Formation and conformation of baicalin-berberine and wogonoside-berberine complexes.
It is well-known that baicalin-berberine complex (1) precipitates in the water decoction of numerous Chinese Medicinal formulae containing Radix Scutellariae and Rhizoma Coptidis or Cortex Phellodendri. In the current study, ionic interaction between the carboxylate ion of baicalin and the quaternary ammonium ion of berberine was revealed to be responsible for the formation of 1 and wogonoside-berberine (2) by using FAB-MS and NMR titration experiments. In addition, nuclear Overhauser effect spectroscopy (NOESY) correlations observed in 1 and 2 suggested quite different conformation of the two complexes, which was further supported by the fact that the [α](D) of the canadine obtained by reduction of 1 is of an opposite sign to that obtained from 2. Partition coefficients (n-octanol/water) determination demonstrated 12-20 times larger partition coefficient of each complex (1, 2) than that of each single compound (baicalin, wogonoside, and berberine), indicating the significant role of the formation of the complex in the bioavailability enhancement of these pharmacologically active constituents.
State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, China.
Jing-Rong
JR
Wang
Takashi
T
Tanaka
Hong
H
Zhang
Isao
I
Kouno
Zhi-Hong
ZH
Jiang
D001599:Berberine / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D004365:Drugs, Chinese Herbal / Q000737:chemistry; D044950:Flavanones / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D000442:Octanols / Q000737:chemistry; D014867:Water / Q000737:chemistry
D056831:Coordination Complexes; D004365:Drugs, Chinese Herbal; D044950:Flavanones; D005419:Flavonoids; D005960:Glucosides; D000442:Octanols; D014867:Water; D001599:Berberine; C038044:baicalin; C473995:wogonoside