Phenolic Compounds from the Fruits of Prunus davidiana (Rosaceae) and Their Antioxidant Activities.

This research was supported by Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ014204032019) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2020R1A6A3A01100042).

Flavonoids from Chionanthus retusus (Oleaceae) Flowers and Their Protective Effects against Glutamate-Induced Cell Toxicity in HT22 Cells.

The dried flowers of Chionanthus retusus were extracted with 80% MeOH, and the concentrate was divided into EtOAc, n-BuOH, and H2O fractions. Repeated SiO2, octadecyl SiO2 (ODS), and Sephadex LH-20 column chromatography of the EtOAc fraction led to the isolation of four flavonols (1-4), three flavones (5-7), four flavanonols (8-11), and one flavanone (12), which were identified based on extensive analysis of various spectroscopic data. Flavonoids 4-6 and 8-11 were isolated from the flowers of C. retusus for the first time in this study. Flavonoids 1, 2, 5, 6, 8, and 10-12 significantly inhibited NO production in RAW 264.7 cells stimulated by lipopolysaccharide (LPS) and glutamate-induced cell toxicity and effectively increased HO-1 protein expression in mouse hippocampal HT22 cells. Flavonoids with significant neuroprotective activity were also found to recover oxidative-stress-induced cell damage by increasing HO-1 protein expression. This article demonstrates that flavonoids from C. retusus flowers have significant potential as therapeutic materials in inflammation and neurodisease.

New furospirostane steroidal saponins from the flowers of Lilium Asiatic hybrids.

Lilium Asiatic hybrids (Lilium spp.) are produced by interspecific crosses of Sinomartagon species belonging to Liliaceae. To date, no phytochemical work appears to have been conducted on Lilium Asiatic hybrids. In the current work, solvent extraction, solvent fractionation, and repeated SiO2 and ODS column chromatography yielded three new steroidal saponins along with a known one, avenacoside A (1). The chemical structures of the new saponins were determined based on extensive spectroscopic methods as well as chemical and biological reactions to be 26-O-ß-D-glucopyranosylnuatigenin 3-O-α-l-rhamnopyranosyl-(1 → 2)-O-[(4-O-methyl)-ß-d-glucopyranosyl-(1 → 6)-ß-d-glucopyranosyl-(1 → 4)]-ß-d-glucopyranoside (2), 26-O-ß-D-glucopyranosylnuatigenin 3-O-ß-d-glucopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-(6-acetoxyl)-ß-d-glucopyranoside (3), and 26-O-ß-D-glucopyranosylnuatigenin 3-O-ß-d-glucopyranosyl-(1 → 2)-O-[ß-d-glucopyranosyl-(1 → 6)]-ß-d-glucopyranoside (4), named lilyasiasides A-C, respectively. The aglycone of the saponins, a nuatigenin, is an atypical spirostanol sapogenin possessing a pentacyclic F-ring, furospirostane steroid, which is very rarely occurred in Lilium species.

New Lignans from the Flower of Forsythia koreana and Their Suppression Effect on VCAM-1 Expression in MOVAS Cells.

Six lignans including two new lignans were obtained as the principal components of the Forsythia koreana flowers via silica gel (SiO2 ), octadecyl SiO2 (ODS) as well as Sephadex LH-20 column chromatography. In addition to two new lignans, named koreanaside A ((7R,8S,7'R,8'S)-7,7'-diepoxy-5'-hydroxy-3,3'-dimethoxylignan 4-O-ß-d-glucopyranoside) and koreanaside B ((7R,8S,7'S,8'R)-7,9'-epoxy-9,5',7'-trihydroxy-3,3'-dimethoxylignan 4-O-ß-d-glucopyranoside), four known lignans were identified to be (+)-phylligenin, (-)-epipinoresinol, pinoresinol, and tinosposide A. The structures and absolute configurations of koreanasides A and B were established by means of analysis of spectroscopic data (NMR, IR, FAB-MS, and CD), whereas the structures of known lignans were identified by comparison their NMR and MS values with those in the reported literature. Their chemical structures including configuration were established by means of analysis of spectroscopic data (NMR, IR, FAB-MS, and CD) but also comparison of their NMR and MS values with those in the reported literature. This is the first article for isolation of six lignans of F. koreana flowers. Koreanasides A and B showed high radical scavenging activity with oxygen radical absorbance capacity (ORAC) values of 0.97 ± 0.01 and 1.02 ± 0.01, respectively. Koreanaside A also prohibited expressing VCAM-1 in MOVAS cells with 80.5% at 25 mg/mL.

