island, though this is being depleted at an alarming 

 rate. Palawan's floristic richness — that is to say, the 

 wealth and diversity of its plant species — qualifies the 

 island as the Philippines' last frontier of wilderness as 

 well as a tropical rain forest reserve. The island's flora 

 bears close relationships with that of Borneo as well as 

 with the more northerly Philippine floras, and it holds 

 an important key to understanding the history of plant 

 distribution in Malesia, that region between and in- 

 cluding Malaysia, the Philippines, Papua New Guinea, 

 the Bismarks, and Indonesia. The economic potential 

 of Palawan's rain forests as a source of timber, food- 

 stuffs, and other forest products (cane, gums, resins, 

 etc. ) was brought to light by a Swedish expedition in 

 1984. Its medical importance, however, has until now 

 been ignored. 



Tropical Rain Forests and Medicine 



Tropical rain forests may contribute to medicine in 

 three ways: They may directly provide pharmaceutical 

 products, such as plant extracts and pure chemical 

 compounds; they may serve as models for chemical syn- 

 thesis of related medicinal compounds; and they may 

 provide investigative, evaluative, and other research 

 tools in drug development and testing. 



Many of our most important plant-derived medi- 

 cinal compounds come from tropical species. Notable 



among such compounds are vincristine and vinblastine 

 (from Catharanthus roseus), used in the treatment of 

 cancer; quinine, used to treat malaria, and quinidine, 

 to control heart arrythmias (both from Cinchona ledge- 

 nana); the contraceptive diosgenin (Dioscorea species); 

 the local anaesthetic cocaine {Erythroxylum coca); re- 

 serpine and deserpidine {Rauvolfia species), used as 

 tranquilizers and to control high blood pressure; castor 

 oil {Riciniis communis); and the heart stimulant oua- 

 bain (Strophanthus gratus). Thus, the possibility exists 

 that additional medicinal compounds remain to be dis- 

 covered among the still unknown plants in Palawan's 

 rain forests. 



Since the importance of Palawan's forests as a 

 medicinal resource has not been explored, I traveled to 

 Manila in July of last year to collect plants in Palawan 

 for anti-cancer and anti-AIDS screening, under the au- 

 spices of the United States National Cancer Institute. 

 This field work was carried out between July 12 and 

 August 23 jointly with Dr. Domingo A. Madulid, 

 botanist at the Philippine National Herbarium, 

 National Museum, Manila, with the assistance of 

 Ernesto Reynoso and Epifanio Sacgal, herbarium tech- 

 nicians at that museum. 



Our collecting was slightly different from the kind 

 one usually hears about — collecting herbarium speci- 

 mens for botanical study. Actually, we did collect her- 

 barium specimens for this purpose, but only secondari- 



The expedition crew having a lunch break. Trident Mining site at the base of Victoria Range. 

 The author is sixth from left. 



25 



