Bioactive metabolites from the leaves of Withania adpressa

CONTEXT

Withania (Solanaceae) species are known to be a rich source of withanolides, which have shown several biological properties.

OBJECTIVE

To identify the compounds responsible for Withania adpressa Coss. antioxidant activity and further test them for their NF-κB inhibition and antiproliferative activity in multiple myeloma cells.

MATERIALS AND METHODS

Compounds were obtained from the EtOAc extract of W. adpressa leaves. Structure elucidation was carried out mainly by 1D- and 2D-NMR, and mass spectrometry. Isolated compounds were tested in a dose-response for their in vitro NF-κB inhibition and antiproliferative activity in multiple myeloma cells after 5 and 72 h treatment, respectively.

RESULTS

The fractionation resulted in the isolation of a new glycowithanolide named wadpressine (5) together with withanolide F, withaferin A, coagulin L, and nicotiflorin. The latter showed a moderate ability to scavenge free radicals in DPPH (IC50 = 35.3 µM) and NO (IC50 = 41.3 µM) assays. Withanolide F and withaferin A exhibited low µM antiproliferative activity against both multiple myeloma cancer stem cells and RPMI 8226 cells. Furthermore, they inhibited NF-κB activity with IC50 values of 1.2 and 0.047 µM, respectively. The other compounds showed a moderate inhibition of cell proliferation in RPMI 8226 cells, but were inactive against cancer stem cells and did not inhibit NF-κB activity.

DISCUSSION AND CONCLUSIONS

One new glycowithanolide and four known compounds were isolated. Biological evaluation data gave further insight on the antitumor potential of withanolides for refractory cancers.

Chemical characterization and insecticidal properties of essential oils from different wild populations of Mentha suaveolens subsp. timija (Briq.) Harley from Morocco

The present study is the first investigation of the volatile-oil variability and insecticidal properties of the endemic Moroccan mint Mentha suaveolens subsp. timija (mint timija). The yield of essential oils (EOs) obtained from different wild mint timija populations ranged from 0.20±0.02 to 1.17±0.25% (v/w). GC/MS Analysis revealed the presence of 44 oil constituents, comprising 97.3-99.9% of the total oil compositions. The main constituents were found to be menthone (1.2-62.6%), pulegone (0.8-26.6%), cis-piperitone epoxide (2.9-25.5%), piperitone (0.3-35.5%), trans-piperitone epoxide (8.1-15.7%), piperitenone (0.2-9.6%), piperitenone oxide (0.5-28.6%), (E)-caryophyllene (1.5-11.0%), germacrene D (1.0-15.7%), isomenthone (0.3-7.7%), and borneol (0.2-7.3%). Hierarchical-cluster analysis allowed the classification of the EOs of the different mint timija populations into four main groups according to the contents of their major components. This variability within the species showed to be linked to the altitude variation of the mint timija growing sites. The results of the insecticidal tests showed that all samples exhibited interesting activity against adults of Tribolium castaneum, but with different degrees. The highest toxicity was observed for the EOs belonging to Group IV, which were rich in menthone and pulegone, with LC50 and LC90 values of 19.0-23.4 and 54.9-58.0 μl/l air in the fumigation assay and LC50 and LC90 values of 0.17-0.18 and 0.40-0.52 μl/cm(2) in the contact assay.

Comparative evaluation of antioxidant and insecticidal properties of essential oils from five Moroccan aromatic herbs

This study describes the antioxidant and insecticidal activities of essential oils (EOs) of Mentha suaveolens subsp. timija, Thymus satureioides, Achillea ageratum, Cotula cinerea and Salvia officinalis widely used in Morocco as flavorings, food additives and preservatives. Sixty seven components were identified accounting for more than 95.0 % of the total oils. M. suaveolens subsp. timija oil had as main components menthone and pulegone. A. ageratum oil was particularly rich in artemisyl acetate and yomogi alcohol. The essential oil of T. satureioides was characterized by high contents of carvacrol and borneol. C. cinerea oil contained trans-thujone and cis-verbenyl acetate as major constituents, whereas S. officinalis oil was characterized by trans-thujone and camphor. Antioxidant activities were examined by means of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), reducing power, β-carotene/linoleic acid bleaching and ABTS radical tests. In all assays, the highest antioxidant potency was observed in T. satureioides EO with IC50 values ranging from 0.15 ± 0.36 μg mL(-1) to 0.23 ± 0.67 μg mL(-1) across the four assays. The in vitro evaluation of the insecticidal activity showed that M. suaveolens subsp. timija EO present the highest insecticidal efficiency against adults of Tribolium castaneum with LD50 and LD90 values of 0.17 μL cm(-2) and 0.26 μL cm(-2), respectively and LT50, LT90 values ranged from 44.19 h to 2.98 h and 98.14 h to 6.02 h, respectively. Our data support the possible use of T. satureioides oil as potential antioxidant agent, while M. suaveolens subsp. timija oil can be developed as a new natural bio-insecticide.

