Do-Gyeong Lee

Lignans from the flowers of Osmanthus fragrans var. aurantiacus and their inhibition effect on NO production

A new lignan, (7R,7′R,8R,8′R)-8-hydroxypinoresinol 8-O-β-D-glucopyranoside 4′-methyl ether (7), was isolated from the flowers of Osmanthus fragrans var. aurantiacus along with six known lignans: (+)-phillygenin (1), phillyrin (2), (−)-phillygenin (3), (−)-epipinoresinol-β-D-glucoside (4), taxiresinol (5), and (−)-olivil (6). The structure of the new compound was elucidated on the basis of 1D- and 2D-NMR spectroscopic analysis and specific rotation data. The compounds isolated from the flowers of O. fragrans var. aurantiacus were evaluated for inhibitory activities on nitric oxide production in lipopolysaccharide-stimulated macrophage RAW 264.7 cells. (+)-Phillygenin (1), phillyrin (2), and (−)-phillygenin (3) exerted the strongest inhibitory activities on NO production with IC50 values of 25.5, 18.9, and 25.5 μM, respectively. These compounds may prove beneficial in the development of natural agents for prevention and treatment of inflammatory diseases.

Isolation of megastigmane sesquiterpenes from the silkworm (Bombyx mori L.) droppings and their promotion activity on HO-1 and SIRT1

The silkworm (Bombyx mori L.) droppings were extracted with 80% aqueous MeOH, and the concentrated extract was partitioned in succession with EtOAc, n-BuOH, and H2O. From the EtOAc fraction, five megastigmane sesquiterpenes were isolated through repeated silica gel and ODS column chromatography. According to the results of spectroscopic data, such as NMR, MS, and IR, the chemical structures of the isolated compounds were determined as (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (1), (S)-dehydrovomifoliol (2), (6R,7E,9R) -9-hydroxy-4,7-megastigmadien-3-one (3), (3S,5R,6S,7E)-3,5,6-trihydroxy-7-megastigmen-9-one (4), (6R,9R)-9-hydroxy-4-megastigmen-3-one (5). Compounds 2 through 5 were isolated for the first time from silkworm droppings. GC/MS analysis indicated silkworm powder contained compound 3, and mulberry leaves contained compound 4. Compounds 1 and 5 increased the expression of heme oxygenase-1 and SIRT1 in HepG2 and HEK239 cells, respectively. Heme oxygenase-1 is considered to be an antioxidant enzyme that catabolizes heme to carbon monoxide, free iron and biliverdin, while SIRT1 is the mammalian homologue of the yeast silent information regulator (Sir)-2, which are involved in the suppression of inflammatory mediators or factors that may be used to improve atopy-related symptoms.

Lignans from the fruits of the red pepper ( Capsicum annuum L.) and their antioxidant effects

The fruits of Capsicum annuum were extracted using 80% aqueous MeOH, and fractionated using EtOAc and water. Repeated column chromatography using silica gel, octadecyl silica gel, and Sephadex LH-20 for the EtOAc fraction led to the isolation of a new lignan glycoside and a known one, icariside E5. From the results of spectroscopic data, including EIMS, FABMS, UV, IR, 1H and 13C-NMR, DEPT, and 2D-NMR (COSY, HSQC, HMBC), the chemical structure of the new lignan glycoside was determined as (8R)-isodehydrodiconiferyl alcohol-4′-O-(6″-vanilloyl)-β-D-glucopyranoside named vanilloylicariside E5. All isolated compounds were tested for antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Icariside E5 (2) and (8R)-Isodehydrodiconiferyl alcohol (3) exhibited a strong scavenging effect on DPPH (2: IC50=42.1 µM, 3: IC50=4.5 µM).

A new lignan glycoside from the rhizomes of Imperata cylindrica

A new lignan glycoside, 6-acetyl-1-[1,3-(4,4′-dihydroxy-3,3′-dimethoxy-β-truxinyl)-β-d-fructofuranosyl]-α-d-glucopyranoside (1), named impecyloside, was isolated from the rhizomes of Imperata cylindrica. The structure of the compound was determined by spectroscopic data including FABMS, UV, IR, 1H NMR and 13C NMR (DEPT) and 2D NMR (COSY, HSQC, HMBC).

Methanol Extract of Bitter Melon Alleviates UVB‐Induced MMPs Expression via MAP Kinase and AP‐1 Signaling in Human Dermal Fibroblasts in vitro

Ultraviolet (UV) irradiation leads to photo‐damage of the skin, which in turn induces expression of matrix metalloproteinases (MMPs) and reduces type I procollagen. Bitter melon (Momordica charantia L.) has been widely used as a traditional medicine. In this study, we tested the photo‐protective effects of methanol extracts of bitter melon pulp (BM) and the mechanism of these effects in normal human dermal fibroblasts (NHDFs). The effects of BM were investigated by measuring the levels of MMP‐1, ‐3 and ‐9, and type I procollagen following UVB irradiation. We found that BM alleviates UVB‐induced MMP‐1, ‐3 and ‐9 expression at 100 µg/mL (down to 52.0%, 73.5%, and 55.6%, respectively). However, cells treated with 100 µg/mL BM had weakly stimulated type I procollagen expression (up to 130.0%). Moreover, treatment with BM significantly reduced UVB‐induced extracellular signal‐regulated kinase (ERK), Jun N‐terminal kinase (JNK), and p38 phosphorylation, which resulted in decreasing UVB‐induced phosphorylation of c‐Fos and c‐Jun. Therefore, our results suggest that BM is a potential agent for regulating skin photoaging. Copyright

Tellimoside, a flavonol glycoside from Brasenia schreberi, inhibits the growth of cyanobacterium (Microcystis aeruginosa LB 2385)

Principal components of aquatic plants responsible for inhibiting the growth of Microcystis aeruginosa, a blue-green alga (cyanobacterium) were determined. Methanol extracts of Brasenia schreberi showed strong inhibitory activity against the growth of the cyanobacterium. Two purified flavonoids were afforded through repeated column chromatographies. The compounds were determined as quercetin (1) and quercetin 3-O-(6″-galloyl)-β-d-glucopyranoside, tellimoside (2) by the interpretation of spectroscopic data including NMR, MS, and IR. Compounds 1 and 2 were first isolated from Brasenia schreberi. In addition, compound 2 showed very strong inhibitory activity against the growth of M. Aeruginosa.

A new miroestrol glycoside from the roots of Pueraria mirifica

A new compound, miroestrol-3-O-β-D-glucopyranoside, was isolated from the roots of Pueraria mirifica (white kwao krua). The structure of the compound was established on the basis of NMR, ESI-MS, and IR spectroscopic data.