Biflavonoids from the bark roots of Poincianella pyramidalis (Fabaceae)

Poincianella pyramidalis (Fabaceae) is an endemic tree that grows in semiarid regions of Brazil. Phytochemical investigations on the bark roots of this plant led to the isolation of four new biflavonoids named (+)-5-hydroxy-7,4′-dimethoxyflavone-3α-2′′′-hydroxy-4′′′,4′′-dimethoxydihydrochalcone (1), (+)-5,7-dihydroxy-4′-methoxyflavone-3α-2′′′-hydroxy-4′′′,4′′-dimethoxydihydrochalcone (2), (−)-7-hydroxy-4′-methoxyflavone-3α-2′′′,4′′′-dihydroxy-4′′-methoxydihydrochalcone (3), (−)-7,4′-dihydroxy-flavanone-3,8-5′′,6′′,4′′-trihydroxy-flavone (4), and the previously identified compound 4,2′,4′,4′′,2′′′,4′′′-hexahydroxy-3,5′′′-bichalcone (rhuschalcone VI, 5). Their structures were determined by HR-ESI-MS and extensive analyses of NMR spectroscopic data.     

Xanthones from the bark of Garcinia pedunculata

Three new xanthones, pedunxanthones A–C (1–3), together with five known compounds, 1,5-dihydroxy-3-methoxy-6′,6′-dimethyl-2H-pyrano(2′,3′:6,7)-4-(3-methylbut-2-enyl)xanthone, 1,5-dihydroxy-3-methoxy-4-(3-methylbut-2-enyl)xanthone, dulxanthone A, garbogiol and oleanolic acid, were obtained from a petroleum ether extract of the bark of Garcinia pedunculata. The new structures were elucidated using spectroscopic methods, mainly 1-D and 2-D NMR.     

Antiproliferative constituents from Aphananthe aspera leaves

Extensive screening for the antiproliferative activity of different compounds found in trees was performed by extracting the leaves of Aphananthe aspera (Thunb.) Planch and then using chromatographic separation to afford 2 new compounds, (2S,4R)-2-carboxy-4-(E)-p-caffeoyl-1-methyl-hydroxyproline (1) and 5-O-caffeoyl quinic acid-(7′R,8′S,7′′E)-3′,4′,3′′-dihydroxy-4′′,7′-epoxy-8′,5′′-neolign-7′-ene-9- carboxyl (2). In addition, 6 known compounds were discovered from the leaves of this plant. The structural determination of all compounds, including their absolute configurations, was established by UV, IR, HRESIMS, 1D and 2D NMR, and CD spectroscopy. The novel compound 1 showed strong antiproliferative activity against human breast adenocarcinoma cells MCF-7 and MDA-MB-231.     

Two new antioxidant flavones from the twigs of Eriosema robustum (Fabaceae)

Phytochemical study of the ethanol extract of the twigs of Eriosema robustum, a Cameroonian medicinal plant resulted to the isolation of two new flavones, 2′,3′,5′,5,7-pentahydroxy-3,4′-dimethoxyflavone (1) and 2′,3,5′,5,7-pentahydroxy-4′-methoxyflavone (2), along with five known compounds: 6-prenylpinocembrin (3), 1-O-heptatriacontanoyl glycerol (4), β-sitosterol (5), stigmasterol (6) and 3-O-β-d-glucopyranoside of sitosterol (7). The structure of the isolated compounds were elucidated on the basis of their NMR, UV and MS data, and by comparison with those reported in the literature. The ethanol crude extract, fractions and some isolated compounds (1–4) were evaluated for their radical scavenging capacity using 2,2-diphenyl-1-picryhydrazyl (DPPH). The crude extract, fraction II, the new compounds namely robusflavones A (1) and B (2) exhibited significant antioxidant activity.     

