Indução de Metabólitos Bioativos em Culturas de Células de Maytenus Ilicifolia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Flavonóides, norisoprenóides e outros terpenos das folhas de Tapirira guianensis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

OFF-LINE SUPERCRITICAL-FLUID EXTRACTION - HIGH-RESOLUTION GAS-CHROMATOGRAPHY APPLIED TO THE STUDY OF MORACEAE SPECIES

Supercritical fluid extraction with CO2, Performed in a home-made system, of rhizomes of Dorstenia bryoniifolia Mart. ex Miq. (Moraceae) and of bark roots of Brosimum gaudichaudii Trecul (Moraceae) afforded crude extracts that were analysed by high resolution gas chromatography (HRGC). The D. bryoniifolia extract contained, besides the previously reported pimpinelin and isobergapten, the furocoumarins psoralen, bergapten, isopimpinelin and the triterpenes alpha- and beta-amyrin and the acetate of the latter. The B. gaudichaudii extract contained a number of terpenoids as well as the previously reported psoralen and bergapten. Supercritical fluid extraction gave extracts qualitatively similar to those obtained by Soxhlet extraction with hexane and, together with off-line HRGC, was shown to be a fast and accurate technique to be used in rapid phytochemical examination.

Acylated flavonol glycosides and terpenoids from the leaves of Alibertia sessilis

Two novel acylated flavonol glycosides, along with iridoids, triterpenes, steroids and alpha-tocopherolquinone, were isolated from the leaves of Alibertia sessilis (Rubiaceae). The determination of the structures of the new compounds was based mainly on H-1- and C-13-NMR.

Prediction of occurrences of diverse chemical classes in the Asteraceae through artificial neural networks

The training and the application of a neural network system for the prediction of occurrences of secondary metabolites belonging to diverse chemical classes in the Asteraceae is described. From a database containing about 604 genera and 28,000 occurrences of secondary metabolites in the plant family, information was collected encompassing nine chemical classes and their respective occurrences for training of a multi-layer net using the back-propagation algorithm. The net supplied as output the presence or absence of the chemical classes as well as the number of compounds isolated from each taxon. The results provided by the net from the presence or absence of a chemical class showed a 89% hit rate; by excluding triterpenes from the analysis, only 5% of the genera studied exhibited errors greater than 10%. Copyright (C) 2004 John Wiley Sons, Ltd.

A constraints generator in structural determination by microcomputer

We present a new expert system: a constraints generator for structure determination of natural products. The constraints that the system furnishes are: skeleton (reliability: 95%), large substructures (reliability: 98%) and their associated assignments (reliability: 90%) This system is intended for structure determination of carbon-rich compounds (sesqui-, di- and triterpenes, sterols etc.) for which most structures generators are not very effective. We also present a new algorithm that can avoid the combinatorial explosion during subspectrum/substructure analysis.

AN OLEANANE ACID FROM ALIBERTIA-EDULIS

A new oleanane, 3 beta,19 alpha,23,24-tetrahydroxy-12-oleanen-28-oic acid, was isolated together with nine known triterpene compounds from the leaves of Alibertia edulis, Rubiaceae.

Biosynthesis of friedelane and quinonemethide triterpenoids is compartmentalized in Maytenus aquifolium and Salacia campestris

Maytenus aquifolium (Celastraceae) and Salacia campestris (Hippocrateaceae) species accumulate friedelane and quinonemethide triterpenoids in their leaves and root bark, respectively. Enzymatic extracts obtained from leaves displayed cyclase activity with conversion of the substrate oxidosqualene to the triterpenes, 3 beta -friedelanol and friedelin. In addition, administration of (+/-)5-H-3 mevalonolactone in leaves of M. aquifolium seedlings produced radio labelled friedelin in the leaves, twigs and stems, while the root bark accumulated labelled maytenin and pristimerin. These experiments indicated that the triterpenes once biosynthesized in the leaves are translocated to the root bark and further transformed to the antitumoral quinonemethide triterpenoids. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Coumarins and terpenoids from Dorstenia asaroides Gardn. in Hook

Phytochemical investigation of rhizomes and leaves of Dorstenia asaroides Gardn. in Hook. (Moraceae) afforded the furocoumarins psoralen and bergapten, the triterpenes α-amyrin, α-amyrin acetate, β-amyrin acetate, lupeyl acetate and simiarenol and saccharose.

