The multiple forms of bovine seminal ribonuclease: Structure and stability of a C-terminal swapped dimer

Bovine seminal ribonuclease (BS-RNase) acquires an interesting anti-tumor activity associated with the swapping on the N-terminal. The first direct experimental evidence on the formation of a C-terminal swapped dimer (C-dimer) obtained from the monomeric derivative of BS-RNase, although under non-native conditions, is here reported. The X-ray model of this dimer reveals a quaternary structure different from that of the C-dimer of RNase A, due to the presence of three mutations in the hinge peptide 111–116. The mutations increase the hinge peptide flexibility and decrease the stability of the C-dimer against dissociation. The biological implications of the structural data are also discussed.     

Synthesis of azide derivative and discovery of glyoxalase pathway inhibitor against pathogenic bacteria

A glyoxalase inhibitor was synthesized and tested against Staphylococcus aureus for first time and showed MIC₉₀ of 20 μg/ml. Henceforth, we synthesized unnatural azide derivative of the same inhibitor to improve the biological activity. In that order, an azide carboxylate was synthesized from dimethyl tartrate by tosylation and azide substitution. The synthesized, azide compound was coupled with glutathione derivative in high yield and tested against S. aureus and showed improved MIC₉₀ of 5 μg/ml. In general, it can be also easily converted to unnatural β-amino acid in good yield. The shown methodology will be extended to study induced suicide in Burkholderia mallei, Francisella tularensis and Mycobacterium tuberculosis in future.     

Polyethylene Glycol–Modified Papain Catalyzed Oligopeptide Synthesis from the Esters of l-Aspartic and l-Glutamic Acids in Benzene

Comparative studies were made of the polymerization of l-aspartic and l-glutamic acid dialkyl esters using polyethylene glycol–modified papain as a catalyst in phosphate buffer (pH 7.5) and in benzene. Changes in the substrate specificity of papain and in the composition of oligomerized products were observed. In the buffer, the diethyl and di-n-propyl esters of l-glutamic acid were sufficiently converted to high molecular weight oligomers with the accumulation of dimer and trimer, but l-aspartic acid esters were very poor substrates. In benzene, l-aspartic acid esters became more reactive than L-glutamic acid esters. In particular, from l-aspartic acid dimethyl ester the product, which was mainly composed of heptamer to decamer, was obtained in a 90% yield. The reaction in benzene required desalted substrates and a small amount of water to proceed extensively.     

Antioxidant Properties of 2-O-β-D-Glucopyranosyl-L-ascorbic Acid

The antioxidant activity of a provitamin C agent, 2-O-β-D-glucopyranosyl-L-ascorbic acid (AA-2βG), was compared to that of 2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G) and ascorbic acid (AA) using four in vitro methods, 1,1-diphenyl-picrylhydrazyl (DPPH) radical-scavenging assay, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^?+)-scavenging assay, oxygen radical absorbance capacity (ORAC) assay, and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis inhibition assay. AA-2βG slowly and continuously scavenged DPPH radicals and ABTS^?+ in roughly the same reaction profiles as AA-2G, whereas AA quenched these radicals immediately. In the ORAC assay and the hemolysis inhibition assay, AA-2βG showed similar overall activities to AA-2G and to AA, although the reactivity of AA-2βG against the peroxyl radical generated in both assays was lower than that of AA-2G and AA. These data indicate that AA-2βG had roughly the same radical-scavenging properties as AA-2G, and a comprehensive in vitro antioxidant activity of AA-2βG appeared to be comparable not only to that of AA-2G but also to that of AA.     

Induction of Non-diapause Eggs by Imidazole Derivative KK-42 in the Diapause Type of Bombyx mori Silkworm

The injection of an imidazole compound, KK-42, into fifth instar larvae of a silkworm (Bombyx mori, Daizo strain), which had been destined to produce diapause eggs, induced the moths to lay non-diapause eggs. The critical period for KK-42 injection in the induction of non-diapause eggs was 24 h to 72 h after the fourth ecdysis. Topical application of KK-42 to 48 h-old fifth instar larvae also induced non-diapause eggs.     