Anti-inflammatory effect of stem bark of Paulownia tomentosa Steud. in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and LPS-induced murine model of acute lung injury.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves, bark, and flowers of Paulownia tomentosa Steud. have been widely used as a traditional medicine in East Asia to treat inflammatory and infectious diseases. AIM OF THE STUDY: We investigated the protective effect of the methanol stem bark extract of P. tomentosa using an animal model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). MATERIALS AND METHODS: The UPLC Q-TOF-MS profiles for the methanol extract of P. tomentosa stem bark showed that verbascoside and isoverbascoside were the predominant compounds. Raw 264.7 cells were used for inhibitory effects of cytokine production in vitro. C57BL/6N mice were administered intranasally with LPS (10µg/per mouse) to induce ALI. H&E staining was used to evaluate histological changes in the lung. RESULTS: Treatment with P. tomentosa stem bark extract (PTBE) suppressed the production of IL-6 and TNF-α in LPS-stimulated RAW 264.7 macrophages, and the recruitment of neutrophils and macrophages in the BALF of mice with LPS-induced ALI. PTBE also decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines in the BALF. PTBE reduced the levels of nitric oxide (NO) in the serum and of inducible nitric oxide synthase (iNOS) in the lung of ALI mice. PTBE also attenuated the infiltration of inflammatory cells and the expression of monocyte chemoattractant protein-1 (MCP-1) in the lung. In addition, PTBE suppressed the activation of NF-κB and the reduced expression of superoxide dismutase 3 (SOD3) in the lung. CONCLUSION: The results suggest that PTBE has a protective effect on LPS-induced ALI.

Potential Anti-inflammatory Effects of the Fruits of Paulownia tomentosa.

As part of an ongoing search for new natural products from medicinal plants to treat respiratory disease, six new compounds, a dihydroflavonol (1) and five C-geranylated flavanones (3, 6, 8, 13, and 14), and 13 known compounds were isolated from mature fruits of Paulownia tomentosa. The structures of the new compounds were determined via interpretation of their spectroscopic data (1D and 2D NMR, UV, IR, ECD, and MS). In biological activity assays with human alveolar basal epithelial cells, the expression of TNF-α-induced proinflammatory cytokines (IL-8 and IL-6) was reduced significantly by the EtOAc fraction of a P. tomentosa extract as well as by the new compounds isolated from this fraction. Furthermore, the majority of the isolates (1-19 except 5-7) were found to inhibit human neutrophil elastase (HNE) activity, with IC50 values ranging from 2.4 ± 1.0 to 74.7 ± 8.5 µM. In kinetic enzymatic assays with the HNE substrate MeOSuc-AAPV-pNA, compound 17 exhibited the highest inhibitory activity (Ki = 3.2 µM) via noncompetitive inhibition. These findings suggest that the flavanone constituents of P. tomentosa fruits may be valuable for the development of new drug candidates to treat airway inflammation.

Dineolignans of 3-O-4' diphenyl ether-type from fruits of Magnolia obovata.

Seven dineolignans of the 3-O-4' diphenyl ether-type (obovatalignans C-I, respectively), were isolated from fruits of Magnolia obovata through repeated silica gel (SiO2), octadecyl SiO2, and Sep-Pak chromatographies. Their chemical structures were determined based on various spectroscopic methods including NMR, HR-MS, IR, specific rotation, and CD spectrometry. Especially, compounds 1-5 include the relatively rare 1,4-benzodioxane ring moiety in the molecular structure.

