Combined experimental powder X-ray diffraction and DFT data to obtain the lowest energy molecular conformation of friedelin

Friedelin molecular conformers were obtained by Density Functional Theory (DFT) and by ab initio structure determination from powder X-ray diffraction. Their conformers with the five rings in chair-chair-chair-boat-boat, and with all rings in chair, are energy degenerated in gas-phase according to DFT results. The powder diffraction data reveals that rings A, B and C of friedelin are in chair, and rings D and E in boat-boat, conformation. The high correlation values among powder diffraction data, DFT and reported single-crystal data indicate that the use of conventional X-ray diffractometer can be applied in routine laboratory analysis in the absence of a single-crystal diffractometer.

Screening of plant extracts from the Brazilian Cerrado for their in vitro trypanocidal activity

In this study we report the screening of the in vitro trypanocidal activity of 20 extracts obtained from 10 different plant species growing in the Brazilian Cerrado: Aspidosperma macrocarpum Mart. (Apocynaceae), Aegiphila sellowiano Cham. (Verbenaceae), Byrsonima intermedia Juss. (Malpighiaceae), Cyperus rotundus L. (Cyperaceae), Leandra lacunosa Cogn. (Melastomataceae), Miconia ligustroides (DC.) Naudin. (Melastomataceae), Miconia sellowiana Naudin.(Melastomataceae),Myrcia variabilis Mart.ex DC. (Myrtaceae), Solanum lycocarpum St. Hil. (Solanaceae), and Tibouchina stenocarpa Cogn. (Melastomataceae). The most active extracts were submitted to phytochemical analyses. High-resolution gas chromatography analysis of the n-hexane extract of T. stenocarpa (IC(50) = 23.6 mu g/mL), the most active extract amongst all the tested samples, allowed the identification of beta-amyrin, alpha-amyrin, lupeol, friedelin, beta-friedelanol, campesterol, stigmasterol, and beta-sitosterol. Oleanolic and ursolic acids were isolated from the methylene chloride extract of T stenocarpa (IC(50) = 51.5 mu g/mL), while ursolic acid was isolated from the methylene chloride extract of M. variabilis (IC(50)=38.4 mu g/mL). Solasonine and solamargine were identified as major compounds by mass spectrometry analysis in the hydroalcoholic extract of the fruits of S. lycocarpum (IC(50)=57.1 mu g/mL).The results showed that the trypanocidal activity may be related to the major compounds identified in the crude active extracts.

PRENYLATED XANTHONES FROM Rheedia acuminata

Pyranojacareubin; 1,5-dihydroxy-6',6'-dimethyl-2H-pyran(2',3':6,7) -6",6"-dim-ethyI-2H,4H-pyran(2",3":2,3)xanthone and a new xanthone l,6-dihydroxy-5-methoxy-6',6'-dim-ethyl-2H-pyran(2',3':3,2)-7-(3,3-dimethylprop-2-enyl)xanthone were isolated from the ether extract of the root bark of Rheedia acuminata together with friedelin and friedelanol.

PRENYLATED XANTHONES FROM Rheedia acuminata (reprinted from Acta Amazônica, 23(2/3):181-185)

Pyranojacareubin; 1,5-dihydroxy-6',6'-dimethyl-2H-pyran(2,,3':6,7) -6",6"-dime-thyl-2H,4H-pyran(2",3":2,3)xanthone and a new xanthone l,6-dihydroxy-5-methoxy-6',6'-dime-thyl-2H-pyran(2',3':3,2)-7-(3,3-dimethylprop-2-enyl)xanthone were isolated from the ether extract of the root bark of Rheedia acuminata together with friedelin and friedelanol.

Pentacyclic triterpenes and steroids from the stem bark of uchi (Sacoglottis uchi, Humiriaceae)

The ethanol extract from stem bark of Sacoglottis uchi Huber (popularly known as “uchi” in the Amazon Region) was submitted to chromatographic fractionation. The dichloromethane fractions provided the pentacyclic triterpene 3-oxo-friedelin (1). The dichloromethane:methanol fractions provided the pentacyclic triterpenes pseudotaraxasterol (2), lupeol (3), a-amyrin (4), betulin (5), and methyl 2ß,3ß-dihydroxy-urs-12-en-28-oate (6) and a mixture of the steroids sitosterol (7) and stigmasterol (8). Their chemical structures were determined by NMR spectroscopy and comparison with spectroscopic data from the literature. All compounds are described for the first time in this species.

