Triterpenoids and steroids of some Sapotaceae and their chemotaxonomic significance

Extraction of the bark and timber of four Madhuca and five Palaquium species has yielded β-amyrin, β-amyrin acetate, β-amyrin cinnamate,     

Composition of α-amylase secreted by aleurone layers of grains of himalaya barley

α-Amylases secreted by the aleurone layer of whole barley grains were relatively rich in histidine and relatively poor in glutamate/glutamine and serine when compared to other eukaryotic proteins. The secreted α-amylases had an estimated 0.5 residues each of glucose, mannose and N-acetylglucosamine per molecule of protein (MW 41 400 daltons), and gave positive staining reactions for carbohydrate on sodium dodecylsulfate polyacrylamide gels. Because the average α-amylase molecule had less than one sugar residue per enzyme molecule, it was concluded that secreted α-amylases were heterogeneous with respect to glycosylation. A second protein co-purified with α-amylase, but the amino acid composition of this protein was different from that of barley or wheat α-amylase. This protein was composed of two 21 500 dalton polypeptides. No significant amounts of L-leucine (¹⁴C-U) were incorporated into this second protein in isolated aleurone tissue during incubation with gibberellic acid, perhaps because much of it was already present in the starchy endosperm at the time of hormone addition.     

Improved synthesis of 16alpha-hydroxylated androgens: intermediates of estriol formation in pregnancy.

16alpha-Hydroxyandrostenedione (16alpha-hydroxyandrost-4-ene-3,17-dione), 16alpha-hydroxytestosterone (16alpha,17beta-dihydroxyandrost-4-en-3-one) and 16alpha-hydroxydehydroepiandrosterone 3-sulfate (3beta, 16alpha-dihydroxyandrost-5-en-17-one 3-monosulfate) were synthesized by a new chemical approach with much improved yield. 16alpha-Bromoandrostendione was converted to the hydrazone of 16alpha-hydroxyandrostenedione which gave 16alpha-hydroxyandrostenedione on acid hydrolysis in total 63% yield. Oxidation of 16alpha-hydroxydehydroepiandrosterone with Jones' reagent also selectively afforded 16alpha-hydroxyandrostenedione. 16alpha-Hydroxytestosterone was observed by selective reduction of 16alpha-hydroxyandrostenedione with sodium borohydride. Reaction of 16alpha-hydroxydehydroepiandrosterone with chlorosulfonic acid in pyridine selectively gave the 3-monosulfate. The structure of the sulfate was deduced from its solvolysis to the starting material, and its acetylation and subsequent solvolysis to 16alpha-hydroxydehydroepiandrosterone 16-acetate. All procedures are suitable for large scale synthesis without the use of microorganisms.     

Radioimmunoassay of 2-hydroxyestrone

Under the protection of ascorbic acid a 2-hydroxyestrone bovine serum albumin conjugate was prepared containing intact 2-hydroxyestrone as determined by gas chromatographymass spectrometry. Using this antigen highly specific antibodies were raised in rabbits. Cross-reactivity for 2-hydroxyestradiol and 2-hydroxyestriol was 26 and 4.5%, respectively. An assay procedure of 2-hydroxyestrone in human plasma is described. Using special precautions the assay allows the determination of 2-hydroxyestrone in plasma samples of women (50–95 pg/ml), pregnant women (105–220 pg/ml), men (45–65 pg/ml) and children (20–40 pg/ml).     

The mechanism of energy conservation and transduction by mitochondrial cytochrome c oxidase

Oxidation of ferrocytochrome c by molecular oxygen catalysed by cytochrome c oxidase (cytochrome aa₃) is coupled to translocation of H⁺ ions across the mitochondrial membrane. The proton pump is an intrinsic property of the cytochrome c oxidase complex as revealed by studies with phospholipid vesicles inlayed with the purified enzyme. As the conformation of cytochrome aa₃ is specifically sensitive to the electrochemical proton gradient across the mitochondrial membrane, it is likely that redox energy is primarily conserved as a conformational “strain” in the cytochrome aa₃ complex, followed by relaxation linked to proton translocation. Similar principles of energy conservation and transduction may apply on other respiratory chain complexes and on mitochondrial ATP synthase.     

Aphid transmission and a polypeptide are specified by a defined region of the cauliflower mosaic virus genome

Infection of young turnip leaves with an aphid-transmissible isolate, Cabb B-JI, of cauliflower mosaic virus (CaMV) causes synthesis of an Mr 18 000 polypeptide (p18) which co-purifies with virus inclusion bodies. This polypeptide is not detectable in leaves infected with either of two aphid non-transmissible isolates. Campbell and CM4-184. Construction in vitro, of hybrid genomes between Cabb B-JI and Campbell isolates demonstrates that aphid transmissibility and presence of p18 is dependent on the small genome fragment from the BstEII site to the XhoI site. A deletion made in this fragment within open reading frame (ORF) II causes loss of aphid transmissibility and also terminates production of p18. We conclude that aphid transmissibility and the presence of p18 are related to the expression of ORF II of the CaMV genome.     

