Preparation of methyl 11,14,17-eicosatrienoate-8,8,9,9-d 4 and methyl 8,11,14,17-eicosatetraenoate-8,9-d 2

Methyl 11,14,17-eicosatrienoate-8,8,9,9-d ₄ was obtained by Wittig coupling of 3,6-nonadienyltriphenylphosphonium iodide with methyl 11-oxoundecanoate-8,8,9,9-d ₄. For the synthesis of the phosphonium salt, 2-pentynol was converted to 1-bromo-2-pentyne with triphenylphosphine dibromide. Grignard coupling of 1-bromo-2-pentyne with 3-butynol in the presence of cuprous chloride gave 3,6-nonadiynol. The latter was hydrogenated in the presence of P-2 nickel catalyst to yield 3,6-nonadienol. The dienol was convertedvia the bromide and iodide to the phosphonium salt. The aldehyde ester was prepared starting with the coupling of 7-bromoheptanoic acid and 3-butynol with lithium amide in liquid ammonia. The hydroxyalkynoic acid obtained was converted to the methyl ester and the hydroxy group was converted to the tetrahydropyranyloxy group. Subsequent deuteration of the methyl 11-(2-tetrahydropyranyloxy)-8-undecynoate with deuterium gas andtris-(triphenylphosphine)chlorohodium gave the corresponding tetradeuterated product. The tetrahydropyranyl group was removed and the methyl 11-hydroxy-undecanoate-8,8,9,9-d ₄ was oxidized to the aldehyde ester with pyridinium chlorochromate. Methyl 8,11,14,17-eicosatetraenoate-8,9-d ₂ was obtained by a similar sequence of reactions. The methyl 11-oxo-8-undecenoate-8,9-d ₂ required for the Wittig coupling was obtained by Lindlar deuteration of the protected alkynoic ester to methyl 11-(2-tetrahydropyranyloxy)-8-undecenoate-8,9d ₂. The unsaturated hydroxy ester was oxidized to the aldehyde ester by periodinane with negligible isomerization. The allcis isomers were isolated by silver resin chromatography. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Synthesis and characterization of [1-13C]-and d8-arachidonic acid

Methyld ₈- and [1-¹³C] 5,8,11,14-eicosatetraenoate (arachidonate) were prepared from a common synthetic precursor, 4,7,10,13-nonadecatetrayn-1-ol. The purified products were characterized by gas chromatography-mass spectrometry. Mass spectra oft-butyldimethylsilyl esters ofd ₈-and [1-¹³C]-arachidonic acid showed a most intense [M-57]⁺ peak at high mass. The isotopic purity of methyl [1-¹³C] arachidonate was 99% and that of methyld ₈-arachidonate was 56%. Whend ₈-arachidonic acid was prepared by direct deuteration of 5,8,11,14-eicosatetraynoic acid, the isotopic purity of the sample was 86%.     

Preparation of deuterated methyl 6,9,12-octadecatrienoates and methyl 6,9,12,15-octadecatetraenoates

Methyl 6,9,12-octadecatrienoate-15,15,16,16-d ₄ was obtained by Wittig coupling between 6,6,7,7-tetradeutero-3-nonenyltriphenylphosphonium iodide, 8, and the aldehyde ester, methyl 9-oxo-6-nonenoate. Methyl 6-oxohexanoate, obtained by ozonolysis of cyclohexene, was coupled in a Wittig reaction with [2-(1,3-dioxan-2-yl)ethyl]triphenylphosphonium bromide to give methyl 8-dioxanyl-6-octenoate. This compound was transacetalized to methyl 9,9-dimethoxy-6-nonenoate, which was then hydrolyzed to the aldehyde ester. For the preparation of compound 8, the tetrahydropyranyl ether of 2-pentynol was deuterated with deuterium gas and tris-(triphenylphosphine)chlororhodium. The tetradeuterated tetrahydropyranyl ether was converted to the bromide with triphenylphosphine dibromide, and the bromide was coupled with 3-butynol by means of lithium amide in liquid ammonia to give 3-nonynol-6,6,7,7-d ₄. Hydrogenation over Lindlar's catalyst converted the deuterated alkynol to 3-nonenol-6,6,7,7-d ₄. This deuterated alkenol was converted to the bromide with triphenylphosphine dibromide, then to the iodide with sodium iodide in acetone, and finally to 8 with triphenylphosphine in acetonitrile. Methyl 6,9,12,15-octadecatetraenoate-12,13,15,16-d ₄ was obtained by Wittig coupling between methyl 9-oxo-6-nonenoate and 3,4,6,7-tetradeutero-3,6-nonadienyltriphenylphosphonium iodide, 15. For the preparation of compound 15, the bromide obtained from the reaction of 2-pentynol with triphenylphosphine dibromide was coupled with 3-butynol with lithium amide in liquid ammonia. The resulting 3,6-nonadiynol was deuterated with deuterium gas in the presence of P-2 nickel, and the resultant deuterated nonadienol was converted to 15 through the bromide and iodide. The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.     

