Comparative phytochemical studies on the roots of Polygala azizsancarii and P. peshmenii and neuroprotective activities of the two xanthones

Six known sucrose mono-, di- and triesters and five xanthone derivatives were isolated from the roots of Polygala peshmenii Eren, Parolly, Raus & Kürschner which is a narrow species endemic to Türkiye. Among the xanthones, 1,7-dihydroxy-2,3-methylenedioxy-5,6-dimethoxy-xanthone is an undescribed compound isolated for the first time from a natural source. The studies on the roots of P. azizsancarii Dönmez have resulted in the isolation of four known compounds including sucrose mono-, di- and triesters. The structures of the sucrose esters and xanthones isolated from P. azizsancarii and P. peshmenii were established by spectroscopic methods, including 1D-NMR (¹H NMR, ¹³C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC). Neuroprotective activities of two xanthones, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone and 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,5,7-trimethoxyxanthone isolated from the roots of P. azizsancarii were evaluated in vitro using in a cellular model of Alzheimer's disease. SKNAS human neuroblastoma cells were used in the study and treated with different consecrations of Aβ₂₅₋₃₅ oligomer for up to 48 h. Cell viability was evaluated using MTT assay. The distribution of β-amyloid, α-synuclein, tau, JAK2, STAT3, caspase 3 and BMP-2 were investigated using indirect immunoperoxidase staining. Our results suggested that both xanthones control tau aggregation with no effect on β-amyloid plaque formation. In addition, for neuronal pathophysiology in AD cell model, decreased distributions of JAK/STAT3 and BMP2 signaling pathways were demonstrated, therefore they play a role in the protective effect on neurons in neurodegenerative disease. A significant decrease in caspase 3 immunoreactivity was detected after the administration of both compounds in AD cells. Therefore, both compounds control neuronal pathophysiology and rescue cell death in AD disease.

Xanthones and Xanthone O-β-D-glucosides from the Roots of Polygala azizsancarii Dönmez

Nine xanthone derivatives (1-9) were isolated from the roots of Polygala azizsancarii, which is a narrow endemic species for the flora of Türkiye. Based on all of the evidence, the structures of 1-9 were established as two previously undescribed xanthone O-glucosides, 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,5,7-trimethoxyxanthone (1), 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,7-dimethoxyxanthone (2), and seven previously described xanthones, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone (3), 1,3,6-trihydroxy-2,7-dimethoxyxanthone (4), 1,2,3,4,7-pentamethoxyxanthone (5), 1,3-dihydroxy-2,5,6,7-tetramethoxyxanthone (6), 1,3-dihydroxy-4,7-dimethoxyxanthone (7), 1,7-dihydroxy-3-methoxyxanthone (8), 1,7-dihydroxy-2,3-methylenedioxy-xanthone (9). The structures of the compounds were determined by spectroscopic methods, including 1D-NMR (1H NMR, 13C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC, INADEQUATE), and HRMS. The solid-state structures of 1-4, including the absolute configurations of the stereogenic carbons of the sugar moiety in 1 and 2, were established by X-ray crystal-structure analyses. For the newly described compounds, the trivial names sancarosides A (1) and B (2) are proposed.

Review of Studies on Phlomis and Eremostachys Species (Lamiaceae) with Emphasis on Iridoids, Phenylethanoid Glycosides, and Essential Oils

As the sixth-largest Angiosperm family, Lamiaceae contains more than 245 genera and 7886 species that are distributed worldwide. It is also the third-largest family based on the number of taxa in Turkey where it is represented by 46 genera and 782 taxa with a high endemism ratio (44%). Besides, Lamiaceae are rich in plants with economic and medicinal value containing volatile and nonvolatile compounds. Many aromatic plants of Lamiaceae such as Salvia, Sideritis, Stachys, Phlomis, and Teucrium species are used in traditional herbal medicine throughout Turkey as well as in other Mediterranean countries. Salvia (Sage tea "Adaçayı"), Sideritis (Mountain tea "Dağçayı"), Stachys (Hairy Tea "Tüylü Çay"), and Phlomis (Turkish sage "Çalba or Şalba") are the largest genera that are used as herbal teas. This review focuses on the volatile and nonvolatile compounds of Lamiaceae from the genera Phlomis and Eremostachys of the subfamily Lamioideae with emphasis on iridoids, phenylethanoid glycosides, and essential oils.

