A Case of Concerted Formation of Five and Six Member Rings; Solvolytic Behavior of 1-Aryl-1-chloro-4,8,13,17,21-pentamethyl-4,8,12,16,20-docosapentaenes

Chlorides 1 (1-aryl-1-chloro-4,8,13,17,21-pentamethyl-4,8,12,16,20-docosapentaenes) with various phenyl substituents were prepared, and solvolysis rates were measured in 80% (v/v) aqueous ethanol, and in 97% (w/w) aqueous 2,2,2-trifluoroethanol. Hammett ρ+ values obtained are -2.18, -2.13, resp., suggesting a concerted bicyclization in the rate determining step

Mikroklima i prirodno pomlađivanje šumskih progala nastalih odumiranjem stabala obične jele (Abies alba Mill.)

Salvage cutting is a frequent operation to remedy the dieback of silver fir trees (Abies alba Mill.), which results in reduced stand canopy density and formation of forest gaps. This study was conducted in the beech-fir forest range of mountainous Croatia. The aim of the study was to determine microclimate conditions and natural regeneration in large and small forest gaps. Microclimate elements were measured and the density of plants from natural regeneration determined within forest gaps, in forest gap edge areas, and in control plots. Soil temperatures were significantly affected by changes in forest gap sizes with respect to the values of air temperatures, and were highest within the gaps as compared to gap edge areas and control forest stands. Microclimate had a significant affect on the number of small seedlings of silver fir and common beech in the large forest gaps, while this was not the case for the small forest gaps.Zbog intenzivnog odumiranja stabala obične jele (Abies alba Mill.) učestale su sanitarne sječe te dolazi do prekidanja sastojinskog sklopa i stvaranja šumskih progala. Istraživanje je obavljeno u bukovo – jelovim šumama na području Gorskog Kotara. Cilj istraživanja bio je utvrditi promjene mikroklimatskih uvjeta i prirodno pomlađivanje u velikim i malim šumskim progalama. U središtu i na rubovima šumskih progala, te u pripadajućim kontrolnim plohama mjereni su mikroklimatski elementi, kao i brojnost biljaka iz prirodnog pomlađenja. Temperature tla su značajnije reagirale na promjene veličine šumskih progala u odnosu na vrijednosti temperature zraka i bile su najveće u progalama u usporedbi s rubom progala i kontrolnim šumskim sastojinama. Broj biljaka obične jele u velikim i malim šumskim progalama je nedovoljan za uraštanje ove vrste u više slojeve sastojine. Brojnost biljaka starijeg pomlatka na rubovima velikih i malih progala te u sredini progala je bila značajno veća za listopadne vrste u odnosu na običnu jelu. Kod biljaka starijeg pomlatka nismo utvrdili značajne razlike u brojnosti biljaka između malih i velikih šumskih progala. Mikroklima je imala značajan utjecaj na broj biljaka mlađeg pomlatka obične jele i bukve u velikoj šumskoj progali, dok za malu šumsku progalu to nije bio slučaj

Synthesis and Anti-inflammatory Activity of Novel Furochromenes

A series of variously substituted furochromenes, hemiacetals 2, acetals 3, and rearranged compounds 4, were synthesized from variously substituted 4-hydroxycoumarins and evaluated in several in vitro assays, inhibition of mast cell degranulation induced by the activation of Fcε receptor type I or calci-um ionophore and leukotriene B4 (LTB4) inhibition. The most active derivatives, 3p and 4p (8-iso-propyl substitution in coumarin ring) and 3r (5-methyl-8-chloro substitution), showed significant inhibition of mast cell degranulation (Fctriggered) and LTB4, and exhibited significant local anti-inflammatory activity in PMA induced ear edema in CD1 mice, with potency equal (compounds 3p and 4p) or better (compound 3r) in comparison with zileuton, a reference drug used. It might be a promising direction for developing novel drugs as potential agents for the treatment of allergies and other inflammatory diseases.(doi: 10.5562/cca2240

Incidence and risk factors for venous and arterial thromboses in hospitalized patients with coronavirus disease 2019: data on 4014 patients from a tertiary center registry

