1. P. Hilendarski University of Plovdiv – Branch “L. Karavelov”, Kardzhali, Bulgaria;
2. Department of Chemical Sciences, Faculty of Pharmacy, Medical University of Plovdiv, Plovdiv, Bulgaria;
3. Autonomous University of Baja California, Mexicali, Mexico;
4. Department of Biochemistry and Microbiology, Biological Faculty, P. Hilendarski University of Plovdiv, Plovdiv, Bulgaria