• 생약학회지
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• 제51권4호
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• pp.238-243
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• 2020

Perilla frutescens Britton var. acuta Kudo, an annual plant primarily cultivated in China, Japan, and Korea, has been used as a traditional medicine to treat inflammatory diseases, depression, and many anxiety-related disorders. Previously, we reported the inhibitory effects of n-hexane layer of P. frutescens var. acuta extract against beta-amyloid (Aβ) aggregation, and the isolation of asarone derivatives as active constituents from n-hexane layer. In this study, dichloromethane layer of P. frutescens var. acuta was applied to bioassay-guided isolation methods accompanied with Thioflavin T (Th T) fluorescence assay to investigate the inhibitory effect on Aβ aggregation and disaggregation. As the results, three triterpenoids including ursolic acid (1), tormentic acid (2) and corosolic acid (3) were isolated. All compounds reduced Aβ aggregation and increased disaggregation of preformed Aβ aggregates in a dose-dependent manner. However, the inhibitory effect of three compounds on Aβ aggregation was not correlated with antioxidant activity, which was measured by DPPH assay. Taken together, these results suggest that the triterpenoid derivatives from P. frutescens have the potential to be developed as good therapeutics or preventatives for AD.

• Natural Product Sciences
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• 제26권4호
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• pp.340-344
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• 2020

A new chromone analogue (1) was isolated from an EtOAc-extract of Pleosporales sp. culture medium, together with five known chromones (2 - 6). The isolation workflow was guided by a Molecular Networking-based dereplication strategy. The chemical structure of the new compound was elucidated using NMR and MS spectroscopy, and the absolute configuration was established by the Mosher's method. All isolated compounds were evaluated for their inhibitory effects on lipopolysaccharide-induced nitirc oxide production in RAW 264.7 macrophages. Compound 1 showed marginal inhibitory activity with an IC50 value of 118.7 μM.

• 동의생리병리학회지
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• 제19권1호
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• pp.119-123
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• 2005

In the courses of in vitro screening for the angiotensin converting enzyme (ACE) inhibitory activity of the various extracts from medicinal plants, n-BuOH soluble extract of the seeds of Xanthium strumarium was found to exhibit distinctive angiotensin converting enzyme (ACE) inhibitory activity. Bioassay-guided fractionation and purification of the n-BuOH soluble extract of the seeds of Xanthium strumarium afforded a new $xanthiazone-11-{\beta}-glucopyranoside$. The ACE activity was significantly inhibited by the addition of a new $xanthiazone-11-{\beta}-glucopyranosidein$ a dose-dependent manner of which $IC_{50}$ value was $21.8\;{\mu}g/ml$.

• Natural Product Sciences
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• 제15권4호
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• pp.241-245
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• 2009

In the course of screening for antioxidant compounds by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging effect and superoxide quenching activity, methanol extract of Cyperus difformis (Cyperaceae) was found to show potent antioxidant activities. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of three phenolic compounds, rosmarinic acid (1), luteolin (2) and caffeic acid (3). Their structures were elucidated by spectroscopic studies. Three compounds showed the significant antioxidative effects on DPPH and nitric oxide radical scavenging effects, riboflavin and xanthin originated superoxide quenching activities. Among them, compound 3 showed the most significant antioxidative effects on those four antioxidant tests. Compound 3 showed better antioxidative activities than vitamin C.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1585-1590
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• 2007

Although a number of melanogenesis inhibitors have recently been reported and used as cosmetic additives, none is completely satisfactory, leaving a need for novel skin-depigmenting agents. Thus, to develop a novel skin depigmenting agent from natural sources, the inhibition of melanogenesis by Chinese plants was evaluated. A methanolic extract of Nigella glandulifera Freyn was found to inhibit the melanin synthesis of murine B16F10 melanoma cells by 43.7% and exhibited a low cytotoxicity (8.1%) at a concentration of $100\;{\mu}g/ml$. Thus, to identify the melanogenesis-inhibiting mechanism, the inhibitory activity towards tyrosinase, the key enzyme of melanogenesis, was further evaluated, and the results showed inhibitory effects on the activity of intracellular tyrosinase yet not on mushroom tyrosinase. Finally, to isolate the compounds with a hypopigmenting capability, activity-guided isolation was performed, and Dioctyl phthalate identified as inhibiting melanogenesis.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1206-1211
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• 2013

