R type of resveratrol dimer, preparation process therefor and purpose thereof in lowering blood sugar level

Abstract

The present invention relates to the field of natural pharmaceutical chemistry, and in particular, to a resveratrol dimer (7R,8R)-trans-δ-viniferin (I), a preparation process therefor and a purpose thereof in lowering a blood sugar level. According to the present invention, an R type of resveratrol dimer is separated from the resveratrol dimer by using high-speed countercurrent chromatography. Pharmacodynamic tests proved that the R type of resveratrol dimer has a better effect in lowering a blood sugar level than a racemate.

Claims

1. A process for preparing a resveratrol dimer (7R,8R)-trans-δ-viniferin in structural formula (I), comprising: preparing a two-phase solvent by using n-hexane, ethyl acetate and water in a volume ratio of 5:5:10, wherein a top phase is a stationary phase, and 22 mmol/L to 28 mmol/L (2-hydroxypropyl)-(β-cyclodextrin is added into a bottom phase to form a mobile phase; pumping the stationary phase into a high-speed countercurrent chromatograph from a top end thereof; simultaneously rotating a main machine until a pipeline is fully filled with the stationary phase and pumping the mobile phase thereinto; dissolving a racemate into a small amount of the top phase when the mobile phase obviously flows from an outlet of the pipeline; then injecting a resulting solution into a sample cell and starting to acquire data; and receiving target compositions according to peaks, to obtain the compound ##STR00004##

2. A method for lowering high blood sugar level, comprising administering a subject with a suspension of resveratrol dimer (7R,8R)-trans-δ-viniferin in structural foimula (I) ##STR00005##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram of an area under a sucrose tolerance test curve for each test group, where: “*”: P<0.05; “**”: P<0.01 (relative to a negative control group);

(2) FIG. 2 is a diagram of separation of a TVN racemate by high-speed countercurrent chromatography;

(3) FIG. 3 is HPLC diagrams of a TVN racemate and HSCCC fractions; and

(4) FIG. 4 is a CD diagram of two HSCCC fractions.

DETAILED DESCRIPTION OF THE INVENTION

(5) Embodiment 1

(6) Separation of a TVN racemate by high-speed countercurrent chromatography:

(7) Preparation of a sample solution: 20 mg of a TVN racemate was dissolved in 10 mL of a top organic phase.

(8) 1,200 mL of a two-phase solvent system consisting of n-hexane, ethyl acetate and 25 mmol/L aqueous solution of (2-hydroxypropyl)-β-cyclodextrin in a volume ratio of 5:5:10 was placed in a 2,000 mL separating funnel for full equilibrium overnight, then separated and ultrasonically processed for 30 min. A top-phase solvent was used as a stationary phase, and injected into a high-speed countercurrent chromatograph at a flow rate of 30 ml/min until an entire pipeline system was filled. A main machine was rotated at a constant rotation rate of 800 r/min. A column oven was started to maintain a temperature at 5° C. A bottom-phase solvent was used as a mobile phase, and the bottom phase was injected into the high-speed countercurrent pipeline at a rate of 1 mL/min. When the bottom phase obviously flowed from an outlet of the pipeline, the sample solution was injected to a mouth of a sample cell, and fractions were collected under ultraviolet detection at 313 nm. For a countercurrent diagram, refer to FIG. 2, where: 1 represents (S,S)-TVN, and 2 represents (R,R)-TVN. To the collected samples, a small amount of hydrochloric acid was added for acidification, and a resulting solution was extracted with ethyl acetate for 3 times, and then vacuum concentrated to obtain a crude product. After a silica gel column chromatography process, the crude product was eluted by using dichloromethane and methanol in a volume ratio of 15:1 to remove a small amount of (2-hydroxypropyl)-β-cyclodextrin, and obtain high purity samples, i.e. 8.2 mng of (S,S)-TVN and 9.4 mg of (R,R)-TVN. A recovery rate exceeded 80%.

(9) The (R,R)-TVN and (S,S)-TVN may be verified by using the following method:

(10) The TVN racemate and two HSCCC fractions were verified by using HPLC, as shown in FIG. 3. In FIG. 3, (a) represents the TVN racemate; (b) represents HSCCC including a fraction of (S,S)-TVN; and (c) represents HSCCC including a fraction of (R,R)-TVN. HPLC conditions: an Agilent HPLC workstation was set by using Agilent 1200 HPLC, and a chromatographic column was Agilent Zorbax SB-C18: column (4.6 mm*250 mm, 5 μm), temperature: 30° C., mobile phase: 25 mmol L-1 HP-β-CD aqueous solution and acetonitrile (75:25, v/v), flow rate: 1.0 mL min-1, and detection wavelength: 320 nm.

(11) In FIG. 3, a retention time (t=21.493 min) of (R,R)-TVN is longer than a retention time (t=19.247 min) of (S,S)-TVN. In addition, purities of two compounds both exceed 98%, and values of enantiomer excess (ee) thereof reach 100%.

(12) FIG. 4 is a circular dichroism (CD) spectrum diagram of two compounds. When the two compounds have a same concentration, CD curves thereof are almost completely symmetric. In the figure, a dotted line shows a CD diagram of HSCCC including a fraction of (S,S)-TVN; and a solid line shows a CD diagram of HSCCC including a fraction of (R,R)-TVN, where concentrations thereof are both 0.2 mg/ml.