Trypanocidal constituents in plants: 7. Mammea-type coumarins

Calophyllum brasiliense and Mammea americana (Clusiaceae) are two trees from the tropical rain forests of the American continent. A previous screening showed high trypanocidal activity in the extracts of these species. Several mammea-type coumarins, triterpenoids and biflavonoids were isolated from the leaves of C. brasiliense. Mammea A/AA was obtained from the fruit peels of M. americana. These compounds were tested in vitro against epimastigotes and trypomastigotes of Trypanosoma cruzi, the etiologic agent of Chagas disease. The most potent compounds were mammea A/BA, A/BB, A/AA, A/BD and B/BA, with MC100 values in the range of 15 to 90 g/ml. Coumarins with a cyclized ,-dimethylallyl substituent on C-6, such as mammea B/BA, cyclo F + B/BB cyclo F, and isomammeigin, showed MC100 values > 200 g/ml. Several active coumarins were also tested against normal human lymphocytes in vitro, which showed that mammea A/AA and A/BA were not toxic. Other compounds from C. brasiliense, such as the triterpenoids, friedelin, canophyllol, the biflavonoid amentoflavone, and protocatechuic and shikimic acids, were inactive against the epimastigotes. The isopropylidenedioxy derivative of shikimic acid was inactive, and its structure was confirmed by X-ray diffraction. Our results suggest that mammea-type coumarins could be a valuable source of trypanocidal compounds.

Flavonóide e triterpenos de Stigmaphyllom paralias

Stigmaphyllom paralias is a herb belonging to the family Malpighiaceae that occurs in sand soil of brazilian " restinga". This is the first report regarding phytochemical study with this species. The hexane extract of the aerial parts of plant afforded the triterpenes friedelin, lupenone, 3-oxo-alpha-amirin and 3-oxo-beta-amirin, the mixture of alpha-amirinyl palmitate and stearate, lupeol and 3,4-seco-friedelan-3-oic acid. The AcOEt extract yielded the flavonoid luteolin-7-rutinoside. All compounds were characterized by analysis of spectrometric data and the fatty acids esterified with alpha-amirine were identified by GC/MS of methyl derivatives of transesterified products . This is the first natural occurence of 3,4-seco-friedelan-3-oic acid and the 13C NMR spectral data were inequivocally assigned by two-dimensional techniques. This work also permitted to correct the 13C NMR resonances attributed to methyl groups C-26 and C-27 of fridelin.

Constituintes químicos da raiz e do talo da folha do açaí (Euterpe precatoria Mart., Arecaceae)

Phytochemical investigation of the hexane, ethyl acetate and methanolic extracts of roots and leaf stalks of Euterpe precatoria Mart. ("açaí"), afforded stigmast-4-en-6beta-ol-3-one (3); p-hydroxy benzoic acid (4); 3beta-O-D-glucopyranosyl-sitosterol (5); beta-sitosterol palmitate (6); mixtures of beta-sitosterol and stigmasterol (1 and 2), alpha-, beta-amirin and lupeol (7, 8 and 9), friedelin-3-one and 28-hydroxy-friedelin-3-one (10 and 11) and alpha-, beta-D-glucose (12, 13). Except for 1, 2 and 4, the other isolated constituents are described in the genus for the first time. Compounds 3 and 5 gave good results in the brine shrimp bioassay, which detects compounds with potential uses as antitumor agents, pesticides, etc..

Constituintes químicos de Vernonia chalybaea mart.

The chemical investigation of the hexane and ethanol extracts from aerial parts of Vernonia chalybaea conducted to the isolation and characterization of a new aliphatic tetrahydroxyl ether, along with a series of known compounds such as 4 α,10 α-epoxyaromadendrane, friedelin, taraxasteryl acetate, pseudotaraxasteryl acetate, lupeyl acetate, lupeol, α-amiryn, β-amiryn, β-sitosterol, stigmasterol, 2,3-dimethyl-1,2,3-tri-hydroxybuthanol, angophorol, angophorol-7-O-glucoside, angophorol-7-O-rutinoside, 3,7-dimethoxy-5,3',4'-trihydroxyflavone and acacetin. The structures of all compounds were determined by spectroscopic analysis and comparison with published spectral data.