Three New Isoprenylated Flavonoids from the Root Bark of Morus alba.

Phytochemical investigation of the root bark of Morus alba has led to the isolation and identification of three new isoprenylated flavonoids, namely sanggenon U (1), sanggenon V (2), and sanggenon W (3), along with four known isoprenylated flavonoids: euchrenone a7 (4), sanggenon J (5), kuwanon E (6), and kuwanon S (7). All compounds were isolated by repeated silica gel (SiO2), octadecyl SiO2 (ODS), and Sephadex LH-20 open column chromatography. The structure of the compounds were determined based on spectroscopic analyses, including nuclear magnetic resonance (NMR), mass spectrometry (MS), circular dichroism (CD), and infrared (IR). In addition, compounds 1-4 were isolated for the first time from the root bark of M. alba in this study.

Magnobovatol inhibits smooth muscle cell migration by suppressing PDGF-Rß phosphorylation and inhibiting matrix metalloproteinase-2 expression.

The migration of vascular smooth muscle cells (VSMCs) may play a crucial role in the pathogenesis of vascular diseases, such as atherosclerosis and post-angioplasty restenosis. Platelet-derived growth factor (PDGF)-BB is a potent mitogen for VSMCs and plays an important role in the intimal accumulation of VSMCs. Magnobovatol, a new neolignan from the fruits of Magnolia obovata, has been shown to have anticancer properties. However, the effects of magnobovatol on VSMCs are unknown. In the present study, we examined the effects of magnobovatol on the PDGF­BB­induced migration of mouse and human VSMCs, as well as the underlying mechanisms. Magnobovatol significantly inhibited the PDGF­BB-induced migration of mouse and human VSMCs without inducing cell death (as shown by MTT assay and wound healing assay). Additionally, we demonstrated that magnobovatol significantly blocked the PDGF­BB-induced phosphorylation of the PDGF receptor (PDGF-R), Akt and extracellular signal­regulated kinase (ERK)1/2 by inhibiting the activation of the PDGF­BB signaling pathway. Moreover, in both mouse and human VSMCs, magnobovatol inhibited PDGF-induced matrix metalloproteinase (MMP)-2 expression at the mRNA and protein level, as well as the proteolytic activity of MMP-2 (as shown by western blot analysis, RT-PCR, gelatin zymography and ELISA). In addition, the sprout outgrowth formation of aortic rings induced by PDGF­BB was inhibited by magnobovatol (as shown by aortic ring assay). Taken together, our findings indicate that magnobovatol inhibits VSMC migration by decreasing MMP-2 expression through PDGF-R and the ERK1/2 and Akt pathways. Our data may improve the understanding of the anti-atherogenic effects of magnobovatol in VSMCs.

c-Jun N-terminal Kinase-Dependent Endoplasmic Reticulum Stress Pathway is Critically Involved in Arjunic Acid Induced Apoptosis in Non-Small Cell Lung Cancer Cells.

Though arjunic acid, a triterpene isolated from Terminalia arjuna, was known to have antioxidant, antiinflammatory, and cytotoxic effects, its underlying antitumor mechanism still remains unclear so far. Thus, in the present study, the molecular antitumor mechanism of arjunic acid was examined in A549 and H460 non-small cell lung cancer (NSCLC) cells. Arjunic acid exerted cytotoxicity by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay and significantly increased sub-G1 population in A549 and H460 cells by cell cycle analysis. Consistently, arjunic acid cleaved poly (ADP-ribose) polymerase (PARP), activated Bax, and phosphorylation of c-Jun N-terminal kinases (JNK), and also attenuated the expression of pro-caspase-3 and Bcl-2 in A549 and H460 cells. Furthermore, arjunic acid upregulated the expression of endoplasmic reticulum (ER) stress proteins such as IRE1 α, ATF4, p-eIF2α, and C/EBP homologous protein (CHOP) in A549 and H460 cells. Conversely, CHOP depletion attenuated the increase of sub-G1 population by arjunic acid, and also JNK inhibitor SP600125 blocked the cytotoxicity and upregulation of IRE1 α and CHOP induced by arjunic acid in A549 and H460 cells. Overall, our findings suggest that arjunic acid induces apoptosis in NSCLC cells via JNK mediated ER stress pathway as a potent chemotherapeutic agent for NSCLC.

