Chemical constituents from Taraxacum officinale and their α-glucosidase inhibitory activities.

Three novel butyrolactones (1-3) and butanoates (4-6), namely taraxiroside A-F, were isolated from Taraxacum officinale along with twenty-two known compounds (7-28). Their chemical structures were elucidated by interpretation of spectroscopic data and comparison with those of literatures. All isolates were evaluated for their α-glucosidase inhibitory activities. Novel compounds 1-6 (IC50 145.3-181.3 µM) showed inhibitory activities similar to that of acarbose (IC50 179.9 µM). Compound 7 and 12 were the most potent inhibitor with IC50 values of 61.2 and 39.8 µM respectively. Compounds 2 and 12 showed as mixed-type inhibition, whereas compound 7 and acarbose showed competitive inhibition.

Flavonoid glycosides from the aerial parts of Acacia pennata in Myanmar.

Phytochemical investigations of the aerial parts of Acacia pennata (Mimosaceae) from Myanmar led to the isolation of five flavonoid glycosides and six known compounds. The new compounds were identified as (2R,3S)-3,5,7-trihdyroxyflavan-3-O-α-L-rhamnopyranoside, (2S)-5,7-dihydroxyflavan-7-O-ß-D-glucopyranoside-(4α → 8)-epiafzelechin-3-O-gallate, (2R)-4',7-dihydroxyflavan-(4α → 8)-(2R,3S)-3,5,7-trihdyroxyflavan-3″-O-α-L-rhamnopyranoside, 5,7-dihydroxyflavone 6-C-ß-boivinopyranosyl-7-O-ß-D-glucopyranoside, and 5,7-dihydroxyflavone 7-O-ß-D-glucopyranosyl-8-C-ß-boivinopyranoside based on interpretation of spectroscopic data.

Rapid separation of cyanidin-3-glucoside and cyanidin-3-rutinoside from crude mulberry extract using high-performance countercurrent chromatography and establishment of a volumetric scale-up process.

This study describes the rapid separation of mulberry anthocyanins; namely, cyanidin-3-glucoside and cyanidin-3-rutinoside, using high-performance countercurrent chromatography, and the establishment of a volumetric scale-up process from semi-preparative to preparative-scale. To optimize the separation parameters, biphasic solvent systems composed of tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, flow rate, sample amount and rotational speed were evaluated for the semi-preparative-scale high-performance countercurrent chromatography. The optimized semi-preparative-scale high-performance countercurrent chromatography parameters (tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, 1:3:1:5, v/v; flow rate, 4.0 mL/min; sample amount, 200-1000 mg; rotational speed, 1600 rpm) were transferred directly to a preparative-scale (tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, 1:3:1:5, v/v; flow rate, 28 mL/min; sample amount, 5.0-10.0 g; rotational speed, 1400 rpm) to achieve separation results identical to cyanidin-3-glucoside and cyanidin-3-rutinoside. The separation of mulberry anthocyanins using semi-preparative high-performance countercurrent chromatography and its volumetric scale-up to preparative-scale was addressed for the first time in this report.

Two new phenolic glucosides from Lagerstroemia speciosa.

Two new phenolic glucosides, 1-O-benzyl-6-O-E-caffeoyl-ß-d-glucopyranoside and 1-O-(7S,8R)-guaiacylglycerol-(6-O-E-caffeoyl)-ß-d-glucopyranoside, were isolated from the aerial parts of Lagerstroemia speciosa, along with ten known compounds. The structures of the isolated compounds were determined based on 1D- and 2D-NMR, Q-TOF MS and optical rotation spectroscopic data. All of the compounds showed moderate inhibitory activities against nitric oxide production in lipopolysaccharide-treated RAW264.7 cells, with IC50 values of 69.5-83.3 µM.

Flavokawains B and C, melanogenesis inhibitors, isolated from the root of Piper methysticum and synthesis of analogs.

The ethanolic extract of the root of Piper methysticum was found to inhibit melanogenesis in MSH-activated B16 melanoma cells. Flavokawains B and C were isolated from this extract based on their anti-melanogenesis activity and found to inhibit melanogenesis with IC50 values of 7.7µM and 6.9µM, respectively. Flavokawain analogs were synthesized through a Claisen-Schmidt condensation of their corresponding acetophenones and benzaldehydes and were evaluated in terms of their tyrosinase inhibitory and anti-melanogenesis activities. Compound 1b was the most potent of these with an IC50 value of 2.3µM in melanogenesis inhibition assays using MSH-activated B16 melanoma cells.

Application of high-performance countercurrent chromatography for the isolation of steroidal saponins from Liriope plathyphylla.

