Zhihui Xiao

Kaempferol and quercetin flavonoids from Rosa rugosa

__________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 600–601, November–December, 2006.

Isolation of esculetin from Cichorium glandulosum by high-speed countercurrent chromatography

Cichorium glandulosum Boiss et Hout (Compositae, Asteraceae) is widely used in Uigur folk medicine as a cholagogic and diuretic agent, to improve the appetite, to increase digestion, and to cure liver diseases etc. [1]. This plant is widely distributed in Xinjiang but its chemical composition has not been reported with the exception of the analysis of its essential oil [2]. Esculetin is the active principle of C. glandulosum. Biological studies have established its hepatoprotective activity [3]. Herein we report a method for isolating and purifying esculetin by preparative high-speed countercurrent chromatography (HSCCC). A crude sample of C. glandulosum was first analyzed by HPLC. The results showed that it contained esculetin and several unknown components. The sample was separated by HSCCC. Fractions containing esculetin were combined and dried. The yield of esculetin was 24 mg; the purity, 98%. Seeds (~1 kg) of C. glandulosum were extracted three times with ethanol (70%). The extracts were combined and evaporated to dryness under reduced pressure to afford a dry powder (150 g). The powder was dissolved in pure water (500 mL). The resulting solution was passed over a column of ion-exchange resin (1.1 kg, grade D 101) with elution by water (8 L) and ethanol (30%, 50, 70, and 95, 8 L each). The effluent from 50% ethanol was evaporated to dryness to afford a crude sample (223 mg). The whole procedure was carried out as follows. An upper phase consisting of CHCl 3:CH3OH:H2O (4:3:2) was pumped into the multiple carbon column of the chromatograph (HSCCC, model GS-10A2) at flow rate 9 mL/min using a model NS-1007 pump to create a constant current. After the column was filled with the upper phase through the sample-injection system, a solution of dry extract (223 mg) dissolved in the upper phase was introduced to the column. Then the lower organic phase was pumped into the column at flow rate 2 mL/min with the column rotating at 800 rpm. The column effluent was monitored by a UV detector at 254 nm. Peaks were collected manually according to the chromatogram. The collected fractions were analyzed by HPLC using CH3OH:CH3CO2H (0.3%) (31:69). The peak fraction obtained from the HSCCC chromatograph was identified using PMR and 13C NMR spectral data. PMR spectrum (400 MHz, DMSO-d 6, δ, ppm, J/Hz): 6.1 (1H, d, J = 9.6, H-3), 6.7 (1H, s, H-5), 6.9 (1H, s, H-8), 7.8 (1H, d, J = 9.6, H-4), 9.4 (1H, s, 6-OH), 10.2 (1H, s, 7-OH). 13C NMR spectrum (100 MHz, DMSO-d 6): 160.6 (C-2), 150.0 (C-6), 148.3 (C-7), 144.3 (C-4), 142.5 (C-9), 112.1 (C-5), 111.4 (C-3), 110.7 (C-10), 102.5 (C-8). These data agreed well with those published [4] and identified the isolated compound as esculetin.

Thiophene derivatives from the aerial part of Pluchea indica

Chemical investigation on the aerial part of Pluchea indica resulted in the isolation of two new thiophene derivatives, 2-(4-hydroxy-3- methoxybut-1-yn-1-yl)-5-(penta-1,3-diyn-1-yl)thiophene (1) and 2-(4-O-beta-glucopyranosyl-3-hydroxybut-1-yn-1-yl -5-(penta-1,3-diyn-1-yl)thiophene (2) along with three known thiophene derivatives 2-(3,4-dihydroxybut-1-yn-1-yl)-5-(penta-1,3-diyn-1-yl)thiophene (3), 2-(3-acetoxy-4-hydroxybut-1-yn-1-yl)-5-(penta-1,3-diyn-1-yl) thiophene (4) and 2-(prop-1-yn-1-yl)-5-(6-acetoxy-5-hydroxyhexa-1,3-diyn-1-yl) thiophene (5). The structures of 1 and 2 were determined on the bases of extensive spectroscopic analysis, including 1D and 2D NMR data. Antimicrobial activities of compounds 1-5 were tested.

Micromelosides A-D, four new coumarins from the stem bark of Micromelum falcatum

Four new coumarins, micromelosides A–D, together with four known coumarins were isolated from the stem bark of Micromelum falcatum. The complete assignments of the 1H and 13C NMR chemical shifts for these new compounds were achieved by means of 1D and 2D NMR techniques, including 1H‐1H COSY, HSQC, HMBC and NOE difference. Copyright

Xyloccensin M and N, two new B,D-seco limonoids from Xylocarpus granatum

Two new mexicanolide-type B, D-seco limonoids named xyloccensin M(1) and N (2) were isolated from the stem bark of Xylocarpus granatum. Their structures were elucidated with the help of modern spectroscopic techniques.

Two new cyclolignan glycosides from Acanthus ilicifolius

Two new cyclolignan glycosides, (+)-lyoniresinol 3a-O-α-D-galactopyranosyl-(1 → 6)-β -D-glucopyranoside (1) and (+)-lyoniresinol 2a-O-α-D-galactopyranosyl-3a-O-β -D-glucopyranoside (2) were isolated from the aerial parts of Acanthus ilicifolius. Their structure elucidation is based on the analyses of spectroscopic data

A new flavanone glucoside from Abrus precatorius

A new flavanone glycoside, (2S)5,7,4′-trihydroxyflavanone-8-C-β-D-(6″-O-acetyl)glucopyranoside (1), together with six known flavonoids, isohemiphloin (2), vitexin (3), cirsimaritin (4), hispidulin (5), apigenin (6), and eupatorin (7), was isolated from the leaves and stems of Abrus precatorius. Their structures were elucidated on the basis of physical and spectral analysis. Rotamers exist for compounds 1, 2, and 3. Compounds 1–3, 6, and 7 were isolated from this plant for the first time.

Scyphiphorins C and D, two new iridoid glycosides from the Chinese mangrove Scyphiphora hydrophyllacea

Two new iridoid glycosides with a lignan substituent, named scyphiphorins C (1) and D (2), were isolated from the stem bark of a Chinese mangrove Scyphiphora hydrophyllacea Gaertn. f., together with five known iridoid glycosides, 10-O-acetylgeniposidic acid (3), 7-deoxy-8-epi-loganic acid (4), mussaenoside (5), 7-deoxygardoside (6), and 10-deoxygeniposidic acid (7). The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic data, especially 2D NMR techniques.

Two New Mexicanolides from the Fruit of the Chinese Mangrove Xylocarpus granatum

Two new mexicanolides, 3-deacetyl xyloccensin M and 3-deacetyl xyloccensin N were isolated from the fruit of the Chinese mangrove Xylocarpus granatum. Their structures were elucidated on the basis of modern spectroscopic techniques.

A New Isoflavan from Abrus precatorius

A new isoflavan, (3S)-1′,4′-dihydroxy-6,7,8,2′,3′-pentamethoxyisoflavan (1), together with six known compounds, abruquinone G (2), abruquinone B (3), isoliquiritigenin (4), gallic acid (5), ethyl gallate (6), and 1-O-galloyl-β-D-glucose (7) were isolated from Abrus precatorius. Their structures were elucidated on the basis of physical and spectral analysis, respectively. Compounds 1, 4, and 7 were isolated from this plant for the first time.