Apoptotic Effect of Sanggenol L via Caspase Activation and Inhibition of NF-κB Signaling in Ovarian Cancer Cells.

In the present study, the underlying apoptotic mechanism of sanggenol L was elucidated in ovarian cancer cells. Sanggenol L showed cytotoxic and antiproliferative effect in A2780, SKOV-3, and OVCAR-3 ovarian cancer cells in a concentration-dependent fashion. Consistently, sanggenol L increased sub-G1 phase population and early and late apoptotic portion in ovarian cancer cells. Also, sanggenol L activated caspase9/3, suppressed the phosphorylation of IκBα and p65 NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), attenuated the expression of Cyclin D1, and cleaved poly(adenosine diphosphate ribose -ribose) polymerase in SKOV-3, A2780, and OVCAR-3 cells. Furthermore, sanggenol L blocked nuclear translocation of NF-κB and also attenuated the expression of NF-κB related genes such as c-Myc, Cyclin D1, and Bcl-X L, Bcl-2, in lipopolysaccharide-treated SKOV-3 cells. Overall, our findings for the first time suggest that sanggenol L induces apoptosis via caspase activation and inhibition of NF-κB/IκBα phosphorylation as a potent chemotherapeutic agent for ovarian cancers.

Identification of bitter components from Artemisia princeps Pamp.

Identification of bitter components from the aerial parts of Artemisia princeps Pamp. was performed to search for a method to eliminate the bitter taste from A. princeps products. The aerial parts of A. princeps were extracted in an aqueous EtOH solution, and the obtained extracts were partitioned into essential-oil, flavonoid-rich, n-BuOH, and aqueous fractions. Two purified bitter sesquiterpenoids were identified through repeated column chromatography of the bitterest fraction, the flavonoid-rich fraction, through an activity-guided fractionation method. The compounds were identified to be 1α,6α,8α-trihydroxy-5α,7ßH-guaia-3,9,11(13)-trien-12-oic acid and artecalin, respectively, based on the interpretation of NMR, MS, and IR spectroscopic data. Both compounds were 50 times bitterer than caffeine and had similar bitterness to quinine HCl. Neither eupatilin nor jaceosidin, the major active components of A. princeps, showed any bitterness.

Two New Cyototoxic Cardenolides from the Whole Plants of Adonis multiflora Nishikawa & Koki Ito.

A phytochemical investigation of the whole plants of Adonis multiflora Nishikawa & Koki Ito. resulted in the isolation and identification of two new cardenolides--adonioside A (1) and adonioside B (6)--as well as four known cardenolides: tupichinolide (2) oleandrine (3), cryptostigmin II (4), and cymarin (5). Their structures were elucidated on the basis of NMR, MS, and IR spectroscopic analyses. Compounds 1, 2, 5, and 6 showed significant cytotoxicity against six human cancer cell lines (HCT-116, HepG2, HeLa, SK-OV-3, and SK-MEL-5, and SK-BR-3).

Antimelanogenic Effects of Picrionoside A Isolated from the Leaves of Korean Ginseng.