Preparation and properties of new surfactants containingd-glucosamine as the building block

Three types of new surfactants were prepared by usingN-acetyl-d-glucosamine as a starting material. The first type of surfactant, sodium methyl 4,6-O-alkylidene-2-(carboxyl-atomethylamino)-2-deoxy-d-glucopyranoside, was prepared successively by the following treatments: methyl glucosidation ofN-acetyl-d-glucosamine, transacetalization with an appropriate aldehyde dimethyl acetal, deacetylation, and finally reaction of the resulting methyl-4,6-O-alkylidene-2-amino-2-deoxy-d-glucopyranoside (2-amino precursor) with bromoacetic acid. The reaction of this 2-amino precursor with methyl iodide yielded the second type of surfactant, methyl 4,6-O-alkylidene-2-deoxy-2-(trimethylammonio)-d-glucopyranoside iodide, in excellent yield. The last type of compound, sodium methyl 2-acetamide-4,6-O-alkylidene-3-O-[1-(carboxylato)-ethyl]-2-deoxy-d-glucopyranoside, was synthesized by the reaction of methyl 2-acetamide-4,6-O-alkylidene-2-deoxy-d-glucopyranoside with 2-chloropropionic acid. Concerning the two carboxylate types of surfactants, the compounds containing a C₉ or C₁₁ hydrophobic chain in the alkylidene part showed higher water solubility than the corresponding compounds containing a C₇ hydrophobic chain. Both the micelle-forming property and the ability to lower the surface tension of these carboxylate types of compounds increased with an increase in the length of the hydrophobic chain in the alkylidene part. These compounds can be applied to new acid-decomposable types of cleavable surfactants because they contain an acetal group. The acetal bond of the ammonium type of compound was cleaved more slowly than that of the corresponding carboxylate types of surfactants in 2% aqueous HCI solution. The biodegradabilities of these compounds were also determined.     

Preparation of deuterium-labelled methyl linoleate and its geometric isomers from natural seed oils

Multi-gram quantities of deuterium-labelled methyl linoleate (methyl cis-9,cis-12-octadecadienoate) and its geometric isomers are readily synthesized fromCrépis alpina (70–80% cis-9-octadecen-12-ynoic acid) andVernonia galamensis (70–80% 12,13-epoxy-cis-9-octadecenoic acid) seed oils. Methylcis- 9,cis- 12- andtrans- 9,cis- – octadecadienoate-12,13-d₂ were prepared by the Lindlar-catalyzed reduction (with D₂ gas) of methylcis- 9- and trans-9-octadecen-12-ynoates, respectively. Methyltrans- 9- octadecen-12-ynoate was synthesized by thep-toluene-sulfinic acid-catalyzed isomerization of the corresponding cis isomer. Methylcis- 9fiis- 12., trans- 9fiis- 12;cis- 9,trans- 12- andtrans- 9, frans-12-octadecadienoate-d₂, d₄ and d₆ were prepared by the Wittig coupling (with stereochemical control) of the appropriate d₂-, d₄- or de-alkyltriphenyl-phosphonium salt with methyl 12-oxo-cis-9- ortrans- 9- dodecenoate (prepared by the para-periodic acid cleavage of methyl 12,13-dihydroxy-cis-9- or trans-9-octadecenoate). Thecis dihydroxy ester was synthesized fromVernonia galamensis seed oil by acetolysis, saponification and then esterification. Thecis dihydroxy ester was isomerized by nitric acid/sodium nitrite to thetrans form and purified by silver resin chromatography. Isotopic purities ranged from 88% (for the d₆ isomers) to 99% (for the d₂ isomers). The mention of firm names or trade products does not imply that they are endorsed or recommended over other firms or similar products not mentioned.     

