Mechanisms underlying the relaxation induced by isokaempferide from Amburana cearensis in the guinea-pig isolated trachea

The present study examines possible mechanisms by which the flavonoid isokaempferide (IKPF; 5,7,4'-trihydroxy-3-methoxyflavone) from Amburana cearensis, a Brazilian medicinal plant popularly used as bronchodilator, induces relaxation of guinea-pig isolated trachea. In the trachea (with intact epithelium) contracted by carbachol, IKPF (1-1000 microM) caused a graded relaxation, and the epithelium removal increased the sensitivity of the airway smooth muscle to IKPF (EC50, in intact tissue: 77.4 [54.8-109.2] microM; in denuded epithelium: 15.0 [11.3-20.1] microM). The IKPF-induced relaxation was inhibited in 41% by the nitric oxide (NO) synthase inhibitor L-NAME (100 microM); in 31% and 50% by the soluble guanylate cyclase (sGC) inhibitor ODQ (3 and 33 microM); by propranolol (31%) and also by capsaicin (37%). In the trachea pre-contracted by 40 mM KCl the pre-incubation with glibenclamide (33 microM) or iberiotoxin (IbTX, 0.1 microM), selective K(+) channel inhibitors, inhibited the IKPF-induced relaxation by 39% and 38%, respectively. On the other hand, 4-aminopyridine (100 microM), a nonselective K(+) channel antagonist, did not significantly influence the effect of IKPF, while IbTX induced a rightward displacement of the IKPF concentration-response curve. However, in muscle pre-contracted with 120 mM KCl the relaxant effect of IKPF was significantly reduced and not affected by glibenclamide. In conclusion, these results indicate a direct and epithelium-independent relaxant effect of IKPF on smooth muscle fibers. Although this IKPF relaxant action seems to be multi-mediated, it occurs via both Ca(2+) and ATP-sensitive K(+) channels, but some other possible mechanisms unrelated to K(+) channels cannot be excluded.     

Effect of water restriction on total phenolics and antioxidant properties of Amburana cearensis (Fr. Allem) A.C. Smith cotyledons during seed imbibition

Amburana cearensis (Fr. Allem) AC Smith is a native Caatinga species commonly found in the semiarid region of North East of Brazil, which possesses resistance to temperature and drought stress and is widely used in the folk medicine. This study aimed at a better understanding of seed imbibition and germination as well as to evaluate the effect of water restriction on total phenolics and antioxidant properties in cotyledons of A. cearensis (Fr. Allem) A.C. Smith. Seeds were imbibed in water (control) or PEG 8000 solution (?1.2 and ?1.4 MPa). Germinability was evaluated up to 180 h of seed imbibition, whereas cotyledons were collected at 0, 24, 48, 72 and 96 h of imbibition. The radical scavenging ability was enhanced in response to the water restriction after 96 h of imbibition as compared to the control. Water restriction affected water uptake and seed germinability while inducing a faster response in terms of biosynthesis of phenolic compounds, although total phenolic content decreased as compared to control. There is a high correlation between total phenolics and antioxidant activity for the seeds subjected to the water restriction conditions. These findings provide insights into the mechanisms underlying plant adaptation to harsh environmental conditions during germination, which would be very helpful to develop germination and seedling production protocols aimed at strategies for the sustainable exploitation of A. cearensis by local folk communities under the typical harsh conditions of the Brazilian Caatinga and semiarid regions.     

Anti-microfouling properties of compounds isolated from several Mediterranean Dictyota spp.

Brown algae of the genus Dictyota are widespread around the world and are common along the coasts of the Mediterranean Sea. These marine organisms keep their surface relatively free from biofouling and are known for their ability to produce a wide array of bioactive compounds, mostly diterpenes, whose ecological functions are not clearly defined. In this study, an evaluation of the chemodiversity of the Dictyota genus was conducted on three samples, harvested on both NW and SW Mediterranean coasts (France and Algeria, respectively). Ten compounds were purified from the organic extracts of these samples; their chemical structures were elucidated by 1D and 2D NMR spectroscopy and were compared with literature data. Among them, three new diterpenes [one dolabellane (1), one xenicane (2), and one prenylated guaiane (3)] were characterized together with five previously described compounds [3,4-epoxy-14-oxo-7,18-dolabelladiene (4), acetoxycrenulide (5), dictyol E (6), 10,18-dihydroxydolabella-2,7-diene (7), and 10-acetoxy-18-hydroxydolabella-2,7-diene (8)]. In addition, the occurrence of two known glycerol derivatives [1-Ο-octadecenoylglycerol (9) and sn-3-Ο-(geranylgeranyl)glycerol (10)] was also determined. Some of the isolated compounds (4–6 and 8–10) were screened for their potential to prevent the adhesion of three bacterial strains isolated from marine biofilms in comparison with four commercial antifoulants (TBTO, Zineb, ZnPT, and CuPT): those bearing a glycerol moiety (compounds 9 and 10) exhibited the strongest anti-adhesion effects, whatever the strain, and with a moderate toxicity. Thus, these chemical structures should be further explored for both their putative involvement in keeping the algal surface free of biofouling and the development of effective and environmentally benign antifoulants.     