High-performance countercurrent chromatography (HPCCC) with electrospray light-scattering detection was applied for the first time to isolate a spirostanol and a novel furostanol saponin from Liriope platyphylla. Due to the large differences in KD values between the two compounds, a two-step HPCCC method was applied in this study. The primary HPCCC employed methylene chloride/methanol/isopropanol/water (9:6:1:4 v/v, 4 mL/min, normal-phase mode) conditions to yield a spirostanol saponin (1). After the primary HPCCC run, the solute retained in the stationary phase (SP extract) in HPCCC column was recovered and subjected to the second HPCCC on the n-hexane/n-butanol/water system (1:9:10 v/v, 5 mL/min, reversed-phase mode) to yield a novel furostanol saponin (2). The isolated spirostanol saponin was determined to be 25(S)-ruscogenin 1-O-ß-D-glucopyranosyl (1→2)-[ß-D-xylopyranosyl (1→3)]-ß-D-fucopyranoside (spicatoside A), and the novel furostanol saponin was elucidated to be 26-O-ß-D-glucopyranosyl-25(S)-furost-5(6)-ene-1ß-3ß-22α-26-tetraol-1-O-ß-D-glucopyranosyl (1→2)-[ß-D-xylopyranosyl-(1→3)]-ß-D-fucopyranoside (spicatoside D).

Flavonoids from Symplocos racemosa.

A novel isoflavone glycoside, peseudobatigenin 7-O-[ß-d-apiofuranosyl-(1''''→5''')-O-ß-d-apiofuranosyl-(1'''→6'')]-ß-d-glucopyranoside, namely sympracemoside (1), was isolated from the aerial parts of Symplocos racemosa along with 15 known flavonoids (2-16). Their structures were characterized by Q-TOF mass, optical rotation, UV, 1D and 2D-NMR spectroscopic data. Compounds 3, 9, 16 showed moderate inhibitory activities against NO production with IC50 value of 88.2, 42.1 and 74.3 µM, respectively.

Separation of five oligostilbenes from Vitis amurensis by flow-rate gradient high-performance counter-current chromatography.

A rapid and efficient high-performance counter-current chromatography (HPCCC) method was developed to separate five oligostilbenes from the roots of Vitis amurensis. An n-hexane/ethyl acetate/methanol/water system (4:8:4:10, v/v/v/v) was selected as an optimal two-phase solvent system of which the upper phase was used as the stationary phase and the lower phase was used as the mobile one. Partition coefficient values for the target compounds under these optimized conditions were 0.28 (1, ampleosin A), 7.12 (2, (+)-g-viniferin), 2.26 (3, vitisin A), 5.38 (4, wilsonol C), and 11.23 (5, vitisin B). Flow-rate gradient HPCCC (4 mL/min in 0-70 min, 8 mL/min in 70-250 min) was applied to isolate the target compounds in as high purity as possible within the shortest possible run time. Under these conditions, ampelopsin A (12.1 mg), (+)-g-viniferin (10.4 mg), vitisin A (2.8 mg), wilsonol C (3.2 mg), and vitisin B (37 mg) were isolated with >95% purity from 150 mg of enriched oligostilbene extract. Although the KD of the last eluted compound, vitisin B (KD = 11.23), was relatively large, it was eluted in 115-145 min using the two-phase solvent system. This study shows that HPCCC is an efficient tool for the isolation and purification of natural products.

Application of high-speed countercurrent chromatography-evaporative light scattering detection for the separation of seven steroidal saponins from Dioscorea villosa.

INTRODUCTION: Steroidal saponins in Dioscorea species are chemically characterised as spirostanol and furostanol saponins, and have been used as standard marker compounds due to their chemotaxonomical significance and their important biological activities. OBJECTIVE: To design a simple, rapid and efficient method for the separation of steroidal saponins with a high degree of purity using high-speed countercurrent chromatography (HSCCC) coupled with evaporative light scattering detection (ELSD). METHODOLOGY: In the first step, reversed-phase mode HSCCC (flow rate: 1.5 mL/min; revolution speed: 800 rpm) using n-hexane:n-butanol:water [3:7:10 (v/v/v)] was employed to separate furostanol saponins from n-butanol soluble extracts of Dioscorea villosa. After the first HSCCC run, spirostanol saponins retained in the stationary phase were subjected to the second HSCCC (normal-phase mode; flow rate: 2.0 mL/min; revolution speed: 800 rpm). A two-phase solvent system composed of chloroform:methanol:isopropanol:water [10:6:1:4 (v/v/v/v)] was employed in the second HSCCC. The structures of isolates were elucidated by (1) H-NMR, (13) C-NMR, ESI-MS and HPLC analysis. RESULTS: Three furostanol saponins, parvifloside (27.3 mg), methyl protodeltonin (67.1 mg) and trigofoenoside A-1 (18.5 mg) were isolated from the n-butanol soluble extract of D. villosa by the first HSCCC run. Subsquent normal-phase HSCCC of the spirostanol-rich extract led to the separation of four spirostanol saponins: zingiberensis saponin I (15.2 mg), deltonin (31.5 mg), dioscin (7.7 mg) and prosapogenin A of dioscin (3.4 mg).