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21.
Vangelis Smyrniotopoulos Christian Merten Daria Firsova Howard Fearnhead Deniz Tasdemir 《Marine drugs》2020,18(11)
Brown alga Bifurcaria bifurcata is a prolific source of bioactive acyclic (linear) diterpenes with high structural diversity. In the continuation of our investigations on Irish brown algae, we undertook an in-depth chemical study on the n-hexanes and chloroform subextracts of B. bifurcata that led to isolation of six new (1–6) and two known (7–8) acyclic diterpenes. Chemical structures of the compounds were elucidated by a combination of 1D and 2D NMR, HRMS, FT-IR, [α]D and vibrational circular dichroism (VCD) spectroscopy. Compounds 1–8, as well as three additional linear diterpenes (9–11), which we isolated from the same seaweed before, were tested against the human breast cancer cell line (MDA-MB-231). Several compounds moderately inhibited the growth of the MDA-MB-231 cell line with IC50 values ranging from 11.6 to 32.0 μg/mL. The present study carried out on the lipophilic extracts of the Irish B. bifurcata shows the enormous capacity of this seaweed to produce a large palette of acyclic diterpenes with diverse oxygenation and substitution patterns and promising bioactivities. 相似文献
22.
Stefanos Hatzilazarou Stefanos Kostas Athanasios S. Economou 《The Journal of Horticultural Science and Biotechnology》2019,94(4):441-447
In this study, an efficient protocol for the regeneration of encapsulated explants of oleander (Nerium oleander L.) has been developed. Shoot tips and 1st nodal segments below the shoot tip, from in vitro-derived oleander microshoots, were encapsulated in 2.5% sodium alginate prepared in liquid MS sucrose-free nutrient medium and hardened in 50 mM of calcium chloride producing solid beads, uniform in shape. These artificial seeds, irrespective of their maintenance under light or in darkness, germinated at frequencies of 38.8–42.2%, producing 3.0–3.3 microshoots per bead. In the case of using 100 mM of calcium chloride for hardening, the beads were firm, of uniform globular shape and suitable for handling, exhibiting a germination response of 68.9%. Encapsulated shoot tip explants, following storage at 4°C for 8 weeks, exhibited a higher regeneration response (60.0%) than non-encapsulated similar explants stored under the same conditions (11.1%). Microshoots, excised from cold-stored encapsulated explants after germination, rooted easily in agar-solidified MS medium with 2 μΜ IBA and after their transplantation into a peat-perlite substrate (3:1, v/v), were acclimatised successfully and established in the greenhouse with minimal losses. The present encapsulation procedure could be applied as an alternative method of micropropagation of desirable elite clones of oleander. 相似文献
23.
Squyres SW Arvidson RE Bell JF Brückner J Cabrol NA Calvin W Carr MH Christensen PR Clark BC Crumpler L Marais DJ d'Uston C Economou T Farmer J Farrand W Folkner W Golombek M Gorevan S Grant JA Greeley R Grotzinger J Haskin L Herkenhoff KE Hviid S Johnson J Klingelhöfer G Knoll AH Landis G Lemmon M Li R Madsen MB Malin MC McLennan SM McSween HY Ming DW Moersch J Morris RV Parker T Rice JW Richter L Rieder R Sims M Smith M Smith P Soderblom LA Sullivan R Wänke H Wdowiak T Wolff M Yen A 《Science (New York, N.Y.)》2004,306(5702):1698-1703
The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water. 相似文献
24.
Gellert R Rieder R Anderson RC Brückner J Clark BC Dreibus G Economou T Klingelhöfer G Lugmair GW Ming DW Squyres SW D'Uston C Wänke H Yen A Zipfel J 《Science (New York, N.Y.)》2004,305(5685):829-832
The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater. 相似文献
25.
A weed survey methodology was used for 2 years in three provinces in Greece to determine the abundance and spatial distribution
of weeds in cotton (Gossypium hirsutum L.) fields. Based on a stratified random sampling procedure, the most frequently occurring weeds were counted in 150 cotton
fields. The field surveys were conducted late in the growing season; hence, the weed populations consisted of species that
had been present during the critical competitive period for the crop and may have contributed to yield losses.Solanum nigrum was the most abundant weed in the surveyed fields of the southern province, followed byCyperus rotundus, Convolvulus arvensis, Xanthium strumarium, Chrozophora tinctoria andCynodon dactylon, in descending order. The ranked weed flora in the fields of the northern province was differentiated, suggesting the geographical
distribution of weed species. The weedsDatura stramonium andS. nigrum were recorded in high abundance and followed byAmaranthus spp.,Abutilon theophrasti, Portulaca oleracea, Chenopodium album andXanthium spinosum, in descending order. Although the use of preplant incorporated herbicides is the dominant practice in cotton cultivation,
certain weeds continue to spread in increasing densities.
http://www.phytoparasitica.org posting July 26, 2005. 相似文献
26.
Investigation of minor metabolites in the extracts of the red alga Sphaerococcus coronopifolius collected from the rocky coasts of Corfu Island in the Ionian Sea yielded two new diterpene alcohols, sphaerollanes I, and II (1, 2) featuring neodolabellane skeletons, and the new sphaeroane diterpene alcohol 16-hydroxy-9S*-acetoxy-8-epi-isosphaerodiene-2 (3), along with two previously reported metabolites 4, 5. The structures of the new natural products, as well as their relative stereochemistry, were elucidated on the basis of extensive spectral analysis, including 2D-NMR experiments. 相似文献
27.
Vangelis Smyrniotopoulos Margaret Rae Sylvia Soldatou Yuanqing Ding Carsten W. Wolff Grace McCormack Christina M. Coleman Daneel Ferreira Deniz Tasdemir 《Marine drugs》2015,13(4):1632-1646
Antifungal bioactivity-guided fractionation of the organic extract of the sponge Polymastia boletiformis, collected from the west coast of Ireland, led to the isolation of two new sulfated steroid-amino acid conjugates (1 and 2). Extensive 1D and 2D NMR analyses in combination with quantum mechanical calculations of the electronic circular dichroism (ECD) spectra, optical rotation, and 13C chemical shifts were used to establish the chemical structures of 1 and 2. Both compounds exhibited moderate antifungal activity against Cladosporium cucumerinum, while compound 2 was also active against Candida albicans. Marine natural products containing steroidal and amino acid constituents are extremely rare in nature. 相似文献
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29.
Van der Sluis Theo Pedroli Bas Frederiksen Pia Kristensen Søren B. P. Busck Anne Gravsholt Pavlis Vangelis Cosor Georgia Lavinia 《Landscape Ecology》2019,34(2):307-323
Landscape Ecology - The reasons for recent landscape change in the European countryside are complex and poorly substantiated. Identification of drivers of landscape transition and assessment of the... 相似文献
30.
G. Economou O. Tzakou A. Gani A. Yannitsaros D. Bilalis 《Journal of Agronomy and Crop Science》2002,188(4):248-253
The allelopathic influence of four plant tissues of Conyza albida (stems, leaves and inflorescences) on oat growth were investigated using in vivo tests. Oat growth (fresh and dry weights of above and underground parts) was inhibited from phytotoxic activity of upper leaves and inflorescence tissues of C. albida in pot studies. The inhibition was significantly higher than in the other tissues studied. The inhibiting action of crude extracts and volatile compounds from young plants (rosette) and mature plants were examined using two bioassay methods: (a) seed germination and radicle growth of oat and (b) fresh weight of duckweed plants. Both bioassayed species exhibited greater phytotoxic response from the young plants, collected in winter, than from the mature ones. 相似文献