• Bulletin of the Korean Chemical Society
• /
• v.32 no.12
• /
• pp.4179-4184
• /
• 2011

The nucleophilic substitution reactions of bis(2,6-dimethylphenyl) chlorophosphate (5), containing the four ortho-methyl substituents, with X-pyridines are investigated kinetically in MeCN at $65.0^{\circ}C$. The free energy correlations for substituent X variations in the nucleophiles exhibit biphasic concave upwards with a breakpoint at a X = 3-Cl. Unusual positive ${\rho}_X$ (= +5.40) and negative ${\beta}_X$ (= -0.83) values are obtained with the weakly basic pyridines. The pyridinolysis rate of 5 is hundreds times slower compared to that of bis(phenyl) chlorophosphate because of the steric hindrance of the four ortho-methyl substituents in the two phenyl rings. Ion-pair mechanism is proposed and positive ${\rho}_X$ and negative ${\beta}_X$ values are substantiated by an imbalance of the transition state.

• Archives of Pharmacal Research
• /
• v.17 no.5
• /
• pp.314-317
• /
• 1994

The studies were camied out to evaluate the constituents in the leaves of Crataegus pinnatifida var. psilosa (Rosaceae) continuously. From the BuOH fraction of the MeOH extract, four flavonoid compounds, hyperoside (1), vitexin (2), 3"-O-rhamnosylvitexin (3) and $quercetin-3-O-{\alpha}-L-rhamnopyranoslyl-(1{\rightarrow}6)-{\beta}$-D-galactopyranoside (4) were isolated and identified on the basis of their physico-chemical properties and spectroscopic evidences by comparison with authentic samples.

• Natural Product Sciences
• /
• v.8 no.1
• /
• pp.23-25
• /
• 2002

Ten compounds were isolated from the stem barks of Acanthopanax gracilistylus WW Smith (AGS) by steam distillation, they were p-menta-1,5,8-triene, n-butyl isobutylphthalate, p-mentha-1,5-diene-8-ol, 8-hydroxy-p-cymene, myrtenol, trans-(+)-carveol, 1,3-di-tert-butylbenzene, 4-methyl-2,6-di-butylphenol, valencene and verbenone, respectively, characterized by GS-Mass spectra. And we have also extracted and isolated from the MeOH extracts of the stem barks of AGS, two compounds were obtained. On the basis of chemical and spectral evidence, they were syringin(l), ${\beta}-sitosterol(2)$.

• Natural Product Sciences
• /
• v.15 no.2
• /
• pp.90-95
• /
• 2009

Phytochemical investigation of the MeOH extract of the leaves of Nelumbo nucifera resulted in the isolation of five norsesquiterpenes, four flavonoids, two triterpenes and one alkaloid. Their chemical structures were characterized by spectroscopic methods to be (E)-3-hydroxymegastigm-7-en-9-one (1), (3S,5R,6S,7E)- megastigma-7-ene-3,5,6,9-tetrol (2), dendranthemoside B (3), icariside $B_2$ (4), sedumoside $F_1$ (5), luteolin (6), quercetin 3-0-${\beta}$-D-glucuronide (7), quercetin 3-0-${\beta}$-D-glucoside (8), isorhamnetin 3-0-rutinoside (9), alphitolic acid (10), maslinic acid (11), and N-methylasimilobine (12). Norsesquiterpenoids (1-5) and triterpenes (10-11) were isolated for the first time from this plant. Compounds 6 and 10-12 exhibited considerable cytotoxicity against four human cancer cell lines in vitro using a SRB bioassay.

• Natural Product Sciences
• /
• v.19 no.3
• /
• pp.221-226
• /
• 2013

Phytochemical investigation of the 80% MeOH extract from the leaves of Allium victorialis var. platyphyllum resulted in the isolation of seventeen compounds; two terpenes, three norsesquiterpenes, one furofuran lignan, and eleven phenolic derivatives. Their chemical structures were characterized by spectroscopic methods to be trans-phytol (1), phytene-1,2-diol (2), icariside B2 (3), (6S,9S)-roseoside (4), sedumoside G (5), pinoresinol-4-O-glucoside (6), 2-methoxy-2-(4'-hydroxyphenyl)ethanol (7), 2-hydroxy-2-(4'-hydroxyphenyl)ethanol (8), Benzyl ${\beta}$-D-glucopyranoside (9), methyl ferulate (10), trans-ferulic acid (11), methyl-p-hydroxycinnamate (12), glucosyl methyl ferulate (13), linocaffein (14), siringin (15), 2-(4-hydroxy-3-methoxyphenyl)-ethyl-O-${\beta}$-Dglucopyranoside (16), and pseudolaroside C (17). All compounds were isolated for the first time from this plant.