Cytotoxic Effects of Verbascoside on MCF-7 and MDA-MB-231

Objectives

Verbascoside, also known as acteoside/kusaginin, has attracted a great attention due to its pharmacological features. In this study, we aimed to determine the cytotoxic effects of pure verbascoside isolated from Phlomis nissolii L. plant in both MCF-7 and MDA-MB-231 cell lines in vitro.

Materials and Methods

MCF-7 and MDA-MB 231 cells were treated with verbascoside (100, 48, 25, 10, 1, 0.5, and 0.1 μM) for 24, 48, and 72 hours. Cytotoxic effect of verbascoside in MCF-7 and MDA-MB-231 cells was assessed using TEBU-BIO cell counting kit 8.

Results and Conclusion

IC₅₀ values for 24, 48, and 72 h verbascoside exposure of MCF-7 cells were determined as 0.127, 0.2174, and 0.2828 μM, respectively. R² values were calculated as 0.9630, 0.8789 and 0.8752, respectively. Two-Way ANOVA multiple comparison test results showed that 100 μM verbascoside has the highest cytotoxic effect on MCF-7 breast cancer (BC) cells after 72 h of exposure. IC₅₀ values for 24, 48 and 72 h verbascoside exposure of MDA-MB 231 cells were determined as 0.1597, 0.2584 and 0.2563 μM, respectively and R² values were calculated as 0.8438, 0.5107 and 0.9203, respectively. Two-Way ANOVA multiple comparisons test results showed that 100 μM verbascoside has the highest cytotoxic effect on MDA-MB 231 BC cells after 24, 48 and 72 h of exposure.

Ecdysteroids from the underground parts of Rhaponticum acaule (L.) DC

In addition to two known ecdysteroids, 20-hydroxyecdysone and turkesterone, three previously undescribed stigmastane-type ecdysteroids were isolated from the underground parts of Rhaponticum acaule (L.) DC. by chromatographic techniques (CC, VLC, MPLC). The structures of the compounds were established by chemical (acetylation) and spectroscopic methods including UV, IR, HRMS, 1D-NMR: ¹H-NMR, ¹³C-NMR, DEPT-135. and 2D-NMR: COSY, NOESY, HSQC, HMBC. Two compounds were isolated as an isomeric mixture and each of them was purified and converted to the corresponding acetylated derivative. Based on all of the evidence, the structures of three undescribed stigmastane-type ecdysteroids were established as 2β,3β,11α,20β,22α,24,28-heptahydroxy-6-oxo-stigmast-7-en-25,29-lactone and the cyclic 22,29-hemiacetals 22R and 22S stigmast-7-en-29-al,2β,3β,11α,20α,22,28-hexahydroxy-6-oxo, and the trivial names acaulesterone and rhapocasterones A and B are suggested, respectively. The structures and absolute configurations of 20-hydroxyecdysone and cyclic-22,29-hemiacetal-22R-stigmast-7-en-29-al,2β,3β,11α,20α,22,28-hexahydroxy-6-oxo were confirmed by X-ray crystal-structure analyses of their acetyl derivatives.

Iridoid glucosides from Wendlandia ligustroides (Boiss. &Hohen.) Blakelock

Eight iridoid glucosides were reported from the aerial parts of Wendlandia ligustroides. 10-deoxygeniposidic acid (1), 7-deoxygardoside (2), geniposidic acid (3), 7-deoxy-8-epi-loganic acid (4), deacetyl-daphylloside (5), scandoside methyl ester (6), 6-O-methyl-deacetyl-daphylloside (7), 6-O-methyl-scandoside methyl ester (8). Compounds 3 - 8 were isolated as a pure form while 1 and 2 as a mixture. The structures of the compounds 1 - 8 were established by spectroscopic methods including 1D-NMR (1H NMR, 13C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC) and HRMS.

