reperfusion, and tested infarct size at 24 h after reperfusion. (see
Supporting information) Compound 6 reduced infarct size in a
dose-dependent manner. (Fig. 7a) The mortality was 2/17, 4/18,
3/17 and 7/20 rats for vehicle and 0.20, 0.50 and 1.0 mg per kg
body weight compound 6, respectively. Compared with ZL006
(2.0 mg/kg, i.v.), compound 6 (1.0 mg/kg, i.v., 1 h after
reperfusion) showed the considerable therapeutic effect on the
MCAO rats, due to improve the permeability across BBB and
extend duration time in brain. (Fig. 7b)
b
a
Figure 4. Concentrations of compounds 1-7 in mice brain at 15, 30 and 60
min after the dosing (μg/g). Compounds 1-7 (20 mg/kg) were administered
intravenously. Values are means ± s.e.m., n = 6.
Figure 7. Effects of compound 6 and ZL006 on cerebral ischemia in rats
subjected to 1 h MCAO and reperfusion. Infarct size was measured at 24 h
after reperfusion. (a) Dose-effect relationship experiments (n = 17–20). (b)
Representative of triphenyltetrazolium chloride–stained slices. Compound 6,
ZL006, or vehicle was administrated at 1 h after reperfusion.
In summary, metabolism investigation of ZL006 (1) and its
analogs suggests that phenolic hydroxyl group of aromatic ring A
is the main conjugation site with glucuronic acid, resulting its
fast metabolism and elimination. Additionally, this study
indicates that ZL006 ester derivatives 4-6 have the better
permeability across BBB than ZL006. Among them, compound 6
as a prodrug of ZL006 has tremendous potentiality for the
treatment of cerebral ischemia.
Figure 5. Concentrations of ZL006 liberated from parent compounds in mice
brain at 15, 30 and 60 min after the dosing (μg/g). Compounds 1-7 (20
mg/kg) were administered intravenously. Values are means ± s.e.m., n = 6.
Acknowledgments
To investigate whether these carboxylate derivatives have
benefits in cerebral ischemia, we first made mice subjected to the
bilateral common carotid arteries occlusion (BCCAO)12 at 1 h
and 4 h after treating with compounds 4-6 (4.0 mg/kg, i.v.), and
detected the surviving times. (see Supporting information)
Compared with ZL006 (1), compounds 4-6 showed the similar
protective effect against acute cerebral ischemia injury and
markedly prolonged the surviving times in BCCAO mice at 1 h
after the dosing. Much to our satisfaction, compounds 5 and 6
still kept benefits in BCCAO mice at 4 h after the dosing, and
This work was supported by the National Natural Science
Foundation of China (No. 21172108), Ordinary University
Natural Science Research Project of Jiangsu Province (No.
15KJB350002), and Nanjing Medical University Education
Development Foundation (No. 2014NJMUZD019).
References and notes
1.
(a) Hillier, B. J.; Christopherson, K. S.; Prehoda, K. E.; Bredt, D.
S.; Lim, W. A. Science 1999, 284, 812. (b) Aarts, M.; Liu, Y.; Liu,
L.; Besshoh, S.; Arundine, M.; Gurd, J. W.; Wang, Y. T.; Salter,
M. W.; Tymianski, M. Science 2002, 298, 846. (c) Lin, Y.;
Skeberdis, V. A.; Francesconi, A.; Bennett, M. V.; Zukin, R. S. J.
Neurosci. 2004, 24, 10138.
compound
consideration of compound
6
had
a
longer surviving time. (Fig. 6) In
having the effective drug
6
concentration for a longer time in mice brain (Fig. 4 and 5), it
might be a potent prodrug of ZL006 (1) for cerebral ischemia.
2.
(a) Lee, W. H.; Xu, Z.; Ashpole, N. M.; Hudmon, A.; Kulkarni, P.
M.; Thakur, G. A.; Lai, Y. Y.; Hohmann, A. G.
Neuropharmacology 2015, 97, 464. (b) Andreasen, J. T.; Bach,
A.; Gynther, M.; Nasser, A.; Mogensen, J.; Strømgaard, K.;
Pickering, D. S. Neuropharmacology 2013, 67, 193. (c) Florio, S.
K.; Loh, C.; Huang, S. M.; Iwamaye, A. E.; Kitto, K. F.; Fowler,
K. W.; Treiberg, J. A.; Hayflick, J, S.; Walker, J. M.; Fairbanks,
C. A.; Lai, Y. Br. J. Pharmacol. 2009, 158, 494.
3.
4.
(a) Zhou, L.; Li, F.; Xu, H. B.; Luo, C. X.; Wu, H. Y.; Zhu. M.
M.; Lu, W.; Ji, X.; Zhou, Q. G.; Zhu, D. Y. Nat. Med. 2010, 16,
1439. (b) Wu, S.; Yue, Y.; Tian, H.; Tao, L.; Wang, Y.; Xiang, J.;
Wang, S.; Ding, H. Neuropharmacology 2014, 83, 107. (c) Hu, Z.;
Bian, X.; Liu, X.; Zhu, Y.; Zhang, X.; Chen, S.; Wang, K.; Wang,
Y. Brain Res. 2013, 1491, 204.
(a) Doucet, M. V.; Harkin, A.; Dev, K. K. Pharmacol. Ther. 2012,
133, 218. (b) Doucet, M. V.; Levine, H.; Dev, K. K.; Harkin, A.
Neuropsychopharmacology 2013, 38, 1575.
Figure 6. Effects of compounds 4-6 and ZL006 on surviving times in
BCCAO mice at 1 h and 4 h after the dosing (4.0 mg/kg, i.v.). Control group:
5% glucose solution, 4.0 mg/kg, i.v. Values are means ± s.e.m., n = 6. ***P <
0. 001 vs control group.
Further more, we treated intraluminal middle cerebral artery
occlusion (MCAO) rat13 with compound 6 (i.v.) at 1 h after