TY - JOUR
T1 - Synthesis, DNA-binding affinities, and binding mode of berberine dimers
AU - Qin, Yong
AU - Pang, Ji Yan
AU - Chen, Wen Hua
AU - CAI, Zongwei
AU - JIANG, Zhi Hong
N1 - Funding Information:
This work was financially supported by the Faculty Research Grants from Hong Kong Baptist University and Research Grants Council, University Grants Committee of Hong Kong.
PY - 2006/1/1
Y1 - 2006/1/1
N2 - Six novel berberine dimers (3a-f) were synthesized in 37-84% yield from the reaction of berberrubine (2) with dihaloalkanes of varying lengths from two to seven carbons. Their interactions with calf thymus (CT) DNA and three double helical oligodeoxynucleotides, d(AAGAATTCTT)2, d(AAGCATGCTT) 2, and d(TAAGAATTCTTA)2, were investigated by means of fluorometric titration and ethidium bromide (EB) displacement experiments. Compared with the monomeric parent berberine (1), these dimers' DNA-binding affinities increased up to approximately 100-fold, suggesting a cooperative interaction of the two berberine subunits in the molecules. Furthermore, these dimers linked by different spacers show a prominent structure-activity relationship when bound with oligodeoxynucleotides. The relative binding affinities are in the order of 3b > 3a > 3c > 3d > 3e > 3f with d(AAGAATTCTT)2 and d(TAAGAATTCTTA)2, and 3b > 3c > 3a > 3d > 3e > 3f with d(AAGCATGCTT)2. Dimer 3b, linked with a propyl chain, exhibits the highest binding affinity. This suggests that a propyl chain may be the most suitable spacer to bridge the two berberine units for DNA binding. Spectrophotometric titration and competitive EB displacement of berberine (1) and dimer 3b indicate that both berberine and its dimers form intercalating complexes with duplex DNA. A larger redshift, a stronger hypochromic effect, and a much higher EB displacement ratio, observed in 3b, indicate that the dimer is in more intimate contact with DNA than berberine. In addition, no obvious binding of canadine (4), a hydrogenated product of berberine, with CT DNA was observed, suggesting critical roles of the quaternary ammonium cation and planar structure in the DNA-binding of berberine.
AB - Six novel berberine dimers (3a-f) were synthesized in 37-84% yield from the reaction of berberrubine (2) with dihaloalkanes of varying lengths from two to seven carbons. Their interactions with calf thymus (CT) DNA and three double helical oligodeoxynucleotides, d(AAGAATTCTT)2, d(AAGCATGCTT) 2, and d(TAAGAATTCTTA)2, were investigated by means of fluorometric titration and ethidium bromide (EB) displacement experiments. Compared with the monomeric parent berberine (1), these dimers' DNA-binding affinities increased up to approximately 100-fold, suggesting a cooperative interaction of the two berberine subunits in the molecules. Furthermore, these dimers linked by different spacers show a prominent structure-activity relationship when bound with oligodeoxynucleotides. The relative binding affinities are in the order of 3b > 3a > 3c > 3d > 3e > 3f with d(AAGAATTCTT)2 and d(TAAGAATTCTTA)2, and 3b > 3c > 3a > 3d > 3e > 3f with d(AAGCATGCTT)2. Dimer 3b, linked with a propyl chain, exhibits the highest binding affinity. This suggests that a propyl chain may be the most suitable spacer to bridge the two berberine units for DNA binding. Spectrophotometric titration and competitive EB displacement of berberine (1) and dimer 3b indicate that both berberine and its dimers form intercalating complexes with duplex DNA. A larger redshift, a stronger hypochromic effect, and a much higher EB displacement ratio, observed in 3b, indicate that the dimer is in more intimate contact with DNA than berberine. In addition, no obvious binding of canadine (4), a hydrogenated product of berberine, with CT DNA was observed, suggesting critical roles of the quaternary ammonium cation and planar structure in the DNA-binding of berberine.
KW - Berberine dimer
KW - DNA-binding
KW - Ethidium bromide displacement
KW - Fluorescence spectrometry
KW - Intercalation
UR - http://www.scopus.com/inward/record.url?scp=27744558555&partnerID=8YFLogxK
U2 - 10.1016/j.bmc.2005.07.069
DO - 10.1016/j.bmc.2005.07.069
M3 - Journal article
C2 - 16169735
AN - SCOPUS:27744558555
SN - 0968-0896
VL - 14
SP - 25
EP - 32
JO - Bioorganic and Medicinal Chemistry
JF - Bioorganic and Medicinal Chemistry
IS - 1
ER -