J. Vet. Sci. 2016; 17(4): 459-465  https://doi.org/10.4142/jvs.2016.17.4.459
Physical-chemical and biological characterization of different preparations of equine chorionic gonadotropin 
Rafael Herrera Alvarez1,*, Fabio Luis Nogueira Natal1, Maria Teresa Carvalho Pinto Ribela2, Beatriz Elane de Almeida2, Jo?o Ezequiel de Oliveira2, Paolo Bartolini2
1Agency for Agribusiness Technology of S?o Paulo, 13400-970 Piracicaba, Brazil
2Biotechnology Department, IPEN-CNEN, Cidade Universit?ria Sao Paulo, 05508-000 S?o Paulo, Brazil
Correspondence to: Rafael Herrera Alvarez
Tel: +55-19-34215196; Fax:+55-19-34215196;
E-mail: rherrera@apta.sp.gov.br
Received: September 25, 2015; Revised: March 17, 2016; Accepted: May 12, 2016; Published online: December 30, 2016.
Ovarian stimulation with commercial preparations of equine chorionic gonadotropin (eCG) produces extremely variable responses in domestic animals, ranging from excessive stimulation to practically no stimulation, when applied on the basis of their declared unitage. This study was conducted to analyze four commercial preparations from different manufacturers via reversed-phase HPLC (RP-HPLC) in comparison with a reference preparation and an official International Standard from the World Health Organization. The peaks obtained by this qualitative and quantitative physical?chemical analysis were compared using an in vivo bioassay based on the ovarian weight gain of prepubertal female rats. The RP-HPLC data showed one or two peaks close to a main peak (tR = 27.9 min), which were related to the in vivo bioactivity. Commercial preparations that have this altered peak showed very little or no in vivo activity, as demonstrated by rat ovarian weight and in peripubertal gilts induced to ovulate. Overall, these findings indicate that RP-HPLC can be a rapid and reliable tool to reveal changes in the physicochemical profile of commercial eCG that is apparently related to decreased biological activity of this hormone.
Keywords: equine chorionic gonadotropin, gilts, high pressure liquid chromatography, ovarian response, rats

© 2016 The Korean Society of Veterinary Science.