Absolute configuration of trisporic acids and the stereochemistry of cyclization in β-carotene biosynthesis

Abstract

SumrnavyThe absolute stereochemistry of trisporic acid C(1) is lS, 13R; the la-methyl, which is equatorial, is selectively labelled by [2-14C]mevalonate, and corresponding chirality at C-1 in [2-14C]mevalonate-labelled p-carotene is thereby indicated with implications for the stereochemistry of cyclization in ,&carotene biosynthesis.

Uptake into Mouse Brain of Four Compounds Present in the Psychoactive Beverage Kava

“…The deuterated aldehyde was then converted to the desired 12-[OC2H31yangonin (6a) by a published procedure. 12 The product had an isotopic purity of 98% 'H3, with no detectable ion current at mlz 259 corresponding to the [MH]' of unlabeled yangonin (6).…”

“…13.5, 7-(4-0C2HJ -'H JDesmethoxyyangonin (3a)-Desmethoxyyangonin (3) was synthesized from benzaldehyde by a published procedure. 12 To desmethoxyyangonin (80 mg) and [2H41methanol (2 mL), sodium (1 mg) was added and the contents were heated at 80 "C for 1.5 h. After removal of solvent (dry Nz gas), the residue was dissolved in dichloromethane and washed with aqueous NaOH (0.4 M, 2 x 2.5 mL). The organic layer yielded a yellow solid (57 mg) shown by GC-MS to be 3a with the following isotopic composition: 1% 2H,, 2% 'H,, 47% 2H6, 3 9 1 'H,, 8% 2H4, and 1% 2H3.…”

An immunofluorescent investigation of the zygophore surface of mucorales

“…The zygophore antigens (ZA) were produced by growing the individual strains ofM. mucedo from a central inoculum in 9 cm diameter petri dishes of medium (15 ml) containing 100-200 #g m1-1 trisporic acids (produced by the method of Bu'Lock and Winstanley [6]) which resulted in cultures producing zygophores but not sporangiophores. After 7 days at 20°C the plates were placed on a shelf in a deep freeze for 1 h to freeze the agar and mycelium.…”

Absolute Konfiguration von α‐Zeacarotin, α‐Apo‐8‐carotinal und α‐Apo‐8‐carotinol

“…Da [3]. Anstelle des von Goodwilz vorgeschlagelien Cyclisationsschemas a) sollte unserer Ansicht nach auch die Cyclisation aus einer enantiomeren Sesselfaltung b) in Betracht gezogen werden, worauf wir [5] und BdLock et al [13] bereits aufmerksam gemacht hatten. Die beiden Ringsysteme scheinen sich auch bei der biologischen Hydroxylierung verschieden zu verhalten, wie die Chiralitat der 3,3'-Hydroxygruppen in Xanthophyll (= Lutein) [S] [9] und Zeaxanthin [14] erkennen lassen.…”