Diosgenin Production in North America A Brief History

Ray F. Dawson1

Additional index words. hormones, , fertility regulants, synthesis intermedi- ates, , Mexican , cultivation, low-tension soil water, , sitosterol

Summary. is a steroidal aglycone occurring in certain species of Dioscorea native principally to eastern Mexico. In the 1940s, diosgenin became a much-sought-after intermedi- ate for the chemical synthesis of certain and structurally related fertility regulants. Various difficulties of access to native sources led to attempts at plantation produc- tion. 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 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 sitos- terol, which became available as a result of advances in microbial fermentation technology. Consequently, the cultivation of Dioscorea was abandoned.

he recent history of diosgenin pro- synthesis intermediate in the pharmaceutical duction and use is marked by an industry for almost 40 years. During those unusual convergence of interests years, great quantities were extracted from T ranging from industrial botany the rhizomes (root or tuber in trade parlance) through medicine, pharmaceutical chemia- of Dioscorea spp. native to and collected from try, business, and international politics. It is a the wild in eastern Mexico. Various pressures tale of extremes. Need for diosgenin arose led to attempted cultivation of some of these precipitously in the 1940s, when no com- species on plantations. Perhaps the most mercial source existed. It remained a favored comprehensive and long-lived effort was that of the Upjohn Company in Guatemala. Un- der intensive cultivation, allowances had to 1Consultant in tropical (retired). 40 Palmer Avenue, be made for support of the long (up to 30 m) Winter Park, FL 32789. woody vines and for removal of rhizomes