Prolactin modifies the prostaglandin synthesis, prolactin binding and fluidity of mouse liver membranes

The objective of these studies was to determine if prolactin, known to induce its own receptors, alters the prostaglandin (PG) synthesis which could, in turn, modify the fluidity of the membrane and thus alter the functionality of prolactin receptors. Adult male C₃H mice were injected subcutaneously with 100 μg of oPRL every 4 h for 0, 24 or 48 h and sacrificed 8 h after receiving the last injection. Liver 100,000 × $\text{g}$ membrane pellets were used in the measurement of these parameters. The amount of binding of prolactin to these membranes increased with the duration of injections, the values being 179 and 244% of control values after 24 and 48 h of injections, respectively. The amounts of PGF_2α and PGE synthesized also increased after these injections, the values being 127 and 270% of control for PGF_2α and 634 and 695% of control values for PGE after 24 and 48 h of injections, respectively. Fluorescence polarization, an index of microviscosity, was decreased by 14 and 20% after 24 and 48 h of PRL administration, respectively. Previous studies have demonstrated simultaneous in vitro effects of prostaglandin on both prolactin receptors and membrane fluidity. The current data are in agreement with those observations and suggest that prolactin may modulate its own receptor by increasing the fluidity of the membrane in which it exists by alterations within the PG cascade. Such biochemical changes may then modify existing restraints and allow the hormone receptor to assume a more functional configuration.     

Induction and repair of DNA strand breaks in cultured human fibroblasts exposed to various phenols and dihydrodiols of benzo[a]pyrene

Cultured human fibroblasts from healthy donors were incubated for 30 min with nine different benzo[a]pyrene (BP) derivatives in the presence or absence of liver microsomes from 3-methylcholanthrene treated rats. The induction and repair of DNA strand breaks were analysed by alkaline unwinding and separation of double and single stranded DNA (SS-DNA) by hydroxylapatite chromatography immediately after the incubation or at various times after the treatment. In the absence of microsomes DNA stand breaks were detected in fibroblasts exposed to 30 microM of each of the six BP phenols (1-, 2-, 3-, 7-, 9- or 11-OH-BP) and the three BP dihydrodiols (BP-4,5-, BP-7,8- or BP-9,10-dihydrodiol). After removal of the BP derivatives from the medium the DNA strand breaks disappeared within 24 h. alpha-Naphthoflavone (alpha-NF) caused a decrease in the induction of strand breaks by 1-, 3- and 9-OH-BP but did not affect the induction of strand breaks in cells exposed to BP-7,8-dihydrodiol. In the presence of microsomes DNA strand breaks were found after exposure to 30 microM of each of the six BP phenols (1-, 2-, 3-, 7-, 9- or 11-OH-BP), as well as BP-7,8- and 9,10-dihydrodiol. In contrast BP-4,5-dihydrodiol did not induce strand breaks under these conditions. The induction of strand breaks by BP-7,8-dihydrodiol was enhanced in the presence of cytosine-1-beta-D-arabinofuranoside (AraC). In all cases the DNA strand breaks had disappeared 24 h after removal of the BP derivatives and microsomes except after treatment with BP-7,8-dihydrodiol.     

Structure-activity relationships of chlorinated benzenes as inducers of different forms of cytochrome P-450 in rat liver

Hexachlorobenzene (HCB) produced increases in ethoxyresorufin (ERR) O-deethylase, aryl hydrocarbon hydroxylase (AHH) and aminopyrine N-demethylase activities in rat liver microsomes which were intermediate between those produced by phenobarbital and 3,4-benzpyrene (BP). α-Naphthoflavone (ANF) selectively inhibited ERR activity in BP and HCB-induced microsomes (94% and 88%). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of liver microsomes indicated that HCB did not produce a detectable increase in a polypeptide with electrophoretic properties similar to those of purified cytochrome P-448 (M_r = 56 000). However, HCB did induce a polypeptide with M_r = 53 000 corresponding to one of two polypeptide bands induced by BP. This polypeptide may represent a second form of cytochrome P-448. Purification of HCB to remove possible dibenzo-p-dioxin impurities did not alter the ‘mixed-type’ induction produced by HCB. In contrast to HCB, all other chlorinated benzenes tested resembled phenobarbital as inducers.