Sedimentation Analysis of the Interacting Mixture of Dextran Sulfate and Low Density Lipoprotein

The reversible interaction between dextran sulfate (D) and the low density lipoprotein of human serum (P) was investigated by sedimentation velocity. Analysis of the velocity patterns of dextran sulfate—lipoprotein mixtures revealed that the maximum number of binding sites on dextran sulfate molecule is approximately 6. It was also shown that the species of the complex formed is affected by the mixing ratio of the two constituents: at the molar ratio (P/D) 0.69, the complex exists in average as DP_1.6 and at 0.98 as DP_2.2. The linear increment of sedimentation coefficient of the complex due to the binding of one lipoprotein molecule was 7.8S. Finally, the mechanism of precipitation of the complexes was discussed.     

Neuroprotective effect of Capsicum annuum var. abbreviatum against hydrogen peroxide-induced oxidative stress in HT22 hippocampus cells

ABSTRACT

Phenolic compounds isolated from pepper (Capsicum annum) have been demonstrated to have neuroprotective effects, whereas the physiological properties of Capsicum annuum var. abbreviatum (CAA) have not been studied. Thus, we investigate the chemical composition and neuroprotective activity of CAA extract (CAAE) in HT22 hippocampus cells against H₂O₂-induced neurotoxicity. CAAE treatment resulted in a significant protection of H₂O₂-exposed HT22, this protection ultimately occurred through an inhibition of MDA and ROS levels and an induction of SOD activity. Furthermore, CAAE treatment reduced H₂0₂-induced apoptosis though decreasing the expression of pro-apoptotic factors (Bax, cytochrome c, and cleaved caspases-3) while increasing the expression of the anti-apoptotic factors (Bcl-2), as well as the accumulation of nucleus-Nrf2-mediated HO-1 signaling. Interestingly, CAAE has a high concentration of unique phenolic compositions (chlrogenic acid, tangeretin, etc.) than other capsicum annum extracts. Altogether, these findings suggest that CAAE can be a useful natural resource for alleviating neurodegenerative diseases.     

Generation of the antioxidant yellow pigment derived from 4-methylthio-3-butenyl isothiocyanate in salted radish roots (takuan-zuke)

2-[3-(2-Thioxopyrrolidin-3-ylidene)methyl]-tryptophan (TPMT) is a yellow pigment of salted radish roots (takuan-zuke) derived from 4-methylthio-3-butenyl isothiocyanate (MTBITC), the pungent component of radish roots. Here, we prepared salted radish and analyzed the behavior of the yellow pigment and related substances in the dehydration process and long-term salting process. All salted radish samples turned yellow, and their b^* values increased with time and temperature. The salted radish that was sun-dried and pickled at room temperature turned the brightest yellow, and the generation of TPMT was clearly confirmed. These results indicate that tissue shrinkage due to dehydration, salting temperature, and pH play important roles in the yellowing of takuan-zuke.     

Nematocidal activity of 6-O-octanoyl- and 6-O-octyl-d-allose against larvae of Caenorhabditis elegans

ABSTRACT

The nematocidal activities of the fatty acid esters of d-allose were examined using the larvae of C. elegans. Among the fatty acid esters, 6-O-octanoyl-d-allose (3) showed significant activity. 6-O-octanoyl-d-glucose (5) showed no activity, indicating that the D-allose moiety is essential for the nematocidal activity of 3. A nonhydrolyzable alkoxy analog 6-O-octyl-d-allose (6) also showed activity equivalent to that of 3.     

Fourth‐derivative synchronous spectrofluorimetry and HPLC with fluorescence detection as two analytical techniques for the simultaneous determination of itopride and domperidone

Two simple, rapid and sensitive methods, namely, fourth‐derivative synchronous spectrofluorimetry (method I) and HPLC with fluorescence detection (method II) were developed for the simultaneous analysis of a binary mixture of itopride HCl (ITP) and domperidone (DOM) without prior separation. The first method was based on measuring the fourth derivative of the synchronous fluorescence spectra of the two drugs at Δλ = 40 nm in methanol. The different experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully optimized. Chromatographic separation was performed in < 6.0 min using a RP C₁₈ column (250 mm × 4.6 mm i.d., 5 µm particle size) with fluorescence detection at 344 nm after excitation at 285 nm. A mobile phase composed of a mixture of 0.02 M phosphate buffer with acetonitrile in a ratio of 55 : 45, pH 4.5, was used at a flow rate of 1 mL/min. Linearity ranges were found to be 0.1–2 µg/mL for ITP in both methods, whereas those for DOM were found to be 0.08–2 and 0.05–1.5 µg/mL in methods I and II, respectively. The proposed methods were successfully applied for the determination of the studied drugs in synthetic mixtures and laboratory‐prepared tablets. Copyright © 2015 John Wiley & Sons, Ltd.