Youngwan Seo

Flavonoid glycosides isolated from Salicornia herbacea inhibit matrix metalloproteinase in HT1080 cells

Flavonoid glycosides, isorhamnetin 3-capital O, Cyrillic-beta-d-glucoside, and quercetin 3-O-beta-d-glucoside were isolated from Salicornia herbacea and their inhibitory effects on matrix metalloproteinase-9 and -2 (MMP-9 and -2) were evaluated in human fibrosarcoma cell line (HT1080). In zymography experiments, these flavonoid glycosides led to the reduction of the expression levels and activities of MMP-9 and -2 without any significant difference between these flavonoid glycosides. Protein expression levels of both MMP-9 and MMP-2 were inhibited and TIMP-1 (tissue inhibitor of metalloproteinase-1) protein level was enhanced by these flavonoid glycosides. Moreover, a transfection study carried out with AP-1 reporter construct revealed that the reporter activity was suppressed by treatment with isorhamnetin 3-capital O, Cyrillic-beta-d-glucoside. Therefore, these results suggested that these flavonoid glycosides have a potential as valuable natural chemopreventive agents for cancer.

Solandelactones A-I, lactonized cyclopropyl oxylipins isolated from the hydroid Solanderia secunda

Abstract Solandelactones A-I(1–9), cyclopropyl and lactone containing novel docosanoids have been isolated from the hydroid Solanderia secunda. The structures of these compounds have been elucidated by combined spectral and chemical studies. Configuration of the cyclopropyl ring has been assigned as the opposite of related oxylipins by NOESY experiments. Absolute stereochemistry has been determined on the basis of chemical transformations and CD measurements of synthetic derivatives. In addition, the biogenetic origin of solandelactones has been discussed. Solandelactones C, D, and G exhibited moderate inhibitory activity against Farnesyl Protein Transferase.

Anti-inflammatory effect of coumarins isolated from Corydalis heterocarpa in HT-29 human colon carcinoma cells.

We investigated anti-inflammatory effects of two coumarins, columbianetin (A) and libanoridin (B), isolated from Corydalis heterocarpa in lipopolysaccharide (LPS)-stimulated HT-29 human colon carcinoma cells. Treatment with compound B inhibited the protein expression levels of inflammatory mediators such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) in a dose-dependent manner in LPS-stimulated HT-29 cells, but compound A did not. Also, compound B had a higher inhibitory effect on production of cytokines such as IL-1 beta and TNF-alpha in LPS-stimulated HT-29 human colon carcinoma cells than those of compound A. Furthermore, we confirmed that LPS-induced transcription activity of NF-kappaB was inhibited by compound B. As a result of this study, compound B can be considered as a potential anti-inflammatory agent.

Protective effect of isorhamnetin 3-О-β-d-glucopyranoside from Salicornia herbacea against oxidation-induced cell damage

Isorhamnetin 3-O-beta-D-glucopyranoside (1) was isolated from Salicornia herbacea. The inhibitory effects of compound 1 on oxidative stress were evaluated in free-cellular and cellular systems. An increased concentration of compound 1 not only exhibited dose-dependent scavenging activities on the generation of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and carbon-centered radicals, but also significantly decreased levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner. Further, antioxidative mechanisms by compound 1 were examined by measuring the intracellular glutathione (GSH) level and expression levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione reductase and heme oxygenase-1 (HO-1). Compound 1 significantly elevated GSH level as well as expression levels of antioxidant enzymes which were closely related with amount of cellular ROS. In addition, it significantly inhibited oxidative damage of purified genomic DNA and suppressed activity of myeloperoxidase (MPO), a generator of potent oxidant (hypochlorous acid), in tumor necrosis factor-alpha (TNF-alpha) stimulated human myeloid cells. Therefore, these results suggested that compound 1 has a therapeutic effectiveness in prevention of ROS-induced cellular damage and is a candidate worthy of being developed as a potential natural antioxidant related to oxidative stress.

Evaluation of novel antioxidant triterpenoid saponins from the halophyte Salicornia herbacea.

