Flavonoids from Andrographis lineata

Three flavonoids, 5,7,2',3',4'-pentamethoxyflavone (1), 2'-hydroxy-2,4',6'-tri methoxychalcone (2) and dihydroskullcapflavone I (3), together with 17,19,20-trihydroxy-5beta, 8alpha H, 9beta H,10alpha-labd-13-en-16,15-olactone (4), a known diterpenoid and six known flavonoids, 5-hydroxy-7,8-dimethoxyflavanone (5), 5-hydroxy-7,8,2',3',4'-pentamethoxyflavone (6), 5,2'-dihydroxy-7-methoxyflavanone (7), 5,2'-dihydroxy-7,8-dimethoxyflavone (8), 5,2'-dihydroxy-7-methoxyflavone (9) and 5,2'-dihydroxy-7-methoxyflavone 2'-O-beta-D-glucopyranoside (10) were isolated from the whole plant of Andrographis lineata. The structures of these compounds were elucidated on the basis of spectral and chemical studies.     

Spasmolytic flavonoids from Syzygium samarangense (Blume) Merr. & L.M. Perry

The hexane extract of Syzygium samarangense (Ss.Hex) dose-dependently (10-1000 microg/ ml) relaxed the spontaneously contracting isolated rabbit jejunum. Four rare C-methylated flavonoids with a chalcone and a flavanone skeleton were isolated from Ss.Hex and were subsequently tested for spasmolytic activity. All flavonoids, identified as 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (1), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (2), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (3), and 7-hydroxy-5-methoxy-6,8-dimethyl-flavanone (4), showed dose-dependent spasmolytic activity in the rabbit jejunum with IC50 values of 148.3 +/- 69.4, 77.2 +/- 43.5, 142.4 +/- 58.6 and 178.5 +/- 37.5 microg/ml (mean +/- SEM), respectively. The dihydrochalcone derivative of compound 1, 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (5), when tested for spasmolytic activity, did not significantly relax the smooth muscle relative to the other compounds. Verapamil, a standard spasmolytic, has an IC50 value of 0.16 +/- 0.04 microg/ml. This is the first report of the relaxant activity of chalcones, specifically of compounds 1-3.     

HPLC-NMR/HPLC-MS analysis of the bark extract of Stauranthus perforatus

A combination of HPLC-MS and HPLC-NMR techniques has been used to analyse the cytotoxic fractions of the dichloromethane extract of bark of Stauranthus perforatus. Six furanocoumarins (byakangelicol, heraclenin, heraclenol, imperatorin, isopimpinellin and xanthotoxin) and nine quinoline alkaloids (two known compounds, veprisine and 5-hydroxy-1-methyl-2-phenyl-4-quinolone, along with seven novel compounds, stauranthine, 3',4'-dihydroxy-3',4'-dihydroveprisine, 3',4'-dihydroxy-3',4'-dihydrostauranthine, 3',6'-dihydroxy-3',6'-dihydroveprisine, 3',6'-dihydroxy-3',6'-dihydrostauranthine, 6'-hydroxy-3'-ketoveprisine and 6'-hydroxy-3'-ketostauranthine) have been identified in the fractions.     

Prolyl endopeptidase inhibitors from Syzygium samarangense (Blume) Merr. & L. M. Perry

Compounds isolated from the hexane extract of the leaves of Syzygium samarangense (Blume) Merr. & L. M. Perry were tested for inhibitory activity against the following serine proteases: trypsin, thrombin and prolyl endopeptidase. The compounds were identified as an intractable mixture of alpha-carotene and beta-carotene (1), lupeol (2), betulin (3), epi-betulinic acid (4), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (5), 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (6), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (7), 2',4'-dihydroxy-6'-methoxy-3'-methyldihydrochalcone (8) and 7-hydroxy-5-methoxy-6,8-dimethylflavanone (9). Hydrogenation of compounds 5, 6 and 7 yielded compound 8, 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (10) and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethyldihydrochalcone (11), respectively. The hydrogenated products of compounds 6 and 7 were also tested for enzyme inhibitory activity. In addition, beta-sitosterol (12) and beta-D-sitosterylglucoside (13) were also isolated. This is the first report of the isolation of compounds 1-6, 8 and 13 from this plant. Compounds 3-8 and 10 exhibited significant and selective inhibition against prolyl endopeptidase among three serine proteases. This is the first report of this kind of activity for all these compounds.     