Flemiphyllin,an isoflavone from stems of Flemingia macrophylla

A new isoflavone, designated flemiphyllin, was isolated from a petrol extract of the stems of Flemingia macrophylla. Its structure was established as 5,7,4′-trihydroxy-3′,5′,8-tri(3-methylbut-2-enyl) isoflavone on the basis of physical and chemical evidence.     

Platachromone A–D: Cytotoxic 2-styrylchromones from the bark of Platanus × acerifolia (Aiton) Willd.

Four novel 2-styrylchromones, 4′,5,7-trihydroxy-6-isopentene-2-styrylchromone (1), 4′,5,7-trihydroxy-8-isopentene-2-styrylchromone (2), 4′,5,7-trihydroxy-6-(2-hydroxy-3-methylbut-3-enyl)-2-styrylchromone (3) and 4′,5,7-trihydroxy-8-(2-hydroxy-3-methylbut-3-enyl)-2-styrylchromone (4), were isolated from shed bark of Platanus × acerifolia (Aiton) Willd., as well as four known compounds, 4′,5,7-trihydroxy-2-styrylchromone (5), scutellarein (6), 4′,5,7-trihydroxy-6-prenylflavone (7), and 4′,5,7-trihydroxy-8-prenylflavone (8). The structures of compounds 1–4 were established by direct interpretation of their spectral data, mainly high resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D and 2D NMR (¹H–¹H COSY, HSQC and HMBC). The cytotoxicity of the compounds 1–8 was evaluated in four human carcinoma cell lines, including HepG2, SMMC-7721, MDA-MB-231, and KB. Compounds 1–4 exhibited significantly cytotoxic activity toward HepG2 and KB cells, with IC₅₀ values ranging from 3.0 to 9.7 μM.     

Four isoflavanones from the stem bark of Platycelphium voënse

From the stem bark of Platycelphium voënse (Leguminosae) four new isoflavanones were isolated and characterized as (S)-5,7-dihydroxy-2′,4′-dimethoxy-3′-(3″-methylbut-2″-enyl)-isoflavanone (trivial name platyisoflavanone A), (±)-5,7,2′-trihydroxy-4′-methoxy-3′-(3″-methylbut-2″-enyl)-isoflavanone (platyisoflavanone B), 5,7-dihydroxy-4′-methoxy-2″-(2?-hydroxyisopropyl)-dihydrofurano-[4″,5″:3′,2′]-isoflavanone (platyisoflavanone C) and 5,7,2′,3″-tetrahydroxy-2″,2″-dimethyldihydropyrano-[5″,6″:3′,4′]-isoflavanone (platyisoflavanone D). In addition, the known isoflavanones, sophoraisoflavanone A and glyasperin F; the isoflavone, formononetin; two flavones, kumatakenin and isokaempferide; as well as two triterpenes, betulin and β-amyrin were identified. The structures were elucidated on the basis of spectroscopic evidence. Platyisoflavanone A showed antibacterial activity against Mycobacterium tuberculosis in the microplate alamar blue assay (MABA) with MIC = 23.7 μM, but also showed cytotoxicity (IC₅₀ = 21.1 μM) in the vero cell test.     

Synthesis and urease inhibitory potential of benzophenone sulfonamide hybrid in vitro and in silico

This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC₅₀ value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC₅₀?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by ¹H NMR, ¹³C NMR, EI-MS and FAB-MS spectroscopic techniques.     

Fungal metabolites of xanthohumol with potent antiproliferative activity on human cancer cell lines in vitro

