Department of Pharmacology, Faculty of Medicine, Preclinical Building, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia. Department of Biomedical Science, Faculty of Science, Lincoln University College, Jalan Stadium, SS 7/15, Kelana Jaya, 47301 Petaling Jaya, Selangor, Malaysia. Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Abdul Aziz, 50300 Kuala Lumpur, Malaysia.