1. Department of Chemistry, Faculty of Science and Mathematics , Universiti Pendidikan Sultan Idris (UPSI) , 35900 Tanjong Malim , Perak , Malaysia
2. School of Environmental and Natural Sciences, Faculty of Science and Technology , Universiti Kebangsaan Malaysia , Bangi , Selangor , Malaysia
3. Natural Products Division, Forest Research Institute Malaysia , Kepong , Selangor , Malaysia