High-fidelity representation of climate variations by Amburana cearensis tree-ring chronologies across a tropical forest transition in South America

Numerous ring-width chronologies from different species have recently been developed in diverse tropical forests across South America. However, the temporal and spatial climate signals in these tropical chronologies is less well known. In this work, annual growth rings of Amburana cearensis, a widely distributed tropical tree species, were employed to estimate temporal and spatial patterns of climate variability in the transition from the dry Chiquitano (16–17°S) to the humid Guarayos-southern Amazon (14–15°S) forests. Four well-replicated chronologies (16–21 trees, 22–28 radii) of A. cearensis were compared with temperature and precipitation records available in the region. The interannual variations in all four A. cearensis tree-ring chronologies are positively correlated with precipitation and negatively with temperature during the late dry-early wet season, the classic moisture response seen widely in trees from dry tropical and temperate forests worldwide. However, the chronologies from the dry Chiquitano forests of southern Bolivia reflect the regional reduction in precipitation during recent decades, while the chronologies from the tropical lowland moist forests in the north capture the recent increase in precipitation in the southern Amazon basin. These results indicate that A. cearensis tree growth is not only sensitive to the moisture balance of the growing season, it can also record subtle differences in regional precipitation trends across the dry to humid forest transition. Comparisons with previously developed Centrolobium microchaete chronologies in the region reveal a substantial common signal between chronologies in similar environments, suggesting that regional differences in climate are a major drivers of tree growth along the precipitation gradient. The difficulty of finding A. cearensis trees over 150-years old is the main limitation involved in the paleoclimate application of this species. The expansion of monocultures and intensive cattle ranching in the South American tropics are contributing to the loss of these old growth A. cearensis trees and the valuable records of climate variability and climate change that they contain.     

Antiproliferative effects of dibenzocyclooctadiene lignans isolated from Schisandra chinensis in human cancer cells

Dibenzocyclooctadiene lignans isolated from Schisandra chinensis showed antiproliferative effects in various human cancer cells. The methoxy groups at C-3, C-4, C-3', and C-4', the hydroxyl group at C-8', and the stereo-configuration of the biphenyl ring and the angeloyl group might have influence on these activities. Additional studies indicate that one of mechanism of action of an active compound schizantherin C in A549 human lung cancer cells was related to the inhibition of cell cycle progression in G0/G1 phase.     

Antiproliferative activity of flavonoids on several cancer cell lines.

Twenty-seven Citrus flavonoids were examined for their antiproliferative activities against several tumor and normal human cell lines. As a result, 7 flavonoids were judged to be active against the tumor cell lines, while they had weak antiproliferative activity against the normal human cell lines. The rank order of potency was luteolin, natsudaidain, quercetin, tangeretin, eriodictyol, nobiletin, and 3,3',4',5,6,7,8-heptamethoxyflavone. The structure-activity relationship established from comparison among these flavones and flavanones showed that the ortho-catechol moiety in ring B and a C2-C3 double bond were important for the antiproliferative activity. As to polymethoxylated flavones, C-3 hydroxyl and C-8 methoxyl groups were essential for high activity.     

