Guaiane sesquiterpene lactones and amino acid-sesquiterpene lactone conjugates from the aerial parts of Saussurea pulchella

Phytochemical investigation of Volutaria lippii and evaluation of the antioxidant activity

Volutaria lippii (L.) Cass. ex Maire, syn. Centaurea lippii (L.), (Asteraceae) is a plant from the central region of Algeria, considerably distributed in all Mediterranean areas. Herein, the antioxidant activity of the three derived fractions [chloroform (CHCl3), ethyl acetate (EtOAc) and n-butanol (n-BuOH)] of the 70% methanol extract of the aerial parts (leaves and flowers), was assessed by using CUPRAC, ABTS, DPPH free radical scavenging, and β-carotene bleaching methods. The results obtained allowed to guide the fractionation of EtOAc and n-BuOH fractions by CC followed by purification by TLC and reverse phase HPLC. A guaianolide glucoside, 3β-hydroxy-11β,13-dihydrodehydrocostuslactone 8α-O-(6'-acetyl-β-glucopyranoside) (1), never reported in the literature, was isolated together with other known compounds (2-14). Their structures were elucidated by the extensive use of 1 D- and 2 D-NMR experiments along with ESI-MS analyses and with comparison with literature data.

Study on the Comprehensive Phytochemicals and the Anti-Ulcerative Colitis Effect of Saussurea pulchella

BACKGROUND

Saussurea pulchella (SP) is a traditional medicinal plant that is widely used in folk medicine because of its diverse biological activities, particularly its anti-inflammatory effects. However, the alleviation effect of SP on ulcerative colitis (UC) has not yet been realized.

PURPOSE

To investigate the chemical composition and therapeutic effect of SP extract against UC.

METHODS

First, qualitative and quantitative analysis of SP 75% ethanol extract was performed by UPLC-Q/TOF-MS. Second, a dextran sodium sulfate (DSS) model of UC mice was developed to study the effects of SP on the symptoms, inflammatory factors, oxidative stress indexes and colon histopathology. Third, an integration of network pharmacology with metabolomics was performed to investigate the key metabolites, biological targets and metabolisms closely related to the effect of SP.

RESULTS

From the SP ethanol extract, 149 compounds were identified qualitatively and 20 were determined quantitatively. The SP could dose-dependently decrease the DAI score, spleen coefficient and the levels of TNF-α, IL-6, iNOS, MPO and MDA; increase the colon length, GSH level and SOD activity; and protect the intestinal barrier in the UC mice. Moreover, 10 metabolite biomarkers,18 targets and 5 metabolisms were found to play crucial roles in the treatment of UC with SP.

CONCLUSIONS

SP 75% ethanol extract could effectively alleviate the progression of UC and, therefore, could be classified as a novel natural treatment for UC.

Antimicrobial and Cytotoxic Activities of Selected Hieracium L. s. str. (Asteraceae) Extracts and Isolated Sesquiterpene Lactones

Antimicrobial and cytotoxic activities were tested for dried MeOH extracts of Hieracium calophyllum (CAL), H. coloriscapum (COL), H. pseudoschenkii (PSE), H. valdepilosum (VAL) and H. glabratum (GLA) herbs (flowering aerial parts), their 2 sesquiterpene lactones (SLs) 8-epiixerisamine A and crepiside E, and dried CH₂ Cl₂ extract of H. scheppigianum (SCH) herb. In microdilution test, extracts showed activity on all tested microorganisms (8 bacteria, 10 fungi). The best effect was exhibited by SCH and CAL on Salmonella Typhimurium (MIC=1.7-2.5 mg/mL MBC=3.4-5.0 mg/mL), and SCH and VAL on Candida albicans (MIC=2.5 mg/mL MFC=5.0 mg/mL). SLs showed notable effect on all tested fungi Aspergillus ochraceus, Penicillium funiculosum, C. albicans and C. krusei (MIC=0.15-0.4 mg/mL MFC=0.3-0.8 mg/mL). In MTT test, extracts inhibited growth of all tested cancer cells (HeLa, LS174 and A549), with the best effect on HeLa (IC₅₀ =148.1 μg/mL for SCH, and 152.3-303.2 μg/mL for MeOH extracts); both SLs were active against HeLa cells (IC₅₀ =46.2 μg/mL for crepiside E and 103.8 μg/mL for 8-epiixerisamine A). Extracts and SLs showed good safety profile on normal MRC-5 cells.

