Changyeol Lee

Antiviral activities of compounds from aerial parts of Salvia plebeia R. Br

ETHNOPHARMACOLOGICAL RELEVANCE Salvia plebeia R. Br. is an edible plant widely spread in many countries. It has been used as a traditional medicine to treat common cold, flu, cough, hepatitis, hemorrhoids, etc. The purpose of the study is to explicate antiviral compounds responsible for its traditional use for the common cold or flu. MATERIALS AND METHODS The methanolic extract of the aerial parts of S. plebeia was extracted with CHCl3, EtOAc, and n-BuOH, successively. The EtOAc and CHCl3 fractions were subjected to a successive of chromatographic method, which led to the isolation of fourteen compounds. Inhibition activities of the isolated compounds were evaluated against influenza A (H1N1) neuraminidase. RESULTS Chemical investigation of the methanolic extracts of S. plebeia resulted in the isolation of two novel benzoylated monoterpene glycosides, named as plebeiosides A (1) and B (2), together with twelve known compounds including four flavonoids (4-5, 7, 10), two sesquiterpenoids (8, 12), four phenolics (9-10, 13-14), a steroid (6), and a triterpenoid (3). Their chemical structures were elucidated based on spectroscopic data and absolute stereochemistries of 1 and 2 were determined by comparison of optical rotations of their hydrolysates with literature values. Compounds 5, 7, 9, and 11 exhibited potent enzymatic inhibition against H1N1 neuraminidase (IC50 values ranging from 11.18±1.73 to 19.83±2.28μM). Furthermore, two flavonoids (5 and 7) and one rosmarinic acid methyl ester (9) reduced cytopathic effects of the H1N1 virus during replication. CONCLUSIONS The antiviral activities of the flavonoids and phenolics isolated from the extracts of S. plebeia supported the traditional application of this medicine on common cold or flu. In this study, benzoylated monoterpene glycosides were first found to exist in this species. Moreover, the present study suggested potential of three compounds (5, 7, and 9) to be new lead structures for the development of new neuraminidase inhibitors in the future.

New Aromatic Compounds from the Fruiting Body of Sparassis crispa (Wulf.) and Their Inhibitory Activities on Proprotein Convertase Subtilisin/Kexin Type 9 mRNA Expression

Successive chromatography of EtOAc-soluble extracts of the fruiting body of Sparassis crispa (Wulf.) resulted in isolation of four new aromatic compounds, sparoside A (1) and sparalides A-C (3-5), two new naturally occurring compounds, 2 and 6, and eight known compounds, 7-14. The chemical structures were determined by interpretation of nuclear magnetic resonance and mass spectrometry spectroscopic data. Extract, solvent-soluble fractions of the extract, and all of the pure compounds isolated from the fractions were subjected to the mRNA expression assay for proprotein convertase subtilisin/kexin type 9 (PCSK9). Among them, sparoside A (1), hanabiratakelide A (8), adenosine (11), and 5α,6α-epoxy-(22E,24R)-ergosta-8(14),22-diene-3β,7β-diol (14) exhibited potent inhibitory activities on PCSK9 mRNA expression, with IC50 values of 20.07, 7.18, 18.46, and 8.23 μM, respectively (berberine, positive control, IC50 = 8.04 μM), suggesting that compounds 1, 8, 11, and 14 are suitable for use in supplements to the statins for hyperlipidemia treatments.

Bioactive secondary metabolites produced by an endophytic fungus Gaeumannomyces sp. JS0464 from a maritime halophyte Phragmites communis

Endophytes, important plant-associated mycobionts, have attracted a great deal of attention because of their bioactive secondary metabolites. Even though halophytes have been reported to overcome salt stress via associations with their endophytes, few studies have investigated the metabolites produced by the endophytes from halophytes. In this study, a dark septate endophytic fungal strain (JS0464), identified as Gaeumannomyces sp. by ITS sequencing, was isolated from the rhizome of a halophyte, Phragmites communis, in Suncheon bay, South Korea. This strain was cultured on a large scale and extracted with ethyl acetate. Chemical investigations of extracts of JS0464 led to the isolation of two glycosylated dialkylresorcinol derivatives (1–2), an anthraquinone derivative (3) and eight known compounds (4–11), which were identified by spectroscopic analyses incorporating one-dimensional/2D NMR and MS. Nine compounds showed significant nitric oxide reduction activity in lipopolysaccharide-stimulated microglia BV-2 cells, seven of which did not impair cell viability. The results suggest that endophytes from the halophytes could be potential resources for bioactive natural products.