Preparation of methyl 5,11,14,17-eicosatetraenoate-8,8,9,9-d 4

For studies of incorporation, elongation and desaturation of fats in humans and animals, methyl 5,11,14,17-eicosatetraenoate-8,8,9,9-d ₄ was prepared by Wittig coupling, in the presence of sodiumbis(trimethylsilyl) amide, of 6,9,12-pentadecatrienal-3,3,4,4-d ₄ and 4-carboxybutyltriphenylphosphonium bromide. The all-cis isomer was separated fromtrans isomers and other impurities by silver resin chromatography. Location and configuration of the double bonds and deuterium atoms were affirmed by nuclear magnetic resonance and mass spectrometry.     

Preparation of specifically dideuterated octadecanoates and oxooctadecanoates

Sixteen methylgem dideuterooctadecanoates with two deuterium atoms at positions 2- to 17- and seven oxo esters, 8-oxooctadecanoate-5,5-d ₂, 8-oxooctadecanoate-11,11-d ₂, 11-oxooctadecanoate-8,8-d ₂, 11-oxooctadecanoate-14,14-d ₂, 12-oxooctadecanoate-9,9-d ₂, 7-oxooctadecanoate-10,10-d ₂ and 13-oxooctadecanoate-16,16-d ₂ with two deuteriums on the carbon γ to the oxo group, have been synthesized. Two principal methods of introducing deuterium were used: preparation of 2,2-dideutero acids by exchange with deuterium oxide followed by chain extension giving dideuteroxooctadecanoates, which were then reduced, as tosylhydrazones, with sodium cyanoborohydride to dideuterooctadecanoates and stepwise introduction by reduction of oxooctadecanoates with sodium borodeuteride, formation of tosylate or mesylate, reduction with lithium aluminium deuteride to tetradeuterooctadecanol and oxidation to dideuterooctadecanoic acid. Presented at the AOCS Meeting, Chicago, September 1976. NRCC No. 15663.     

Preparation of methylcis-9,cis-12,cis-15-octadecatrienoate-15,16-d 2 and methylcis-9,cis-12,cis-15-octadecatrienoate-6,6,7,7-d 4

Methylcis-9,cis-12,cis-15-octadecatrienoate-15,16-d ₂ was obtained from Wittig coupling of methyl 12-oxo-cis-9-dodecenoate,18, and 3,4-dideutero-cis-3-hexenyltriphenylphosphonium bromide,16. Compound18 was obtained by periodic acid oxidation of methyl 12,13-dihydroxy-cis-9-octadecenoate,17, obtained fromVernonia oil. Compound18 also was synthesized from methyl oleate as the starting material. The deuterated fragment,16, was prepared from 3-hexynol and using Lindlar's catalyst and deuterium gas to introduce the deuterium atoms. Methylcis-9,cis-12,cis-15-octadecatrienoate-6,6,7,7-d ₄ was prepared by Wittig coupling of 3,6-nonadienyltriphenylphosphonium iodide,5, with methyl 9-oxononanoate-6,6,7,7-d ₄,11. Deuterium atoms were introduced during the synthesis of11 from 3-butynol and 5-bromopentanoic acid with deuterium gas in the presence of [Ph₃P]₃-RhCl. For the preparation of5, the 3,6-nonadiynol intermediate was reduced to 3,6-nonadienol with P-2 Nickel and hydrogen. The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.     