Constituintes de Sorocea bomplandii Baillon

The chemical investigation of the leaves of Sorocea bomplandii Baillon (Moraceae) led to the identification of pentacyclic triterpenes, fatty acid ester and isoprenoids. Chromatographyc comparison between the infusion S. bomplandii with that of Maytenus aquifolium - a Celastraceae with proved antiulcer activity - has shown that they have different compositions: the first one is based on sugars and the last one is based on flavonoid glycosides.

Chemistry and bioactivity of Raulinoa echinata Cowan, an endemic Brazilian rutaceae species

The hexane extract of the stems of Raulinoa echinata afforded the sesquiterpenes germacrene D (6), 1β,6α-dihydroxy-4-(15)-eudesmene (4) and oplopanone (5); the triterpenes squalene, isomultiflorenol (7), isobauerenol (8) and friedelin (9); the protolimonoids melianone (2) and melianodiol (3); and the pyranocoumarin 3-(1′-1′-dimethylallyl)-lomatin (1), which has not been reported previously as a natural product; together with β-sitosterol. The hexane extract and some of these compounds were assayed in vitro against trypomastigote forms of Trypanosoma cruzi. Brine shrimp lethality and antimicrobial activities of the crude extract and pure compounds were also evaluated.

Microbial transformation of cadina-4,10(15)-dien-3-one, aromadendr-1(10)-en-9-one and methyl ursolate by Mucor plumbeus ATCC 4740

The sesquiterpenes cadina-4,10(15)-dien-3-one (1) and aromadendr-1(10)-en-9-one (squamulosone) (14) along with the triterpenoid methyl ursolate (21) were incubated with the fungus Mucor plumbeus ATCC 4740. Substrates 1, 14 and ursolic acid (20) were isolated from the plant Hyptis verticillata in large quantities. M. plumbeus hydroxylated 1 at C-12 and C-14. When the iron content of the medium was reduced, however, hydroxylation at these positions was also accompanied by epoxidation of the exocyclic double bond. In total nine new oxygenated cadinanes have been obtained. Sesquiterpene 14 was converted to the novel 2α,13-dihydroxy derivative along with four other metabolites. Methyl ursolate (21) was transformed to a new compound, methyl 3β,7β,21β-trihydroxyursa-9(11),12-dien-28-oate (22). Two other triterpenoids, 3β,28-dihydroxyurs-12-ene (uvaol) (23) and 3β,28-bis(dimethylcarbamoxy)urs-12-ene (24) were not transformed by the micro-organism, however. © 2002 Elsevier Science Ltd. All rights reserved.

Flavonoids from Chiococca braquiata (Rubiaceae)

A new flavonol 4′-methoxykaempferol-7-(acetyloxy)-3,5-O-α-L- rhamnoside (1), was isolated from the leaves of Chiococca braquiata, along with three known flavonoids apigenin, 7-O-methoxyquercetrin and quercetrin and four triterpenes α-amirin, β-amirin, ursolic and oleanolic acids . Their structures were established on the basis of spectroscopic methods.

Limonoids from Cipadessa fruticosa and Cedrela fissilis and their insecticidal activity

The chemical investigation of the fruits of Cipadessa fruticosa (Meliaceae) afforded the new limonoid cipadesin B and the known swietemahonolide. From the roots of Cedrela fissilis (Meliaceae) were isolated the limonoid 3β-acetoxycarapin, new as natural product, along with the triterpenes oleanolic and oleanonic acid. These compounds and other six mexicanolide limonoids previously isolated from C. fruticosa showed insecticidal activity against the leaf-cutting ants Atta sexdens rubropilosa. ©2005 Sociedade Brasileira de Química.

A new ent-kaurane diterpene from stems of Alibertia macrophylla K. Schum. (Rubiaceae)

Phytochemical investigations of the stems of a specimen of Alibertia macrophylla led to the isolation and characterization of the new diterpene ent-kaurane-2β,3α,16α-triol (1), along with triterpenes 2-8, iridoids 9-12, and phenolic acids 13-15. The structure of 1 was established based on spectroscopic studies (1H- and 13C-NMR, IR, and HR-ESI-MS). This is the first report of the isolation of a diterpene from the Alibertia genus in Rubiaceae. © 2007 Verlag Helvetica Chimica Acta AG.