Dibenzocyclooctadiene-type lignans from Magnolia pyramidata

Eight dibenzocyclooctadiene-type lignans, pyramidatin A-H, were isolated from the leaves of Magnolia pyramidata. Their structures were established by spectral methods, mainly 2D NMR spectroscopic techniques, which involved combined applications of COSY, DEPT. 1H, 13C correlations, COLOC, INAPT and long-range inverse 1H, 13C NMR correlations. The molecular structures of pyramidatin A and B were determined by single crystal X-ray diffraction. The absolute configurations of all eight lignans were derived from CD spectral correlations with structurally related dibenzocyclooctadienes of known absolute configuration.     

Evolution of the Selfing Syndrome in Arabis alpina (Brassicaceae)

Introduction

The transition from cross-fertilisation (outcrossing) to self-fertilisation (selfing) frequently coincides with changes towards a floral morphology that optimises self-pollination, the selfing syndrome. Population genetic studies have reported the existence of both outcrossing and selfing populations in Arabis alpina (Brassicaceae), which is an emerging model species for studying the molecular basis of perenniality and local adaptation. It is unknown whether its selfing populations have evolved a selfing syndrome.

Methods

Using macro-photography, microscopy and automated cell counting, we compared floral syndromes (size, herkogamy, pollen and ovule numbers) between three outcrossing populations from the Apuan Alps and three selfing populations from the Western and Central Alps (Maritime Alps and Dolomites). In addition, we genotyped the plants for 12 microsatellite loci to confirm previous measures of diversity and inbreeding coefficients based on allozymes, and performed Bayesian clustering.

Results and Discussion

Plants from the three selfing populations had markedly smaller flowers, less herkogamy and lower pollen production than plants from the three outcrossing populations, whereas pistil length and ovule number have remained constant. Compared to allozymes, microsatellite variation was higher, but revealed similar patterns of low diversity and high Fis in selfing populations. Bayesian clustering revealed two clusters. The first cluster contained the three outcrossing populations from the Apuan Alps, the second contained the three selfing populations from the Maritime Alps and Dolomites.

Conclusion

We conclude that in comparison to three outcrossing populations, three populations with high selfing rates are characterised by a flower morphology that is closer to the selfing syndrome. The presence of outcrossing and selfing floral syndromes within a single species will facilitate unravelling the genetic basis of the selfing syndrome, and addressing which selective forces drive its evolution.     

Structure–Activity Relationship Studies on Derivatives of Eudesmanolides from Inula helenium as Toxicants against Aedes aegypti Larvae and Adults

An Aedes aegypti larval toxicity bioassay was performed on compounds representing many classes of natural compounds including polyacetylenes, phytosterols, flavonoids, sesquiterpenoids, and triterpenoids. Among these compounds, two eudesmanolides, alantolactone, and isoalantolactone showed larvicidal activities against Ae. aegypti and, therefore, were chosen for further structure–activity relationship study. In this study, structural modifications were performed on both alantolactone and isoalantolactone in an effort to understand the functional groups necessary for maintaining and/or increasing its activity, and to possibly lead to more effective insect‐control agents. All parent compounds and synthetic modification reaction products were evaluated for their toxic activities against Ae. aegypti larvae and adults. Structure modifications included epoxidations, reductions, catalytic hydrogenations, and Michael additions to the α,β‐unsaturated lactones. None of the synthetic isomers synthesized and screened against Ae. aegypti larvae were more active than isoalantolactone itself which had an LC₅₀ value of 10.0 μg/ml. This was not the case for analogs of alantolactone for which many of the analogs had larvicidal activities ranging from 12.4 to 69.9 μg/ml. In general, activity trends observed from Ae. aegypti larval screening were not consistent with observations from adulticidal screening. The propylamine Michael addition analog of alantolactone was the most active adulticide synthesized with an LC₅₀ value of 1.07 μg/mosquito. In addition, the crystal structures of both alantolactone and isoalantolactone were determined using CuK_α radiation, which allowed their absolute configurations to be determined based on resonant scattering of the light atoms.     