22 American Society for Horticultural Science from soil depths up to 1 m at harvest. The required. The small amounts then available most exacting site requirement was for a were said to be under monopolistic control continuous and abundant source of low- by three European manufacturers (see Senate tension soil water. Eventually, diosgenin lost Hearings, 1956). Only 3 years ahead of the its preferred position, so far as the Upjohn crisis of supply, Marker et al. (1947) devised Company was concerned when stigmasterol a synthesis ofprogesterone , the corpus luteum and sitosterol became accessible microbially hormone, from diosgenin. On a hunch forthe preparation of avarietyof commercially (Marker, 1987), he explored the useful steroid intermediates. As so often of eastern Mexico, where he found substan- happens, displacement of a reigning botani- tial quantities of diosgenin-containing raw cal resulted from advances in industrial mi- material. His successes in both chemical and crobiology and in organic chemistry. But, plant exploratory facets of this field have won while demand remained high, it would be for him far greater attention in Mexico difficult to name a more-challenging project (Lehmann et al., 1973) in the field of industrial botany than was the than they have in his attempted cultivation in the American tropics native land. He ex- of the Mexican yam, tracted diosgenin from Hems!' (Matuda, 1953) and its variants. the woody rhizomes of Diosgenin isfound in the stDioscorea mexicana occur in Mexico and adjacent Guatemala. Guillemin, and pre- Chemically,diosgenin isthe steroidal aglycone pared from it 3 kg of (Fig. 1), released upon acid hydrolysis, of a .progesterone (Marker, saponaceous , dioscin. Dioscin- 1987), by far the larg- Fig. l.Diol8enin. containing plant parts, when macerated in est quantity ever before water, impart a surfactant property that the seen. Marker had not long to wait. In 1949, indigens of Mexico and Central America two developments in medicine set off the employed for cleaning purposes. The starchy explosive demand that he had foreseen. From rhizomes were eaten, albeit without relish, in the Mayo Clinic there came an announce- seasons of maize crop failure (de Landa, ment of the dramatic effect of administered medi- 1566). Dioscin is also hemolytic (Coursey, cortisone upon symptoms of rheumatoid ar- terol, 1967). Pre-Columbian inhabitants of the re- thritis. And, from the Worcester Inst. for gion dispersed pulped rhizomes in slowly Developmental Biology, came the first prac- moving streams, whereupon fish suffocated, tical fertility regulants. Although the earliest ltive floated to the surface, and could be retrieved intermediates for cortisone synthesis were the ,ermedi- easilyby hand. The archeological museum at steroidal bile acids, both cortisone and the r the Tikal ruins in Guatemala contains an fertility regulants could be made, at that time, ~roduc- incised bone depiction of a Mayan fishing much more easily from diosgenin. Conse- located foam- for abun- lology party removing very limp fish from quently, a world -wide search began Che covered waters. More recently, North Ameri- dant and inexpensive supplies of intermedi- lfrom canpatent medicines of the late 19th and early ates, including diosgenin, that could be used :ension) 20th centuries made use of dioscin-contain- advantageously for the manufacture of desired but ing extracts in the concoction of remedies for steroid compounds (for two interesting ex- ay 1980, "female troubles," but uses still to come amples, see Landrum, 1986). sitos- could not have been foreseen by either stone- Total synthesis of from the logy. age Maya or our forebearers. simplest organic compounds was still years in Diosgenin was isolated first from the the future-and that route would be pro- rhizomes of anAsiaticspecies,Dioscorea tokoro hibitively expensive in any case. In the words Makino (Tsukamotoetal., 1936). Fouryears of George Pucher, at one time of the Con- later, R.E. Marker (1940a, 1940b, 1943), of necticut Agricultural Experiment Station, published came to be laceutical the Pennsylvania State College, New Haven, the plant world occur- of rare chemicals, ing those the molecular structure and botanical regarded as a storehouse interest top to bottom in :ted from rences of this aglycone. Marker's and it was ransacked from to the realm of intermediates. parlance) went far beyond the academic search of ever more useful of the by discovering, ctedfrom prescience. At that time, knowledge Marker scored a third time hor- populations pressures chemistry and physiology of mammalian alsoin eastern Mexico, enormous Research known locally Ieofthese mones was expanding rapidly. of Dioscorea composita Hems!., constituents tractable source of the most quantities were needed of those as "barbasco," a far more that, up to that time, had than was D. mexicana. Mexican 1:wasthat of the animal body diosgenin by rhizome mala.Un- been known only in trace amounts. Should resources began to be "mined" reasoned, estimated that :eshad to therapeutic uses emerge, Marker collectors. Mexican authorities alone )to 30 m) the pharmaceutical industry would be wholly the states of Vera Cruz and Oaxaca rhizomes unprepared to produce the bulk quantities contained up to 25 t of dry root equivalent! 23 Oct/Dec. 1991 :ural Science HortTechnology. km2, and that » 5500 t of air-dried mate- bunda Mart et Gal., a less vigorous species rial was then being removed annually (Senate possessing a higher average diosgenin con- Hearings, 1956). Giral (1958) stated that the tent (» 5%) and recognized by the yellow flesh diosgenin concentration in this material of its rhizomes (those of D. composita are ranged between 3% and 4% on a dry basis, white). Substantial quantities were processed despite many more optimistic reports. As a by the Compania Agricola Industrial consequence of Marker’s work, and of con- Guatemalteca (CAIGSA). tinuing improvements in chemical technol- Ultimately, Mexico lost its preferred po- ogy, the price of progesterone to manufac- sition as a consequence of several ongoing turers of hormonal products fell from about factors. First, continued exploitation of natu- $200/g in 1940, to $80 in 1943, and to 30¢ ral stands of Dioscorea led to ever higher in 1955 (Senate Hearings, 1956). Owing to transportation costs as distances between its fortunate position with respect to the jungle and processing centers increased and geographical distribution of diosgenin-con- as second-growth stands suffered in terms of taining species, Mexico became the world yield per unit area of terrain and of assay. capital of the steroid intermediates industry, Second, other intermediates were brought a position that it held for more than 20 years. along, including stigmasterol and sitosterol A parallel, although much smaller, industry from soya oils and hecogenin from sisal wastes. sprang up in neighboring Guatemala that was The third factor was Mexico’s attempt to based on the occurrence there of D. flori- protect its national industry in a classic paral- lel to the earlier attempts of Peru to preserve Cinchona bark production in the Andes and of Brazil to prevent loss of Hevea rubber to foreign planters. Political repercussions of Mexico’s efforts in this direction were aired before a Senate Subcommittee on the ‘Won- der Drugs” (1956) chaired by Sen. Joseph O’Mahoney. Testimony before this group affords a broad insight concerning the technolo- gies, the botany, and chemistry, as well as the business and international trade aspects of a new and turbulent industry. Inevitably, commercial-scale cultivation of suitable Dioscorea spp. was contemplated by those firms unable to gain unrestricted access to Mexican raw materials and by Mexi- can firms concerned about the uncertainty of future supplies. Edible yams of the same genus had been cultivated for a very long time in and the Indies, and considerable technology had accumulated (Coursey, 1967). The earliest attempts to cultivate genin- containing yams in the western hemisphere are believed to have taken place in Guatemala (Bruhn et al., 1972), in Costa Rica and in Puerto Rico. One of the more systematic and comprehensive efforts was that of the U. S. Dept. of Agriculture in Mayaguez and an- other at the Puerto Rican Experiment Station in Rio Piedras. The first Guatemalan and Costa Rican attempts were terminated pre- maturely. Yield extrapolations from field plots to commercial-scale plantings were published by Puerto Rican workers (Martin et al., 1966), with recommendations for cultivation. It is understood that Irving Sollins, one of the more knowledgeable witnesses before the O’Mahoney subcommittee, formed a com- pany to make use of Puerto Rican technolo- gies. However, the clay soils and inclement weather combined to make harvesting both difficult and costly. An earlier journal paper

