1. Department of Chemistry, Organic and Bioorganic Chemistry, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany, Institute of Forestry, Pokhara Campus, Tribhuvan University, P.O. Box 43, Pokhara, Kaski, Nepal, HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan, and Department of Botany, University of Dar es Salaam, P.O. Box 35060, Dar es Salaam, Tanzania