Bio-Guided Fractionation of Retama raetam (Forssk.) Webb & Berthel Polar Extracts.

The fractionation of the methanolic extract (MeOH-E) of Retama raetam (Forssk.) Webb & Berthel and further analysis by thin layer chromatography resulted in four fractions (F1, F2, F3 and F4) that, in parallel with the MeOH-E, were screened for antioxidant, cytotoxic, antidiabetic and antibacterial properties. In addition, chemical characterization of their bioactive molecules was performed using LC-DAD-ESI/MSn. The results indicated that F3 was the most promising regarding antioxidant and cytotoxicity abilities, possibly due to its richness in flavonoids class, particularly isoflavones. In turn, F1 was characterized by the presence of the most polar compounds from MeOH-E (organic acids and piscidic acid) and showed promising abilities to inhibit α-amylase, while F4, which contained prenylated flavonoids and furanoflavonoids, was the most active against the tested bacteria. The gathered results emphasize the distinct biological potentials of purified fractions of Retama raetam.

Phenolic Extract from Aralia nudicaulis L. Rhizomes Inhibits Cellular Oxidative Stresses.

UV-B and IR-A radiation are important inducers of biological changes in skin involving ROS generation. The overloading of antioxidant defense mechanisms by ROS production could lead to photoaging and photocarcinogenesis processes. Various traditional usages are reported for Aralia nudicaulis L. extracts, including treatment of dermatological disorders. Antioxidant and anti-inflammatory properties have already been reported for other Aralia species possibly due to the presence of phenolic compounds. However, the phenolic composition and the potential activity of A. nudicaulis rhizomes extract against oxidative stress and UV/IR damages have not been investigated. The main aims of this study were to prepare a fraction enriched in phenolic compounds (FEPC) from A. nudicaulis rhizomes, to identify its major phenolic compounds and to assess its potential for protective effects against oxidative stress induced by UV-B, IR-A or inflammation. A quantitative LC-MS study of FEPC shows that chlorogenic, caffeic and protocatechuic acids are the main phenolic compounds present, with concentrations of 15.6%, 15.3% and 4.8% of the total composition, respectively. With a validated analytical method, those compounds were quantified over different stages of the growing period. As for biological potential, first this extract demonstrates antioxidant and anti-inflammatory activities. Furthermore, ROS generation induced by IR-A and UV-B were strongly inhibited by A. nudicaulis extract, suggesting that Aralia nudicaulis L. rhizome extract could protect dermal cells against oxidative stress induced by UV-B and IR-A.

The genus Daphne: A review of its traditional uses, phytochemistry and pharmacology.

The genus Daphne belongs to the Thymeleaceae family and contains over 90 species that are distributed in Asia, Europe and parts of North Africa. The species of the genus Daphne are used in the traditional medicine of China, Tibet, Korea, and the Middle East for the treatment of various conditions. A broad range of studies has shown the significant biological potential of these species as sources of biologically and pharmacologically active compounds. Daphne species are a source of several classes of valuable phytochemicals such as coumarins, flavonoids, lignans, steroids and different classes of terpenes. The phytochemical diversity of this genus is demonstrated by over 350 secondary metabolites isolated from various species. The genus possesses a broad spectrum of biological activities including antibacterial, antifungal, antioxidant, analgesic, anti-inflammatory, cytotoxic, antiviral, abortive and haemostatic effects. A variety of bioactive secondary metabolites found in this genus may have potential use in pharmaceutical, cosmetic and food industries. Thus, species belonging to the genus Daphne can be considered an important source both for the treatment of various disorders, due to the presence of a plethora of bioactive constituents with potent bioactivities, and as possible leads in the discovery and synthesis of new medications.

Chemical composition and anti-herpes simplex virus type 1 (HSV-1) activity of extracts from Cornus canadensis.