24 American Society for Horticultural Science (Kennard and Morris, 1956) had already encouraged those who would attempt culti- vation under more favorable conditions for harvesting activities. In 1957, Percy L. Julian, well-known organic chemist and my one- time mentor in that subject at DePauw Univ., came to New York to discuss possibilities for growing Dioscorea successfully in Guatemala, where I had some experience with the intro- duction of Cinchona. On the evidence avail- able, a rough estimate of 60% in favor of success was enough to set Julian on a course ofaction. For the purpose, he formed Empresa Agro-Quimica Guatemalteca, S.A., where- upon I began a 20-year-long schedule of commuting between New York and Guate- mala. Empresa’s first plantings were made late in 1958, employing material purchased from B.A. Krukoff of Ensayos Agricolas, S.A. (Landrum, 1986). First harvests were disap- pointing. The project survived only because one field or block on the farm yielded at or even above our best expectation. We took this ex- ception as a measure of species potential and so defined our task in terms of learning how to achieve the latter routinely. In 1962, the Fine Chemicals Division of the Upjohn Company acquired the project, moved it to an area of low- bulk-density soils that were derived from recent volcanic ash falls (see Dawson et al., 1980), and growth of Dioscorea rhizomes in terms of dry proceeded patiently to develop technology. matter accumulation were identified by the This is designated herein as the central farm. above means. The first occupied benches of Production objectives were set minimally at 18 alluvium above the flood plains of rivers such t·ha-l of dry rhizome material assaying 4% as the Motagua in Guatemala and the Aguan diosgenin, all within a 3-year crop cycle. There in Honduras. The second lay over relatively was reason to believe that these figures might shallow permanent water tables such as the be improved to as much as 28 t of dry material black sands below Tiquesate, Guatemala, or with a content of 5.5% to 6.0% diosgenin. the peats of the Florida Everglades. In both Harvested crops on the new site gave on aver- places, water tables could be controlled by age 4% of diosgenin, but dry rhizome yields fell dry-season irrigation or by poldering and to 50% of the minimum expected or less. pumping. The third was characterized by a Consequently, a three-tiered experimental ap- friable topsoil over a barrier to percolation. proach was devised to identify the limiting Old marine sediments (Bucul clay with 14% factor(s) and means for rectification. Field plot organic matter in the topsoil) near Retalhuleu, tests employing the usual management vari- Guatemala, and an old lava flow from volcano ables failed to affect either growth rates or Turrialba in Costa Rica, were representative. diosgenin concentrations. Off-farm tests scat- The principal point is that subsoil profile with tered from Florida to Costa Rica gave clear respect to the storage and facile delivery of indication that this heretofore wild plant re- water to yam roots is much more important quired unusually great quantities of soil water to the growth of this crop than is topsoil and that this water must be within reach of the classification. Gross yields on each of these long coarse roots but not the rhizome meris- sites came close to the initial objective. For tems. A mini-scale greenhouse experimental example, 32 ha of cotton land below Tiquesate system that measured relative growth rates of gave 15 t of dry rhizome/ha in 3 years. In all very small tubers formed by young seedlings such cases, however, diosgenin concentra- not only confirmed interpretation of the site tion (assay) in the dry material fell to 3% or testing outcome, but also gave an explanation. lower. Because of this totally unexpected That was, D. composita rhizome growth rates development, estimated diosgenin yield depend linearly upon the supply of readily equivalents at Tiquesate, 400 kg·ha-1 in 3 years, available (low-tension) soil water (Dawson et fell slightly below those (450-kg equivalents) al., 1980, 1983). on the central farm. This negative relationship Three site categories well-suited to rapid between vigorous rhizome growth and high

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Sapogenins. 69. Isolation andstructure ofthirteen Matuda, E. 1953. Las Dioscoreas de Mexico. An. new steroidal . New sources for known Inst. Biol. México 24(2):279-390. sapogenins. Amer. Chem. Soc. J. 65:1199-1209. Senate subcommittee hearings of the Committee of Marker, R.E., R.B. Wagner, P.R.. Ulshafer, E.L. the Judiciary, 5-6 July 1956.1957. “The Wonder Wittbecker, D.P.J. Goldsmith, and C.H. Ruof. 1947 Drugs”. Senate Res. no. 167. U.S. Govt. Printing Sterols CLX. Sapogenins. 72. Steroidal sapogenins. Office, Washington, D.C. Amer. Chem. Soc. J. 69:2167-2230. [See also US. patents no. 2,352,852,4 July 1944, and no. Tsukamoto, T. and Y. Ueno. 1936. Isolation of 2,420,489,13 May 1947, issued to RE. Marker.] dioscin and diosgenin from Dioscorea tokoro Makino. Pharm. Soc. Jpn. J. 56:802. [German, p. Marker, R.E. 1987. The early production of ste- 135-140. Chem. Abstr. 32:7470/1938.] roidal hormones. CHOC News of the Center for History of Chemistry 4(2):3-6. [A somewhat different view occurs in what is purported to be an Acknowledgements interview with Marker by members of a German The manuscript was read by Alexander W. television crew that was printedwithout the author’s name in LA SEMANA, a weekly newspaper once Schneider, vice-president (retired), Fine published in Guatemala City. A translation of this Chemicals Division, the Upjohn Company, article from the Spanish has been depositedwith the who sponsored the project; by Jeffery E. Archives of The Pennsylvania State Univ.] Shrum, Jr., (retired) formerly project manager, and by Lloyd W. Nystrom, Martin, F. W., E. Cabanillas, and M.H. Gaskins. formerly assistant manager and presently 1966. Economics of the - bearing yam as a crop plant in Puerto Rico. Agr. Res. J., Univ. Director of International Purchasing, Puerto Rico (50(1):53-64. Mallinckrodt Specialty Chemical Company.

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