Yeon Hee Choi

Antiproliferative effects of saponins from the roots of Platycodon grandiflorum on cultured human tumor cells.

Three new triterpenoid saponins, platyconic acid B lactone (1), deapio-platyconic acid B lactone (2), and deapio-platycodin D(2) (3), together with 17 known triterpenoid saponins, were isolated from a root extract of Platycodon grandiflorum. The structures of 1-3 were determined on the basis of spectroscopic data interpretation and chemical transformation. Saponins with a platycodigenin or polygalacic acid unit as a sapogenin demonstrated significant inhibitory effects on the proliferation of a small panel of cultured human tumor cells.

A new specific BACE-1 inhibitor from the stembark extract of Vitis vinifera.

A new resveratrol dimer, (+)-vitisinol E (1) which demonstrated inhibitory activity on BACE-1 (beta-site APP-cleaving enzyme 1) in vitro, was isolated from the stembark extract of Vitis vinifera (Vitaceae) together with four known resveratrol oligomers, (+)-epsilon-viniferin (2), (+)-ampelopsin A (3), (+)-vitisin A (4) and (-)-vitisin B (5). The chemical structure of 1 was established by MR spectroscopic analyses, including HMBC. All isolated resveratrol derivatives (1-5) demonstrated significant inhibition on baculovirus-expressed BACE-1 in a dose-dependent manner, which was assessed with the FRET assay using Rh-EVNLDAEFK as a substrate in vitro.

Platyconic Acid A, a Genuine Triterpenoid Saponin from the Roots of Platycodon grandiflorum

A genuine triterpenoid saponin, platyconic acid A (1) was isolated from the roots extract of Platycodon grandiflorum, together with five known saponins: deapioplatycoside E (2), platycoside E (3), platycodin D3 (4), platycodin D2 (5) and platycodin D (6). The structure of 1 was determined on the basis of spectral analysis and chemical evidence.

In Vitro BACE-1 Inhibitory Activity of Resveratrol Oligomers from the Seed Extract of Paeonia lactiflora

A new resveratrol oligomer (1) together with eight related components (2- 9) were isolated from the seed extract of Paeonia lactiflora (Paeoniaceae) as active principles responsible for the inhibition of beta-site APP-cleaving enzyme 1 (BACE-1) in vitro. The chemical structure of 1 was established as (-)-7a,8a- CIS- ε-viniferin with the aid of spectroscopic analyses including NOESY experiments. All isolated resveratrol oligomers (1- 9) demonstrated significant inhibition on baculovirus-expressed BACE-1 in a dose-dependent manner, which was assessed by the FRET assay using Rh-EVNLDAEFK as a substrate in vitro.

A new stilbene glucoside gallate from the roots of Polygonum multiflorum

A new stilbenoid (1) was isolated from the root extract of Polygonum multiflorum together with eight known constituents (2∼9). The chemical structure of 1 was established as the 6″-O-monogalloyl ester of (E)-2,3,4′,5-β-tetrahydroxystilbene-2-β-D-glucopyranoside based on physicochemical and spectroscopic analyses, particularly by NMR spectroscopic data, i.e., COSY, HMQC and HMBC. Compound 1 weakly inhibited acetylcholinesterase in vitro.

HPLC-ELSD analysis of 18 platycosides from balloon flower roots (Platycodi Radix) sourced from various regions in Korea and geographical clustering of the cultivation areas

An effective HPLC method to analyse platycosides from the balloon flower root was developed using ELSD. The optimum resolution of the platycosides was achieved on an ODS column with gradient elution of eluent A, 30mM ammonium acetate buffer (pH 4.81): methanol: acetonitrile=75:5:20 (v/v/v), and B, 69:5:26 (v/v/v). Amongst 18 platycosides, platycoside E showed the highest content, followed by polygalacin D2 and 3″-O-acetylplatyconic acid A. The sum of these three compounds was recommended for quality control of balloon flower root for medicinal purposes. The samples could be clustered into groups based on platycoside content. Group I, characterised by a high concentration of platycosides, was located near the west coast of Korea, whereas group II, characterised by a low concentration of platycosides, was located inland or in mountainous area. The method could be used to control the quality of balloon flower root.

