Publications by authors named "Ji Sang Hwang"

Recently, denoising diffusion models have demonstrated remarkable performance among generative models in various domains. However, in the speech domain, there are limitations in complexity and controllability to apply diffusion models for time-varying audio synthesis. Particularly, a singing voice synthesis (SVS) task, which has begun to emerge as a practical application in the game and entertainment industries, requires high-dimensional samples with long-term acoustic features.

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The activity-guided fractionation of the MeOH extract of the rhizomes and roots of Nardostachys chinensis led to the isolation of two new sesquiterpenoids, narchinol B (8) and narchinol C (9), along with 10 known compounds, ursolic acid (1), nardosinone (2), pinoresinol (3), desoxo-narchinol A (4), kanshone B (5), epoxyconiferyl alcohol (6), debilon (7), 4α,5-dimethyl-1,3-dioxo-1,2,3,4,4α,5,6,7-octahydronaphthalene (10), p-coumaric acid (11), and isoferulic acid (12). Their structures were determined using spectroscopic techniques, which included 1D- and 2D-NMR. Among the isolates, compounds 2, 4, 5, 8 and 9 showed inhibitory activity against LPS-induced NO production with IC(50) values of 4.

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A new pyrrolidinone diterpenoid, excisusin F (1), was isolated from the aerial parts of Isodon excisus (Lamiaceae), together with four known compounds, and their structures were determined mainly by NMR (1D and 2D) and mass spectrometry. Excisusin F (1) and inflexarabdonin E (3) showed potent inhibitory effects of LPS-induced nitric oxide production in RAW264.7 cells with the IC(50) value of 10.

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Bioactivity-guided isolation of the methanol extract of the stems of Dendrobium nobile yielded a new phenanthrene together with nine known phenanthrenes and three known bibenzyls. Their structures were elucidated by analysis of the spectroscopic data including 2D-NMR. All of the isolates were evaluated for their potential to inhibit the LPS-induced production of nitric oxide in murine macrophage RAW 264.

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We have previously reported that piperine, a known piperidine alkaloid from Piper longum, competitively inhibited mouse brain MAO-A and MAO-B activities. Piperine also showed in vivo antidepressant-like activity against the tail suspension test. In the present study, we further expanded on the identification of MAO inhibitors from the fruit of P.

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Five ent-kaurane diterpenoids, 6beta,7beta,14beta-trihydroxy-1alpha,19-diacetoxy-7alpha,20-epoxy- ent-kaur-16-en-15-one (1), 1alpha,6beta,7beta-trihydroxy-11alpha,19-diacetoxy-7alpha,20-epoxy-ent-kaur-16-en-15-one (2), 6-hydroxy-1alpha,19-diacetoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide (3), 19-hydroxy-1alpha,6-diacetoxy-6,7-seco- ent-kaur-16-en-15-one-7,20-olide (4), and 6-aldehyde-1alpha,19-diacetoxy-6,7-seco- ent-kaur-16-en-15-one-7,20-olide (5), along with 10 known ent-kaurane diterpenoids, pseurata C (6), longikaurin C (7), effusanin C (8), longikaurin B (9), longikaurin D (10), effusanin D (11), excisanin B (12), lasiokaurin (13), megathyrin A (14), and loxothyrin A (15), were isolated from the aerial parts of Isodon japonicus. Their structures were determined on the basis of spectroscopic (1D-, 2D-NMR and MS) and chemical evidence. The isolates were evaluated for their inhibitory effects on LPS-induced production of nitric oxide in murine macrophage RAW264.

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Two new melampolide-type sesquiterpene lactones, 8beta-epoxyangeloyloxy-9alpha-ethoxy-14-oxo-acanthospermolide (1) and 8beta-angeloyloxy-9alpha-ethoxy-14-oxo-acanthospermolide (2), were isolated from the leaves of yacon [Smallanthus sonchifolia (POEPP. et ENDL.) H.

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Four new prenylated xanthones, cudratricusxanthones J-M (1-4), were isolated from the CH2Cl2-soluble extract of the root bark of Cudrania tricuspidata, along with four known prenylated xanthones, isocudraxanthone K (5), cudraxanthone C (6), cudratricusxanthone A (7), and cudraxanthone L (8), and three known prenylated flavonoids, cudraflavone A (9), cudraflavanone A (10), and cudraflavone B (11). The structures of compounds 1-4 were elucidated using spectroscopic methods. Cudratricusxanthone A (7), cudraflavanone A (10), and cudraflavone B (11) showed moderate inhibitory effects on mouse brain monoamine oxidase (MAO) with IC50 values of 88.

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Seven flavonoids were isolated from the whole plants and fruits of Cayratia japonica through the activity-guided isolation of a methanol extract using a monoamine oxidase (MAO) inhibition assay as a monitor. The chemical structures of the isolates were assigned as apigenin-7-O-beta-D-glucuronopyranoside (1), apigenin (2), luteolin (3), luteolin-7-O-beta-D-glucopyranoside (4), (+)-dihydroquercetin (taxifolin) (5), (+)-dihydrokaempferol (aromadendrin) (6) and quercetin (7). Among the isolated compounds, flavones such as apigenin (2) and luteolin (3), as well as the flavonol, quercetin (7) showed potent inhibitory effects against the MAO activity with IC50 values of 6.

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The methanol extract from the aerial parts of Dictamnus albus was active in inhibiting monoamine oxidase (MAO) from the mouse brain. Activity-guided fractionation led to the isolation of four known coumarins, 7-(6'R-hydroxy-3', 7'-dimethyl-2'E, 7'-octadienyloxy) coumarin (1), auraptene (2), umbelliferone (3), and xanthotoxin (4), as active compounds along with an inactive alkaloid, skimmianine (5). Compounds 1 and 2 inhibited MAO activity in a concentration-dependent manner with IC50 values of 0.

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A new butyrolactone sesquilignan, isolappaol C (1), together with four known lignans, lappaol C (2), lappaol D (3), lappaol F (4), and diarctigenin (5), were isolated from the methanolic extract of the seeds from the Arctium lappa plant. The structure of isolappaol C (1) was determined by spectral analysis including 1D- and 2D-NMR. All the isolates were evaluated for their inhibitory effects on the LPS-induced nitric oxide production using murine macrophage RAW264.

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A methylene chloride soluble fraction of the fruits of Cudrania tricuspidata significantly inhibited the mouse brain monoamine oxidase (MAO). Three known prenylated isoflavones were isolated and identified by activity-guided fractionation. Gancaonin A (1), 4'-O-methylalpinumisoflavone (2), and alpinumisoflavone (3) inhibited MAO activity in a concentration-dependent manner with IC50 values of 19.

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A bioassay-guided isolation of the ethanol extract from the fruits of Piper longum yielded a known piperidine alkaloid, piperine, as a monoamine oxidase (MAO) inhibitor. Piperine showed an inhibitory effect against MAO-A (IC50 value: 20.9 microM) and MAO-B (IC50 value: 7.

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In our search for monoamine oxidase (MAO) inhibitors from natural resources, we found that the methanol extract of the roots of Sophora flavescens showed an inhibitory effect on mouse brain monoamine oxidase (MAO). Bioactivity-guided isolation of the extract yielded two known flavonoids, formononetin (1) and kushenol F (2), as active compounds along with three inactive compounds, oxymatrine (3), trifolirhizin (4), and beta-sitosterol (5). Formononetin (1) and kushenol F (2) showed significant inhibitory effects on MAO in a dose-dependent manner with IC50 values of 13.

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