Cytotoxic withanolides from the leaves of Moroccan Withania frutescens

CONTEXT

Withania species are a rich source of interesting phytochemical substances (withanolides) which have shown several biological properties.

OBJECTIVE

To investigate the cytotoxic potential of Withania frutescens (L.) Pauquy (Solanaceae) leaf extracts and isolated active compounds against cultured tumor cell lines.

MATERIALS AND METHODS

The crude methanol extract of W. frutescens leaves was partitioned with dichloromethane, ethyl acetate and n-butanol. MeOH extract and its fractions were tested for their cytotoxic activity against cancer cell lines (HepG2 and HT29) using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Bioassay-guided fractionation was performed for the active CH₂Cl₂ fraction employing column chromatography and preparative high-performance liquid chromatography. Structural elucidation of the isolated active compounds was carried out mainly by 1D and 2D NMR and mass spectrometry. The compounds were then tested for their cytotoxic activity.

RESULTS

The CH₂Cl₂ fraction was the most active against HT29 cell line. The fractionation procedure resulted in the isolation of 4β,17α,27-trihydroxy-1-oxo-22-R-witha-2,5,24-trienolide (1), 5β,6β-epoxy-4β,17α,27-trihydroxy-1-oxowitha-2,24-dienolide (2) and 2,3-dihydroxywithaferin A-3β-O-sulfate (3). The latter exhibited the strongest cytotoxic activity against HT29 cancer cell lines (IC₅₀ of 1.78 ± 0.09 µM) which was comparable to that of 5-fluorouracil (5-FU) used as the positive antimitotic control.

DISCUSSION AND CONCLUSION

Compounds 2 and 3 were isolated from W. frutescens for the first time. Data obtained suggest that the sulfated steroidal lactone (3) can be considered as a compound with potential application in the new anticancer drugs development field.

Essential oil composition and antimicrobial activity of wild and cultivated mint timija (Mentha suaveolens subsp. timija (Briq.) Harley), an endemic and threatened medicinal species in Morocco

The hydro-distilled essential oils obtained from aerial parts of the wild (w) and cultivated (c) mint timija (Mentha suaveolens subsp. timija), an endemic medicinal species of Morocco, have been analyzed by GC-MS and screened for antimicrobial activity. In total, 35 compounds representing more than 98% of the oils were identified. Menthone (39.4(w)-10.8(c)%), pulegone (62.3(c)-34.3(w)%) and isomenthone (9.3(c)-7.8(w)%) were found as the main components for the two oils. The volatiles of the wild and cultivated material differed significantly in both the percentage of the main components and antimicrobial effect. Pulegone was more dominant in cultivated mint timija (62.3%) than in wild one (34.3%), while menthone was more abundant in the wild material (39.4%). In the antimicrobial assays, both oils displayed good to excellent activity against all microorganisms tested with the oil of the cultivated form being more active.

Essential oil composition and antimicrobial activity of wild and cultivated Moroccan Achillea ageratum L.: a rare and threatened medicinal species

The essential oils of leaves and flowers of the wild and cultivated Moroccan Achillea ageratum L., a rare and threatened medicinal species, were examined by GC/MS, and their chemical compositions were compared. At least nine components were identified in both wild and cultivated A. ageratum oils, representing more than 95% of the oils. Artemisyl acetate (62.34-78.79%), yomogi alcohol (4.89-12.40%), santolina alcohol (4.86-11.77%), and artemisia alcohol (3.36-7.04%) were the major compounds. Terpene-alcohol proportion was higher in wild A. ageratum than in cultivated A. ageratum. The antibacterial analysis showed that both oils presented high activity against all the studied Gram-positive strains in a range of MIC values from 2.55 to 7.02 mg/ml, but they appeared not effective against the tested Gram-negative ones (MIC values 20.40-41.10 mg/ml). They also exhibited remarkable antifungal activities against Candida species with MIC values ranging from 5.83 to 8.42 mg/ml. From these results, it was concluded that domestication of this threatened medicinal species using clonal propagation did not significantly affect its chemical composition and consequently its antimicrobial properties.

