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- Author or Editor: Ray F. Dawson x
Diosgenin is a steroidal aglycone occurring in certain species of Dioscorea native principally to eastern Mexico. In the 1940s, diosgenin became a much-sought-after intermediate for the chemical synthesis of certain corticosteroids and structurally related fertility regulants. Various difficulties of access to native sources led to attempts at plantation production. One of these, supported by the Upjohn Company between 1962 and 1980, was located on the Pacific coast of Guatemala and is described herein from the standpoint of technology development. The Dioscorea plant produces a long, coarse vine that requires support. The deep-growing, fleshy rhizome contains the diosgenin and, at harvest, must be removed from soil depths up to 1 m. Dry rhizome yield depends on supply of readily available (low-tension) soil water. Sites located over abundant water reserves give satisfactory rhizome yields, but diosgenin concentrations fall to uneconomically low levels under such circumstances. By 1980, diosgenin had been displaced by two products of soya oil processing, stigmasterol and sitosterol, which became available as a result of advances in microbial fermentation technology. Consequently, the cultivation of Dioscorea was abandoned.
Quinine, oldest of the anti-malarials still in use, and quinidine, an anti-arrythmic, have been extracted from Cinchona bark since about 1823. Exploitation of natural stands of Cinchona in the Andes led to several attempts at plantation production. Of these, the most successful were in Netherlands Indonesia (Java). Just before World War II, a cooperative effort to develop technologies for successful cultivation of Cinchona in the western hemisphere was undertaken by the governments of the United States and Guatemala, a major pharmaceutical firm, and four Guatemalan coffee planters. Cultural requirements of this cloud-forest genus were ascertained, and selection of clones for superior yield and disease resistance was achieved. Guatemalan plantings continue production despite the excessively cyclic nature of the market.
Production of rubber from Hevea brasiliensis (Willd. ex A. Juss) Muell.-Arg. (Euphorbiaceae) is greatest in southeastern Asia where the South American leaf blight disease is absent. Except for the Pacific Piedmont of Guatemala, plantation production in the Americas is limited severely by the now widespread presence of the pathogen Microcyclus ulei (P. Henn.) Arx. Mean latex yields from trees growing on the Piedmont approximate those of Indonesia and Malaysia, with little evidence of damage from leaf blight. The scope and scale of the Guatemalan anomaly suggest that environmentally modulated escape rather than previously assumed disease resistance may be the key to successful production of natural rubber in this hemisphere. The Guatemalan industry is presently well-organized to service regional markets in Mexico and the Caribbean Basin. Given due attention to environmental analysis, it may serve also as a model for the development of regional production facilities in other parts of tropical America.