9,10-seco-9,19-Cyclolanostane arabinosides from the roots of Actaea podocarpa

Seven 9,10-seco-9,19-cyclolanostane arabinosides, named podocarpasides A-G (1-7), were isolated from the roots of Actaea podocarpa DC., a species closely related to black cohosh (a well known dietary supplement). Their structures were determined with the help of spectroscopic data including extensive 2D NMR spectroscopy. The isolates were found inactive, when tested for cytotoxic, estrogenic, and antioxidant activities in cell based assays. They were also tested for anticomplement activity against the classical pathway of complement system and only podocarpaside C (3) inhibited modest complement activity with an IC50 value of 200 microM.     

Identification of antitumour activity of novel derivatives of 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione and 8-aryl-4-imino-2,3,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3(6H)-one

The series of 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones (11-20) and 8-aryl-4-imino-2,3,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3(6H)-ones (21-25) were designed and their in vitro cytotoxic activities against human LS180, HeLa, T47D, A549 and RPMI 8226 carcinoma cells are presented. In the crystalline state molecule 12 exists as the predominant tautomeric 3-oxo form, whereas the second possible 3-hydroxy tautomer is not observed. Compound 19 revealed a strong affection to LS180 cancer cells at lower tested concentration (37.9 microM) and simultaneously was found to be non-toxic towards the normal cell line investigated--GMK cells. Furthermore, this compound was proved to possess the efficiency for DNA strand breakage of the examined cancer cell lines. However, imidazotriazin-3,4-dione 20 was able to cause significant viability decreases in human RPMI 8226 peripheral blood myeloma cells. Compound 22 has exhibited remarkable inhibitory effects against LS180 and A549 carcinoma cells, whereas 24 revealed the highest growth inhibition against A549 cell line. Simultaneously, at lower tested concentration these compounds were proved to be completely non-toxic for GMK cells. Moreover, cytotoxic and antibacterial properties of starting, tautomeric 1-aryl-2-hydrazonoimidazolidines (1-6 and 8-9) are presented. Six of them (1-2, 4-6 and 9) proved active as antimicrobials. All these compounds revealed MIC values in the range of 15.0-78.6 microM. Their activities were compared to those of ampicillin and chloramphenicol.     

Structural studies of the C‐terminal 19‐peptide of serum amyloid A and its Pro→Ala variants interacting with human cystatin C

Serum amyloid A (SAA) is a multifunctional acute‐phase protein whose concentration in serum increases markedly following a number of chronic inflammatory and neoplastic diseases. Prolonged high SAA level may give rise to reactive systemic amyloid A (AA) amyloidosis, where the N‐terminal segment of SAA is deposited as amyloid fibrils. Besides, recently, well‐documented association of SAA with high‐density lipoprotein or glycosaminoglycans, in particular heparin/heparin sulfate (HS), and specific interaction between SAA and human cystatin C (hCC), the ubiquitous inhibitor of cysteine proteases, was proved. Using a combination of selective proteolytic excision and high‐resolution mass spectrometry, a hCC binding site in the SAA sequence was determined as SAA(86–104). The role of this SAA C‐terminal fragment as a ligand‐binding locus is still not clear. It was postulated important in native SAA folding and in pathogenesis of AA amyloidosis. In the search of conformational details of this SAA fragment, we did its structure and affinity studies, including its selected double/triple Pro→Ala variants. Our results clearly show that the SAA(86–104) 19‐peptide has rather unordered structure with bends in its C‐terminal part, which is consistent with the previous results relating to the whole protein. The results of affinity chromatography, fluorescent ELISA‐like test, CD and NMR studies point to an importance of proline residues on structure of SAA(86–104). Conformational details of SAA fragment, responsible for hCC binding, may help to understand the objective of hCC–SAA complex formation and its importance for pathogenesis of reactive amyloid A amyloidosis. Copyright © 2015 John Wiley & Sons, Ltd.     

