Neurotrophic phenolic glycosides from the roots of Armoracia rusticana.

Armoracia rusticana P. G. Gaertner. belongs to the Brassicaceae family and has aroused scientific interest for its anti-inflammatory and anticancer activities. In a continuing investigation to discover bioactive constituents from A. rusticana, we isolated 19 phenolic glycosides including three undescribed flavonol glycosides and one undescribed neolignan glycoside from MeOH extract of this plant. Their structures were elucidated based on NMR spectroscopic analysis (1H, 13C, 1H-1H COSY, HSQC, and HMBC), HRESIMS, and chemical methods. The determination of their absolute configuration was accomplished by ECD and LC-MS analysis. All the compounds were assessed for their potential neurotrophic activity through induction of nerve growth factor in C6 glioma cell lines and for their anti-neuroinflammatory activity based on the measurement of inhibition levels of nitric oxide production and pro-inflammatory cytokines (i.e., IL-1ß, IL-6, and TNF-α) in lipopolysaccharide-activated microglia BV-2 cells.

Neurotrophic neolignans of Pinus koraiensis twigs.

Four undescribed neolignan analogs, together with eight known compounds, were isolated from the twigs of Pinus koraiensis (Korean pine). The chemical structure of the isolated compounds was determined through extensive spectroscopic analysis and chemical method. Their relative and absolute configurations were assigned through a well-established empirical rule and electronic circular dichroism (ECD) analysis, respectively. Four compounds (3 and 9-11) at 20 µM concentration showed significant neurotrophic effect by inducing nerve growth factor (NGF) secretion in C6 cells with the stimulation levels a range of 140.82 ± 4.62% to 160.04 ± 11.04%. Additionally, the result indicated that the glycosylation of neolignan led to an improvement in neurotrophic activity compared to their aglycone form. A compound (7) inhibited nitric oxide production with an IC50 value of 31.74 µM in LPS-activated BV2 cells.

Triterpenoids from the leaves of Abies koreana and their biological activities.

Seven undescribed triterpenoids, abikoranes A-G, along with three known triterpenoids were isolated from the leaves of Abies koreana E. H. Wilson. The structures of compounds were elucidated by 1D and 2D NMR, HRMS, ECD, specific rotation, and DP4+ analysis. Abikorane A represents the second example of nor-3,4-seco-17,14-friedo-lanostane triterpenoid. Among the isolates, some compounds showed strong cytotoxic activities against some of four tested cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-116) with the values of IC50 0.89-9.62 µM, inhibited lipopolysaccharide-stimulated nitric oxide production with IC50 values of 11.57-15.16 µM, and exhibited significant nerve growth factor release effect (192.54 ± 12.33%) from C6 glioma cells.

Terpenoids from Glechoma hederacea var. longituba and their biological activities.

Glechoma hederacea var. longituba (common name: ground ivy) has been used for the treatment of asthma, bronchitis, cholelithiasis, colds, and inflammation. In the present study, three new sesquiterpene glycosides (1-3), two new diterpene glycosides (4 and 5), and four known compounds (6-9) were isolated from its MeOH extract. A structure elucidation was performed for the five new compounds (1-5) using 1D and 2D NMR, HRESIMS, DP4+ and ECD calculations, and chemical methods. All the isolates (1-9) were assessed for their antineuroinflammatory activities on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells, nerve growth factor (NGF) secretion stimulation activities in C6 glioma cells, and cytotoxic activities against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 2 and 5-7 exhibited inhibitory effects on the NO production with IC50 values of 52.21, 47.90, 61.61, and 25.35 µM, respectively. Compound 5 also exhibited a significant stimulating effect on NGF secretion (122.77 ± 8.10%). Compound 9 showed potent cytotoxic activity against SK-OV-3 (IC50 = 3.76 µM) and SK-MEL-2 (IC50 = 1.48 µM) cell lines, while 7 displayed a strong cytotoxic activity against the SK-MEL-2 (IC50 = 9.81 µM) cell line.

Procyanidins and Phlobatannins from the Twigs of Rosa multiflora and Their Neuroprotective Activity.