BACKGROUND: Many plants of boreal forest of Quebec have been used by Native Americans to treat a variety of microbial infections. However, the antiviral activities of these plants have been seldom evaluated on cellular models to validate their in vitro efficiencies. In this study, Cornus canadensis L. (Cornaceae), a plant used in Native American traditional medicine to treat possible antiviral infections, has been selected for further examination. METHODS: The plant was extracted by decoction and infusion with water, water/ethanol 1:1 and ethanol to obtain extracts similar to those used by Native Americans. The effects of the extracts were tested on herpes simplex virus type-1 (HSV-1) using a plaque reduction assay. Moreover, bioassay-guided fractionation was achieved to isolate bioactive compounds. RESULTS: Water/ethanol 1:1 infusion of C. canadensis leaves were the most active extracts to inhibit virus absorption with EC50 of about 9 µg mL-1, whereas for direct mode, both extraction methods using water or water/ethanol 1:1 as solvent were relatively similar with EC50 ranging from 11 to 17 µg mL-1. The fractionation led to the identification of active fractions containing hydrolysable tannins. Tellimagrandin I was found the most active compound with an EC50 of 2.6 µM for the direct mode and 5.0 µM for the absorption mode. CONCLUSION: Altogether, the results presented in this work support the antiviral activity of Cornus canadensis used in Native American traditional medicine.

Structure elucidation of anti-methicillin resistant Staphylococcus aureus (MRSA) flavonoids from balsam poplar buds.

There is nowadays an urgent need for developing novel generations of antibiotic agents due to the increased resistance of pathogenic bacteria. As a rich reservoir of structurally diverse compounds, plant species hold promise in this regard. Within this framework, we isolated a unique series of antibacterial flavonoids, named balsacones N-U, featuring multiple cinnamyl chains on the flavan skeleton. The structures of these compounds, isolated as racemates, were determined using extensive 1D and 2D NMR analysis in tandem with HRMS. Balsacones N-U along with previously isolated balsacones A-M were evaluated for their antibacterial activity against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA). Several of the tested balsacones were potent anti-MRSA agents showing MIC values in the low micromolar range. Structure-activity relationships study highlighted some important parameters involved in the antibacterial activity of balsacones such as the presence of cinnamyl and cinnamoyl chains at the C-3 and C-8 positions of the flavan skeleton, respectively. These results suggest that balsacones could represent a potential novel class of naturally occurring anti-MRSA agents.

DFT Calculations and ROESY NMR Data for the Diastereochemical Characterization of Cytotoxic Tetraterpenoids from the Oleoresin of Abies balsamea.

Eight non-carotenoid tetraterpenoids, abibalsamins C-J (3-10), were isolated from the oleoresin of Abies balsamea. Their chemical structures were determined based on analysis of 1D/2D NMR and MS data. The assignment of their relative configurations was accomplished using homonuclear coupling constants in tandem with ROESY data. However, the presence of two stereogenic centers on a flexible side chain complicated the characterization. In silico models and ROESY data were analyzed in order to assign relative configurations of the isolated tetraterpenoids. Abibalsamins B and H-J showed moderate cytotoxicity against human A549 lung carcinoma cells, with IC50 values ranging between 6.7 and 10 µM.

Dirchromones: Cytotoxic Organic Sulfur Compounds Isolated from Dirca palustris.

Eight novel organic sulfur compounds featuring an unprecedented structure among natural organosulfur molecules are reported. The identified compounds, named dirchromones (1-8), were isolated from a dichloromethane extract of the roots, bark, and wood of Dirca palustris, an endemic shrub of eastern North America. Their identification was based on thorough NMR, IR, and HRMS spectroscopic data interpretation. These compounds showed cytotoxic and mild Gram-positive antibacterial activities in vitro, while being inactive against Gram-negative Escherichia coli and the yeast Candida albicans. This is the first report of sulfur-containing compounds from a species of the Thymelaeaceae.

Antibacterial Balsacones J-M, Hydroxycinnamoylated Dihydrochalcones from Populus balsamifera Buds.

A phytochemical investigation of buds from the hardwood tree Populus balsamifera led to the isolation of six new cinnamoylated dihydrochalcones as pairs of racemates and one as a racemic mixture along with the known compound iryantherin-D (2), the absolute configuration of which was determined for the first time. The structures of balsacones J (1), K (3), L (4), and M (5) were elucidated on the basis of spectroscopic data (1D and 2D NMR, IR, and MS). Chiral HPLC separations were carried out, and the absolute configuration of the isolated enantiomers unambiguously established via X-ray diffraction analyses and electron circular dichroism spectroscopic data. Each of the purified enantiomers exhibited potent in vitro antibacterial activity against Staphylococcus aureus with IC50 values ranging from 0.61 to 6 µM.

Isolation of a new disaccharide nucleoside from Helleborus caucasicus: structure elucidation and total synthesis of hellecaucaside A and its ß-anomer.

