100 micromol m(-2) s(-1)). To evaluate the C(3)-photosynthesis/CAM transition, nocturnal CO(2) uptake, daytime stomatal closure and organic acid levels were monitored. Light at wavelengths longer than 530 nm was not effective for the induction of the C(3)/CAM switch in C. minor. In this case CAM was present in the control leaf while the opposite leaf continued performing C(3)-photosynthesis, indicating that CAM induction triggered by high light conditions is wavelength-dependent and a leaf internal process. Leaves subjected to wavelengths in the range of 345-530 nm performed nocturnal CO(2) uptake, (partial) stomatal closure during the day (CAM-phase III), and decarboxylation of citric acid within the first 2 d after the switch to high light conditions. Based on these experiments and evidence from the literature, it is suggested that a UV-A/blue light receptor mediates the light-induced C(3)-photosynthesis/CAM switch in C. minor.  (+info)

Antibacterial xanthones from Kielmeyera variabilis mart. (Clusiaceae). (3/44)

The bioassay-guided fractionation of stems from Kielmeyera variabilis, traditionally used in Brazilian folk medicine, yielded assiguxanthone-B (1), kielcorin (4), 2,5-dihydroxybenzoic acid (3), and a mixture of xanthones containing assiguxanthone-B (1) and 1,3,5,6-tetrahydroxy-2-prenylxanthone (2) (1:1 w/w). The xanthone mixture inhibited Staphylococcus aureus and Bacillus subtilis at a concentration of 6.25 g/ml. When tested alone, the minimal inhibitory concentration of assiguxanthone-B was 25 g/ml against B. subtilis. Kielcorin and 2,5-dihydroxybenzoic acid were inactive against both strains. None of the fractions was active against Escherichia coli or Pseudomonas aeruginosa. Viable cells of S. aureus were reduced by a 1-3 log CFU/ml within 12 h after exposure of one to eight times the MIC of the xanthone mixture. It is not known whether the tetrahydroxy-2-prenylxanthone or other components of the xanthone mixture are responsible for the main antibacterial activity or whether additive or synergistic action is involved  (+info)

HIV-1 inhibition by extracts of Clusiaceae species from Mexico. (4/44)

The organic plant extracts of 21 species of Clusiaceae from Mexico were screened for anti HIV-1 reverse transcriptase activity in a non-radioactive immuno colorimetric assay. The extracts of 5 species (23.8%) exhibited significant inhibition (> or =70%) of HIV-1 RT activity; of these, only 4 extracts showed reduced toxicity to human lymphocytic MT2 cells and were further tested as inhibitors of HIV-1 IIIb/LAV replication in a cellular system. The best extracts were Calophyllum brasiliense (hexane) and Clusia quadrangula (CH(2)Cl(2)-MeOH) which inhibited HIV-1 RT (IC(50)=29.6 microg/ml and 42 microg/ml), and showed an EC(50)=92.5 microg/ml and 91 microg/ml, respectively, on MT2 cells. However, only Calophyllum brasiliense hexane extract showed significant inhibition on viral replication (ED(50)=37.1 microg/ml), while Clusia quadrangula was less active (ED(50)=124 microg/ml). These results support the idea that plant extracts represent a valuable source of potential anti HIV compounds.  (+info)

Prenylated xanthone derivatives with antiplasmodial activity from Allanblackia monticola STANER L.C. (5/44)

Further study of the methanol extract of the stem bark of Allanblackia monticola STANER L.C. resulted in the isolation of a new prenylated xanthenedione, designated allanxanthone C, together with the five known xanthones, garciniafuran, tovophyllin A, rubraxanthone, norcowanin and mangostin and one saponin, stigmasterol-3-O-beta-D-glucopyranoside. The structure of the new compound was established by detailed spectroscopic analysis to be 1,2-dihydro-3,6,8-trihydroxy-1,1,7-tri(3-methylbut-2-enyl)xanthen-2,9-dione (3-hydroxyapetalinone C). The methanol extract and pure compounds were tested on two strains of Plasmodium falciparum, F32 (chloroquine sensitive) and FcM29 (chloroquine resistant). The IC50 values obtained ranged from 0.6 to 8.9 microg/ml. Their cytotoxicity was estimated on human melanoma cells (A375) and the cytotoxicity/antiplasmodial ratio was found to be between 15.45 and 30.46. The antimicrobial activities against a range of microorganisms of the crude extract and some of these compounds are also reported.  (+info)

Cytotoxic and antimalarial prenylated xanthones from Cratoxylum cochinchinense. (6/44)

A new prenylated xanthone, 5-O-methylcelebixanthone (1), together with six known compounds; celebixanthone (2), 1,3,7-trihydroxy-2,4-di(3-methylbut-2-enyl)xanthone (3), cochinchinone A (4), alpha-mangostin (5), beta-mangostin (6) and cochinchinone C (7) were isolated from roots of Cratoxylum cochinchinense. Their structures were elucidated by spectroscopic methods. Compounds 2 and 4-7 showed cytotoxic activity against the human lung cancer cell line (NCI-H187) with IC(50) values ranging from 0.65 to 5.2 microg/ml. Compounds 1, 2, 6 and 7 also showed antimalarial activity against Plasmodium falciparum with IC(50) values of 3.2, 4.9, 7.2 and 2.6 microg/ml, respectively.  (+info)

Antibacterial and cytotoxic activity of Brazilian plant extracts--Clusiaceae. (7/44)

Twelve extracts obtained from nine plants belonging to six different genera of Clusiaceae were analyzed against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria using the microdilution broth assay. Tovomita aff. longifolia, T. brasiliensis, Clusia columnaris, Garcinia madruno, Haploclathra paniculata, and Caraipa grandifolia extracts showed significant results against the bacteria. The organic extract obtained from the leaves of T. aff. longifolia showed minimal inhibitory concentration (MIC) = 70 microg/ml and minimal bactericidal concentration (MBC) = 90 microg/ml against E. faecalis and the organic extract made with the stem of C. columnaris showed MIC = 180 microg/ml and MBC = 270 microg/ml against P. aeruginosa. None of the antibacterial extracts showed lethal activity against brine shrimp nauplii. On the other hand, both aqueous and organic extracts obtained from the aerial organs of Vismia guianensis that were cytotoxic to brine shrimp nauplii did not show a significant antibacterial activity in the assay.  (+info)

Cytotoxic activities of chemical constituents from Mesua daphnifolia. (8/44)

Detail chemical investigations on the stem bark of Mesua daphnifolia gave three triterpenoids and four xanthones. They are friedelin (1), friedelan-1,3-dione (2), lup-20(29)- en-3ss-ol (3), cudraxanthone G (4), ananixanthone (5), 1,3,5-trihydroxy-4-methoxyxanthone (6) and euxanthone (7). These chemical constituents were tested in vitro for their cytotoxic activities against four cell lines, MDA-MB-231 (human estrogen receptor negative breast cancer), HeLa (cervical carcinoma), CEM-SS (T-lymphoblastic leukemia) and CaOV3 (human ovarian cancer). Compound 4 showed a broad spectrum of activity against the MDA-MB-231, HeLa and CEM-SS cell lines with IC5 0 values of 1.3, 4.0 and 6.7 microg/ml respectively. Meanwhile, the other compounds 1, 2, 3, 5, 6 and 7 gave only selective activities against the cell lines.  (+info)

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