Three new procyanidins (1-3), two new phlobatannins (6 and 7), a new flavan-3,4-diol glycoside (9), and a new neolignan glycoside (10), along with three previously reported compounds (4, 5, and 8) were isolated from the twigs of Rosa multiflora. The chemical structures of the new compounds (1-3, 6, 7, 9, and 10) were characterized by spectroscopic data interpretation, including NMR (1H and 13C NMR, 1H-1H COSY, HSQC, HMBC, and NOESY) and HRESIMS analysis. Experimental ECD data analysis was conducted to assign the absolute configurations of the new compounds (1-3, 6, 7, 9, and 10). The absolute configuration of the sugar moieties was verified through a chiral derivatization method and LC-MS analysis. All the isolated compounds (1-10) were evaluated for their anti-neuroinflammatory activity based on inhibitory effects on nitric oxide production using a lipopolysaccharide-stimulated murine microglia BV-2 cell line and for their neurotrophic effects on nerve growth factor induction in C6 glioma.

Anticancer and Anti-Neuroinflammatory Constituents Isolated from the Roots of Wasabia japonica.

Wasabi (Wasabia japonica (Miq.) Matsum.) is a pungent spice commonly consumed with sushi and sashimi. From the roots of this plant, a new 2-butenolide derivative (1) and 17 previously reported compounds (2-18) were isolated and structurally characterized. Their chemical structures were characterized based on the conventional NMR (1H and 13C, COSY, HSQC, and HMBC) and HRESIMS data analysis. All of these phytochemicals (1-18) were evaluated for their antiproliferative effects on the four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and MKN-1), for their inhibitory activity on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 microglia cells, and for their nerve growth factor (NGF)-releasing effect from C6 glioma cells. Among the isolated compounds, compound 15 showed powerful antiproliferative activities against A549 and SK-MEL-2 cell lines with IC50 values of 2.10 and 9.08 µM, respectively. Moreover, the new compound 1 exhibited moderate NO inhibition activity with IC50 value of 45.3 µM.

Phenolic constituents from twigs of Aleurites fordii and their biological activities.

Three new neolignan glycosides (1-3), a new phenolic glycoside (15), and a new cyanoglycoside (16) were isolated and characterized from the twigs of Aleurites fordii together with 14 known analogues (4-14 and 17-19). The structural elucidation of the new compounds was performed through the analysis of their NMR, HRMS, and ECD spectra and by chemical methods. All isolated compounds were tested for their antineuroinflammatory and neuroprotective activities.

Neurotrophic and anti-neuroinflammatory constituents from the aerial parts of Coriandrum sativum.

In the course of our continuing search for biologically active compounds from medicinal sources, we investigated the MeOH extract of the aerial parts of Coriandrum sativum Linn. An extended phytochemical investigation of the aerial parts of C. sativum led to the isolation and identification of seven compounds (1-7) including two new isocoumarin glycosides (1-2) and a new phenolic glycoside (5). The chemical structures of the new compounds (1, 2, and 5) were elucidated by analysis of 1D and 2D NMR (1H and 13C NMR, COSY, HSQC, and HMBC) and HRESIMS data as well as by using chemical methods. All the isolates were evaluated not only for their potential neurotrophic activity by means of induction of nerve growth factor (NGF) in C6 glioma cells but also for production of nitric oxide (NO) levels in lipopolysaccharide (LPS)-activated murine microglia BV-2 cells to assess their anti-neuroinflammatory activity. Compounds 1-3 and 7 were stimulants of NGF release, with levels of NGF stimulated at 127.23 ± 1.89%, 128.22 ± 5.45%, 121.23 ± 6.66%, and 120.94 ± 3.97%, respectively. Furthermore, the aglycones of 1 and 2 (1a and 2a) showed more potent NGF secretion activity and anti-neuroinflammatory effect than did their glycosides (1a : 130.81 ± 5.45% and 2a : 134.44 ± 5.45%).

Three New Oleanane-Type Triterpenoidal Glycosides from Impatiens balsamina and Their Biological Activity.

Three new oleanane-type triterpenoidal glycosides, imbalosides A-C (1-3), were isolated from the white flowers of Impatiens balsamina. The structures of these phytochemical constituents (1-3) were elucidated through 1D and 2D Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS) data analyses followed by chemical methods. All the characterized compounds (1-3) were evaluated for their antiproliferative activity against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and BT549) and their anti-neuroinflammatory activity on the basis of inhibition levels of nitric oxide (NO) in the lipopolysaccharide (LPS)-stimulated murine microglia BV-2 cell lines.

Antineurodegenerative Labdane Diterpenoid Glycosides from the Twigs of Pinus koraiensis.