Guaiane-Type Sesquiterpenoids from the Roots of Daphne genkwa and Evaluation of Their Neuroprotective Effects

Chromatographic purification of the roots of Daphne genkwa led to 11 new guaiane-type sesquiterpenoids (1-11), named genkwanoids A-K, and six known analogues (12-17). A comprehensive set of spectroscopic methods including IR, UV, HRESIMS, and 1D/2D NMR were used to elucidate the structures and relative configurations of 1-11. The absolute configurations were determined by the optical rotation calculations and the modified Mosher's method. The possible biosynthetic pathways for 1-11 are proposed. Furthermore, the neuroprotective effects of 1-17 on H₂O₂-induced damage in human neuroblastoma SH-SY5Y cells were screened using an MTT assay. Compounds 9, 10, and 16 exhibited moderate neuroprotective effects, with survival rates of 79.34%, 79.94%, and 75.64% after treatment with 12.5 μM, values that were comparable to the positive control, Trolox (78.65%). Furthermore, annexin V-FITC/PI staining of cells treated with 9, 10, and 16 showed that the neuroprotective effects of these compounds may arise from inhibiting cell apoptosis.

Sesquiterpene lactones from the methanol extracts of twenty-eight Hieracium species from the Balkan Peninsula and their chemosystematic significance

Four sesquiterpene lactones (SLs), including three undescribed proline-SL conjugates, the guaianolides calophyllamine A and 8-epiixerisamine A, and the eudesmanolide calophyllamine B, were isolated from the methanol extract of Hieracium calophyllum R. Uechtr. (Compositae) flowering heads. Another known guaianolide, crepiside E, was detected in Hieracium L. species for the first time. Their structures were elucidated using extensive 1D and 2D NMR spectroscopy in combination with HRMS. The isolated SLs were used as external standards for qualitative and quantitative LC-MS analysis of the dry methanol extracts of the flowering aerial parts of 28 Hieracium species from the Balkan Peninsula. Guaianolides were the dominant SLs in 27 species studied. The chemosystematic significance of detected SLs was evaluated using multivariate statistics (PCA, nMDS and UPGMA). Differentiation between the main groups was well supported. All four compounds significantly and equally contributed to the differences between the species. In addition, the eudesmanolide calophyllamine B could be a significant chemosystematic marker for H. sect. Villosa (Griseb.) Gremli s.l. and Glauciformia (Freyn) Zahn-Italica (Fr.) Av. Touv.

New anti-inflammatory guaianes from the Atlantic hydrotherm-derived fungus Graphostroma sp. MCCC 3A00421

Nine new guaianes (graphostromanes A-I, 1-9) were isolated from the deep-sea-derived fungus Graphostroma sp. MCCC 3A00421, along with four known ones (10-13). The relative configurations were established mainly by detailed analysis of the NMR and HRESIMS data, while the absolute configurations were assigned using the X-ray crystallography and modified Mosher's method. All isolates were evaluated for their inhibitory effects against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. Graphostromanes F (6) showed remarkable inhibitory effect with an IC₅₀ value of 14.2 μM, which was even stronger than that of aminoguanidine, a positive control with an IC₅₀ value of 23.4 μM.

Specialized metabolites from the aerial parts of Centaurea polyclada DC

The genus Centaurea L. (Asteraceae) is represented by 200 taxa in the flora of Turkey and several Centaurea species are used as herbal remedies against different conditions. Previous phytochemical investigations on this genus generally revealed the isolation of sesquiterpene lactones and flavonoid derivatives. In our continuous search on Centaurea genus, a phytochemical study was performed on Centaurea polyclada DC., an endemic of West Anatolia. Previously undescribed two sesquiterpene-amino acid conjugates, an elemane and an eudesmane derivative were isolated from the aerial parts of Centaurea polyclada, together with eight known compounds; two elemane derivatives, three flavonoids, a lignan, a phenolic glucoside and a phenylpropanoid glucoside. Structural elucidation of the compounds was based on spectroscopic evidence, including 1D and 2D NMR and high-resolution mass spectrometry, chemical degradation results and reference data comparison. Sesquiterpene-amino acid conjugates are representatives of an unusual group of sesquiterpenes, and elemane-amino acid conjugates are herein reported for the first time in nature.