Switchable-hydrophilicity solvent liquid-liquid microextraction versus dispersive liquid-liquid microextraction prior to HPLC-UV for the determination and isolation of piperine from Piper nigrum L

Switchable-hydrophilicity solvent liquid-liquid microextraction and dispersive liquid-liquid microextraction were compared for the extraction of piperine from Piper nigrum L. prior to its analysis by using high-performance liquid chromatography with UV detection. Under optimum conditions, limits of detection and quantitation were found as 0.2-0.6 and 0.7-2.0 μg/mg with the two methods, respectively. Calibration graphs showed good linearity with coefficients of determination (R² ) higher than 0.9962 and percentage relative standard deviations lower than 6.8%. Both methods were efficiently used for the extraction of piperine from black and white pepper samples from different origins and percentage relative recoveries ranged between 90.0 and 106.0%. The results showed that switchable-hydrophilicity solvent liquid-liquid microextraction is a better alternative to dispersive liquid-liquid microextraction for the routine analysis of piperine in food samples. A novel scaled-up dispersive liquid-liquid microextraction method was also proposed for the isolation of piperine providing a yield of 102.9 ± 4.9% and purity higher than 98.0% as revealed by NMR spectroscopy.

Protoscolicidal effect of oleuropein: an in vitro study

OBJECTIVES

Hydatid disease is a parasitic disease caused by Echinococcus granulosus and is still endemic in many parts of the world. Scolicidal solutions are generally used in any type of intervention, either surgical or percutaneous, to neutralize the cyst contents, although completeness of their effect is obscure and solid evidence is scarce. On the other hand, the use of these scolicidal solutions is not devoid of complications and many serious complications such as caustic sclerosing cholangitis may be seen in relation with their usage. Recent investigations proved protoscolicidal properties of olive leaf extract although the active ingredient has not been attributed to any component. The aim of this experimental study was to isolate oleuropein and test for in vitro protoscolicidal activity.

MATERIAL AND METHODS

Oleuropein, a phenolic compound found in olive leaves, is extracted and prepared in different concentrations. Echinococcal cyst containing livers of sheep are obtained from the government slaughterhouse. Cysts were punctured and live protoscolex suspensions were prepared under aseptic conditions. Different concentrations of oleuropein solutions were prepared and protoscolicidal property is analyzed and compared with positive and negative controls for different exposure times.

RESULTS

Oleuropein 2% concentration was found to be protoscolicidal in all exposure times starting from 5 minutes.

CONCLUSION

2% oleuropein is a powerful, natural protoscolicidal agent which should be evaluated clinically before its application in routine treatment practice.

Flavonoids from Sideritis Species: Human Monoamine Oxidase (hMAO) Inhibitory Activities, Molecular Docking Studies and Crystal Structure of Xanthomicrol

The inhibitory effects of flavonoids on monoamine oxidases (MAOs) have attracted great interest since alterations in monoaminergic transmission are reported to be related to neurodegenerative diseases such as Parkinson's and Alzheimer's diseases and psychiatric disorders such as depression and anxiety, thus MAOs may be considered as targets for the treatment of these multi-factorial diseases. In the present study, four Sideritis flavonoids, xanthomicrol (1), isoscutellarein 7-O-[6'''-O-acetyl-β-D-allopyranosyl-(1→2)]-β-D-glucopyranoside (2), isoscutellarein 7-O-[6'''-O-acetyl-β-D-allopyranosyl-(1→2)]-6''-O-acetyl-β-D-glucopyranoside (3) and salvigenin (4) were docked computationally into the active site of the human monoamine oxidase isoforms (hMAO-A and hMAO-B) and were also investigated for their hMAO inhibitory potencies using recombinant hMAO isoenzymes. The flavonoids inhibited hMAO-A selectively and reversibly in a competitive mode. Salvigenin (4) was found to be the most potent hMAO-A inhibitor, while xanthomicrol (1) appeared as the most selective hMAO-A inhibitor. The computationally obtained results were in good agreement with the corresponding experimental values. In addition, the x-ray structure of xanthomicrol (1) has been shown. The current work warrants further preclinical studies to assess the potential of xanthomicrol (1) and salvigenin (4) as new selective and reversible hMAO-A inhibitors for the treatment of depression and anxiety.