Triterpenes and antitubercular activity of Byrsonima crassa

We evaluated the potential antitubercular activity of triterpenes obtained from leaves and bark of Byrsonima crassa. From chloroform extracts of the leaves, by bioassay-guided fractionation, we obtained mixtures of known triterpenes: α-amyrin, β-amyrin and their acetates, lupeol, oleanolic acid, ursolic acid and α-amyrinone. Tested against Mycobacterium tuberculosis, the triterpenes exhibited minimum inhibitory concentrations (MICs) of 31.25 - 312.25 µg/mL. β-amyrin and friedelin, isolated from the chloroform extract of bark, showed MICs of 312.25 and 125 µg/mL respectively. This is the first report of the identification and determination of the activity of B. crassa triterpenes against M. tuberculosis.

Variabilidade química de compostos orgânicos voláteis e semivoláteis de populações nativas de Maytenus ilicifolia

This work is focused on the chemical distribution of volatile and semi-volatile compounds of 18 native populations of Maytenus ilicifolia collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by supercritical CO2 extraction technique, and analyzed by GC/MS. The quantification of compounds (phytol, squalene, vitamin E, limonene, stigmasterol, friedelan-3-ol, friedelin, fridelan-3-one, palmitic acid and geranyl acetate) showed significant variations within the different populations, which could be related tom microclimate characteristics.

Constituintes químicos das folhas de Senna spectabilis (DC) Irwin & Barneby var. excelsa (Schrad.) Irwin & Barneby

From leaves of Senna spectabilis var. excelsa were isolated caffeine, the triterpenes lupeol, α-amyrin, β-amyrin, cycloeucalenol, friedelin and ursolic, oleanolic and betulinic acids, besides the steroids sitosterol and stigmasterol and their respective glucosides. The structures of these compounds were established by spectroscopic analysis including two-dimensional NMR methods and comparison with published spectral data. This paper deals with the first report of these compounds in S. spectabilis var. excelsa.

De scriptura stigmatis

Painovuosi nimekkeestä.

Constituintes químicos e atividade Leishmanicida de Gustavia elliptica (Lecythidaceae)

The phytochemical investigation of the stem bark and leaves of G. elliptica provided a mixture of the norisoprenoids blumenol B and 6-epiblumenol B along with the triterpenes friedelin, as the major constituent, friedelanol, ursa-9(11),12-dien-3-ol, a-amyrin, β-amyrin, morentenol, epifriedelanol, as well as the sesquiterpenes trans-caryophyllene, α-humulene, ethyl hydnocarpate and other fatty acid esters. The identification of the compounds was performed on basis of spectrometric methods such as GC-MS, IR, MS and 1D and 2D NMR. Stem bark extracts showed significant leishmanicidal activity against promastigote forms of Leishmania braziliensis, with the best results for the chloroform extract.

Constituintes químicos e atividade antioxidante de folhas e galhos de Eugenia copacabanensis Kiaersk (Myrtaceae)

Phytochemical investigation of Eugenia copacabanensis allowed for the isolation and identification of following compounds: β-sitosterol, β-sitosterol-glucoside, eight triterpenes, (mixture of α- and β-amyrins, ursolic acid, 30-hydroxy-ursolic acid, betulin, friedelin, friedelan-3,4-lactone, and taraxerol), a mixture of three sesquiterpenes, (clovandiol, globulol, and viridiflorol), three flavonoids (kaempferol-3-O-β-D-rhamnoside, quercetin-3-O-α-L-arabinoside, and quercetin), and a mixture of four coumaroyl esters (octacosanyl, heptacosanyl, hexacosanyl, and tetracosanyl coumarates). The structures of these compounds were assigned based on comparison with literature data and spectroscopic analysis, including analysis by two-dimensional NMR techniques. Total phenolic content and total flavonoids were evaluated. Antioxidant activities of methanol extracts and fractions were measured by the 1,2-diphenyl-2-picryl-hidrazyl free radical scavenging assay.