As a part of an ongoing search for novel antioxidants from the salt marsh plants, bioactivity-isolation and structure determination of constituents from Salicornia herbacea were performed. One new triterpenoid saponin (4), along with three known saponins (1-3), has been isolated from n-BuOH fraction of S. herbacea. On the basis of the spectroscopic methods, the structure of the new saponin 4 was elucidated as 3β-hydroxy-23-oxo-30-noroleana-12, 20(29)-diene-28-oic acid 3-O-β-D-glucuronopyranosyl-28-O-β-d-glucopyranoside. Scavenging effects of saponins 1-4 were examined on 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical and peroxynitrite. Particularly, saponin 3 exerted significant antioxidant activity on both authentic peroxynitrite and peroxynitrite generated from morpholinosydnonimine (SIN-1).

Osirisynes A-F, highly oxygenated polyacetylenes from the sponge Haliclona osiris

Abstract Osirisynes A-F( 1–6 ), highly oxygenated C 47 polyacetylenes have been isolated from the sponge Haliclona osiris collected from Guam. These compounds possess a diacetylenic carbinol and an α-acetylenic carboxylic acid as common structural features. The structures of osirisynes have been determined by combined spectroscopic methods. These compounds exhibited moderate cytotoxicity and inhibitory activities against Na + K + -ATPase and reverse transcriptase (RT).

CYCLOREDUCTIONS VIA ALKYLPALLADIUM INTERMEDIATES : AN IMPORTANT MECHANISTIC CLUE FOR PALLADIUM-CATALYZED ENEDIYNE CYCLIZATIONS

Abstract Various enediynes have been successfully cyclized via the alkylpalladium intermediates to the corresponding [m, 5,n] tricyclic compounds.

Antioxidant properties ofErigeron annuus extract and its three phenolic constituents

The antioxidant activity of the extract ofErigeron annuus was assessed by means of two differentin vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and the scavenging of authentic peroxynitrite in company with peroxynitrite generation from 3-morpholinosydnonimine (SIN-1). In both tests, the 85% aq. MeOH andn-BuOH soluble fractions of the crude extract showed a significant scavenging effect on peroxynitrite and DPPH radical in comparison to L-ascorbic acid. And bioassay-guided fractionation of then-BuOH soluble fraction led to the isolation of three compounds: Apigenin (1), quercetin-3-O-glucoside (2), and caffeic acid (3). The structures of the isolated compounds were elucidated on the basis of their spectroscopic data and their antioxidant activities were measured by determining their capacity to scavenge peroxynitrite and the DPPH radical.

Peroxynitrite-scavenging constituents from the brown algaSargassum thunbergii

Peroxynitrite formationin vivo is implicated in numerous human diseases and there is considerable interest in the use of antioxidants and natural products for their treatment. The three components (1–3) isolated fromSargassum thunbergii as well as the organic solventsoluble fractions and the aqueous layer ofS. thunbergii were evaluated for their potential to scavenge authentic ONOO and ONOO derived from 3-morpholinosydnonimine (SIN-1). The antioxidant activity of the individual fractions was in the order of 85% aquaous (aq.) MeOH>n-BuOH>n-hexane> H2O. The three known compounds sargahydroquinoic acid (1), sargaquinoic acid (2) and sargachromenol (3) showed peroxynitrite-scavenging activities comparable to those of L-ascorbic acid and penicillamine. These results showed a possible antioxidant activity in major constituents ofS. thunbergii.

Isolation of novel bioactive steroids from the soft coral Alcyonium gracillimum

Abstract Seven steroids including five new compounds ( 1–5 ) have been isolated from the soft coral Alcyonium gracillimum . Compound 1 is a spiroketal of the furospirostan class while compounds 2 and 3 are hemiketals of the corresponding furostan class. Compound 4 possesses an unusual cyclic enolether linkage between the C-18 and C-22 carbons of the cholestane skeleton. The structures of these compounds were determined by combined spectroscopic methods. The hemiketals 2 and 3 exhibited moderate cytotoxicity and antiviral activity.