Hellecaucaside A, a new disaccharide nucleoside featuring a 2'-O-α-D-ribofuranosyluridine skeleton and a 4-hydroxybenzoyl group at the 5' position, was isolated from the underground part of Helleborus caucasicus. The structure of the compound was elucidated by means of chemical degradation and spectroscopic analyses, such as 1D/2D NMR, chiral-GC, and HRMS. The total synthesis of hellecaucaside A and its ß-anomer was accomplished, unequivocally confirming the structure of the natural product.

A new flavonol glycoside from the medicinal halophyte Suaeda fruticosa.

A new flavonol glycoside, namely 3-(α-rhamnopyranosyl-(1 → 2)-[ß-xylopyranosyl-(1 → 6)]-ß-glucopyranosyloxy) isorhamnetin was reported from methanol extracts of aerial parts of Suaeda fruticosa for the first time. In this work, liquid chromatography coupled to atmospheric pressure chemical ionisation mass spectrometry, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy were used to identify this new compound. Structure was elucidated on the basis of extensive spectroscopic analysis, including HSQC, HMBC and (1)H-(1)H COSY. Antioxidant potentialities of a pure compound were evaluated. The estimation of antioxidant capacities using oxygen radical absorbance capacity (ORAC method) and a cell based-assay (WS1) indicated that this new flavonol exhibited the highest antioxidant activities with an ORAC value of 5.0 ± 0.3 µmol Trolox/µmol and inhibited the tBH-induced oxidation of 2',7'-dichlorofluorescin with an IC50 value of 4.9 ± 0.6 µM.

Lanostane- and cycloartane-type triterpenoids from Abies balsamea oleoresin.

Phytochemical analysis of A. balsamea oleoresin led to the isolation of three new 3,4-seco-lanostane triterpenoids 1-3, one new cycloartane triterpenoid 4 along with fourteen known terpenoids. Structure determinations were based on extensive 1D/2D NMR, IR and MS spectroscopic analyses, and comparison with literature data. The isolated compounds were evaluated in vitro for their cytotoxicity against human cell lines (A549, DLD-1, WS1) and their antibacterial activity against E. coli and S. aureus. Abiesonic acid (6) exhibited weak cytotoxic activity against A549 (IC50 = 22 µM) while compounds 1 and 4 were weakly active against S. aureus (MIC = 25 µM).

Abibalsamins A and B, two new tetraterpenoids from Abies balsamea oleoresin.

Abibalsamins A (1) and B (2), two unprecedented tetraterpenoids featuring a 3,4-seco-rearranged lanostane system fused with a ß-myrcene lateral chain via a [4 + 2] Diels-Alder cycloaddition, were isolated from the oleoresin of Abies balsamea. Their structures were elucidated by means of extensive 2D NMR, IR, and MS spectroscopy analyses. The absolute configuration of 1 was determined by single-crystal X-ray diffraction. Both compounds exhibited significant cytotoxic activity against cancer cell lines.

Antioxidant and anti-inflammatory activities of quercetin 7-O-ß-D-glucopyranoside from the leaves of Brasenia schreberi.

Brasenia schreberi Gmel. (Cabombaceae) is an aquatic plant that grows in eastern Asia, Australia, Africa, and North and Central America. B. schreberi leaf extracts were obtained by sequential solvent extraction with dichloromethane, methanol, and water. The antioxidant potential of each extract was assessed by using the oxygen radical absorbance capacity (ORAC) assay. With this method, methanol and water extracts were found to be active with mean ± standard deviation values of 7 ± 2 and 5.1 ± 0.5 µmol Trolox® equivalents (TE)/mg, respectively. Two major phenolic compounds, quercetin-7-O-ß-D-glucopyranoside and gallic acid, were respectively isolated from the methanolic and water extracts. Both compounds exhibited antioxidant activities, in particular quercetin-7-O-ß-D-glucopyranoside (ORAC value, 18 ± 4 µmol TE/µmol). In contrast to its well-known antioxidant homologue quercetin, quercetin-7-O-ß-D-glucopyranoside does not inhibit growth of human fibroblasts (WS-1) or murine macrophages (RAW 264.7). Some flavonoids have been reported to possess beneficial effects in cardiovascular and chronic inflammatory diseases associated with overproduction of nitric oxide. Quercetin-7-O-ß-D-glucopyranoside possesses anti-inflammatory activity, inhibiting expression of inducible nitric oxide synthase and release of nitric oxide by lipopolysaccharide-stimulated RAW 264.7 macrophages in a dose-dependent manner. Quercetin-7-O-ß-D-glucopyranoside also inhibited overexpression of cyclooxygenase-2 and granulocyte macrophage-colony-stimulating factor.

