1. Chemistry of Natural Compounds Department National Research Center Dokki Giza 12622 Egypt
2. Radioisotopes Department Nuclear Research Centre Egyptian Atomic Energy Authority Cairo Egypt
3. Microbial Chemistry Department Biotechnology Research Institute National Research Centre 33 El Bohouth St. (Former El Tahrir St.) Giza P.O. 12622 Egypt
4. Chemistry of Natural and Microbial Products Department Pharmaceutical and Drug Industries Research Institute National Research Centre, Dokki Cairo 12622 Egypt E-mail: hr.rashdan.nrc.sci.eg