Isolation of an oleanane-type saponin active from Bellis perennis through antitumor bioassay-guided procedures

CONTEXT

Bellis perennis L. (Asteraceae) (common daisy) is a herbaceous perennial plant known as a traditional wound herb; it has been used for the treatment of bruises, broken bones, and wounds. Bellis perennis has also been used in the treatment of headache, common cold, stomachache, eye diseases, eczema, skin boils, gastritis, diarrhea, bleeding, rheumatism, inflammation, and infections of the upper respiratory tract in traditional medicine.

OBJECTIVE

Antitumor activities of different fractions of B. perennis flowers at different concentrations were evaluated and through bioassay-guided fractionation and isolation procedures a saponin derivative (1) was isolated from the active fraction obtained from the n-butanol extract of flowers of the title plant by column chromatography.

MATERIALS AND METHODS

Antitumor activities of different fractions of B. perennis flowers at different concentrations were evaluated using Potato Disc Tumor Induction Bioassay. Structure elucidation of 1 was accomplished by spectroscopic methods [1D- and 2D-NMR, and LC-ESI(APCI)-TOF-MS(MSn)].

RESULTS

The present study showed the antitumor activity of fractions obtained from B. perennis flowers for the first time. The most active fraction showed 99% tumor inhibition at 3000 mg/L. An oleanane-type saponin was isolated through bioassay-guided studies.

DISCUSSION AND CONCLUSION

Through antitumoral bioassay-guided fractionation and isolation procedures, 1 was isolated from the active fraction of B. perennis. The detailed NMR data of compound 1 is given for the first time.

Bioactive Cycloartane-Type Triterpene Glycosides from Astragalus elongatus

Together with two known cycloartane-type glycosides, askendosides D (3-O-[α-arabinopyranosyl-( 1→2)-β-xylopyranosyl]-6-O-β-xylopyranosyl-cycloastragenol, 2) and G (3-O- [α-arabinopyranosyl-(1→2)-β-xylopyranosyl]-16-O-β-glucopyranosyl-3β,6α,16β,24(R),25- pentahydroxycycloartane, 3), also a new monodesmosidic cycloartane-type glycoside, elongatoside (1), was isolated from the roots of Astragalus elongatus and identified as 3-O- [α-arabinopyranosyl-(1→2)-β-xylopyranosyl]-cycloastragenol. All structures were unambiguously determined by means of spectroscopic and spectrometric methods (1D and 2D NMR, ESI-MS). The isolated compounds were tested for the inhibition of proliferation and ICAM-1 expression in vitro using the human microvascular endothelial cell line (HMEC-1). 1 showed weak activity in the ICAM-1 assay.

Flavonoid, Phenylethanoid and Iridoid Glycosides from Globularia aphyllanthes

A new flavone glycoside, 6-hydroxyluteolin 7-O-[6m-benzoyl-β -D-glucopyranosyl-(1 → 2)]-β - D-glucopyranoside (aphyllanthoside, 1) was isolated from the MeOH extract of the aerial parts of Globularia aphyllanthes. Besides this new compound, two flavonoid glycosides (6-hydroxyluteolin 7-O-[6m-(E)-caffeoyl-β -D-glucopyranosyl-(1 → 2)]-β -D-glucopyranoside and isoquercitrin), three phenylethanoid glycosides (verbascoside, rossicaside A, and trichosanthoside A), and 11 iridoid glycosides (aucubin, catalpol, 10-O-benzoylcatalpol, globularin, asperuloside, besperuloside, asperulosidic acid, daphylloside, scandoside, alpinoside and baldaccioside) were also obtained and characterized. Identification of the isolated compounds was carried out by spectroscopic analysis including 1D and 2D NMR experiments as well as HRMS