This study was initiated to isolate active metabolites from the leaves of Panax ginseng. Among them, picrionoside A, a megastigmane glucoside, was isolated from the leaves of P. ginseng C. A. MAYER and its chemical structure was determined based on spectroscopic methods, including FAB-MS, one-dimensional (1D)-NMR, 2D-NMR, and IR spectroscopy. Picrionoside A from P. ginseng has not been investigated previously, and its biological or pharmaceutical activities have not been reported elsewhere. The IC50 value of mushroom tyrosinase-inhibitory activity of picrionoside A was 9.8 µM, and the rate of inhibition of synthesized melanin content in melan-a cells was 17.1% at a concentration of 80 µM without cytotoxicity. Furthermore, picrionoside A dramatically reduced body pigmentation in the zebrafish model. Taken together, the results suggest that picrionoside A isolated from the leaves of P. ginseng may be an effective skin-whitening agent that could be a potent candidate material in the cosmetic industry.

Recovery effect of phenylpropanoid glycosides from Magnolia obovata fruit on alloxan-induced pancreatic islet damage in zebrafish (Danio rerio).

Investigation of phytochemicals from Magnolia obovata fruit led to the isolation of three novel phenylpropanoid glycosides: obovatoside A-C (1-3) and two known phenylpropanoids, syringin (4) and pavonisol (5). The structures of 1-5 were determined by NMR, HRMS, IR and CD spectroscopic analyses. All compounds were evaluated for their effects on recovery from alloxan-induced pancreatic islet damage in zebrafish. All compounds increased the size of the injured pancreatic islet from 0.60- to 1.14-fold. Compounds 1 and 3-5 significantly increased glucose absorption in zebrafish.

Isoprenylated flavonoids from the root bark of Morus alba and their hepatoprotective and neuroprotective activities.

A new isoprenylated flavonoid, 2S-5,7,2',4'-tetrahydroxy-3',5'-di-(γ,γ-dimethylallyl)flavanone, sanggenol Q (1), along with seven known isoprenylated flavonoids, sanggenol A (2), sanggenol L (3), kuwanon T (4), cyclomorusin (5), sanggenon F (6), sanggenol O (7), and sanggenon N (8), three known Diels-Alder type adducts, sanggenon G (9), mulberrofuran G (10), and mulberrofuran C (11), and a known benzofuran, moracin E (12), were isolated from the root bark of Morus alba using silica gel, ODS, and Sephadex LH-20 column chromatography. Chemical structures were determined based on spectroscopic data analyses including NMR, MS, CD, and IR. For the first time, compounds 1 and 7 were isolated from the root bark of M. alba. All compounds were evaluated for hepatoprotective activity on t-BHP-induced oxidative stress in HepG2 cells and neuroprotective activity on glutamate-induced cell death in HT22 cells. Compounds 1, 4, 8, 10, and 11 showed protective effects on t-BHP-induced oxidative stress with EC50 values of 6.94 ± 0.38, 30.32 ± 6.82, 23.45 ± 4.72, 15.31 ± 2.21, and 0.41 ± 0.48 µM, respectively, and compounds 1, 2, 10, 11, and 12 showed protective effects on glutamate-induced cell death with EC50 values of 5.54 ± 0.86, 34.03 ± 7.71, 19.71 ± 0.71, 16.50 ± 7.82, and 1.02 ± 0.13 µM, respectively.

Neuroprotective effect of prenylated arylbenzofuran and flavonoids from morus alba fruits on glutamate-induced oxidative injury in HT22 hippocampal cells.

A prenylated arylbenzofuran and six flavonoids were isolated from the fruits of Morus alba L. through silica gel, octadecyl silica gel, and Diaion HP-20 column chromatography. Based on the nuclear magnetic resonance, mass spectrometry, and infrared spectroscopic data, the chemical structures of the compounds were determined to be artoindonesianin O (1), isobavachalcone (2), morachalcone A (3), quercetin (4), astragalin (5), isoquercetin (6), and rutin (7). The isolated compounds were evaluated for protection of HT22-immortalized hippocampal cells against glutamate-induced oxidative stress. Compounds 1 and 3 exhibited protective effects with EC(50) values of 19.7±1.2 and 35.5±2.1 µM, respectively. The major compounds 1-3 and 7 were quantified using liquid chromatography/mass spectrometry analysis and were determined to be 1.88±2.1, 1.90±1.8, 0.78±1.5, and 37.29±2.2 mg/kg, respectively, in the ethanol extract of M. alba L. fruits.