Flavonoids and terpenoids from Luma gayana (Barn.) Burret

The flavonoids 5-hydroxy-7-methoxyflavanone, 6,8-dimethyl-5,7-dihydroxyflavanone and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, a mixture of alkyl esters of p-coumaric acid, the triterpenoids oleanolic acid and maslinic acid, the monoterpenoid 1 alpha,2 beta,4 beta-trihydroxy-p-menthane, the sesquiterpenoid clovandiol and beta-sitosterol were isolated from the aerial parts of Luma gayana (Barn.) Burret. This is the first report on the chemistry of this species.     

Pyrano chalcones and a flavone from Neoraputia magnifica and their Trypanosoma cruzi glycosomal glyceraldehyde-3-phosphate dehydrogenase-inhibitory activities

The fruits of Neoraptua magnifica var. magnifica afforded three new flavonoids: 2'-hydroxy-4,4',-dimethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, 2'-hydroxy-3,4,4'-trimethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, and 3',4'-methylenedioxy-5,7-dimethoxyflavone which were identified on the basis of spectroscopic methods. The known flavonoids 2'-hydroxy-3,4,4',5-tetramethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, 2'-hydroxy-3,4,4',5,6'-pentamethoxychalcone, 3',4'-methylenedioxy-5,6,7-trimethoxyflavone, 3',4'-methylenedioxy-5',5,6,7-tetramethoxyflavone, 3',4',5',5,7-pentamethoxyflavanone and 3',4',5'5,7-pentamethoxyflavone were also identified. The latter flavone was the most active as glyceraldehyde-3-phosphate dehydrogenase-inhibitor.     

New erythroxane-type diterpenoids from Fagonia boveana (Hadidi) Hadidi & Graf

The aerial parts of Fagonia boveana afforded two new erythroxane-type diterpenes, 3beta,15,16-trihydroxy-erythrox-4(18)-ene (2) and 15,16-dihydroxy-cis-ent-erythrox-3-ene (fagonene) (3) together with two known ones; 16-O-acetylfagonone (1) and 7beta-hydroxy fagonene (8). Also a new guaiane sesquiterpene alcohol, 6,10-epoxy-4alpha-hydroxy guaiane type sesquiterpene (4) has been isolated. In addition three 8-methoxy flavonols, 8-methoxy-quercetin-3,7,3'-trimethyl ether (ternatin) (5), gossypetin, 3,8,3',4' tetramethyl ether (6) and herbacetin-3,8-dimethyl ether (7) were also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. On performing different assays for biological activities, 6 displayed significant cytotoxic activity against KA3IT and NIH3T3 cell lines, 8 was the most active antiviral against Herpes simplex type 1 while 7 was the most active cancer-preventive agent using protein-tyrosine kinase inhibitory method.     

Flavonoids from two Lonchocarpus species of the Yucatan Peninsula

Leaves, stem bark and root of Lonchocarpus xuul and Lonchocarpus yucatanensis were studied separately. A chalcone, 2',4-dimethoxy-6'-hydroxylonchocarpin (), and the flavones 5,4'-dihydroxy-3'-methoxy-(6:7)-2,2-dimethylpyranoflavone (2) and 5,4'-dimethoxy-(6:7)-2,2-dimethylpyrano-flavone (3), together with the known carpachromene (4), were isolated from the leaves of both species. Similarly, the previously reported flavans xuulanin (5) and 3beta-methoxyxuulanin (6), together with the novel 3beta,4beta,5-trimethoxy-4'-hydroxy-(6:7)-2,2-dimethylpyranoflavan (7), 3-hydroxy-4,5-dimethoxy-(6:7)-2,2-dimethyl-pyranoflavan (8), and 3,4-dihydroxy-5-methoxy-(6:7)-2,2-dimethylpyranoflavan (10), were isolated from the stem bark and root of both species. Finally, the known 2',4'-dihydroxy-3'-(3-methylbut-2-enyl) chalcone (13) was obtained from the root of L. xuul only. The structures of the various metabolites were established by interpretation of their spectroscopic data.     

An lonone Derivative from Isodon leucophyllus

A new ionone derivative and six known flavonoids were isolated from the aerial parts of Isodon leucophyllus (Dunn) Kudo. Their structures were respectively elucidated as 13-carboxy-blumenol C (1), 5, 7, 3', 4'-tetramethoxyflavone (2), cirsiliol (3), 5-hydroxy-6, 7, 3', 4'-tetramethoxyflavone (4), 3'-hydroxy-5, 7, 8, 4'-tetramethoxyflavone (5), isosinensetin (6) and isoquercetrin (7), based on their spectra analysis. All of the six flavonoids were reported firstly from this plant.     