Hepatoprotective and cytotoxic activities of Anvillea garcinii and isolation of four new secondary metabolites

Anvillea garcinii is a medicinal plant traditionally used for the treatment of dysentery, gastrointestinal troubles, hepatitis, lung disease, colds, digestive problems and pulmonary affections and in liver diseases. Four new sesquiterpene lactones, garcinamines A-D, along with seven known compounds, were isolated from the leaves of A. garcinii. This is the first report of the isolation of amino acid analogues of parthenolide-type sesquiterpene lactones from the family Asteraceae. Total ethanol extract of leaves as well as the chloroform and n-butanol fractions were tested for their hepatoprotective effect using the carbon tetrachloride liver toxicity model. The chloroform fraction, at a dose of 400 mg/kg, demonstrated a significant hepatoprotective effect comparable to silymarin in all serum and tissue parameters. The cytotoxicity of all extracts and compounds were evaluated against five human cancer cell lines: MCF-7, HCT-116, HepG2, Hela and A-549. The results indicated that the chloroform and n-butanol fractions and compounds 3, 4, 7 and 8 displayed significant cytotoxic activity against these cell lines.

Chemical constituents from the genus Saussurea and their biological activities

The genus

Cynaropicrin: A Comprehensive Research Review and Therapeutic Potential As an Anti-Hepatitis C Virus Agent

The different pharmacologic properties of plants-containing cynaropicrin, especially artichokes, have been known for many centuries. More recently, cynaropicrin exhibited a potential activity against all genotypes of hepatitis C virus (HCV). Cynaropicrin has also shown a wide range of other pharmacologic properties such as anti-hyperlipidemic, anti-trypanosomal, anti-malarial, antifeedant, antispasmodic, anti-photoaging, and anti-tumor action, as well as activation of bitter sensory receptors, and anti-inflammatory properties (e.g., associated with the suppression of the key pro-inflammatory NF-κB pathway). These pharmacological effects are very supportive factors to its outstanding activity against HCV. Structurally, cynaropicrin might be considered as a potential drug candidate, since it has no violations for the rule of five and its water-solubility could allow formulation as therapeutic injections. Moreover, cynaropicrin is a small molecule that can be easily synthesized and as the major constituent of the edible plant artichoke, which has a history of safe dietary use. In summary, cynaropicrin is a promising bioactive natural product that, with minor hit-to-lead optimization, might be developed as a drug for HCV.

Essential oils and diethyl ether extracts of Serbian Xeranthemum cylindraceum and X. annum: chemical composition, antimicrobial activity, and chemotaxonomic implications

Detailed GC and GC-MS analyses of the essential oils and Et2 O extracts of two Xeranthemum species - X. cylindraceum and X. annum - resulted in the identification of 254 components, in total. Terpenoids constituted the major part of both X. cylindraceum and X. annum essential oils and extracts (51.8-65.7%, and 50.7%, resp.). Among the sesquiterpenoids, the extracts of both investigated taxa contained the guaianolide xerantholide, its 11,13-dihydro derivatives, and two additional sesquiterpene lactones: an eudesmanolide, 11,13-dihydroisoalantolactone, and a pseudoguaianolide, confertin. The last two lactones and both isomers of 11,13-dihydroxerantholide have not been previously detected in Xeranthemum species. The isolated extracts of X. cylindraceum and X. annum were tested in a broth microdilution assay against a panel of microorganisms. The tested extracts demonstrated significant antimicrobial inhibitory activity, ranging from 30 to 260 μg/ml, being most active against Bacillus cereus and Staphylococcus aureus, an important human pathogen, with MIC close in value to those of chloramphenicol. Chemotaxonomic significance of the sesquiterpene lactones' distribution in the taxa investigated in this study and those detected earlier in phylogenetically close species (up to the level of the tribe Cardueae) was also discussed.