Cytotoxic activity of withanolides isolated from Tunisian Datura metel L.

Withanolide-type steroids, withametelin Q (1) and 12α-hydroxydaturametelin B (2) along with three known withanolides, were isolated from leaves of Datura metel L. (Solanaceae). The respective structures, characterized mainly by NMR spectroscopy, were identified as (20R,22R,24R)-21,24-epoxy-1α,3ß-dihydroxywitha-5,25(27)-dienolide-3-O-ß-D-glucopyranoside (1) and (20R,22R,24R)-12α,21,27-trihydroxy-1-oxowitha-2,5,24-trienolide-27-O-ß-D-glucopyranoside (2). The cytotoxicity of isolated compounds was evaluated against human lung carcinoma cells (A549) and human colorectal adenocarcinoma cells (DLD-1), respectively. Compound 2 exhibited cytotoxicity against A549 and DLD-1 cell lines, with IC50 values of 7 and 2.0 µM, respectively. However, for compounds 6 and 7, cytotoxicities were higher against DLD-1 cells with IC(50) values of 0.6 and 0.7 µM. Both compounds blocked the cell cycle in the S-phase and induced apoptosis.

New triterpenoid saponins from Leontice smirnowii.

Three new triterpene saponins, leonticins I (1), J (2) and L (3) were isolated from the tubers of Leontice smirnowii. On the basis of spectroscopic methods, including 2D NMR experiments (DEPT, gs-COSY, gs-HMQC, gs-HMBC and gs-HSQC-TOCSY), mass spectrometry (HR-ESI-MS) and chemical degradation, the structures of the new compounds were elucidated as 3-O-ß-D-glucopyranosyl-(1 → 3)-[ß-D-xylopyranosyl-1 → 2)]-α-L-arabinopyranosyl-28-O-[α-L-rhamnopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 6)-ß-D-glucopyranosyl]-3ß-hydroxy-30-norolean-12,20(29)-dien-28-oic acid (1), 3-O-[ß-D-xylopyranosyl-(1 → 3)-ß-D-galactopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranosyl]-28-O-[α-L-rhamnopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 6)-ß-D-glucopyranosyl]-3ß-hydroxy-30-norolean-12,20(29)-dien-28-oic acid (2) and 3-O-[ß-D-xylopyranosyl-(1 → 3)-ß-D-galactopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)]-[ß-D-xylopyranosyl-(1 → 2)]-α-L-arabinopyranosyl]-28-O-[α-L-rhamnopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 6)-ß-D-glucopyranosyl]-3ß-hydroxy-30-norolean-12,20(29)-dien-28-oic acid (3), respectively. The aglycone 3ß-hydroxy-30-norolean-12,20(29)-dien-28-oic acid was observed for the first time in Leontice species.

Haemolytic activity, cytotoxicity and membrane cell permeabilization of semi-synthetic and natural lupane- and oleanane-type saponins.

The haemolysis of red blood cells inducing toxicity in most animals including humans is a major drawback for the clinical development of saponins as antitumour agents. In this study, the haemolytic and cytotoxic activities as well as the membrane cell permeabilization property of a library of 31 semi-synthetic and natural lupane- and oleanane-type saponins were evaluated and the structure-activity relationships were established. It was shown that lupane-type saponins do not exhibit any haemolytic activity and membrane cell permeabilization property at the maximum concentration tested (100 microM) independently of the nature of the sugar moieties. While oleanane-type saponins such as beta-hederin (25) and hederacolchiside A(1) (27) cause the death of cancer cell lines by permeabilizing the cellular membranes, lupane-type saponins seem to proceed via another mechanism, which could be related to the induction of apoptosis. Altogether, the results indicate that the cytotoxic lupane-type glycosides 10 and 22 bearing an alpha-l-rhamnopyranose moiety at the C-3 position represent promising antitumour agents for further studies on tumour-bearing mice since they are devoid of toxicity associated with the haemolysis of red blood cells.

Cytotoxic steroidal saponins from the flowers of Allium leucanthum.