Phenolic glycosides from Phagnalon rupestre

Analysis of the butanol-soluble fraction from the methanolic extract of the aerial parts of Phagnalon rupestre (Asteraceae) has led to the isolation of seven phenolic compounds. Three have been identified on the basis of their NMR spectra as new natural compounds: the lignan 7,7'-bis-(4-hydroxy-3,5-dimethoxyphenyl)-8,8'-dihydroxymethyl-tetrahydrofuran-4-O-beta-glucopyranoside (1), the prenylhydroquinone glycoside 1-O-beta-glucopyranosyl-1,4-dihydroxy-2-(3'-hydroxy-3'-methylbutyl) benzene (2) and the acetophenone glycoside 12-O-beta-glucopyranosyl-9beta,12-dihydroxytremetone (3). The known flavonoids apigenin-7-O-beta-glucoside, luteolin-7-O-beta-glucoside, luteolin-7-O-beta-glucuronide and the acetophenone picein were also isolated.     

Minor phenolics from Crinum bulbispermum bulbs

From the bulbs of Crinum bulbispermum Milne, four new minor compounds were isolated viz. 4-hydroxy-2',4'-dimethoxydihydrochalcone (1), 4,5-methylenedioxy-4'-hydroxy-2-aldehyde[1,1'-biphenyl] (4), hippacine (6), and 4'-hydroxy-7-methoxyflavan-3-ol (7). In addition, four known compounds were isolated and identified as 2(S),3',4'-dihydroxy-7-methoxy flavan (2), isolarrien (3), isoliquiritigenin (5) and liquiritigenin (8). The structures of the isolated compounds were established by spectral evidence.     

Antimicrobial and radical scavenging flavonoids from the stem wood of Erythrina latissima

From the stem wood of Erythrina latissima, two isoflavones and a flavanone were isolated and characterized as 7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)isoflavone (erylatissin A), 7,3'-dihydroxy-6',6'-dimethyl-4',5'-dehydropyrano [2',3': 4',5']isoflavone (erylatissin B), (-)-7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)flavanone (erylatissin C), respectively, in addition to 10 known flavonoids. Structures of these compounds were determined on the basis of their spectroscopic data. These compounds showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida mycoderma. The isolated compounds also exhibited weak radical scavenging properties towards DPPH radical.     

Furoquinoline alkaloids of Ertela (Monnieria) trifolia (L.) Kuntze from the Suriname rainforest

7-(2'-Hydroxy-3'-chloroprenyloxy)-4,8-dimethoxyfuroquinoline (1) and 6-(2'-hydroxy-3'-chloroprenyloxy)-4,7-dimethoxyfuroquinoline (2), together with ten known compounds, have been isolated from the aerial parts of Ertela (Monnieria) trifolia (L.) Kuntze. All the isolates were tested for antiproliferative activity against the A2780 human ovarian cancer cell line.     

Rare biscoumarins and a chlorogenic acid derivative from Erycibe obtusifolia

Three coumarins, 7,7'-dihydroxy-6,6'-dimethoxy-3,3'-biscoumarin (1), 7,7'-dihydroxy-6,6'-dimethoxy-8,8'-biscoumarin (2) and 7-O-[4'-O-(3',4'-dihydroxycinnamyl)-beta-d-glucopyranosyl]-6-methoxycoumarin (3), and a chlorogenic acid derivative, methyl-3-O-(4'-hydroxy-3',5'-dimethoxybenzoyl)-chlorogenate (4) were isolated from the roots of Erycibe obtusifolia along with four known coumarins, scopoletin (5), scopolin (6), cleomiscosin A (7) and cleomiscosin B (8). Their structures were elucidated by spectroscopic methods. Among them, compounds (1) and (2) are rare carbon-carbon linked symmetrical biscoumarins.     

Flavonoids from Cleistocalyx operculatus

Two flavonoids 3'-formyl-4',6'-dihydroxy-2'-methoxy-5'-methylchalcone and (2S)-8-formyl-5-hydroxy-7-methoxy-6-methylflavanone together with five known compounds, were isolated from the dried buds of Cleistocalyx operculatus. Their structures were determined on the basis of spectroscopic analyses (UV, IR, EIMS, (1)H, (13)C NMR and HMBC).     