Xanthohumol (1) and xanthohumol D (2) were isolated from spent hops. Isoxanthohumol (3) was obtained from xanthohumol by isomerisation in alkaline solution. Six metabolites were obtained as a result of transformation of xanthohumol (1) by selected fungal cultures. Their structures were established on the basis of their spectral data. One of them: 2″-(2′′′-hydroxyisopropyl)-dihydrofurano-[4″,5″:3′,4′]-4′,2-dihydroxy-6′-methoxy-α,β-dihydrochalcone (6) has not been previously reported in the literature. The antioxidant properties of hops flavonoids and xanthohumol derivatives were investigated using the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. The effects of these compounds on proliferation of MCF-7, PC-3 and HT-29 human cancer cell lines were determined by the SRB assay. With the exception of one metabolite, all tested compounds showed antiproliferative activity against the tested human cancer lines. α,β-Dihydroxanthohumol (4), obtained through the biotransformation of xanthohumol, showed higher antiproliferative activity against MCF-7 human breast carcinoma cell line than cisplatin, a widely used anticancer therapeutic agent, and a comparably high activity against PC-3 human prostate cancer cell line.     

Anti-plasmodial and antioxidant activities of constituents of the seed shells of Symphonia globulifera Linn f

A xanthone derivative, named gaboxanthone (1), has been isolated from the seed shells of Symphonia globulifera, together with known compounds, symphonin (2), globuliferin (3), guttiferone A (4), sistosterol, oleanolic acid and methyl citrate. The structure of the compound was assigned as 5,10-dihydroxy-8,9-dimethoxy-2,2-dimethyl-12-(3-methylbut-2-enyl) pyrano [3,2-b]xanthen-6(2H)-one, by means of spectroscopic analysis. The anti-plasmodial and antioxidant activities of the phenolic compounds were evaluated, respectively, in culture against W2 strain of Plasmodium falciparum and using the free radical scavenging activity of the DPPH radical, respectively. Compounds 1-4 were found to be active against the Plasmodium parasites (IC(50) of 3.53, 1.29, 3.86 and 3.17 microM, respectively). Guttiferone A (4) showed a potent free radical scavenging activity compared to the well-known antioxidant caffeic acid.     

Two Oxazolyl Compounds and a Monosubstituted α-Pyrone as Free-radical Scavengers Isolated from a Fungus

In the course of our screening for free radical scavengers, (1′E)-erythro-4-(3′,4′-dihydroxypentenyl)oxazole (1) (1′E,4′S)-4-(3′-oxo-4′-hydroxypentenyl)oxazole (2) and 6-pentyl-α-pyrone (3) were isolated from an unidentified fungal metabolite. These compounds, especially novel oxazolyl compound 2, inhibited the bactericidal effect of the Fenton reagent toward Bacillus subtilis. They and their acetylated compounds (diAc-1 and Ac-2) also showed inhibitory activity against linoleate autoxidation. Furthermore, 1–3 inhibited oxidative enzymes (soybean lipoxygenase and mushroom tyrosinase).

To investigate the radical scavenging mechanism of 3, two oxidized products (4 and 5) were isolated from the reaction mixture of 3 and the Fenton reagent. Compounds 4 and 5 seemed to be derived from 3 by scavenging the hydroxyl radical.     

Pterocarpans and isoflavones from the root bark of Millettia micans and of Millettia dura

From the CH₂Cl₂/CH₃OH (1:1) extract of the root bark of Millettia micans, a new pterocarpan, (6aR,11aR)-3-hydroxy-7,8,9-trimethoxypterocarpan (1), named micanspterocarpan, was isolated. Similar investigation of the CH₂Cl₂/CH₃OH (1:1) extract of the root bark of Millettia dura gave a further new pterocarpan, (6aR,11aR)-8,9-methylenedioxy-3-prenyloxypterocarpan (2), named 3-O-prenylmaackiain, along with six known isoflavones (3-8) and a chalcone (9). All purified compounds were identified by NMR and MS, whereas the absolute configurations of the new pterocarpans were established by chriptical data analyses including quantum chemical ECD calculation. Among the isolated constituents, calopogonium isoflavone B (3) and isoerythrin A-4′-(3-methylbut-2-enyl) ether (4) showed marginal activities against the 3D7 and the Dd2 strains of Plasmodium falciparum (70–90% inhibition at 40 μM). Maximaisoflavone B (5) and 7,2′-dimethoxy-4′,5′-methylenedioxyisoflavone (7) were weakly cytotoxic (IC₅₀ 153.5 and 174.1 μM, respectively) against the MDA-MB-231 human breast cancer cell line. None of the tested compounds showed in-vitro translation inhibitory activity or toxicity against the HEK-293 human embryonic kidney cell line at 40 μM.     