Sesquiterpenoids and tirucallane triterpenoids from the roots of Scorzonera divaricata

A sulfated guaiane sesquiterpene lactone, an unusual pyridinium alkaloid with a sulfated guaiane sesquiterpene lactone nucleus, an amino conjugate of a sulfated guaiane sesquiterpene lactone, a bisabolane sesquiterpene, three tirucallane triterpenes, and six known compounds, were isolated from roots of Scorzonera divaricata. Their structures and absolute configurations were established based on chemical and spectroscopic methods, X-ray single crystal crystallography, and also by comparison with experimental and calculated ECD spectra. One of the tirucallane triterpenes exhibited significant cytotoxic activities against four human cancer cell lines (HL60, HeLa, HepG2, and SMMC-7721) in vitro. Two of sulfated guaiane sesquiterpenoids also exhibited antioxidant activities by scavenging ABTS cation free radicals. Tirucallane-type and dammarane-type triterpenes were not previously known in the genus Scorzonera. The study suggests that sulfated guaiane-type sesquiterpenoids are a valuable marker for systematic chemical studies in the Lactuceae tribe of the Asteraceae.

Dehydroleucodine inhibits tumor growth in a preclinical melanoma model by inducing cell cycle arrest, senescence and apoptosis

Malignant melanoma represents the fastest growing public health risk of all cancer types worldwide. Several strategies and anti-cancer drugs have been used in an effort to improve treatments, but the development of resistance to anti-neoplastic drugs remains the major cause of chemotherapy failure in melanomas. Previously, we showed that the sesquiterpene lactone, dehydroleucodine (DhL), promotes the accumulation of DNA damage markers, such as H2AX and 53BP1, in human tumor cells. Also DhL was shown to trigger either cell senescence or apoptosis in a concentration-dependent manner in HeLa and MCF7 cells. Here, we evaluated the effects of DhL on B16F0 mouse melanoma cells in vitro and in a pre-clinical melanoma model. DhL inhibited the proliferation of B16F0 cells by inducing senescence or apoptosis in a concentration-dependent manner. Also, DhL reduced the expression of the cell cycle proteins cyclin D1 and B1 and the inhibitor of apoptosis protein, survivin. In melanomas generated by subcutaneous injection of B16F0 cells into C57/BL6 mice, the treatment with 20 mg DhL /Kg/day in preventive, simultaneous and therapeutic protocols reduced tumor volumes by 70%, 60% and 50%, respectively. DhL treatments reduced the number of proliferating, while increasing the number of senescent and apoptotic tumor cells. To estimate the long-term effects of DhL, a mathematical model was applied to fit experimental data. Extrapolation beyond experimental time points revealed that DhL administration following preventive and therapeutic protocols is predicted to be more effective than simultaneous treatments with DhL in restricting tumor growth.

Reversed-phase ultra-high-performance liquid chromatography coupled to electrospray ionization-quadrupole-time-of-flight mass spectrometry as a powerful tool for metabolic profiling of vegetables: Lactuca sativa as an example of its application

Lettuce (Lactuca sativa), a leafy vegetal widely consumed worldwide, fresh cut or minimally processed, constitutes a major dietary source of natural antioxidants and bioactive compounds. In this study, reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) coupled to electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-QTOF-MS) was applied for the comprehensive profiling of polar and semi-polar metabolites from three lettuce cultivars (baby, romaine, and iceberg). The UHPLC systems allowed the use of a small-particle-size C18 column (1.8 μm), with very fine resolution for the separation of up to seven isomers, and the QTOF mass analyzer enabled sensitive detection with high mass resolution and accuracy in full scan. Thus, a total of 171 compounds were tentatively identified by matching their accurate mass signals and suggested molecular formula with those previously reported in family Asteraceae. Afterwards, their structures were also corroborated by the MS/MS data provided by the QTOF analyzer. Well-known amino acids, organic acids, sesquiterpene lactones, phenolic acids and flavonoids were characterized, e.g. lactucin, lactucopicrin, caftaric acid, chlorogenic acid, caffeoylmalic acid, chicoric acid, isochlorogenic acid A, luteolin, and quercetin glycosides. For this plant species, this is the first available report of several isomeric forms of the latter polyphenols and other types of components such as nucleosides, peptides, and tryptophan-derived alkaloids. Remarkably, 10 novel structures formed by the conjugation of known amino acids and sesquiterpene lactones were also proposed. Thus, the methodology applied is a useful option to develop an exhaustive metabolic profiling of plants that helps to explain their potential biological activities and folk uses.