Chemical composition and anticandidal properties of the essential oil isolated from aerial parts of Cotula cinerea: a rare and threatened medicinal plant in Morocco

The chemical composition and anticandidal properties of the essential oil of Moroccan Cotula cinerea aerial parts have been examined. GC-MS data were used to identify 24 constituents. Oxygenated monoterpenes constituted the main fraction with trans-thujone (41.4%), cis-verbenyl acetate (24.7%), 1,8-cineole (8.2%) and camphor (5.5%) as the major components. The anticandidal activity of the essential oil was evaluated using a panel of human pathogenic fungi (Candida albicans CCMM L4 and CCMM L5, C. krusei CCMM L10, C. glabrata CCMM L7 and C. parapsilosis CCMM L18). The oil showed high anticandidal activity against all investigated strains with minimal inhibitory concentrations of 3.2 to 4.7 mg/mL depending on the tested yeast and 5.9 mg/mL as a minimal candidicidal concentration value. These findings add significant information to the pharmacological activity of Cotula cinerea essential oil, which may present a good alternative to antibiotics for the treatment of resistant strains of Candida.

Chemical Composition and Anticandidal Properties of the Essential Oil Isolated from Aerial parts of Cotula cinerea: A Rare and Threatened Medicinal Plant in Morocco

The chemical composition and anticandidal properties of the essential oil of Moroccan Cotula cinerea aerial parts have been examined. GC-MS data were used to identify 24 constituents. Oxygenated monoterpenes constituted the main fraction with trans-thujone (41.4%), cis-verbenyl acetate (24.7%), 1,8-cineole (8.2%) and camphor (5.5%) as the major components. The anticandidal activity of the essential oil was evaluated using a panel of human pathogenic fungi (Candida albicans CCMM L4 and CCMM L5, C. krusei CCMM L10, C. glabrata CCMM L7 and C. parapsilosis CCMM L18). The oil showed high anticandidal activity against all investigated strains with minimal inhibitory concentrations of 3.2 to 4.7 mg/mL depending on the tested yeast and 5.9 mg/mL as a minimal candidicidal concentration value. These findings add significant information to the pharmacological activity of Cotula cinerea essential oil, which may present a good alternative to antibiotics for the treatment of resistant strains of Candida.

Antioxidant and antimicrobial activities of Withania frutescens

In the present study, we report for the first time the antioxidant and antimicrobial activities of Withania frutescens (L.) Pauquy roots and leaves. Total phenolic content was determined using the Folin-Ciocalteu method and antioxidant activity was evaluated by the DPPH free radical scavenging and reducing power methods. Antimicrobial activity tests were carried out against ten bacterial species involved in nosocomial infections and two opportunistic clinical yeast isolates. The ethyl acetate and n-butanol leaf fractions exhibited the highest DPPH radical scavenging activity with IC50 = 4.53 +/- 0.12 and 8.49 +/- 0.46 microg/mL, respectively. The n-butanol root fraction showed the greatest reducing power comparable with that of quercetin at 0.4 mg/mL. The dichloromethane leaf fraction exhibited the highest antibacterial activity against both Gram-positive and Gram-negative bacteria with MIC values ranging between 50 and 400 microg/mL, depending on the tested bacteria. However, none of the examined extracts exhibited anticandidal activity. The polyphenol and glycowithanolide constituents appeared to be responsible for the antioxidant capacity of W. frutescens, whereas the observed antimicrobial activity may be due to the presence of withanolides.

Antioxidant and Antimicrobial Activities of Withania frutescens

In the present study, we report for the first time the antioxidant and antimicrobial activities of Withania frutescens (L.) Pauquy roots and leaves. Total phenolic content was determined using the Folin-Ciocalteu method and antioxidant activity was evaluated by the DPPH free radical scavenging and reducing power methods. Antimicrobial activity tests were carried out against ten bacterial species involved in nosocomial infections and two opportunistic clinical yeast isolates. The ethyl acetate and n-butanol leaf fractions exhibited the highest DPPH radical scavenging activity with IC50 = 4.53 ± 0.12 and 8.49 ± 0.46 μg/mL, respectively. The n-butanol root fraction showed the greatest reducing power comparable with that of quercetin at 0.4 mg/mL. The dichloromethane leaf fraction exhibited the highest antibacterial activity against both Gram-positive and Gram-negative bacteria with MIC values ranging between 50 and 400 μg/mL, depending on the tested bacteria. However, none of the examined extracts exhibited anticandidal activity. The polyphenol and glycowithanolide constituents appeared to be responsible for the antioxidant capacity of W. frutescens, whereas the observed antimicrobial activity may be due to the presence of withanolides.

The antipyretic activity of some Moroccan medicinal plants

The antipyretic activity of different extracts from Calotropis procera, Cotula cinerea and Zygophyllum gaetulum was investigated experimentally in rats. The antipyretic effect was retained in all extracts tested and was comparable to that of acetylsalicylic acid used as the standard drug.

