Physico-chemical and synthetic studies on carotenoids

Abstract

-A study of the C30 analogue of 6,6-carotene at 360 MHz 'H-n.m.r. and 90.5 MHz '3C-n.m.r. confirms all of the signal assignments. Staphylloxanthin is identified as a 6-0-ester of u-D-glucopyranosyl 8'-apo-iPcarotenoate.

Properties of Astaxanthin/Ca2+Complex Formation in the Deceleration of Cis/Trans Isomerization

“…This significant twist also reflects the nuclear downfield shift of C6 (Δδ shift = 3.78 ppm), C7 (Δδ shift = 1.47 ppm), and H7 (Δδ shift = 0.10 ppm). This structure contrasts the previously reported X-ray analysis of uncomplexed ASTX with ω6 torsion of 59.3° (Figure A) . Our chelation model of ASTX(Ca 2+ ) 2 complex indicated a better π-electron conjugation system of the cyclohexenone moiety to polyene, and the metal ion induced conformational regidification 14 thus provided a reasonable explanation for the increase in absorbance.…”

Structure and Biosynthesis of Staphyloxanthin from Staphylococcus aureus

“…In nature, D-sugars in glycosides are normally ␤-glycosidically linked, whereas l-sugars are ␣-glycosidically linked. Moss (27) proposed ␣-D-glucose as the glycoside of staphyloxanthin. Here we show that the core is a ␤-D-glucopyranose.…”

?-Carotene cis isomers as products and substrates in the plant poly-cis carotenoid biosynthetic pathway to lycopene

“…Several groups have established the isomeric structure as 7,9,7¢,9¢-tetracis-lycopene (w,wcarotene ;Englert 1979;Moss 1979) from the tangerine tomato mutant. In addition, Clough and Pattenden (1983) identified 15,9¢-dicis-phytofluene (7,8,11,12,7¢,8¢-hexahydro-w,w-carotene), 9,9¢-dicis-f-carotene (7,8,7¢,8¢-tetrahydro-w,w-caroten\e) and 7,9,9¢-tricis-neurosporene (7,8-dihydro-w,w-carotene) as intermediates of a cis biosynthetic pathway in this tomato mutant.…”