• YAKHAK HOEJI
• /
• v.37 no.2
• /
• pp.193-197
• /
• 1993

For the investigation of medicinal resources in Crataegus species, a study was carried out to clarify the constituents in the leaves of Crataegus Pinnatifida var. pubescens (Rosaceae), of which fruits have been used to stomachic, digestive, astringent, analgesic, and cardiotonic, etc. as a folk medicine in Korea. From the n-BuOH fraction of MeOH extract two flavone glycosides, vitexin(apigenin-8-C-$\beta$-D-glucopyranoside) and 2"-O-rhamnosyl vitexin(apigenin-8-C-$\alpha$-L-rhamnosyl-(1$\rightarrow$2)-$\beta$-D-glucopyrano side) were isolated and identified on the basis of their physico-chemical properties and spectroscopic evidences(UV, IR, NMR, FAB-Mass etc.) in comparision with authentic samples.amples.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.4
• /
• pp.1016-1022
• /
• 2014

The kinetic studies on the reactions of O-methyl N,N-diisopropylamino phosphonochloridothioate with X-anilines and X-pyridines have been carried out in acetonitrile. The free energy relationship with X in the anilines exhibits biphasic concave upwards with a break region between X = (H and 4-F), giving unusual negative ${\beta}_X$ and positive ${\rho}_X$ values with weakly basic anilines. The unusual phenomenon is rationalized by isokinetic relationship. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed based on the selectivity parameter and variation trend of the deuterium kinetic isotope effects with X. The free energy relationship with X in the pyridines exhibits biphasic concave upwards with a break point at X = 3-MeO. A concerted mechanism is proposed based on relatively small ${\beta}_X$ value, and frontside and backside nucleophilic attack are proposed with strongly and weakly basic pyridines, respectively.

• Archives of Pharmacal Research
• /
• v.20 no.3
• /
• pp.280-282
• /
• 1997

A genuine dammarane-glycoside, named as ginsenoside $ Rs_3$, was isolated from the MeOH extracts of Korean red ginseng (Panax ginseng C.A. Meyer) through repeated silica gel column chromatographies and its chemical structure was determined as (20S)-protopanaxadiol $3-O-[6^{11}-O-acetyl-{\beta}-D-glucopyranosyl (1{\rightarrow2)-{\beta}-D-$glucopyranoside on the basis of several spectral and physical evidences including HMBC and FAB-MS.

• YAKHAK HOEJI
• /
• v.49 no.1
• /
• pp.11-19
• /
• 2005

The root of Astragalus membranaceus (Leguminosae) has been used in traditional chinese prescriptions for strengthning the superficial resistance, promoting pus discharge and tissue regeneration, diuretis and alleviating edema. Lipid peroxidation has been suggested as a major cause of atherosclerosis, cancer, liver disease, and the aging process. In order to investigate the anti-lipid peroxidation activity, Astragali Radix was extracted with $80\%$ MeOH and fractionated with hexane, $CH_{2}Cl_2$, EtOAc, BuOH and Water. The antilipid peroxidation activities of them were determined by human erythrocyte ghost and $CCl_4$-induced lipid peroxidation. $CH_{2}Cl_2$ and EtOAc fractions, especially, isoflavonoids, 7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-${\beta}$-D-glucoside and calyco sin-7-O-${\beta}$-D-glucoside from EtOAc fraction showed anti-lipid peroxidation activities.

• YAKHAK HOEJI
• /
• v.45 no.5
• /
• pp.529-536
• /
• 2001

The root of Astragalus membranaceus Bunge (Leguminosae), which has been used for the treatment of hypertension, chronic hepatitis, duodenal ulcers, chronic nephritis and promotion of immunity in folk remedies. Several lines of evidence indicate that oxidative modification of low-density lipoprotein (Ox-LDL) may play an important role in atherogenesis. Hence, the role of antioxidants in the prevention of LDL oxidation needs to be determined. To investigate the antioxidant activity. we determined the MeOH ex. and fractions of Astragali Radix on the inhibition of LDL oxidation. The CH$_2$C1$_2$ and EtOAc orations inhibited the oxidative modification of LDL by a decrease in the lipid peroxide content and the electrophoretic mobility of LDL. Calycosin-7-0-$\beta$-D -glucoside which was isolated from EtOAc fraction inhibits the oxidative modification of LDL.