The selective inhibition of PTP1B has been widely recognized as a potential drug target for the treatment of type 2 diabetes and obesity. In the course of screening for PTP1B inhibitory fungal metabolites, the organic extracts of several fungal species isolated from marine environments were found to exhibit significant inhibitory effects, and the bioassay-guided investigation of these extracts resulted in the isolation of fructigenine A (1), cyclopenol (2), echinulin (3), flavoglaucin (4), and viridicatol (5). The structures of these compounds were determined mainly by analysis of NMR and MS data. These compounds inhibited PTP1B activity with 50% inhibitory concentration values of 10.7, 30.0, 29.4, 13.4, and 64.0 ${\mu}M$, respectively. Furthermore, the kinetic analysis of PTP1B inhibition by compounds 1 and 5 suggested that compound 1 inhibited PTP1B activity in a noncompetitive manner, whereas compound 5 inhibited PTP1B activity in a competitive manner.

• Natural Product Sciences
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• 제19권3호
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• pp.242-250
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• 2013

The autophagy-lysosomal pathway is an important protein degradation system, and its dysfunction has been implicated in a number of neurodegenerative diseases, including Parkinson's disease. Raphani Semen, one of the herbs of Yeoldahanso-tang (YH), has neuroprotective effects via the autophagy pathway. The activity-guided method was used to isolate and identify the components of Raphani Semen. In this experiment, the total extract of Raphani Semen was partitioned to n-butanol, methylene chloride, and water fractions. Flow cytometry data showed that only the water fraction showed autophagy-inducing activity in vitro. Compounds 1 and 2 were isolated from this water fraction by preparative HPLC separation. The structures of compounds 1 and 2 were identified as stachyose and raffinose, respectively, by the analysis of various spectral data ($^1H$ NMR, $^{13}C$ NMR, and MS) and comparisons with standard stachyose and raffinose. Of these two compounds, raffinose showed autophagy-inducing activity in PC12 cells through the mTOR pathway.

• 한국어병학회지
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• 제18권3호
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• pp.227-237
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• 2005

본 연구에서는 주요 어류 병원성 그람음성세균인 E. tarda 및 V. anguillarum에 대하여 14 종의 생약 추출물의 항균활성을 검색하였다. 그 결과, 감초, 지유 및 칠피 추출물이 항균활성을 나타냄을 밝혔다. 그 중, 가장 우수한 항균활성을 나타낸 칠피 추출물에 대하여 활성지향적인 분리기법을 적용하여 활성분획물인 EtOAc분획물로부터 항균활성물질 1종을 분리하고 페놀성 화합물인 methyl gallate로 동정하였다. methyl gallate는 실험에 사용된 E. tarda 및 V. anguillarum의 균주들의 증식을 효과적으로 저해하였으며 이에 대한 MIC는 모두 1 mg/ml로 측정되었다.

• Food Science and Biotechnology
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• 제16권2호
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• pp.265-269
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• 2007

There is significant interest in finding new sources of acetylcholinesterase (AChE) inhibitors for use in treating Alzheimer's disease, since only a few AChE inhibitors are available for clinical use, such as galanthamine, physostigmine, and tacrine. The ethanol extract of Chrysanthemum indicum Linne flowers was analyzed and found to markedly decrease AChE activity. Acaciin and $acacetin-7-O-{\beta}-D-galactopyranoside$ were identified as the active compounds responsible for the AChE inhibition by using an activity-guided fractionation strategy. The relationship between structure and activity for five flavonoids (acaciin, $acacetin-7-O-{\beta}-D-galactopyranoside$, luteolin, and two other commercially available flavonoids, i.e., apigenin and acacetin) was also investigated, revealing that the presence of methoxy groups at C-4' in the B ring and a sugar at O-7 in ring A appear to be essential for the inhibition of AChE.

• Natural Product Sciences
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• 제29권2호
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• pp.59-66
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• 2023

The anti-melanogenic activity of 259 actinomycete strains was tested, and based on the results for the inhibition of mushroom tyrosinase activity and the reduction in melanin content, Micromonospora sp. JCS1 and JCS7 were selected as the strains with the highest anti-melanogenic potential. The activity-guided fractionation of extracts from JCS1 and JCS7 led to the isolation of the dipeptides cyclo(ʟ-Phenyl alanine (Phe)-ʟ-Proline (Pro)) (1) and cyclo(ʟ-Tryptophan (Trp)-ʟ-Proline (Pro)) (2). These two compounds were tested for their inhibition of mushroom tyrosinase by monitoring ʟ-DOPA levels and melanin production. Cyclo(ʟ-Phe-ʟ-Pro) (1) and cyclo(ʟ-Trp-ʟ-Pro) (2) were thus confirmed to have the potential for use in functional whitening cosmetics containing actinomycete-derived secondary metabolites.