Search results for "Organisk kemi"
showing 10 items of 10 documents
Modified ent-Abietane Diterpenoids from the Leaves of Suregada zanzibariensis
2022
The leaf extract of Suregada zanzibariensis gave two new modified ent-abietane diterpenoids, zanzibariolides A (1) and B (2), and two known triterpenoids, simiarenol (3) and β-amyrin (4). The structures of the isolated compounds were elucidated based on NMR and MS data analysis. Single-crystal X-ray diffraction was used to establish the absolute configurations of compounds 1 and 2. The crude leaf extract inhibited the infectivity of herpes simplex virus 2 (HSV-2, IC50 11.5 μg/mL) and showed toxicity on African green monkey kidney (GMK AH1) cells at CC50 52 μg/mL. The isolated compounds 1–3 showed no anti-HSV-2 activity and exhibited insignificant toxicity against GMK AH1 cells at ≥100 μM. p…
Crystal Structures and Cytotoxicity of ent-Kaurane-Type Diterpenoids from Two Aspilia Species
2018
A phytochemical investigation of the roots of Aspilia pluriseta led to the isolation of ent-kaurane-type diterpenoids and additional phytochemicals (1⁻23). The structures of the isolated compounds were elucidated based on Nuclear Magnetic Resonance (NMR) spectroscopic and mass spectrometric analyses. The absolute configurations of seven of the ent-kaurane-type diterpenoids (3⁻6, 6b, 7 and 8) were determined by single crystal X-ray diffraction studies. Eleven of the compounds were also isolated from the roots and the aerial parts of Aspilia mossambicensis. The literature NMR assignments for compounds 1 and 5 were revised. In a cytotoxicity assay, 12α-methoxy-ent-kaur-9(11),1…
Crotofolane Diterpenoids and Other Constituents Isolated from Croton kilwae
2023
Six new crotofolane diterpenoids (1-6) and 13 known compounds (7-19) were isolated from the MeOH- CH2Cl2 (1:1, v/v) extracts of the leaves and stem bark of Croton kilwae. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and mass spectrometric data. The structure of crotokilwaepoxide A (1) was confirmed by single -crystal X-ray diffraction, allowing for the determination of its absolute configuration. The crude extracts and the isolated compounds were investigated for antiviral activity against respiratory syncytial virus (RSV) and human rhinovirus type-2 (HRV-2) in HEp-2 and HeLa cells, respectively, for antibacterial activity against the Gram-posit…
A New Benzopyranyl Cadenane Sesquiterpene and Other Antiplasmodial and Cytotoxic Metabolites from Cleistochlamys kirkii
2019
Phytochemical investigations of ethanol root bark and stem bark extracts of Cleistochlamys kirkii (Benth.) Oliv. (Annonaceae) yielded a new benzopyranyl cadinane-type sesquiterpene (cleistonol, 1) alongside 12 known compounds (2&ndash
Hofmann-Like Frameworks Fe(2-methylpyrazine)n[M(CN)2]2 (M = Au, Ag) : Spin-Crossover Defined by the Precious Metal
2020
Hofmann-like cyanometalates constitute a large class of spin-crossover iron(II) complexes with variable switching properties. However, it is not yet clearly understood how the temperature and cooperativity of a spin transition are influenced by their structure. In this paper, we report the synthesis and crystal structures of the metal–organic coordination polymers {FeII(Mepz)[AuI(CN)2]2} ([Au]) and {FeII(Mepz)2[AgI(CN)2]2} ([Ag]), where Mepz = 2-methylpyrazine, along with characterization of their spin-state behavior by variable-temperature SQUID magnetometry and Mössbauer spectroscopy. The compounds are built of cyanoheterometallic layers, which are pillared by the bridging Mepz…
Secoiridoids and Iridoids from Morinda asteroscepa
2020
The new 2,3-secoiridoids morisecoiridoic acids A (1) and B (2), the new iridoid 8-acetoxyepishanzilactone (3), and four additional known iridoids (4–7) were isolated from the leaf and stem bark methanol extracts of Morinda asteroscepa using chromatographic methods. The structure of shanzilactone (4) was revised. The purified metabolites were identified using NMR spectroscopic and mass spectrometric techniques, with the absolute configuration of 1 having been established by single-crystal X-ray diffraction analysis. The crude leaf extract (10 μg/mL) and compounds 1–3 and 5 (10 μM) showed mild antiplasmodial activities against the chloroquine-sensitive malaria parasite Plasmodium falciparum (…
Prenylated Flavonoids from the Roots of Tephrosia rhodesica
2020
Five new compounds—rhodimer (1), rhodiflavan A (2), rhodiflavan B (3), rhodiflavan C (4), and rhodacarpin (5)—along with 16 known secondary metabolites, were isolated from the CH2Cl2–CH3OH (1:1) extract of the roots of Tephrosia rhodesica. They were identified by NMR spectroscopic, mass spectrometric, X-ray crystallographic, and ECD spectroscopic analyses. The crude extract and the isolated compounds 2–5, 9, 15, and 21 showed activity (100% at 10 μg and IC50 = 5–15 μM) against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum. peerReviewed
Indefinitely stable iron(IV) cage complexes formed in water by air oxidation
2017
In nature, iron, the fourth most abundant element of the Earth's crust, occurs in its stable forms either as the native metal or in its compounds in the +2 or +3 (low-valent) oxidation states. High-valent iron (+4, +5, +6) compounds are not formed spontaneously at ambient conditions, and the ones obtained synthetically appear to be unstable in polar organic solvents, especially aqueous solutions, and this is what limits their studies and use. Here we describe unprecedented iron(IV) hexahydrazide clathrochelate complexes that are assembled in alkaline aqueous media from iron(III) salts, oxalodihydrazide and formaldehyde in the course of a metal-templated reaction accompanied by air oxidation…
Topical glaucoma medications – Clinical implications for the ocular surface
2022
Glaucoma is a leading cause of irreversible blindness. The use of topical eye drops to reduce intraocular pressure remains the mainstay treatment. These eye drops frequently contain preservatives designed to ensure sterility of the compound. A growing number of clinical and experimental studies report the detrimental effects of not only these preservatives but also the active pharmaceutical compounds on the ocular surface, with resultant tear film instability and dry eye disease. Herein, we critically appraise the published literature exploring the effects of preservatives and pharmaceutical compounds on the ocular surface. publishedVersion
Water oxidation catalyzed by molecular di- and nonanuclear Fe complexes: importance of a proper ligand framework.
2016
The synthesis of two molecular iron complexes, a dinuclear iron(III,III) complex and a nonanuclear iron complex, based on the di-nucleating ligand 2,2-(2-hydroxy-5-methyl-1,3-phenylene)bis(1H-benzo[d]imidazole-4-carboxylic acid) is described. The two iron complexes were found to drive the oxidation of water by the one-electron oxidant [Ru(bpy)(3)](3+). Funding Agencies|Knut and Alice Wallenberg Foundation; Swedish Research Council [621-2013-4872]; Carl Trygger Foundation; DFG (Metal Sites in Biomolecules: Structures, Regulation and Mechanisms) [IRTG 1422]; Swedish Energy Agency