Isochromans and Related Constituents from the Endophytic Fungus Annulohypoxylon truncatum of Zizania caduciflora and Their Anti-Inflammatory Effects

Six new isochroman derivatives (annulohypoxylomans A-C, 1-3; annulohypoxylomanols A and B, 6 and 7; and annulohypoxyloside, 8), an isocoumarin (annulohypoxylomarin A, 4), and an azaphilone derivative (xylariphilone, 5) were isolated from an ethyl acetate extract derived from cultures of the endophytic fungus JS540 found in the leaves of Zizania caduciflora. The JS540 strain was identified as Annulohypoxylon truncatum. The structures of the isolated compounds were elucidated by one- and two-dimensional nuclear magnetic resonance and mass spectrometry and by comparison with related compounds from the literature. The anti-inflammatory activities of the isolated compounds were evaluated in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells. Xylariphilone (5) exhibited significant inhibitory effects on LPS-induced interleukin (IL)-6, IL-12 p40, and tumor necrosis factor (TNF)-α production with IC50 values of 5.3, 19.4, and 37.6 μM, respectively.

Neuroprotective Compound from an Endophytic Fungus, Colletotrichum sp. JS-0367

Colletotrichum sp. JS-0367 was isolated from Morus alba (mulberry), identified, and cultured on a large scale for chemical investigation. One new anthraquinone (1) and three known anthraquinones (2-4) were isolated and identified using spectroscopic methods including 1D/2D-NMR and HRESIMS. Although the neuroprotective effects of some anthraquinones have been reported, the biological activities of the four anthraquinones isolated in this study have not been reported. Therefore, the neuroprotective effects of these compounds were determined against murine hippocampal HT22 cell death induced by glutamate. Compound 4, evariquinone, showed strong protective effects against HT22 cell death induced by glutamate by the inhibition of intracellular ROS accumulation and Ca2+ influx triggered by glutamate. Immunoblot analysis revealed that compound 4 reduced the phosphorylation of MAPKs (JNK, ERK1/2, and p38) induced by glutamate. Furthermore, compound 4 strongly attenuated glutamate-mediated apoptotic cell death.

Anti-influenza effect of the major flavonoids from Salvia plebeia R.Br. via inhibition of influenza H1N1 virus neuraminidase

Abstract To determine the compounds responsible for its anti-influenza activities, we isolated the three flavonoids, 6-hydroxyluteolin 7-O-β-d-glucoside (1), nepitrin (2), homoplantaginin (3) from the MeOH extract of Salvia plebeia R.Br. and identified them by comparing the spectroscopic data with that reported in the literature. The contents of the three flavonoids in the whole extract were 108.74 ± 0.95, 46.26 ± 2.19, and 69.35 ± 1.22 mg/g for 6-hydroxyluteolin 7-O-β-d-glucoside, nepitrin, and homoplantaginin, respectively, which demonstrates that they are the major constituents of this plant. The three flavonoids were evaluated for their inhibitory activities against influenza virus H1N1 A/PR/9/34 neuraminidase and H1N1-induced cytopathic effect (CPE) on Madin-Darby canine kidney (MDCK) cells. Our results demonstrated the following arrangement for their anti-influenza activities: nepitrin (2) > 6-hydroxyluteolin 7-O-β-d-glucoside (1) > homoplantaginin (3). The potent inhibitory activities of these flavonoids against influenza suggested their potential to be developed as novel anti-influenza drugs in the future.

Chemical constituents of the aerial part of Taraxacum mongolicum and their chemotaxonomic significance

Abstract A phytochemical investigation of Taraxacum mongolicum led to the isolation of 24 compounds, including six flavonoids (1–6), four sesquiterpenes (7–10), two sphingolipids (11 and 12), six glycerols (13–18) and six triterpenoids and sterols (19–24). The structures of these compounds were identified by spectroscopic methods, and their data compared with those reported in the literature. This is the first report of compounds 11–19 from T. mongolicum and the genus Taraxacum, and compounds 11, 12, 15, 16, 18 and 19 from the Asteraceae family. The chemotaxonomic relationship between T. mongolicum and other Taraxacum species is also discussed.

A New Neolignan from the Aerial Parts of Prunella vulgaris var. lilacina

Prunella vulgaris is known to contain pentacyclic triterpenoids, flavonoids, phenolic compounds, and steroids. Among the triterpenoids, the oleanane-type, ursane-type, and lupane-type triterpenoids have been known to be predominant. Our phytochemical study led to the isolation of a new neolignan, 9′-O-butyl dehydrodiconiferyl alcohol 4-O-β-D-glucopyranoside (1), together with four known compounds, astragalin (2), benzyl-O-β-D-glucopyranoside (3), paeonoside (4), and 4-hydroxybenzoic acid (5). It is noteworthy that all the isolated compounds are reported for the first time from the genus Prunella.