. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS melons,^*^ and 1:8m European peaches.^'"^ On the other hand, Hunter and his colleagues ^ * ^'^ * * found only small amounts of lycopene in red palm oil. According to Brockman ^^^ the apricot contains only 2-3 mg. per cent, (wet wt.) of lycopene compared with 50-80 mg. per cent, of ^-carotene. It is interesting to note at this point that whilst apricots contain only carotenes,^^^ xanthophylls pre- dominate in peaches. ^ ^ •- (v) ^-carotene. Winterstein ^ * * gave the name S-carotene to a fraction obtained from the frui
. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS melons,^*^ and 1:8m European peaches.^'"^ On the other hand, Hunter and his colleagues ^ * ^'^ * * found only small amounts of lycopene in red palm oil. According to Brockman ^^^ the apricot contains only 2-3 mg. per cent, (wet wt.) of lycopene compared with 50-80 mg. per cent, of ^-carotene. It is interesting to note at this point that whilst apricots contain only carotenes,^^^ xanthophylls pre- dominate in peaches. ^ ^ •- (v) ^-carotene. Winterstein ^ * * gave the name S-carotene to a fraction obtained from the fruit hulls of Gonocaryum pyriforme. It also occurs in traces in ordinary tomatoes ^ * ^ {Lycopersicum esculentum)^ but crosses of L. esculentum and L. pimpinellifolium can contain up to 40 (jLg. of S-carotene/g. fruit. ^ * * From such crosses Porter and Murphey ^ *' have recently been able to isolate S-carotene in crystalline form (Table 4). It contains eleven double bonds ten of which are conjugated, one closed ring (which cannot have the p-ionone con- figuration because the pigment has no Vitamin A activity) and one open ring. Winterstein had previously suggested the following structure for S-carotene. This cannot be completely reconciled with the findings of Porter and Murphey ^ *', although it may well be near the (vi) Z,-carotene. A carotenoid, first isolated from carrots by Strain in 19391*^ {see p. 54) and which, although not yet prepared in a completely pure state, has been well characterized chromatographic- ally, 1 *». 16 0 spectroscopically ^ ^ ^ and chemically, ^ ^ ^ jg ^-carotene. The suggestions'^'' that because of the similarity in the position of their visible absorption bands ^-carotene and aurochrome (Karrer and Jucker s ^ ^'s'^') are probably identical, has been disproved by carrying out mixed chromatograms with the two pigments. Auro- chrome is much more tightly absorbed than is ^-carotene, ^' ^ which has now been shown to be in all probability 5 : 6
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