Antiproliferative compounds of Cyphostemma greveana from a Madagascar dry forest

Bioassay‐guided fractionation of the EtOH extracts obtained from a plant identified as Cyphostemma greveana Desc . (Vitaceae) led to the identification of one macrolide, lasiodiplodin ( 1 ), three sesquiterpenoids, 12‐hydroxy‐15‐oxoselina‐4,11‐diene ( 2 ), 1β,6α‐dihydroxyeudesm‐4(15)‐ene ( 3 ), and (7R*)‐opposit‐4(15)‐ene‐1β,7‐diol ( 5 ), and a new diterpenoid, 16,18‐dihydroxykolavenic acid lactone ( 4 ). All the isolates were tested against the A2780 human ovarian cancer cell line, and compound 4 and a fraction containing 5 as the major constituent showed antiproliferative activities with IC₅₀ values of 0.44 μM (0.14 μg/ml) and 0.045 μg/ml, respectively. A partial synthesis of compound 5 was carried out, but the pure synthetic compound was inactive, indicating that the activity of the fraction containing it must be due to a very minor and as yet unidentified substance.     

Antiproliferative and apoptotic effects of compounds from the flower of Mammea siamensis (Miq.) T. Anders. on human cancer cell lines

On the search for anti-cancer compounds from Thai traditional herb medicines, a bioassay-guided fractionation and chemical investigation of the methanol extract of Mammea siamensis flower resulted in the isolation and identification of eight compounds (1–8) including a novel geranylated coumarin, namely mammeanoyl (2), and seven known compounds (1 and 3–8). The structure of new compound 2 was elucidated based on the extensive spectroscopic and chemical methods. Among the isolated compounds, three structurally related coumarins 3, 4, and 5 showed significant antiproliferative activities against human leukemia and stomach cancer cell lines. However, these compounds did not affect the cell viabilities of colon cancer, hepatoma, and normal skin fibroblast cell lines. Further analysis demonstrated that the morphological features of apoptosis including DNA fragmentation and chromatin condensation were observed in human leukemia HL-60 cells treated with compounds 3, 4, and 5. In addition, compound 3 led to caspase-3 activation and cleavage of poly (ADP-ribose) polymerase (PARP), and compound 3-induced DNA fragmentation was inhibited by caspase-specific inhibitors. These results suggest that compound 3, 4, and 5 exert antiproliferative actions through apoptotic cell death in leukemia cells and these compounds may have the potential to be developed into new anti-cancer drug candidates.     

Antimicrobial activity of the extract and isolated compounds from Baccharis dracunculifolia D. C. (Asteraceae)

Baccharis dracunculifolia D.C. (Asteraceae) is the most important plant source of the Brazilian green propolis. Since propolis is known for its antimicrobial activity, the aim of this work was to evaluate the antimicrobial activities of B. dracunculifolia and some of its isolated compounds. The results showed that the leaves extract of B. dracunculifolia (BdE) presents antifungal and antibacterial activities, especially against Candida krusei and Cryptococcus neoformans, for which the BdE showed IC50 values of 65 microg mL(-1) and 40 microg mL(-1), respectively. In comparison to the BdE, it was observed that the green propolis extract (GPE) showed better antimicrobial activity, displaying an IC50 value of 9 microg mL(-1) against C. krusei. Also, a phytochemical study of the BdE was carried out, affording the isolation of ursolic acid (1), 2a-hydroxy-ursolic acid (2), isosakuranetin (3), aromadendrin-4'-methylether (4), baccharin (5), viscidone (6), hautriwaic acid lactone (7), and the clerodane diterpene 8. This is the first time that the presence of compounds 1, 2, and 8 in B. dracunculifolia has been reported. Among the isolated compounds, 1 and 2 showed antibacterial activity against methicillin-resistant Staphylococcus aureus, displaying IC50 values of 5 microg mL(-1) and 3 microg mL(-1), respectively. 3 was active against C. neoformans, showing an IC50 value of 15 microg mL(-1) and a MIC value of 40 microg mL(-1), while compounds 4-8 were inactive against all tested microorganisms. The results showed that the BdE, similar to the GPE, displays antimicrobial activity, which may be related to the effect of several compounds present in the crude extract.     

Antiproliferative effects of homogenates derived from five strains of candidate probiotic bacteria.

Unheated and heat-treated homogenates were separately prepared from candidate probiotic bacteria, including Lactobacillus rhamnosus GG, Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Streptococcus thermophilus. We compared the phytohemagglutinin-induced proliferation of mononuclear cells in the presence of homogenates and in the presence of a control containing no homogenate by assessing thymidine incorporation in cell cultures. All homogenates suppressed proliferation, whether the enzymatic activity was inactivated or not inactivated by heating. When the proliferation assays were repeated with cytoplasmic and cell wall extracts derived from the homogenate of L. rhamnosus GG, the cytoplasmic extract but not the cell wall extract was suppressive. These findings indicate that candidate probiotic bacteria possess a heat-stable antiproliferative component(s). These bacteria may be used to generate microbiologically nonviable yet immunologically active probiotic food products that are easier to store and have a longer shelf life.     

