Two new polycyclic polyprenylated acylphloroglucinols derivatives from Hypericum acmosepalum.

Polycyclic polyprenylated acylphloroglucinols (PPAPs) were mainly obtained from the plants of Hypericum genus of Guttiferae family, and possessed intriguing chemical structures and appealing biological activities. Two new PPAPs derivatives, hyperacmosin C (1) and hyperacmosin D (2) were isolated from H. acmosepalum. Their structures were established by NMR, HREIMS, and experimental electronic circular dichroism spectra. Besides, compound 1 showed significant hepatoprotective activity at 10 µM against paracetamol-induced HepG2 cell damage and compound 2 could moderately increase the relative glucose consumption.

Philicity of Acetonyl and Benzoyl Radicals: A Comparative Experimental and Computational Study.

In this work, the reactivities of acetonyl and benzoyl radicals in aromatic substitution and addition reactions have been compared in an experimental and computational study. The results show that acetonyl is more electrophilic than benzoyl, which is rather nucleophilic. A Hammett plot analysis of the addition reactions of the two radicals to substituted styrenes clearly support the nucleophilicity of benzoyl, but in the case of acetonyl, no satisfactory linear correlation with a single substituent-related parameter was found. Computational calculations helped to rationalize this effect, and a good linear correlation was found with a combination of polar parameters (σ+ ) and the radical stabilization energies of the formed intermediates. Based on the calculated philicity indices for benzoyl and acetonyl, a quantitative comparison of these two radicals with many other reported radicals is possible, which may help to predict the reactivities of other aromatic radical substitution reactions.

Separation of Four Phenylpropanoid Glycosides from a Chinese Herb by HSCCC.

Four phenylpropanoid glycosides (PPGs), such as echinacoside, wiedemannioside C, forsythoside B and verbascoside, were isolated and purified from the Tibetan medicinal herb Pedicularis longiflora Rudolph. var. tubiformis (Klotz) Tsoong by high-speed counter-current chromatography (HSCCC) combined with macroporous resin (MR) column separation for the first time. In the present study, the two-phase solvent system composed of ethyl acetate-n-butanol-water (10 : 6:15, v/v/v) was used for HSCCC separation. A total of 3.5 mg of echinacoside, 12.6 mg of wiedemannioside C, 22.7 mg of forsythoside B and 48.7 mg of verbascoside with the purity of 93.6, 97.9, 97.8 and 98.1%, respectively, were obtained from 120 mg of crude sample. The HSCCC fractions were analyzed by HPLC, and the chemical structures were identified by (1)H NMR and (13)C NMR. The results demonstrate that MR coupled with HSCCC is a powerful technique for separation of PPGs from natural products.

Separation of phenylpropanoid glycosides from a Chinese herb by HSCCC.

An effective high-speed counter-current chromatography method was established for the preparative isolation and purification of two phenylpropanoid glycosides from the Tibetan medicinal plant Pedicularis longiflora Rudolph. var. tubiformis (Klotz). Tsoong. With a two-phase solvent system composed of chloroform-n-butanol-methanol-water (4:3:4:5, v/v), 40 mg of an extract of Pedicularis longiflora Rudolph. var. tubiformis (Klotz). Tsoong was separated to yield 20 mg of verbascoside and 18 mg of isoacteoside, with purity values of 97 and 98%, respectively. The chemical structures of these two components were identified by proton and carbon nuclear magnetic resonance. In addition, the antioxidant activity of the two phenylpropanoid glycosides was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH)-high-performance liquid chromatography, and the results showed that the two components exhibited strong antioxidant DPPH radical scavenging activity, with IC50 values of 15.6 and 18.9 µg/mL, respectively.

Separation and purification of water-soluble iridoid glucosides by high speed counter-current chromatography combined with macroporous resin column separation.

Four iridoid glucosides, shanzhiside methyl ester, phloyoside II, chlorotuberside, and penstemonoside, were isolated and purified from an herbal medicinal plant for the first time by high-speed counter-current chromatography (HSCCC) using a two-phase solvent system composed of ethyl acetate-n-butanol-water (5:14:12, v/v/v). A total of 37mg of shanzhiside methyl ester, 29mg of phloyoside II, 27mg of chlorotuberside, and 21mg of penstemonoside with the purity of 99.2%, 98.5%, 97.3%, and 99.3%, respectively, were obtained in one-step separation within 4h from 150mg of crude extract. To the best of our knowledge, this is the first report of separation and purification of iridoid glucosides from natural sources by HSCCC. The chemical structures of all the four compounds were identified by ESI-MS, (1)H NMR, and (13)C NMR.

Separation and purification of five phenylpropanoid glycosides from Lamiophlomis rotata (Benth.) Kudo by a macroporous resin column combined with high-speed counter-current chromatography.

Five phenylethanoid glycosides (PhGs), forsythoside B, verbascoside, alyssonoside, isoverbascoside, and leucosceptoside B, were isolated and purified from Lamiophlomis rotata (Benth.) Kudo by high-speed counter-current chromatography (HSCCC) combined with macroporous resin (MR) column separation. In the present study, the two-phase solvent system composed of ethyl acetate/n-butanol/water (13:3:10, v/v/v) was used for HSCCC separation. A total of 27 mg of forsythoside B, 41 mg of verbascoside, 29 mg of alyssonoside, 23 mg of isoverbascoside, and 13 mg of leucosceptoside B with purities of 97.7, 99.2, 99.5, 99.3, and 97.3%, respectively, were obtained in a one-step separation within 4 h from 150 mg of crude extract. The recoveries of the five PhGs after MR-HSCCC separation were 74.5, 76.5, 72.5, 76.4, and 77.0%, respectively. The chemical structures of all five compounds were identified by (1) H and (13) C NMR spectroscopy.

Preparative isolation and purification of three stilbene glycosides from the tibetan medicinal plant Rheum tanguticum maxim. Ex Balf. by high-speed counter-current chromatography.

INTRODUCTION: Stilbene glycosides are the primary constituents of Rheum tanguticum Maxim. ex Balf., to which different bioactivities has been attributed, including: anti-HIV, anti-oxidant, anti-tumour, anti-malarial, and anti-allergy activity. However, effective methods for the isolation and purification of stilbene glycosides, such as trans-rhapontin, cis-rhapontin and trans-desoxyrhaponticin, from this herb are not currently available. OBJECTIVE: To develop an efficient method for the preparative isolation and purification of three stilbene glycosides from Rheum tanguticum Maxim. ex Balf. via high-speed counter-current chromatography (HSCCC). METHODS: A solvent system composed of chloroform:n-butanol:methanol:water (4:1:3:2, v/v/v/v) was developed for the separation. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase. The flow rate was 1.8 mL/min. The apparatus was controlled at 800 rpm and 25 °C, and the effluent was monitored at 280 nm. Chemical constituents were analysed by high-performance liquid chromatography (HPLC), and their structures were identified by ¹H- and ¹³C-NMR. RESULTS: Under the optimised conditions, 25.5 mg trans-rhapontin, 16.0 mg cis-rhapontin and 20.5 mg trans-desoxyrhaponticin were separated from 80 mg crude sample; the isolates had purities of 99.6, 97.2 and 99.2%, respectively. CONCLUSION: A simple and efficient HSCCC method has been optimised for the preparative separation of stilbene glycosides from Rheum tanguticum Maxim. ex Balf.