Biosynthesis of isoprenoid compounds in Schistosoma mansoni.

The isoprenoid biosynthetic capacity of digenetic trematodes was investigated by following the fate of [14C]mevalonic acid incorporated by Schistosoma mansoni during maintenance in axenic culture. Isoprenoid compounds were analyzed by thin-layer chromatography and high-performance liquid chromatography. Of the nonsaponifiable lipid classes, radioactivity was recovered in the dolichols, ubiquinones and in the short-chain isoprenoid alcohols. The latter group of lipids included geraniol, farnesol, geranylgeraniol and a compound tentatively identified as 2,3-dihydrogeranylgeraniol. Radioactivity derived from [14C]mevalonate was also incorporated into the saponifiable lipids, with 2,3-dihydrogeranylgeranoic acid accompanied by much less geranylgeranoic acid being detected in the triacylglycerol-containing fraction. Similarly, geranylgeraniol and the dihydro derivative were also detected as esters, presumably with fatty acids. The possible significance of the results is discussed.

In vitro effects of an azo compound on the haemolysis and unsaturated fatty acids of red blood cells.

Human red blood cells were treated with 4,4'-azo-bis-(4-cyanovaleric acid) (0-27 x 10(-3) M) in order to determine the effect of the compound on red blood cell haemolysis and unsaturated fatty acids. Maximum haemolysis amounting to approximately 100%, occurred after 60 min incubation with 15 x 10(-3) M azo compound and did not change to any significant extent by increasing incubation time to 4 h. The azo compound caused a decrease in unsaturated fatty acids unrelated to the number of double bonds. The percentage loss of unsaturated fatty acids was 60-100. Therefore the present study reveals that incubation of red blood cells with 15 x 10(-3) M 4,4'-azo-bis-(4-cyanovaleric acid) for 1 h causes maximum haemolysis. Also the damaging effect of the compound on red blood cell unsaturated fatty acids is parallel to haemolysis. These results show that this compound might have relevance for pathophysiology of red blood cells.

Oxidation of human red blood cells by a free radical initiator and effects of radical scavengers.

Haemolysis induced by a free radical initiator (4,4'azobis-(4-cyanovaleric acid) has been studied with transfusion blood. Azobis cyanovaleric acid caused an increase in haemolysis. The effect of alpha- and gamma-tocopherol, 2,2,5,7,8 pentamethyl-6-chromanol and 2,2,7,8 tetramethyl-6-chromanol on the red blood cell haemolysis was studied. There was little difference in the antioxidant action of four chromanols studied. Compounds without the side chain appeared to suppress haemolysis as well as alpha- and gamma-tocopherol. These results suggest that the long side chain of vitamin E has little or no effect on its antioxidant activity in red blood cells. However "protection against haemolysis" was related to total chromanol content of red blood cells. Therefore by dividing "protection" by "total chromanol content" it can be seen that alpha-tocopherol has the highest antioxidant potency.

Fatty acids in plasma and red blood cell membranes in humans, rats, rabbits and dogs.

Fatty acids were estimated in plasma and red blood cell membrane in rats, rabbits, dogs and humans. The fatty acid pattern of plasma and red blood cell membrane was similar in all species and humans with little exceptions. C18:2 was higher in plasma than red blood cell membrane whereas C20:4 was higher in red blood cell membrane than plasma except rabbit. C18:2 was high in rabbit red blood cell membrane when compared to others. Dog was exceptionally very low in C18:2 and high in C20:4 in red blood cell membrane whereas rabbit was low in C20:4 and high in C18:2. 22-Carbon fatty acids showed some variation. Among 22-carbon fatty acids C22:6 was found highest in human red blood cell membrane, with quite high amounts in rat and rabbit but not in dog. Rats were closest to human in their fatty acid patterns.

Some studies on the biosynthesis of ubiguinone, isoprenoid alcohols, squalene and sterols by marine invertebrates.