Synthesis of ethyl arachidonate-19,19,20,20-d 4 and ethyl dihomo-γ-linolenate-19,19,20,20-d 4

Ethyl 5,8,11,14-eicosatetraenoate-19,19,20,20-d ₄ and ethyl 8,11,14-eicosatrienoate-19,19,20,20-d ₄ were synthesized by Grignard coupling of the methanesulfonyl ester of 2,5-undecadiyn-1-ol-10,10,11,11-d ₄ with 5,8-nonadiynoic acid and 8-nonynoic acid, respectively. The coupled products upon Lindlar reduction, followed by the preparation of their ethyl esters, yielded deuteriated ethyl arachidonate and ethyl dihomo-γ-linolenate, which were completely characterized by¹³C and¹H nuclear magnetic resonance and mass spectral analysis.     

An efficient ultrasound-assisted zinc reduction of fatty esters containing conjugated enynol and conjugated enynone systems

Reduction of methyl 8-hydroxy-11-E/Z-octadecen-9-ynoate (1) with zinc in either aqueous n-propanol or water under concomitant ultrasound irradiation furnished a mixture of methyl 8-hydroxy-9Z,11E-octadecadienoate (3a) and methyl 8-hydroxy-9Z, 11Z-octadecadienoate (3b) (96% yield). Reduction of methyl 8-oxo-11-E/Z-octadecen-9-ynoate (2) under similar conditions gave methyl 8-oxo-10-Z-octadecenoate exclusively (4, 70%). The latter compound was epoxidized and converted to a C₁₈ furanoid fatty ester (6, methyl 8,11-epoxy-8,10-octadecadienoate) in 70% yield.     

Preparation of some linseed esters of methyla-d-glucopyranoside using the methoxycarbonyl blocking group

The three possible methoxycarbonyl derivatives of methyl 4,6-O-benzylidene-a-d-glucopyranoside have been prepared. The methoxycarbonyl at the C₂ position in the 2,3-di-O-methoxycarbonyl derivative is removed selectively in anhydrous ammonia. The ability of the methoxycarbonyl group to block selectively the C₂ hydroxyl in methyl glucoside has been utilized to synthesize some mono-, di-, and tri-linseed esters of methyl glucoside. The use of this new blocking group has permitted the first synthesis of some unsaturated esters of methyl glucoside. Presented in part at AOCS meeting in Minneapolis, Minn., 1963. A laboratory of the No. Utiliz. Res. Dev. Div., ARS, USDA.     

Syntheses of tetra- and hexadeuterated octadecenoates

A study of the metabolism in man ofcis andtrans monoenoic acids required the synthesis of tetra- and hexadeutero-9-octadecenoates. Preparation of methyl 9-octadecenoate-8,8,11,11-d ₄ (90 mol % deuterium) by the Wittig reaction was accompanied by deuterium scattering with sodium methoxide as the base but not with alkyllithium. Scattering occurred in both the aldehyde and phosphorane moieties only when the aldehyde contained deuterium on the alpha carbon. Methyl 9-octadecenoate-8,8,13,13,14-14-d ₆ (98 mol % deuterium) was also prepared by the Wittig reaction. The deuterated octadecenoates were formed principally ascis isomers. Thetrans isomers were produced by nitrogen oxide isomerization and separation on a silver ion column. Presented at the AOCS Fall Meeting in Cincinnati, September 28–October 1, 1975.     

Effect of dietary conjugated linoleic acid (CLA) on metabolism of isotope-labeled oleic,linoleic, and CLA isomers in women