Phenolic compounds from Gastrodia rhizome and relaxant effects of related compounds on isolated smooth muscle preparation

Gastrol (1), together with 10 known phenolic compounds, has been isolated from the MeOH extract of the rhizomes of Gastrodia elata Blume (Orchidaceae), and their structures were elucidated by detailed spectral analyses including by 2D NMR spectroscopic analyses. The relaxant effects of these constituents on smooth muscle preparations isolated from guinea-pig ileum were also studied in order to reveal their characteristic pharmacological activities.     

Antiproliferative metabolites from the endophytic fungus Penicillium sp. FJ-1 isolated from a mangrove Avicennia marina

Two new compounds, named as 4-(2′,3′-dihydroxy-3′-methyl-butanoxy)-phenethanol (1), and 15-hydroxy-6α,12-epoxy-7β,10αH,11βH-spiroax-4-ene-12-one (2), were isolated from the endophytic fungus Penicillium sp.FJ-1 of Avicennia marina. Their structures were elucidated on the basis of spectroscopic analysis. Additionally, compounds 1 and 2 exhibited antiproliferative activities, and compound 2 significantly inhibited the tumor growth of human xenograft osteosarcoma in nude mice.     

Antiproliferative activities of isolated flavone glycosides and fatty acids from Stachys byzantina

From the aerial parts of Stachys byzanthina C. Koch., a new flavone glycoside, was isolated for the first time in addition to known two flavone glycosides. Structures were established by conventional methods of analysis and confirmed by ¹H, ¹³C NMR and mass spectral analysis. Antiproliferative activities of isolated compounds, crude extract and fractions, fatty acids (extracts of hexane and hexane:ethyl acetate, 9:1) of aerial parts of S. byzantina were investigated against Vero (African green monkey kidney), HeLa (human uterus carcinoma) and C6 (rat brain tumor) cells in vitro and compared with 5-fluorouracil (5-FU). Antiproliferative effect of the extract, isolated flavonoids and fatty acids were tested at 100, 250, 500 and 1000 μg/mL using BrdU cell proliferation ELISA.     

Antiproliferative effects of peracetylated naphthoxylosides

The antiproliferative activity, and the capability of priming of glycosaminoglycan chains, of two series of peracetylated mono- and bis-xylosylated dihydroxynaphthalenes have been investigated for normal HFL-1 cells, as well as transformed T24 cells, and compared to the unprotected analogs. Our data show increased antiproliferative activity upon peracetylation, but a loss of selectivity towards T24 cells.     

Antiproliferative effects of some N-benzylideneanilines

A series of Schiff bases including N-benzylideneaniline (NBA) nuclei were prepared. The chemical products obtained were characterized by mass spectometry (APCI), 1H NMR, and IR spectroscopy in order to seek their cytotoxic and proliferation effects on human small lung (A549) and cervical (HeLa) cancer cell lines with biochemical assays. All of the synthesized compounds showed antiproliferative effects to different extents.     

Chemical constituents from Salacia impressifolia (Miers) A. C. Smith collected at the Amazon rainforest

The phytochemical investigation of Salacia impressifolia (Miers) A. C. Smith led to the isolations of 15 compounds, including triterpene quinonemethides, which are employed as the common characteristic constituents of the Celastraceae family. Pristimerin (9) and tingenone (12) were isolated as the main compounds in the studied tissues. Additionally, friedelane, lupane, oleanane, and ursane triterpenoids were also isolated. All of them were isolated from this plant for the first time.     

A study of the polygalacturonase activity of several yeast strains isolated from cocoa

Summary During the traditional fermentation of cocoa, yeasts with pectinolytic activity are involved in the degradation of the pulp. Saccharomyces chevalieri, Torulopsis candila, and Candida norvegensis, as well as Kluyveromyces fragilis included in this study as a control strain all have a pectinolytic activity (endopolygalacturonase E.C. 3.2.1.15). The enzymes studied have the same optimal pH of activity [5] but are different from each other in their optimal temperature and their thermal stability. The enzymes of Torulopsis candida and Kluyveromyces fragilis have the highest optimal temperature (60° C). Among the strains studied, Candida norvegensis produced the greatest amount of exocellular enzyme.