Triterpene Saponins from Calendula arvensis

From the aerial parts of Calendula arvensis a new triterpene saponin arvensoside C (1) was isolated together with four known triterpene saponins. The aglycon moieties had the oleanane skeleton for all of them. Three known flavonol glycosides, isorhamnetin 3-O-β -D-glucopyranoside, quercetin 3-O-β -D-glucopyranoside and quercetin 3-O-β -D-galactopyranoside were also obtained and characterized. Their structures were elucidated by 1D and 2D NMR experiments including 1D-TOCSY, DQF-COSY, HOHAHA, HSQC and HMBC spectroscopy as well as HRESIMS analysis.

In vitro effects of compounds isolated from Sideritis brevibracteata on bovine kidney cortex glutathione reductase

Glutathione reductase (GR, E.C 1.6.4.2) is a flavoprotein that catalyzes NADPH-dependent reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). The aim of this study was to investigate in vitro effects of phenolic compounds isolated from Sideritis brevibracteata on bovine kidney GR. The Sideritis species are widely found in nature and commonly used as medicinal plants. 7-O-glycosides of 8-OH-flavones (hypolaetin, isoscutellarein and 3'-hydroxy-4'-O-methylisoscutellarein) were isolated from aerial parts of Sideritis brevibracteata. These compounds inhibited bovine kidney cortex GR in a concentration-dependent manner. Kinetic characterization of the inhibition was also performed.

In vitro effects of compounds isolated from Sideritis brevibracteata on bovine kidney cortex glutathione reductase

Glutathione reductase (GR, E.C 1.6.4.2) is a flavoprotein that catalyzes NADPH-dependent reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). The aim of this study was to investigate in vitro effects of phenolic compounds isolated from Sideritis brevibracteata on bovine kidney GR. The Sideritis species are widely found in nature and commonly used as medicinal plants. 7-O-glycosides of 8-OH-flavones (hypolaetin, isoscutellarein and 3'-hydroxy-4'-O-methylisoscutellarein) were isolated from aerial parts of Sideritis brevibracteata. These compounds inhibited bovine kidney cortex GR in a concentration-dependent manner. Kinetic characterization of the inhibition was also performed.

Secondary Metabolites from Eremostachys Laciniata

From the aerial parts of Eremostachys laciniata (Lamiaceae), a new acidic iridoid glucoside, 5-desoxysesamosidic acid (1) was isolated in addition to thirteen known iridoid glucosides, 5-desoxysesamoside (2), sesamoside (3), 6β-hydroxy-7- epi-loganin (4), chlorotuberoside (5), 5-deoxypulchelloside I (6), lamalbide (7), lamalbidic acid (8), phloyosides I (7- epi-phlomiol) (9), and II (10), phlomiol (11), shanzhiside (12), shanzhiside methyl ester (13), and barlerin (8- O-acetylshanzhiside methyl ester) (14), four phenylethanoid glycosides, verbascoside (15), leucosceptoside A (16), martynoside (17), and forsythoside B (18), and five flavone derivatives, luteolin (19), luteolin 7- O-β-D-glucopyranoside (20), luteolin 7- O-(6″- O-β-D-apiofuranosyl)-β-D-glucopyranoside (21), apigenin 7- O-β-D-glucopyranoside (22), and apigenin 7- O-(6″- O-p-coumaroyl)-β-D-glucopyranoside (23). The structures of the metabolites were elucidated from spectroscopic (UV, IR, 1D- and 2D-NMR) and ESI-MS evidence, as well as from their specific optical rotations. The presence of these metabolites of three different classes strongly supports the close relationship of the genera Eremostachys and Phlomis.