Systematic characterisation of secondary metabolites from Ixeris sonchifolia by the combined use of HPLC-TOFMS and HPLC-ITMS

INTRODUCTION

Ixeris sonchifolia (Bunge) Hance, a folk medicine, has been widely used in China for its anti-inflammatory and haemostatic effects. However, the miscellaneous component composition of this herbal medicine is not well known.

OBJECTIVE

To develop a fast and comprehensive analytical method for the characterisation of various components from I. Sonchifolia, as a tool for the quality control of the herb and its related preparations.

METHODOLOGY

Ixeris sonchifolia samples were extracted with 60% aqueous methanol, purified by solid-phase extraction and then analysed by the combinatorial use of HPLC-TOFMS and HPLC-ITMS.

RESULTS

A total of six sesquiterpene lactones, six phenolic acids and seven flavonoids were identified or tentatively characterised. Five of them were reported for the first time in I. sonchifolia and, in particular, two amino acid-sesquiterpene lactone conjugates, 11,13-dihydro-13-prolyl-ixerin Z and 11,13-dihydro-13-prolyl-ixerin Z(1), that were first found in this plant source.

CONCLUSION

A global profile of I. sonchifolia constituents was described, which could be useful for the quality control of this herb and its related preparations. The employed combination of HPLC-TOFMS and HPLC-ITMS could also be a promising tool for the analysis of other herbal medicines containing sesquiterpene lactones, phenolic acids or flavonoids.

Lignans from the tuber-barks of Colocasia antiquorum var. esculenta and their antimelanogenic Activity

Colocasia antiquorum var. esculenta , a variant of C. antiquorum , commonly known as "Imperial Taro", is an edible vegetable in many tropical and subtropical regions of the world. This study with the aim of evaluating the potential of C. antiquorum var. esculenta as a functional food with a depigmenting effect resulted in the identification of a new sesquilignan, named colocasinol A (1), and a new acyclic phenylpropane lignanamide, named cis-grossamide K (2), together with 10 known compounds (3-12). The identification and structural elucidation of these compounds were based on 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data analysis as well as high-resolution fast atom bombardment mass spectrometry (FABMS) and electron impact mass spectrometry (EIMS). Quantitation of the melanin contents and cell viability in murine melanocyte melan-a cells was used to assess the antimelanogenic activities of the isolated compounds. Among them, cis-grossamide K (2), isoamericanol A (3), americanol A (4), 2-hydroxy-3,2'-dimethoxy-4'-(2,3-epoxy-1-hydroxypropyl)-5-(3-hydroxy-1-propenyl)biphenyl (5), and (-)-pinoresinol (6) showed inhibitory effects on melanin production. Compounds 2, 5, and 6 exerted a particularly strong antimelanogenic activity on the cells without high cell toxicity (IC(50) = 54.24, 53.49, and 56.26 microM, and LD(50) = 163.60, 110.23, and >500 microM, respectively).

The renaissance of alpha-methylene-gamma-butyrolactones: new synthetic approaches

The amount of research activity concerning alpha-methylene-gamma-butyrolactones and alpha-alkylidene-gamma-butyrolactones has increased dramatically in recent years. This Review summarizes the structural types, biological activities, and biosynthesis of these compounds, concentrating on publications from the past 10 years. Traditional approaches to alpha-methylene-gamma-butyrolactones and alpha-alkylidene-gamma-butyrolactones are then reviewed together with novel approaches, including those from our own research group, reported more recently.

Phytochemicals and biological activities of Saussurea species

The genus Saussurea has been studied from phytochemical and pharmacological viewpoints for years, which resulted in the discovery of hundreds of secondary metabolites with various kinds of bioactivities. This review summarizes the research progress of the genus of Saussurea in the phytochemical and pharmacological viewpoints, which covered the period of 1990-June 2009.