Physiological effects and metabolism of gossypol.

Abstract

Gossypol1 is a yellow coloring matter which occurs in various parts of the cotton plant. Longmore (1886) first isolated it as a crude pigment from cottonseed oil “foots,” a material which results from the refinement of crude cottonseed oil with sodium hydroxide and contains free fatty acids, phospholipids, gossypol, and other pigments. Marchlewski (1899) crystallized the acetic acid derivative of a compound from the same source, which he named “gossypol” to designate its origin, genus Gossypium (family Malvaceae), and its chemical nature as a phenol. Gossypol is found in the pigment “glands” (ovispherical bodies about 100 to 400 µm long) of the seed, leaf, stem, laproot bark, and roots of the cotton plant (Royce et al. 1941, Smith 1962). Studies of changes in the gossypol content of cottonseed during different stages of development of the bolls showed that the greatest increase in gossypol occurs between the time of maturity of the boll and the time it is about to open (Adams et al. 1960). Gossypol synthesis in all tissues of the cotton plant was induced in response to such irritants as pathogens, metabolic inhibitors, and cupric and mercuric ions (Bell 1967). Gossypol constitutes 20 to 40% of the weight of the pigment glands in cottonseed (Boatner 1948). Cottonseed usually contains 0.4 to 1.7% gossypol. The total world production of cottonseed is about 25 million tons/year (containing approximately 78,000 tons of gossypol) and about three to six million tons are produced in the United States (Decossas et al. 1968). An average ton of cottonseed gives about 335 pounds of oil and 945 pounds of meal (Altschul et al. 1958). If refined 60% protein cottonseed flour is prepared for human use, 300 to 400 pounds/ton is produced; the remainder can be used for animal feed. It is estimated that only onefourth of the cottonseed flour potentially available could satisfy the present worldwide shortage of protein (Gillham 1969).