The purpose of this study was to investigate the effect of dietary CLA on accretion of 9c-18∶1, 9c, 12c-18∶2, 10t, 12c-18∶2, and 9c, 11t-18∶2 and conversion of these FA to their desaturated, elongated, and chain-shortened metabolites. The subjects were six healthy adult women who had consumed normal diets supplemented with 6 g/d of sunflower oil or 3.9 g/d of CLA for 63 d. A mixture of 10t, 12c-18∶2-d ₄, 9c, 11t-18∶2-d ₆, 9c-18∶1-d ₈, and 9c, 12c-18∶2-d ₂, as their ethyl esters, was fed to each subject, and nine blood samples were drawn over a 48-h period. The results show that dietary CLA supplementation had no effect on the metabolism of the deuterium-labeled FA. These metabolic results were consistent with the general lack of a CLA diet effect on a variety of physiological responses previously reported for these women. The ²H-CLA isomers were metabolically different. The relative percent differences between the accumulation of 9c, 11t-18∶2-d ₆ and 10t, 12c-18∶2-d ₄ in plasma lipid classes ranged from 9 to 73%. The largest differences were a fourfold higher incorporation of 10t, 12c-18∶2-d ₄ than 9c, 11t-18∶2-d ₆ in 1-acyl PC and a two- to threefold higher incorporation of 9c, 11t-18∶2-d ₆ than 10t, 12c-18∶2-d ₄ in cholesterol esters. Compared to 9c-18∶1-d ₈ and 9c, 12c-18∶2-d ₂, the 10t, 12c-18∶2-d ₄ and 9c, 11t-18∶2-d ₆ isomers were 20–25% less well absorbed. Relative to 9c-18∶1, incorporation of the CLA isomers into 2-acyl PC and cholesterol ester was 39–84% lower and incorporation of 10t, 12c-18∶2 was 50% higher in 1-acyl PC. This pattern of selective incorporation and discrimination is similar to the pattern generally observed for trans and cis 18∶1 positional isomers. Elongated and desaturated CLA metabolites were detected. The concentration of 6c, 10t, 12c-18∶3-d ₄ in plasma TG was equal to 6.8% of the 10t, 12c-18∶2-d ₄ present, and TG was the only lipid fraction that contained a CLA metabolite present at concentrations sufficient for reliable quantification. In conclusion, no effect of dietary CLA was observed, absorption of CLA was less than that of 9c-18∶1, CLA positional isomers were metabolically different, and conversion of CLA isomers to desaturated and elongated metabolites was low.     

Stereochemistry of Electrophilic Reactions of 4-t-Butyl-1-phenylcyclohexyllithium, -sodium, -potassium and -cesium

The first three title compounds were prepared by treating the diastereomeric 4-t-butyl-1-phenyl-1-phenylthiocyclohexanes 8 or 9 (Scheme 3) with lithium, sodium, or potassium naphthalenide, respectively. The potassium derivative was also obtained by treatment of 9 with sodium/potassium alloy and the cesium derivative was similarly obtained by reaction with cesium/potassium/sodium alloy. Quenching of any of these salts with D₂O gave cis- and trans-4-t-butyl-1-phenylcyclohexane-1-d(cis- and trans- 7 -d) in an approximately 1:1 ratio. The reaction was stereoconvergent and the product ratio independent of the metal; the result is explained in terms of a diffusion controlled reaction of a planar or near-planar carbanion. In contrast, methylation with methyl iodide gave the product of axial methylation 10 in an approximately 2:1 predominance over diastereomer 11 . This result is explained in terms of Curtin-Hammett kinetics involving a stereoelectronically preferred axial approach to the electrophile. ¹³C NMR spectral studies of the lithium, potassium, and cesium salts indicate extensive delocalization of the anionic charge into the ring—somewhat more so with the K and Cs than with the Li salt. This finding supports the hypothesis that at least the K and Cs salts involve a planar carbanion moiety, whereas the Li salt may be slightly nonplanar. Both spectrally and stereochemically, the title compounds differ substantially from the earlier studied 2-phenyl-1,3-dithianes.     

