Cotton compounds, identification

Identification of cotton plant compounds. The Identity of gossypol was confirmed by comparison of the spectral (NMR, MS) and chromatographic properties with an authentic sample. The Identity of the cotton leaf anthocyanln was confirmed by comparison of the chromatographic and spectral properties of the... 

The germination stimulant or stimulants from host plants have not yet been identified, but research on isolation and identification of these allelopathic compounds continues. Other nonhost plants, such as cotton, also release chemicals which stimulate the germination of witchweed seed and these crops can replace the cereal crops in witchweed-infected fields. If no acceptable host is present, the witchweed plant is unable to mature and produce seed. The importance of cereal crops as a staple food in underdeveloped countries makes growth of nonhost crops only partially acceptable, and there are numerous wild hosts that allow the witchweed to germinate, mature, and produce more seed (several thousand seeds can be produced by a single plant). Nevertheless, application of either natural or synthetic stimulants in the absence of a host plant is an effective way of reducing and eventually eliminating the witchweed problem. 

A few groups have made substantial progress toward the identification of Gossypium secondary metabolites. Stlpanovic, in collaboration with Wakelyn, Bell, and others, has identified several compounds, primarily cadlnane sesquiterpenolds (17, 21 - 28, 31). Hedin s group has used gas chromatography-mass spectrometry to identify a wide variety of substances which may be derived from the cotton plant (8 - 1, 20). Brzozowska, Hanower,... 

Qccurance and Identification. An early report of cotton volatile composition by Minyard et al. (44) involved steam distillation of large quantities of leaves and flowers. Major compounds identified included the monoterpenes a-pinene, B-pinene, myrcene, trans-B-ocimene, and limonene ( 4). Several other monoterpene hydrocarbons were also present in low concentration. Since that report, many other terpenes have been identified in cotton essential oil steam distillates and solvent extracts. These compounds include cyclic hydrocarbons such as bisabolene, caryophyllene, copaene and humulene (45-47), the cyclic epoxide caryophyllene oxide (45), cyclic alcohols such as bisabolol, spathulenol, and the aromatic compound... 

The usual chemical and spectroscopic techniques such as elemental analyses, molecular weight determinations, and infrared, NMR, and electronic spectroscopy, are frequently useful for the characterization of transition metal cluster compounds. However, x-ray crystallography and, to a lesser extent, mass spectrometry, are almost indispensable for the unambiguous identification of new metal cluster systems. Indeed, much of the rapid progress in metal cluster chemistry since the appearance of Cotton s review article in 1965 (98) can be attributed to the widespread availability of automated x-ray-diffraction equipment. This increases significantly the number and accuracy of crystal structures that can be determined with a given amount of manpower, and thus the analyses of a great many more new metal cluster crystal structures are completed each year. 

Chemical studies on the sex attractant of the boll weevil led to the isolation (454) and identification (38) of four terpenoid compounds. Tumlinson et al. (455) suggested a hypothetical biosynthetic scheme in which all four compounds could be derived from a geraniol-like compound. Hardee (45 showed that male boll weevils required feeding for the synthesis of the attractant substances. Cotton squares proved to be the best diet, but pheromone production was demonstrated on a variety of diets. Mitlin and Hedin (457), using C tracers, obtained evidence... 

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