Cardiovascular Effects of Lignans Isolated from Saururus chinensis

Saururus chinensis has been widely used as a traditional medicine for the treatment of beriberi, hypertension, pneumonia, edema, jaundice and gonorrhea. However, there is only limited information on the cardiovascular effects of S. chinensis extract or its single compounds. The present study was performed to investigate the effects of active lignans isolated from the extract of S. chinensis on vascular responses and heart functions. The vasorelaxant activity-guided fractionation of roots extract of S. chinensis led to the isolation of eight lignans as active principles. These lignans produced concentration-dependent relaxations of the endothelium-intact aortic preparations of rat aorta. Particularly, saucerneol ( 1), saucerneol D ( 2) and machilin D ( 8) exhibited distinctive vasorelaxant activity (EC (50) values: 2.2, 12.7 and 17.8 microM, respectively), which were significantly inhibited by removal of functional endothelium or pretreatment with N(G)-nitro-L-arginine methyl ester. Saucerneol ( 1) and saucerneol D ( 2) caused a significant decrease in left ventricular pressure, +dP/dt (max) and heart rate in isolated hearts. These results suggest that several lignans including saucerneol ( 1), saucerneol D ( 2) and machilin D ( 8), isolated from the ethanol extract of the roots of S. chinensis, have significant cardiovascular effects such as vasorelaxant and negative inotropic actions.

Galbanic Acid, a Cytotoxic Sesquiterpene from the Gum Resin of Ferula asafoetida, Blocks Protein Farnesyltransferase

Farnesylation of the activated RAS oncogene product by protein farnesyltransferase (FTase) is a critical step for its oncogenic function. Bioassay-guided purification of Ferula asafoetida (Umbelliferae) extract led to the isolation of the coumarin-derived sesquiterpene galbanic acid (1) as an active principal for FTase inhibitory activity, together with the four structurally related sesquiterpenes karatavicinol (2), umbelliprenin (3), farnesiferol B (4), and farnesiferol C (5). The 50 % inhibitory concentration (IC (50)) of 1 against FTase in an enzyme-based assay was calculated as 2.5 µM. Compound 1 also demonstrated potent inhibition of the proliferation of oncogenic RAS-transformed NIH3T3/Hras-F in a dose-dependent manner. The IC (50) value of 1 on the proliferation of oncogenic RAS-transformed NIH3T3/Hras-F cells was calculated as 16.2 µM, whereas its IC (50) value on control vector-transfected normal RAS-containing NIH3T3/ZIPneo cells was 58.5 µM.

Anti-resorptive saurolactam exhibits in vitro anti-inflammatory activity via ERK–NF-κB signaling pathway

Natural products and their derivatives have historically been an invaluable a source of therapeutic agents. In this report, we demonstrated the anti-inflammatory activity of saurolactam, a compound isolated from the aerial portions of the Chinese lizard, Saururus chinensis. In RAW264.7 macrophage cells, saurolactam significantly inhibited the lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 and, consequently, inhibited the release of NO and prostaglandin E2. Moreover, real-time PCR and multiplex cytokine assays showed that saurolactam (10 microM) significantly inhibited the LPS-induced mRNA and protein expression levels of pro-inflammatory genes, including interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha. Finally, western blot analysis showed that saurolactam dose-dependently inhibited LPS-induced extracellular signal-regulated kinase (ERK)/mitogen-activated protein (MAP) kinase activation and nuclear factor (NF)-kappaB translocation into the nucleus. The inhibitory activity of saurolactam on the activation of NF-kappaB was confirmed by a NF-kappaB luciferase reporter gene assay. In conclusion, we propose that the in vitro anti-inflammatory activity of saurolactam is produced by blocking ERK/MAP kinase and NF-kappaB activation.

Antiosteoporotic Activity of Saururus chinensis Extract in Ovariectomized Rats

Recent studies suggest that phytoestrogens may exert a protective effect against osteoporosis. This study examined whether treatment with phytoestrogen extracts from Saururus chinensis (SC) exerted a preventive effect on estrogen‐deficiency‐induced osteoporosis. Six‐ to seven‐month‐old female Sprague–Dawley rats were randomly assigned into either a sham‐operated group or one of three ovariectomy (OVX) subgroups: OVX treated with vehicle, OVX with alendronate, and OVX with SC extract (SC). Rats began receiving treatment 4 weeks before the OVX treatment and continued receiving treatment for an additional 10 weeks after OVX (for a combined total of 14 weeks). The results showed that the SC treatment prevented loss of femur bone mineral density after OVX, as determined by a significant decrease in the levels of serum bone turnover markers osteocalcin and alkaline phosphatase as well as urinary deoxypyridinoline. Micro‐computed tomography analysis showed that the SC treatment significantly prevented decreases in bone volume/tissue volume, trabecular number and trabecular thickness, while also preventing an increase in trabecular separation. It was concluded that SC treatment could prevent OVX‐induced loss of bone mass and deterioration in trabecular microarchitecture by suppressing bone turnover, thereby maintaining bone structural integrity. Further, no stimulation of proliferation of uterine tissue was noted. Therefore, it is suggested that treatment with S. chinensis extracts might be a potential alternative therapy for treating postmenopausal osteoporosis. Copyright