Lignan and flavonoids from the stems of Zea mays and their anti-inflammatory and neuroprotective activities.

The stems of Zea mays L., otherwise known as cornstalks, were extracted with 80 % aqueous MeOH, and the concentrated extract was successively partitioned with ethyl acetate (EtOAc), normal butanol, and water. From the EtOAc fraction, a new lignan along with three known flavonoids, tricin (1), salcolin A (2), and salcolin B (3), were isolated. The chemical structure of the lignan was determined to be tetrahydro-4,6-bis(4-hydroxy-3-methoxyphenyl)-1H,3H-furo[3,4-c]furan-1-one (4) through spectroscopic data analyses including NMR, MS, and IR. All compounds were isolated for the first time from this plant. The isolated compounds were evaluated for their inhibitory activity against NO production in Lipopolysaccharide-induced RAW 264.7 cells and their protective activity in glutamate-induced cell death in HT22 cells. The compounds 1, 2 and 4 showed anti-inflammatory effects with IC50 values of 2.63, 14.65, and 18.91 µM, respectively, as well as neuroprotective effects with EC50 values of 25.14, 47.44, and >80 µM, respectively.

Lignans and neolignans from the stems of Vibrunum erosum and their neuroprotective and anti-inflammatory activity.

A new lignan, (7'S,8S,8'S)-3,5'-dimethoxy-3',4,9'-trihydroxy-7',9-epoxy-8,8'-lignan, named vibruresinol (1), was isolated from the stems of Viburnum erosum by silica gel, ODS, and Sephadex LH-20 column chromatography. In addition, four other known lignans, (7'R,8S,8'S)-3,5'-dimethoxy-3',4,8',9'-tetrahydroxy-7',9-epoxy-8,8'-lignan (2), (+)-syringaresinol (3), (+)-pinoresinol (4), and (+)-pinoresinol-4-O-ß-D-glucopyranoside (5), and five known neolignans, herpetol (6), vibsanol (7), (-)-dehydrodiconiferyl alcohol (8), icariside E4 (9), and dihydrodehydrodiconiferyl alcohol (10), were isolated in the same manner. The chemical structures of the compounds were determined based on spectroscopic data including NMR, MS, and IR. All of the compounds described above were isolated from V. erosum for the first time. The isolated compounds 3, 4, and 6 were evaluated for neuroprotective activity on glutamate-induced cell death in HT22 cells and had EC50 values of 6.33 ± 1.22, 6.96 ± 0.65, and 9.15 ± 0.36 µM, respectively. Likewise, the same compounds had inhibitory activity on NO production in LPS-induced RAW 264.7 cells with IC50 values of 8.30 ± 1.56, 7.89 ± 1.22, and 9.32 ± 0.36 µM, respectively.

Quality evaluation of Panax ginseng roots using a rapid resolution LC-QTOF/MS-based metabolomics approach.

Korean ginseng (Panax ginseng C.A. Meyer) contains several types of ginsenosides, which are considered the major active medicinal components of ginseng. The types and quantities of ginsenosides found in ginseng may differ, depending on the location of cultivation, making it necessary to establish a reliable method for distinguishing cultivation locations of ginseng roots. P. ginseng roots produced in different regions of Korea, China, and Japan have been unintentionally confused in herbal markets owing to their complicated plant sources. PCA and PLS-DA using RRLC-QTOF/MS data was able to differentiate between ginsengs cultivated in Korea, China, and Japan. The chemical markers accountable for such variations were identified through a PCA loadings plot, tentatively identified by RRLC-QTOF/MS and partially verified by available reference standards. The classification result can be used to identify P. ginseng origin.