云南常见牛肝菌属真菌中汞含量及食用安全评价

汞(Hg)是危害人类健康的主要重金属元素之一,多数食用菌对Hg有很强的富集能力,测定食用菌中Hg含量,并对其进行食用安全性评价具有重要意义。采用冷原子吸收直接测汞仪系统测定85份云南常见牛肝菌属真菌菌盖、菌柄中总Hg含量;以同一牛肝菌子实体菌盖与菌柄总Hg含量比(Q(C/S))分析牛肝菌属真菌对Hg的富集特征;根据联合国粮农组织和世界卫生组织(FAO/WHO)现行每周Hg允许摄入量(provisional tolerable weekly intake,PTWI)标准和中国GB 2762—2012规定的食用菌中Hg限量标准评价样品的食用安全性。结果表明,菌盖和菌柄中总Hg含量分别在0.13~22.00、0.20~8.40 mg·kg-1DW,不同产地、种类及不同采集年份的样品中总Hg含量存在明显差异;同一牛肝菌菌盖、菌柄总Hg含量比(Q(C/S))在0.28~4.08,92%的样品Q(C/S)1,表明多数样品中菌盖对Hg的富集能力强于菌柄。根据GB 2762—2012规定的食用菌及其制品中总Hg含量限量标准(≤0.1 mg·kg-1),发现所有测试样品的总Hg含量均超标;根据PTWI标准,假设成年人(60 kg)每周食用300 g新鲜牛肝菌,则多数样品Hg摄入量低于允许摄入量,无安全风险,而少数样品Hg摄入量高于允许摄入量,食用有一定的潜在风险。同时,牛肝菌总Hg含量与种类、产地、采集时间等因素密切相关,采食及安全评价需综合考虑这些因素。     

The crystal structure of 6-epi-desacetyllaurenobiolide,a germacra-1(10),4-diene-12,8α-olide from Montanoa grandiflora

A chloroform extract of Montanoa grandiflora afforded a novel 6β-hydroxy-germacradien-8,12-olide. Its structure was shown to be 6-epi-desacetyllaurenobiolide by spectral studies, chemical transformations and single crystal X-ray diffraction. The X-ray data demonstrate that the ten-membered ring exists in the crystal in the highly unusual [₁₅D⁵,₁D¹⁴] conformation, in which the methyl group at C-4 is α-oriented and the methyl group at C-10 is β-oriented. The two double bonds are approximately parallel rather than crossed.     

Demonstration of Kynurenine Aminotransferases I and II and Characterization of Kynurenic Acid Synthesis in Oligodendrocyte Cell Line (OLN-93)

In the present study we demonstrate for the first time that both kynurenine aminotransferase (KAT) isoforms I and II are present in the permanent immature rat oligodendrocytes cell line (OLN-93). Moreover, we provide evidence that OLN-93 cells are able to synthesize kynurenic acid (KYNA) from exogenously added l-kynurenine and we characterize its regulation by extrinsic factors. KYNA production in OLN-93 cells was depressed in the presence of aminotransferase inhibitor, aminooxyacetic acid and was not affected by depolarizing agents such as 50 mM K⁺ and 4-aminopyridine. Glutamate agonists, l-glutamate and d,l-homocysteine significantly decreased KYNA production. Selective agonist of ionotropic glutamate receptors Amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropionic acid (AMPA) lowered KYNA production in OLN-93 cell line, whereas N-methyl-d-aspartate (NMDA) had no influence on KYNA production. Furthermore, KYNA synthesis in OLN-93 cells was decreased in a concentration-dependent manner by amino acids transported by l-system, l-leucine, l-cysteine and l-tryptophan. The role of KYNA synthesis in oligodendrocytes needs further investigation.     

Reduction of image artifacts in mice by bladder flushing with a novel double-lumen urethral catheter

In electron paramagnetic resonance imaging (EPRI), the accumulation of contrast agent in the bladder can create a very large source of signal, often far greater than that of the organ of interest. Mouse model images have become increasingly important in preclinical testing. To minimize bladder accumulation on mouse images, we developed a novel, minimally invasive, MRI/EPRI-friendly procedure for flushing a female mouse bladder. It is also applicable to other imaging techniques, for example, PET, SPECT, etc., where contrast agent accumulation in the bladder is also undesirable. A double-lumen urethral catheter was developed, using a standard IV catheter with a silicone tube extension, having a polyethylene tube threaded into the IV catheter. Flushing of the bladder provides a substantial reduction in artifacts, as shown in images of tumors in mice.