Allium leucanthum C. Koch is an endemic Caucasian species that grows in Georgia. The flowers are used in traditional medicine. Phytochemical investigation allowed the isolation of seven spirostanol type saponins from the flowers. Their structures were elucidated on the base of NMR and HRESIMS spectrometry data. A new compound, which we have named leucospiroside A (5), has been identified as (25R)-5alpha-spirostane-2alpha,3beta,6beta-triol 3-O-beta-glucopyranosyl-(1-->3)-beta-glucopyranosyl-(1-->2)-[beta-glucopyranosyl-(1-->3)]-beta-glucopyranosyl-(1-->4)-beta-galactopyranoside. The six others were known substances, but are described in this plant for the first time. The crude extract, spirostanol and furostanol fractions, as well as isolated compounds, were evaluated for their in vitro cytotoxic activity. Compounds 1-3 and 5 were found to be the most active, with relatively similar IC50 values ranging from 3.7 to 5.8 microM for a lung cancer cell line (A549) and 5.6 to 8.2 microM for a colon cancer cell line (DLD-1).

Isolation and identification of cytotoxic compounds from the wood of Pinus resinosa.

Methanol extracts of wood from Pinus resinosa were found to be selectively cytotoxic against human lung carcinoma cells, A549 (IC50 41 +/- 6 microg/mL), human colorectal adenocarcinoma cells, DLD-1 (IC50 47 +/- 4 microg/mL) in comparison with healthy cells, WS1 (IC50 130 +/- 11 microg/mL). Five known compounds were isolated and identified by 1H, 13C NMRspectroscopy and HR-ESI-MS mass spectrometry as, pinosylvin monomethyl ether (1), pinosylvin (2), pinosylvin dimethyl ether (3), pinobanksin (4) and (-)-norachelogenin (5). Compound 4 was isolated for the first time in P. resinosa. The cytotoxicity of compounds 1-5 was evaluated against A549, DLD-1 and WS1. Compound 1 exhibited the strongest cytotoxicity against both tumor cell lines and the healthy cell line with an IC50 of 25 +/- 4 microm for A549, 20 +/- 1 microm for DLD-1 and 34 +/- 3 microm for WS1.

Anticancer diarylheptanoid glycosides from the inner bark of Betula papyrifera.

Phytochemical investigations of the MeOH extract of Betula papyrifera inner bark led to the isolation of ten phenolic compounds of the following types: diarylheptanoid glycosides (1-4), a diarylheptanoid (5), a lignan (6), flavonoids (7-8) and chavicol glycosides (9-10). Among them, the diarylheptanoid glycoside, (S)-1,7-bis-(4-hydroxyphenyl)-heptan-3-one-5-O-alpha-L-arabinofuranosyl-(1-->6)-beta-D-glucopyranoside, papyriferoside A (1), was isolated and its structure was determined on the basis of 1D and 2D NMR, HPLC-MS, as well as high resolution mass spectroscopic data. Platyphylloside (4) exerted the strongest cytotoxic activity of all isolated compounds with IC(50) values ranging from 10.3 to 13.8 microM.

Antioxidant, anti-inflammatory and anticancer activities of methanolic extracts from Ledum groenlandicum Retzius.

Labrador tea (Ledum groenlandicum Retzius) is an ericaceae widely distributed in North America. The leaves and twigs were used in Native American traditional medicine to treat several inflammatory pathologies such as asthma, rheumatisms and burns. Reactive oxygen species as well as reactive nitrogen species such as nitric oxide (NO) contribute significantly to these pathologies. In this study, the antioxidant, anti-inflammatory and anticancer activities of crude methanol extracts of leaves and twigs from Ledum groenlandicum were investigated. Both extracts showed a strong antioxidant activity using the ORAC method and a cell based-assay. Moreover, the twig and leaf extracts showed significant anti-inflammatory activity, inhibiting NO release, respectively, by 28 and 17% at 25 microg/ml in LPS-stimulated RAW 264.7 macrophages. In comparison, N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, reduced NO release by 24% at 25 microg/ml. The twig extract was also found to be active against DLD-1 colon carcinoma and A-549 lung carcinoma cells, with IC(50) values of 43+/-1 and 65+/-8 microg/ml, respectively. The bioguided study of the twig extract resulted in the isolation and identification of ursolic acid, a known triterpene. Ursolic acid was active against DLD-1 (IC(50): 9.3+/-0.3 microM) and A-549 (IC(50): 8.9+/-0.2 microM), suggesting it is, in part, responsible of the anticancer activity of the twig extract.