Five crystalline retinenes have been isolated, which have every appearance of being cis-trans isomers of one another. They are all-trans retinene; three apparently mono-cis isomers: neoretinenes a and b and isoretinene a; and isoretinene b, an apparently di-cis isomer. The absorption spectra of these substances display the relations expected of cis-trans isomers. The main absorption band is displaced 5.5 to 7 mmicro toward shorter wave lengths for each presumptive cis linkage. Some of the presumptive cis isomers also display a cis peak at 255 to 260 mmicro. All five substances yield an identical blue product on mixing with antimony chloride. All of them are converted by light to what appears to be an identical mixture of stereoisomers. Heat isomerizes them very slowly; only neoretinene b exhibits large changes on heating at 70 degrees C. for 3 hours. The various isomers have been extensively interconverted by gentle procedures, and all of them have been converted to all-trans retinene. The present theory of cis-trans isomerism in carotenoids predicts the existence of four stable isomers of retinene. Instead we seem to have five-specifically three mono-cis forms where two are expected. There is no doubt that all these substances are closely related isomers of one another. The only point in question is whether they differ in part by something other than cis-trans configuration. One possibility, as yet little supported by evidence, is that isomerization between beta- and alpha-ionone rings may be involved. If, however, as seems more likely, all these substances are geometrical isomers of one another, some modification is needed in the present theory of configurational relationships in this class of compounds.

Hot Temperature↗

PubMed1952

Adrenalin and hydroxytyramine in the parotid gland venom of the toad, Bufo marinus.

Preparations from the parotid gland venom of the toad Bufo marinus have been analyzed by paper chromatography for the presence of adrenalin precursors. In addition to adrenalin itself, hydroxytyramine was identified and a second compound which appeared to be an adrenalin ester-perhaps lactyl-adrenalin. Two other compounds which appeared on the chromatogram could not be identified. Neither noradrenalin nor another possible precursor, epinine, appeared to be present.

Animals↗

PubMed1952

The alleged occurrence of adrenalin in the mealworm.

Wense has reported the isolation of crystalline adrenalin from larvae of the beetle Tenebrio molitor. An attempt to repeat his procedures failed to yield any evidence of adrenalin. Analysis of mealworm extracts by paper chromatography and colorimetric means also yielded no indication of adrenalin, though adrenalin added to mealworms can be detected by these procedures in amounts less than 1 mg. per 100 gm. Mealworm extracts reveal on the paper chromatogram the presence of two other orthodiphenols, neither of which appears to be dopa but which may be 3,4-dihydroxyphenyllactic acid and 3,4-dihydroxyphenylacetic acid, compounds recently isolated elsewhere from this organism.

Animals↗