Calystegine distribution in some solanaceous species

The distribution of eight calystegines (A(3), A(5), B(1), B(2), B(3), B(4), C(1) and N(1)) and their content was investigated by gas chromatography coupled to mass spectrometry (GC-MS) in Datura metel, Atropa belladonna, Hyoscyamus albus, Mandragora autumnalis, Solanum sodomaeum, Withania somnifera, Withania frutescens and Brunfelsia nitida. The most frequently encountered calystegines were A(3), B(1), B(2) and B(3), while distribution of N(1) and C(1) was more limited. In all the investigated samples, calystegines A(5) and B(4) were never detected. This report focuses for the first time on calystegines in Withania and Brunfelsia genera and in Mandragora autumnalis and Solanum sodomaeum species.

Non-aqueous capillary electrophoresis with diode array and electrospray mass spectrometric detection for the analysis of selected steroidal alkaloids in plant extracts

Nonaqueous capillary electrophoresis coupled to UV detection is described for the separation and determination of steroidal alkaloids. After optimization of electrophoretic parameters, including the electrolyte nature and the organic solvent composition, a reliable separation of solasodine and solanidine was achieved in a methanol-acetonitrile (20:80, v/v) mixture containing 25 mM ammonium acetate and 1 M acetic acid. For quantitative purposes, a fused-silica capillary with a bubble cell was used and detection was performed at low wavelength (195 nm). Method performances, including migration time and peak area reproducibility, linearity, sensitivity and accuracy, were also evaluated. The method was applied to determine solasodine in Solanum elaeagnifolium berries and Solanum sodomaeum leaves and seeds. To further improve sensitivity in the analysis of solasodine-related compounds, solanidine, demissidine and tomatidine, the developed method was interfaced with electrospray ionization mass spectrometry. In the case of solasodine, the detection limit was estimated at 3 microg/ml for NACE-UV and at 0.05 microg/ml for NACE-MS, in the selected ion-monitoring mode.

Antibacterial activity of some Moroccan medicinal plants

The extracts of 12 plants selected on the basis of the folk-medicine reports were examined for their antibacterial effects against eight pathogenic bacteria. The n-butanol extract of Calotropis procera flowers and the aqueous extract of Eugenia caryophyllata proved to be the most effective against the bacteria tested.

Use of borate complexation for the separation of non-UV-absorbing calystegines by capillary electrophoresis

A capillary zone electrophoresis method was developed for the simultaneous analysis of seven closely related polyhydroxyalkaloids called calystegines. Successful results were obtained with a fused-silica capillary, 80 mM sodium tetraborate at pH 9.2 and temperature of 50 degrees C. Detection of non-UV-absorbing calystegines was achieved through in-situ complexation with borate ions. To further improve method sensitivity, a capillary with a bubble cell was used and detection performed at low wavelength (191 nm). Effects of buffer concentration, pH and temperature on migration times and efficiency are discussed. Migration behavior of selected compounds was significantly affected by their chemical structure (i.e., number and position of hydroxy groups). Under optimized conditions, baseline separation of the selected compounds was achieved in less than 12 min. Precision was evaluated by measuring repeatability and intermediate precision of migration times and corrected peak areas. Finally, the method was applied to the qualitative analysis of calystegines in plant extracts and results were confirmed by GC-MS.

Evaluation of some Moroccan medicinal plant extracts for larvicidal activity

The larvicidal properties of 16 extracts of four Moroccan medicinal plants: Calotropis procera (Wild.), Cotula cinerea (L.), Solanum sodomaeum (L.) and Solanum elaeagnifolium (CAV.) were tested against Anopheles labranchiae mosquito larvae. Among the extracts tested, nine exhibited high larvicidal activity with LC(50) (24 h) ranging from 28 to 325 ppm.

Molluscicidal properties of glycoalkaloid extracts from Moroccan solanum species

The glycoalkaloid extracts of seeds and leaves of Solanum sodomaeum and berries of Solanum elaeagnifolium were shown to have molluscicidal activity against Bulinus truncatus.

Preliminary screening of antiprotozoal activity of extracts from Cotula cinerea L

Ethyl ether, ethyl acetate and n.butanol extracts of Cotula cinerea L. were tested for their antiprotozoal activity against two species of Trichomonas: Trichomonas intestinalis and Trichomonas vaginalis. It has been found that the growth of both Trichomonas was significantly inhibited.

Screening of antibacterial and antiparasitic activities of six Moroccan medicinal plants

The extracts of six plants selected on the basis of folk-medicine reports were examined for their antibacterial effects against eight pathogenic bacteria. The results showed that n-butanol extract of Calotropis procera proved to be the most effective against the bacteria tested using the paper disc diffusion method. The antiprotozoal activity was also examined and showed that ethyl ether extract of Sium nodiflorum exhibits a parasiticidal effect against Trichomonas intestinalis and vaginalis.