The ability of fourteen marine invertebrates to utilize [(14)C]mevalonate for the biosynthesis of isoprenoid compounds was investigated. Several of the animals, in particular crustaceans, bivalve molluscs, a coelenterate and a sponge, were unable to synthesize squalene and sterols, whereas gastropod molluscs, echinoderms, an annelid and a sponge could. Regardless of sterol-synthesizing ability the animals (with the exception of a sponge) always made dolichol and ubiquinone, and thus a specific block in squalene and sterol synthesis was indicated in some animals. Radioactivity accumulated in relatively large amounts in farnesol and geranylgeraniol in those animals incapable of making sterols.

Intermediates of tocopherol biosynthesis in the unicellular alga Scenedesmus obliquus. The presence of three isomeric methylphytylbenzoquinones.

Three isomers of methylphytylbenzoquinone have been isolated from lipids of the unicellular alga Scenedesmus obliquus, the most abundant being 2-methyl-6-phytylbenzoquinone (65% of the total). The 2-methyl-3-phytyl and 2-methyl-5-phytyl isomers amounted to 8 and 27% respectively. Previously problems have been encountered in the separation of the 3-phytyl and the 6-phytyl isomers, but in the present study it was found that they separated readily as quinols. Phytyl plastoquinone was also found and the relevance of these compounds to the biosynthesis of alpha-tocopherol is discussed. As well as phylloquinone, a hydroxyphylloquinone was detected, and studies indicated that it is the 5' carbon atom to which the hydroxy group is attached. Such a compound has been found by workers using other unicellular algae.

The isolation and properties of delta-tocotrienol from Hevea latex.

1. delta-Tocotrienol (8-methyltocotrienol) was isolated from the latex of Hevea brasiliensis. This new member of the tocopherol family is a pale-yellow oil at room temperature. 2. The properties of delta-tocotrienol are very similar to those of delta-tocopherol and the small differences can be explained by the change in side chain. 3. The ultraviolet and infrared spectra of delta-tocotrienol were determined and a conversion factor for use with the Emmerie-Engel reaction was worked out. Details are given for the chromatography of delta-tocotrienol on thin layers (adsorption and partition) and reversed-phase paper, and the nitroso derivatives were formed. 4. An ethyl carbonate ester of delta-tocotrienol was prepared and compared with a similar ester of delta-tocopherol. 5. Hydroxymethylation of delta-tocotrienol followed by reduction gave beta-tocotrienol as a major product.

The formation of menaquinone-4 (vitamin K) and its oxide in some marine invertebrates.

Three echinoderms, a crustacean, a mollusc and a coelenterate were injected with either [2-14C]mevalonate and unlabelled menadione (2-methyl-1,4-naphthaquinone) or 2-[14C]methyl-1,4-naphthaquinone. In each case the label was incorporated into menaquinone-4.[2-14C]Mevalonate was incorporated into menaquinone-4 in the crab (Carcinus maenas) only in the presence of menadione, the organism presumably being unable to synthesize the naphthaquinone nucleus. The starfish Asterias rubens and C. maenas incorporated the label into a compound which was identified chromatographically as 2,3-epoxymenaquinone-4. The significance of menaquinone-4 and these animals is discussed.

The characterization of ficaprenol-10, -11 and 12 from the leaves of Ficus elastica (decorative rubber plant).

Evidence from mass, nuclear-magnetic-resonance and infrared spectrometry and from gas-liquid and thin-layer chromatography is presented in favour of the presence of cis-trans-decaprenol, -undecaprenol and -dodecaprenol in the mixture of polyprenols (2.6mg./g.) isolated from leaf tissue of Ficus elastica. The trivial names ficaprenol-10, -11 and -12 are proposed. Nuclear-magnetic-resonance studies showed that each of these prenols contains three trans internal isoprene residues and a cis ;OH-terminal' isoprene residue. Ficaprenol-11 is the major component of the mixture. Chromatographic evidence suggests the presence also of small amounts of ficaprenol-9 and -13. The precise position of the three trans internal isoprene residues was not determined but it is suggested that these are adjacent to the omega-terminal isoprene residue and that the ficaprenols are formed from all-trans-geranylgeranyl pyrophosphate. It is also suggested that ficaprenol-10, -11, -12 and -13 are probably the same compounds as castaprenol-10, -11, -12 and -13.