Prenylated flavonoids of Erythrina lysistemon grown in Egypt

Three prenylated flavonoid derivatives; 5,7,4′-trihydroxy-8-(3-methylbut-2-enyl)-6-(2″-hydroxy-3″-methylbut-3″enyl) isoflavone (isoerysenegalensein E), 5,7,2′-trihydroxy-4′-methoxy-5′-(3″-methylbut-2″-enyl) isoflavanone (lysisteisoflavanone), 5, 4′-dihydroxy-6-(3-methylbut-2-enyl)-2″-hydroxyisopropyl dihydrofurano [4″,5″:8,7] isoflavone (isosenegalensin), together with the four known flavonoids abyssinone V-4′-methylether, alpinumisoflavone, wighteone and burttinone were isolated from the stem bark of Erythrina lysistemon Hutch. (Leguminosae). Structures were elucidated by spectroscopic methods.     

Prenylated flavonoids from Moghania philippinensis

Five prenylated flavonoids, 8-(1,1-dimethylallyl)genistein (1), 5,7,3',4'-tetrahydroxy-2',5'-di(3-methylbut-2-enyl)isoflavone (2), 5,7,3'-trihydroxy-2'-(3-methylbut-2-enyl)-4',5'-(3,3-dimethylpyrano)isoflavone (3), (2R)-5,2',4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4a) and (2S)-5, 2', 4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4b), were isolated from the roots of Moghania philippinensis. The structures of these compounds were determined on the basis of spectroscopic and chemical means.     

Two new flavonols,including one flavan dimer,from the roots of Indigofera stachyodes

A new flavan dimer, 2α,3α-epoxyflavan-5,7,3′,4′-tetraol-(4β→8)-flavan-5′′,7′′,4′′′-triol (1), and a new flavonol, 3-O-(3-nitropropanoyl)-2,3-cis-5,7,3′,4′-tetrahydroxyflavan (2), together with a known compound, 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β→8)-epicatechin (3), were isolated from the roots of Indigofera stachyodes. Their structures were elucidated by spectroscopic techniques including MS, 1D NMR, and 2D NMR. Compounds 2 and 3 were evaluated to determine their protective effects against carbon tetrachloride (CCl₄)-induced hepatotoxicity in the human liver cell line HL-7702. The results showed that 2 and 3 could protect HL-7702 cells from injury induced by CCl₄, with cell survival rates of 122.0% and 72.5%, respectively.     

Prenylated flavonoids of Erythrina lysistemon grown in Egypt

Three prenylated flavonoid derivatives; 5,7,4′-trihydroxy-8-(3-methylbut-2-enyl)-6-(2″-hydroxy-3″-methylbut-3″enyl) isoflavone (isoerysenegalensein E), 5,7,2′-trihydroxy-4′-methoxy-5′-(3″-methylbut-2″-enyl) isoflavanone (lysisteisoflavanone), 5, 4′-dihydroxy-6-(3-methylbut-2-enyl)-2″-hydroxyisopropyl dihydrofurano [4″,5″:8,7] isoflavone (isosenegalensin), together with the four known flavonoids abyssinone V-4′-methylether, alpinumisoflavone, wighteone and burttinone were isolated from the stem bark of Erythrina lysistemon Hutch. (Leguminosae). Structures were elucidated by spectroscopic methods.     

Steroidal saponins and homoisoflavanone from the aerial parts of Sansevieria cylindrica Bojer ex Hook.

