1. Natural Products Research Group; Department of Chemistry; Faculty of Engineering and Physical Sciences; University of Surrey; Guildford GU2 7XH UK
2. School of Chemistry and Physics; University of KwaZulu-Natal; Durban 4041 South Africa
3. Centre for Drug Research; Division of Pharmaceutical Biosciences; Faculty of Pharmacy; University of Helsinki; FI-00014 Helsinki Finland
4. Department of Agricultural Sciences; University of Helsinki; FI-00014 Helsinki Finland
5. Sector of Biologically Active Substances; Department of Forestry; Far East Forestry Research Institute; Khabarovsk Vo-lochaevskaya 71 Russia