Antioxidant aryl-prenylcoumarin, flavan-3-ols and flavonoids from Eysenhardtia subcoriacea

Antioxidant activity (AOA) assay-guided chemical analysis, using a rat pancreas homogenate model, of aerial parts from Eysenhardtia subcoriacea, led to isolation of the new compound subcoriacin (3-(2'-hydroxy-4',5'-methylendioxyphenyl)-6-(3'-hydroxymethyl-4'-hydroxybut-2'-enyl)-7-hydroxycoumarin) together with the known substances: (+)-catechin, (-)-epicatechin, (+)-afzelechin, eriodictyol, (+)-catechin 3-O-beta-D-galactopyranoside and quercetin 3-O-beta-D-galactopyranoside as bioactive constituents. The structure of the compound was determined from 1D and 2D NMR spectroscopic analyses. Additional known constituents were characterized. The bioactive compounds showed also moderate to strong radical scavenging properties against diphenylpicrylhydrazyl radical (DPPH). In addition, subcoriacin, (+)-catechin, (-)-epicatechin and (+)-afzelechin improved the reduced glutathione levels in rat pancreatic homogenate.     

Three isoflav-3-enes and a 2-arylbenzofuran from the root bark of Erythrina burttii

From the root bark of Erythrina burttii three isoflav-3-enes, 7,4'-dihydroxy-2'-methoxy-6-(1",1"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-A), 4'-hydroxy-2'-methoxy-2",2"-dimethylpyrano[5",6":8,7]isoflav-3-ene (trivial name, burttinol-B), 7,4'-dihydroxy-2'-methoxy-8-(3",3"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-C), and 2-arylbenzofuran, 6,4'-dihydroxy-2'-methoxy-5-(1",1"-dimethylallyl)-2-arylbenzofuran (trivial name, burttinol-D) were isolated. In addition, the known compounds, abyssinone V-4'-methyl ether, bidwillol A, calopocarpin, erybraedin A, erythrabyssin II, isobavachalcone, phaseollidin and phaseollin were identified. The structures were determined on the basis of spectroscopic evidence.     

Prenylated flavonoids from the aerial parts of Dorstenia mannii

Four new prenylated flavanones, dorsmanins 1, J and epi-dorsmanins F, G, identified, respectively, as 6,7-(2,2-dimethylpyrano)-8-prenyl-5,3',4'-trihydroxyflavanone, 6,7-(2,2-dimethyldihydropyrano)-8-prenyl-5,3',4'-trihydroxflavanone, and 2'-epimers of dorsmanins F and G were isolated from the aerial parts of Dorstenia mannii together with 13 known flavonoids: 4-hydroxylonchocarpin, 4-methoxylonchocarpin, 6-prenylchrysoeriol, 6,8-diprenyleriodictyol, gancaonin P and dorsmanins A-H. The structures of these secondary metabolites were determined by spectroscopic means and by comparison with published data and with authentic specimens for some of the known compounds.     

Flavones and isoflavones from the west African Fabaceae Erythrina vogelii

The CH(2)Cl(2)/MeOH extract of the stem bark of Erythrina vogelii (Fabaceae) from Nigeria has yielded two novel isoflavones, 7,4'-dihydroxy-8-(gamma,gamma-dimethylallyl)-2'zeta-(4'-hydroxyisopropyl)dihydrofurano[1',3':5,6]isoflavone (vogelin H) (1) and 7,4'-dihydroxy-8-[(2'zeta,3'-dihydroxy-3'-methyl)butyl]-2',2'-dimethyl-3',4'-dehydropyrano[1',4':5,6]isoflavone (vogelin I) (2), a novel flavone, 7,4'-dihydroxy-2',2'-dimethyl-3',4'-dehydropyrano[1',4':5,6]flavone (vogelin J) (3), and eight known flavonoids.     

Flavonoids from Tephrosia major. A new prenyl-beta-hydroxychalcone

The roots and aerial parts of Tephrosia major Micheli, afforded a new prenylated-beta-hydroxychalcone, characterized as 2',6'-dihydroxy-3'-prenyl-4'-methoxy-beta-hydroxychalcone. In addition, seven prenylated flavonoids, two rotenoids, beta-sitosterol, stigmasterol, lupeol and quercetin were isolated. The structure of the new beta-hydroxy chalcone was established by spectroscopic methods, including 2D NMR experiments.