Phytochemical study on the methanolic extract of Sansevieria cylindrica aerial parts lead to the isolation, characterization and structure elucidation of a new steroidal saponin, 1β-hydroxy-kryptogenin-1-O-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranoside (1), a new homoisoflavanone, (3S)-3,7-dihydroxy-8-methoxy-3-(3′,4′-methylenedioxybenzyl) chroman-4-one (2) and the known saponin alliospiroside A (3). To the best of our knowledge, the genin 1β-hydroxy-kryptogenin is reported here for the first time. The structures of the new compounds were determined by UV, IR, EIMS, HRESIMS together with 1D (¹H and ¹³C) and 2D (HSQC and HMBC) NMR spectral analysis. The isolated compounds 1–3 were tested for their radical scavenging activity (DPPH). Compound 2 exhibited activity compared to that of ascorbic acid as a standard. The cytotoxicity of the isolated compounds and the standard doxorubicin was tested against the three human tumor cell lines HT116, MCF-7 and PC-3. The results showed that the isolated compounds were inactive.     

Benzophenones and xanthones from Garcinia cantleyana var. cantleyana and their inhibitory activities on human low-density lipoprotein oxidation and platelet aggregation

Three benzophenones, 2,6,3′,5′-tetrahydroxybenzophenone (1), 3,4,5,3′,5′-pentahydroxybenzophenone (3) and 3,5,3′,5′-tetrahydroxy-4-methoxybenzophenone (4), as well as a xanthone, 1,3,6-trihydroxy-5-methoxy-7-(3′-methyl-2′-oxo-but-3′-enyl)xanthone (9), were isolated from the twigs of Garcinia cantleyana var. cantleyana. Eight known compounds, 3,4,5,3′-tetrahydroxy benzophenone (2), 1,3,5-trihydroxyxanthone (5), 1,3,8-trihydroxyxanthone (6), 2,4,7-trihydroxyxanthone (7), 1,3,5,7-tetrahydroxyxanthone (8), quercetin, glutin-5-en-3β-ol and friedelin were also isolated. The structures of the compounds were elucidated by spectroscopic methods. The compounds were investigated for their ability to inhibit low-density lipoprotein (LDL) oxidation and platelet aggregation in human whole blood in vitro. Most of the compounds showed strong antioxidant activity with compound 8 showing the highest inhibition with an IC₅₀ value of 0.5 μM, comparable to that of probucol. Among the compounds tested, only compound 4 exhibited strong inhibitory activity against platelet aggregation induced by arachidonic acid (AA), adenosine diphosphate (ADP) and collagen. Compounds 3, 5 and 8 showed selective inhibitory activity on platelet aggregation induced by ADP.     

New metabolites from the alga-derived fungi Penicillium thomii Maire and Penicillium lividum Westling

A new meroterpenoid, austalide H acid ethyl ester (1), 5-(2′,4′-dihydroxy-6′-methylphenyl)-3-methylfuran-2-carboxylic acid (2), 5-(2′-hydroxy-6′-methylphenyl)-3-methylfuran-2-carboxylic acid (3) and 5-((6′-methyl-4′-oxo-3′,4′-dihydro-2H-pyran-2′-yl)methyl)-3-methylfuran-2-carboxylic acid (4), along with six known compounds, austalides H, J, K, and P (5–8), questin (9) and sulochrin (10) were isolated from the lipophilic extract of the alga-derived fungi Penicillium thomii KMM 4645 and Penicillium lividum KMM 4663. The structures of the isolated compounds were determined based on spectroscopic methods. The austalides showed significant inhibitory activity against endo-1,3-β-d-Glucanase from a crystalline stalk of the marine mollusk Pseudocardium sachalinensis.     

Evaluation of natural antioxidants of Leuzea carthamoides as a result of a screening study of 88 plant extracts from the European Asteraceae and Cichoriaceae

In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC₅₀ parameter. 29 extracts exhibited IC₅₀ value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC₅₀ = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4′,5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3′, 4′- tetrahydroxyflavanone (eriodictyol) (2), 3′,4′,5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-β-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6″-O-acetyl-β-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.