2-alkenyl-4,4-dimethyloxazolines as derivatives for the structural elucidation of iosmeric unsaturated fatty acids

Several types of unsaturated fatty acid methyl esters were converted into 4,4-dimethyloxazoline (DMOX) derivatives and analyzed by mass spectrometry to further evaluate the feasibility of using this derivative for locating the positions of double bonds in isomeric fatty acids. Five isomeric 20-carbon tetraenoic acids were analyzed in which the fourcis double bonds were systematically moved from the 4,7,10,13- to the 8,11,14,17-positions. It was possible to locate the positions of all four double bonds in the 7,10,13,16- and 8,11,14,17-isomers by appropriate ions differing by 12 atomic mass units. In a similar way the three terminal double bonds in the 4,7,10,13-, 5,8,11,14- and 6,9,12,15-isomers could be assigned. Odd-numbered ions atm/z 139, 153 and 167 which are accompanied by an even mass ion at 138, 152 and 166, respectively, are diagnostic for DMOX derivatives of acids with their first double bond, respectively, at positions 4, 5 and 6. It was thus possible to assign the location of all four double bonds in these three isomers. A comparison of the spectra of the DMOX derivatives of 17,17,18,18-d ₄ vs. 9,10,12,13-d ₄ linoleic acid suggests that double bonds preferentially migrate toward the polar end of the molecule prior to fragmentation. The merit of using DMOX derivatives to locate double-bond positions in mono- and dicarboxylic acids, produced during β-oxidation of polyunsaturated fatty acids, was evaluated. The spectra of 3-cis- and 4-cis-decenoic acids differ as do the spectra of 8-carbon dicarboxylic acids with their double bonds at positions 3 and 4.     

New cerebrosides from the basidiomycete <Emphasis Type="Italic">Cortinarius tenuipes</Emphasis>

Five cerebrosides (1–5), including three new ones named cortenuamide A (1), cortenuamide B (2), and cortenuamide C (3), were isolated from the fruiting bodies of the basid-iomycete Cortinarius tenuipes. The structures of those compounds were elucidated as (4E,8E)-N-d-2′-hydroxytetracosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (1), (4E,8E)-N-d-2′-hydroxytricosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8 sphingadienine (2), (4E, 8E)-N-d-2′-hydroxydocosanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (3), (4E, 8E)-N-d-2′-hydroxyoctadecanoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (4), and (4E, 8E)-N-d-2′-hydroxypalmitoyl-1-O-β-d-glycopyranosyl-9-methyl-4,8-sphingadienine (5) by spectral and chemical methods.     

New coupling method without heavy metals for the synthesis of a new class of fatty acid methyl ester oligoglycoside ethers

A new method, using poly-O-acetyl-β-d-glycopyranosylbromide, methyl 9-or methyl 12-hydroxyoctadecanoate and triethylamine as catalyst, is described for the synthesis of a new class of nonionic surfactants. Chemical structures were identified using ¹H and ¹³C nuclear magnetic resonance spectroscopy including two-dimensional techniques and Fourier transforming infrared. Critical micelle concentrations and surface tension profiles of these O-alkyl-β-d-glycosides in water were determined.     

Comb-shaped diblock copolystyrene for anion exchange membranes

To improve the properties of diblock copolystyrene-based anion exchange membranes (AEMs), a series of AEMs with comb-shaped quaternary ammonium (QA) architecture (QA-PS_m-b-PDVPPA_n-xC where x denotes the number of carbon atoms in different alkyl tail chains and has values of 1, 4, 8, and 10 and C denotes carbon) were designed and synthesized via subsequent quaternization reactions with three different alkyl halogens (methyl iodide and N-alkane bromines (CH₃[CH₂] _x-1Br where x = 4, 8, and 10). Compared with triblock analogues quaternized with methyl iodide in our previous research, QA-PS_m-b-PDVPPA_n-xC (x = 4, 8, and 10) AEMs are more flexible with the introduction of a long alkyl tail chain; this probably impedes crystallization of the rigid polystyrene-based main chain and induces sterically adjustable ionic association. An increase in the pendant alkyl tail chain length generally led to enhanced microphase separation of the obtained AEMs, and this was confirmed using small-angle X-ray scattering and atomic force microscopy. The highest conductivity (25.5 mS cm⁻¹) was observed for QA-PS₁₂₀-b-PDVPPA₈₀-10C (IEC = 1.94 meq g^–1) at 20 °C. Furthermore, the water uptake (<30%) and swelling ratio (<13.1%) of QA-PS_m-b-PDVPPA_n-xC AEMs are less than half of these corresponding values for their triblock counterparts. The QA-PS₁₂₀-b-PDVPPA₈₀-10C membrane retained a maximum stability that was as high as 86.8% of its initial conductivity after a 40-day test (10 M NaOH, 80 °C), and this was probably because of the steric shielding of the cationic domains that were surrounded by the longest alkyl tail chains. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47370.     