Eleven new labdane-type diterpenoid glycosides, koraiensides A-K (1-11), together with two known analogues were isolated from the twigs of Pinus koraiensis. Their structures were elucidated via NMR, HRMS, and ECD data, DP4+ statistical analysis, and hydrolysis. The metabolites were tested for induction of nerve growth factor in C6 glioma cells to evaluate their potential neuroprotective activity. The compounds were measured for production of nitric oxide levels in lipopolysaccharide (LPS)-activated murine microglia BV2 cells to assess their antineuroinflammatory activity. Compounds 10 and 13 showed NGF secretion inducing effects from C6 glioma cells (162.3 ± 13.9% and 162.7 ± 6.9%, respectively). Compound 6 showed an IC50 value of 24.1 µM, implying significant inhibition of NO production.

Thiohydantoin and Hydantoin Derivatives from the Roots of Armoracia rusticana and Their Neurotrophic and Anti-neuroinflammatory Activities.

Two new thiohydantoins (1 and 3) and three new hydantoins (2, 4, and 5) along with three known compounds (6-8) were isolated from roots of horseradish. Physical data analysis including NMR (1H and 13C NMR, 1H-1H COSY, HSQC, and HMBC), HRESIMS, and ECD were employed for structure elucidation of the new compounds 1-5. Potential neuroprotective effects of all compounds (1-8) on nerve growth factor (NGF) induction in C6 glioma were also evaluated. Among these compounds, 1b and 2a exhibited potent NGF secretion stimulation activities (NGF secretion levels: 153.59 ± 5.44% and 141.99 ± 5.21%, respectively). Their anti-neuroinflammatory activities were also assessed based on their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide-stimulated murine microglia. Compound 7 marginally inhibited NO production with an IC50 value of 32.6 µM.

Phenolic constituents from the twigs of Betula schmidtii collected in Goesan, Korea.

Six undescribed phenolic derivatives along with thirty two known compounds were isolated from the twigs of Betula schmidtii. The chemical structures were characterized through extensive spectroscopic analysis and chemical methods. All known compounds were first isolated in this plant. The anti-inflammatory effect of the isolates was tested by measuring nitric oxide production in lipopolysaccharide-activated BV-2 cells. Isotachioside, 4-allyl-2-hydrophenyl 1-O-ß-D-apiosyl-(1 → 6)-ß-D-glucopyranoside, genistein 5-O-ß-D-glucoside, and prunetinoside showed a slight potency to lower the NO production against LPS-activated microglia with IC50 values of 23.9, 25.3, 28.8, and 34.0 µM, respectively.

Identification of a novel S6K1 inhibitor, rosmarinic acid methyl ester, for treating cisplatin-resistant cervical cancer.

BACKGROUND: The mTOR/S6K1 signaling pathway is often activated in cervical cancer, and thus considered a molecular target for cervical cancer therapies. Inhibiting mTOR is cytotoxic to cervical cancer cells and creates a synergistic anti-tumor effect with conventional chemotherapy agents. In this study, we identified a novel S6K1 inhibitor, rosmarinic acid methyl ester (RAME) for the use of therapeutic agent against cervical cancer. METHODS: Combined structure- and ligand-based virtual screening was employed to identify novel S6K1 inhibitors among the in house natural product library. In vitro kinase assay and immunoblot assay was used to examine the effects of RAME on S6K1 signaling pathway. Lipidation of LC3 and mRNA levels of ATG genes were observed to investigate RAME-mediated autophagy. PARP cleavage, mRNA levels of apoptotic genes, and cell survival was measured to examine RAME-mediated apoptosis. RESULTS: RAME was identified as a novel S6K1 inhibitor through the virtual screening. RAME, not rosmarinic acid, effectively reduced mTOR-mediated S6K1 activation and the kinase activity of S6K1 by blocking the interaction between S6K1 and mTOR. Treatment of cervical cancer cells with RAME promoted autophagy and apoptosis, decreasing cell survival rate. Furthermore, we observed that combination treatment with RAME and cisplatin greatly enhanced the anti-tumor effect in cisplatin-resistant cervical cancer cells, which was likely due to mTOR/S6K1 inhibition-mediated autophagy and apoptosis. CONCLUSIONS: Our findings suggest that inhibition of S6K1 by RAME can induce autophagy and apoptosis in cervical cancer cells, and provide a potential option for cervical cancer treatment, particularly when combined with cisplatin.

Securinega Alkaloids from the Twigs of Securinega suffruticosa and Their Biological Activities.