Aim To evaluate the burden and predictors of throm - boembolic complications in a large real-life cohort of hos - pitalized patients with established coronavirus disease 2019 (COVID-19). Methods We retrospectively reviewed the records of 4014 consecutive adult patients admitted to a tertiary-level insti - tution because of COVID-19 from March 2020 to March 2021 for the presence of venous and arterial thrombotic events. Results Venous-thromboembolic (VTE) events were pres - ent in 5.3% and arterial thrombotic events in 5.8% patients. The majority of arterial thromboses occurred before or on the day of admission, while the majority of VTE events oc - curred during hospitalization. The majority of both types of events occurred before intensive care unit (ICU) admis - sion, although both types of events were associated with a higher need for ICU use and prolonged immobilization. In multivariate logistic regression, VTE events were inde - pendently associated with metastatic malignancy, known thrombophilia, lower mean corpuscular hemoglobin con - centration, higher D-dimer, lower lactate dehydrogenase, longer duration of disease on admission, bilateral pneu - monia, longer duration of hospitalization, and immobiliza - tion for at least one day. Arterial thromboses were inde - pendently associated with less severe COVID-19, higher Charlson comorbidity index, coronary artery disease, pe - ripheral artery disease, history of cerebrovascular insult, as - pirin use, lower C reactive protein, better functional status on admission, ICU use, immobilization for at least one day, absence of hyperlipoproteinemia, and absence of meta - static malignancy. Conclusion Among hospitalized COVID-19 patients, ve - nous and arterial thromboses differ in timing of presenta - tion, association with COVID-19 severity, and other clinical characteristics

A case of concerted formation of five and six member rings; solvolytic behavior of 1-aryl-1-chloro-4,8,13,17,21-pentamethyl-4,8,12,16,20-docosapentaenes

Chlorides 1 (1-aryl-1-chloro-4,8,13,17,21-pentamethyl-4,8,12,16,20-docosapentaenes) with various phenyl substituents were prepared, and solvolysis rates were measured in 80% (v/v) aqueous ethanol, and in 97% (w/w) aqueous 2,2,2-trifluoroethanol. Hammett ρ+ values obtained are -2.18, -2.13, resp., suggesting a concerted bicyclization in the rate determining step

Extended π-participation in biomimetic cyclization of squalene derivatives

Chlorides 4 (1-aryl-1-chloro-5,9,14,18,22-pentamethyl-5,9,13,17,21- tricosapentaenes) with various phenyl substituents were prepared, and solvolysis rates were measured in aqueous ethanol Op = 95% and 80%) and in aqueous 2,2,2-trifluoroethanol (w = 97%). Hammett p+ values obtained are -1.86, —1.81 and —1.56, respectively, suggesting concerted cyclization of at least two double bonds in the rate determining step

Solvolysis kinetics of 1-chloro-1-phenyl-5,9,14,18,22-pentamethyl-5,9,13,17,21-tricosapentaene, a squalene derivative. indication of participation

The title compound 1 was prepared starting from squalene and the solvolysis rates were measured in 80% (v/v) aqueous ethanol. The relative solvolysis rate and activation parameters were calculated. According to the values obtained it is concluded that 1 solvolyzes probably with participation of at least one double bond

Izolacija solanesola iz duhana (Nicotiana tabacum L.) klasičnom ekstrakcijom i ultrazvučnom ekstrakcijom

Solanesol (C45H740H) is natural acyclic trisesquiterpenoid alcohol. It was first isolated from tobacco, Nicotiana tobacum L. (Solanaceae) in 1956 (3). Since then solanesol, as well as some of its derivatives, have been studied by various scientists. The studies concentrated on isolation procedures, analysis, synthesis and the use of solanesol and its derivatives. Isolation of solanesol is carried out using the procedure of classical extraction by methanol. We have isolated solanesol from tobacco dust using the procedure of classical extraction and the extraction by ultrasound. The extraction procedure was shortened with the use of ultrasound for the period of 27 hours, which points out the great advantages of ultrasound in extraction of plant material, in this case extraction of solanesol from tobacco dust. The amount of solanesol obtained after the extraction procedure was established by fluid chromatography with high efficency. The amounts of solanesol obtained by classical extraction and extraction by ultrasound were the same

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

Three novel spiroketals were prepared by a one-pot transformation of 6-O-methyl-9(E)-hydroxyiminoerythronolide A. We present the formation of a [4.5]spiroketal moiety within the macrolide lactone ring, but also the unexpected formation of a 10-C=11-C double bond and spontaneous change of stereochemistry at position 8-C. As a result, a thermodynamically stable structure was obtained. The structures of two new diastereomeric, unsaturated spiroketals, their configurations and conformations, were determined by means of NMR spectroscopy and molecular modelling. The reaction kinetics and mechanistic aspects of this transformation are discussed. These rearrangements provide a facile synthesis of novel macrolide scaffolds