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).

Physiological effects and metabolism of gossypol.

Gossypol (Gsp), a natural toxin concentrated in cottonseeds, poses great risks to the safe consumption of cottonseed products, which are used extensively throughout the food industry. In this work, we report the first luminescence "turn-on" sensors for Gsp using near-infrared emitting lanthanide (Ln3+) materials, including Ln3+ MOFs and Ln3+ salts. We first demonstrate that the Yb3+ photoluminescence of a Yb3+ MOF, Yb-NH2-TPDC, can be employed to selectively detect Gsp with a limit of detection of 25 μg/mL via a "turn-on" response from a completely nonemissive state in the absence of Gsp. The recyclability and stability of Yb-NH2-TPDC in the presence of Gsp was demonstrated by fluorescence spectroscopy and PXRD analysis, respectively. A variety of background substances present in practical samples that would require Gsp sensing, such as refined cottonseed oil, palmitic acid, linoleic acid, and α-tocopherol, did not interfere with the Yb3+ photoluminescence signal. We further identified that the "turn-on" of Yb-NH2-TPDC photoluminescence was due to the "antenna effect" of Gsp, as evidenced by spectroscopic studies and supported by computational analysis. This is the first report that Gsp can effectively sensitize Yb3+ photoluminescence. Leveraging this sensing mechanism, we demonstrate facile, highly sensitive, fast-response detection of Gsp using YbCl3·6H2O and NdCl3·6H2O solutions. Overall, we show for the first time that Ln3+-based materials are promising luminescent sensors for Gsp detection. We envision that the reported sensing approach will be applicable to the detection of a wide variety of aromatic molecules using Ln3+ compounds including MOFs, complexes, and salts.

Luminescence “Turn-On” Detection of Gossypol Using Ln3+-Based Metal–Organic Frameworks and Ln3+ Salts

Determination of methyltin(IV) and tin(IV) species in water by gas chromatography/atomic absorption spectrophotometry

A method for the purification of gossypol has been developed which yields material differing in optical properties from those previously reported for gossypol preparations A colorimetric test for extractable gossypol has been described It has been shown that cottonseed contains at least three pigments in addition to gossypol Some of the properties of the three pigments have been reported One of these newly detected pigments, gossypurpurin, has been shown to be the substance which, mixed with gossypol, constitutes the so-called “red gossypol” of Podol’skaja The frequently reported water-dispersable blue pigment of cottonseed has been shown to be either a complex of gossypol, gossypurpurin and protein or a mixture of two protein-pigment complexes Its dissociation into the two pigments and protein has been accomplished

The pigments of cottonseed

1.

The pigmentation of cooked cottonseed has been shown to depend principally upon the moisture content and period of heating of the seed.




2.

Several samples of crude hydraulic-pressed and screw-pressed oils produced under known processing conditions were found to differ markedly from each other with respect to their original colors and refining characteristics.




3.

The screw-pressed crude oils were more deeply colored and contained one principal pigment, whereas the hydraulic-pressed oils contained two principal pigments.




4.

The absence of significant amounts of gossypol in the crude oils has been demonstrated by means of a new technic for the quantitative isolation of gossypol.




5.

The crude oil pigments differed from gossypol, but like gossypol, they were removed during alkali refining.




6.

The pigmentation of the crude oils has been shown to depend principally upon the pigmentation of the original seed and the moisture content of the seed during cooking.




7.

On the basis of their absorption spectra it has been deduced that the alkali-refined hydraulic-pressed oils contain two to three pigments originally present in the crude oils whereas the alkali-refined serewpressed oils contain these same pigments as well as a large number of decomposition products of the principal crude oil pigment.

Processing of cottonseed

Quantitative Determination of Extractable Gossypol in Cottonseed and Cotton seed Meal A Spectrophotometric Method

Treatment of moist cottonseed with ammonia prior to storage has been shown to reduce self-heating of the seed and the rate of formation of free fatty acids during storage. The color of oils obtained by solvent extraction from ammonia-treated cottonseed is considerably lighter than that of oils obtained from untreated cottonseed.

Lillian. Kyame

Papers

Quantitative Determination of Extractable Gossypol in Cottonseed and Cotton seed Meal A Spectrophotometric Method

The storage of cottonseed

Catalase and peroxidase in germinating cottonseed.