Biokinetics of dietaryRRR-α-tocopherol in the male guinea pig at three dietary levels of vitamin C and two levels of vitamin E. Evidence that vitamin C does not “spare” vitamin Ein vivo

The net rates of uptake of “new” and loss of “old”2R,4′ R,8′ R-α-tocopherol (RRR-α-TOH, which is natural vitamin E) have been measured in the blood and in nine tissues of male guinea pigs over an eight week period by feeding diets containing deuterium-labelled α-tocopheryl acetate (d ₆-RRR-α-TOAc). There was an initial two week “lead-in” period during which 24 animals [the “high” vitamin E (HE) group] received diets containing 36 mg of unlabelled (d ₀)RRR-α-TOAc and 250 mg of ascorbic acid per kg diet, while another 24 animals [the “low” vitamin E (LE) group] received diets containing 5 mgd ₀-RRR-α-TOAc and 250 mg ascorbic acid per kg diet. The HE group was then tivided into three equal subgroups, which were fed diets containing 36 mgd ₆-RRR-α-TOAc and 5000 mg [the “high” vitamin C (HEHC) subgroup], 250 mg [the “normal” vitamin C (HENC) subgroup] and 50 mg [the “low” vitamin C (HELC) subgroup] ascorbic acid per kg diet. One animal from each group was sacrificed each week and the blood and tissues were analyzed ford ₀- andd ₆-RRR-α-TOH by gas chromatography-mass spectrometry. The LE group was similarly divided into three equal subgroups with animals receiving diets containing 5 mgd ₆-RRR-α-TOAc and 5,000 mg (LEHC), 250 mg (LENC) and 50 mg (LELC) ascorbic acid per kg diet with a similar protocol being followed for sacrifice and analyses. In the HE group the totald ₀-+d ₆-)RRR-α-TOH concentrations in blood and tissues remained essentially constant over the eight week experiment, whereas in the LE group the totalRRR-α-TOH concentrations declined noticeably (except in the brain, an organ with a particularly slow turnover of vitamin E). There were no significant differences in the concentrations of “old”d ₀-RRR-α-TOH nor in the concentrations of “new”d ₆-RRR-α-TOH found in any tissue at a particular time between the HEHC, HENC and HELC subgroups, nor between the LEHC, LENC and LELC subgroups. We conclude that the long-postulated “spring” action of vitamin C on vitamin E, which is well documentedin vitro, is of negligible importancein vivo in guinea pigs that are not oxidatively stressed in comparison with the normal metabolic processes which consume vitamin E (e.g., by oxidizing it irreversibly) or elminate it from the body. This is true both for guinea pigs with an adequate, well-maintained vitamin E status and for guinea pigs which are receiving insufficient vitamin E to maintain their body stores. The biokinetics of vitamin E uptake and loss in the HE guinea pigs are compared with analogous data for rats reported previously (Lipids 22, 163–172, 1987). For most guinea pig tissues the uptake of vitamin E under “steadystate” conditions was faster than for the comparable rat tissues. However, the brain was an exception with the turnover of vitamin E occurring at only one-third of the rate for the rat. NRCC Publication No. 30775.     

A Simple Method for Obtaining Kinetic Equations to Describe the Enzymatic Hydrolysis of Biopolymers

A procedure to obtain the overall rate of hydrolysis of biopolymers is proposed, based on the fitting of the experimental data x=f(t) to cubic spline functions and from these, by differentiation, to obtain dx/dt. The values of these dx/dt slopes are an exclusive function of the conversion, x, when E₀, S₀, pH and temperature are constant. The fitting of dx/dt versus x leads to equations of the type dxdt=a · x exp(-b · x) for the glucoamylase–starch system, where b=8·75 and a=f(E₀, T).