Seven new Securinega alkaloids, securingines A-G (1-7), together with seven known analogues (8-14), were isolated from the twigs of Securinega suffruticosa. Their chemical structures were elucidated by a combined approach of spectroscopic analysis, chemical methods, ECD calculations, and DP4+ probability analysis. The full NMR assignments and the absolute configuration of compound 8 are also reported. In addition, all the isolated phytochemicals (1-14) were assessed for their cytotoxic, anti-inflammatory, and potential neuroprotective activities. Compound 4 showed cytotoxic activity (IC50 values of 1.5-6.8 µM) against four human cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 3, 10, 12, and 13 showed potent inhibitory effects on nitric oxide production (IC50 values of 12.6, 12.1, 1.1, and 7.7 µM, respectively) in lipopolysaccharide-stimulated murine microglia BV-2 cells. Compound 5 exhibited a nerve growth factor production effect (172.6 ± 1.2%) in C6 glioma cells at 20 µg/mL.

New bis-thioglycosyl-1,1'-disulfides from Nasturtium officinale R. Br. and their anti-neuroinflammatory effect.

As a part of our continuing search for bioactive constituents from Brassicaceae family, three new bis-thioglycosides (1-3) were isolated from the 80% MeOH extract of Nasturtium officinale, together with 13 known compounds (4-16). The chemical structures of three new bis-thioglycosides (1-3) were elucidated using NMR techniques (1H and 13C NMR, 1H-1H COSY, HSQC, and HMBC), HRESIMS, and a chemical method. All the compounds were evaluated for their inhibitory effects on nitric oxide (NO) levels in lipopolysaccharide (LPS)-stimulated murine microglia BV-2 cells. Among the isolates, compound 5 exhibited a strong inhibitory effect on NO production, and compounds 4 and 15 showed moderate inhibitory activities, suggesting the neuroprotective and anti-neuroinflammatory effects of bis-thioglycosides from N. officinale.

Three New Lignan Glycosides from the Firmiana simplex.

In our quest for structurally intriguing compounds from Korean medicinal plant sources, chromatographic separation of the 80% MeOH extract from Firmiana simplex resulted in the isolation and identification of three new lignan glycosides (1-3), together with six known lignan glycosides (4-9). The structures of 1-3 were determined on the basis of spectroscopic analyses, including extensive 2D-NMR and enzyme hydrolysis. Nitric oxide (NO) production was evaluated in the lipopolysaccharide-activated microglial cell line, BV-2 to investigate the anti-neuroinflammatory effects of the isolated compounds (1-9). Compound 7 marginally inhibited NO levels with IC50 values of 59.83 µM.

Identification of protoberberine alkaloids as novel histone methyltransferase G9a inhibitors by structure-based virtual screening.

The protein lysine methyltransferase G9a, which controls gene expression by epigenetic regulation of H3K9 methylation, is related to various human diseases, including cancer, drug addiction, and mental retardation. In recent years, genetic, biological, and physiological evidence has established G9a inhibitors as potential chemotherapeutic agents for cancer treatment. In this study, we identified protoberberine alkaloid pseudodehydrocorydaline (CT13) as a novel G9a inhibitor, by structure-based virtual screening of in-house library containing natural product compounds. The activity of CT13 was determined by biophysical analyses involving MALDI-TOF mass spectrometry and western blot analysis. CT13 showed selective inhibitory activity against G9a and suppressed the level of H3K9me2 in MCF7 human breast cancer cells. Molecular docking analysis suggested the binding mode of CT13 which occupies the binding site of histone H3 substrate. CT13 provides a novel scaffold for further development of analogous synthetic G9a inhibitors.

Rare Thioglycosides from the Roots of Wasabia japonica.

Six new thioglycosides (1-6) were characterized from the roots of Wasabia japonica along with a known analogue (7). Of these compounds, 1-3 possess a disulfide bridge connecting the carbohydrate motif and the aglycone, which is extremely rare in Nature. In particular, compound 1 forms an unusual 1,4,5-oxadithiocane ring system. The structures of the isolated compounds were determined through conventional NMR and HRMS data analysis procedure, and computational methods with advanced statistics were used for the configurational assignments of 1 and two pairs of inseparable epimers, 2/3 and 4/5. All compounds were evaluated for their anti-inflammatory, neuroprotective, and cytotoxic activities, with 1 showing weak anti-inflammatory activity (IC50 41.2 µM).

Two New Phenolic Glycosides from Sorbus commixta.

From the stem bark of Sorbus commixta, two new phenolic glycosides, sorcomisides A and B (1 and 2), were isolated along with 10 known compounds. The structures of the isolates were determined by analysis of one-dimensional and two-dimensional NMR (1D- and 2D-NMR) data and high resolution (HR)-MS, chemical reaction, and computational methods. All the isolated compounds (1-12) were tested for their neuroprotective, anti-inflammatory, and cytotoxic activities.