184 research outputs found
Low-molecular-weight components of olive oil mill wastewaters
A new lignan 1-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-6-(3-acetyl-4-hydroxy-5-methoxyphenyl)-3,7-dioxabicyclo[
3.3.0]octane, the secoiridoid 2H-pyran-4-acetic acid,3-hydroxymethyl-2,3-dihydro-5-(methoxycarbonyl)-2-
methyl-, methyl ester, the phenylglycoside 4-[β -D-xylopyranosyl-(1→6)]-β -D-glucopyranosyl-1,4-dihydroxy-2-
methoxybenzene and the lactone 3-[1-(hydroxymethyl)-1-propenyl] δ -glutarolactone were isolated and identified
on the basis of spectroscopic data including two-dimensional NMR, as components of olive oil mill waste-waters.
The known aromatic compounds catechol, 4-hydroxybenzoic acid, protocatechuic acid, vanillic acid, 4-hydroxy-
3,5-dimethoxybenzoic acid, 4-hydroxyphenylacetic acid, 3,4-dihydroxyphenylacetic acid, tyrosol, hydroxytyrosol,
2-(4-hydroxy-3-methoxy)phenylethanol, 2-(3,4-dihydroxy)phenyl-1,2-ethandiol, p-coumaric acid, caffeic acid,
ferulic acid, sinapic acid, 1-O-[2-(3,4-dihydroxy)phenylethyl]-(3,4-dihydroxy)phenyl-1,2-ethandiol, 1-O-[2-(4-
hydroxy)phenylethyl]-(3,4-dihydroxy)phenyl-1,2-ethandiol, D(+)-erythro-1-(4-hydroxy-3-methoxy)-phenyl-1,2,3-
propantriol, p-hydroxyphenethyl-β-D-glucopyranoside, 2(3,4-dihydroxyphenyl)ethanol 3β-D-glucopyranoside, and
2(3,4-dihydroxyphenyl)ethanol 4β-D-glucopyranoside were also confirmed as constituents of the waste-waters
ABIOTIC DEGRADATION OF IODOSULFURON-METHYL-ESTER IN AQUEOUS SOLUTION
The abiotic degradation of iodosulfuron-methyl-ester was investigated under both alkaline and acidic
pH conditions in the dark, and results showed it to be a rather stable molecule in neutral or slightly
alkaline environments. Photochemical reactions were studied using a high-pressure mercury arc lamp,
and results showed that direct phototransformation is possible under normal environmental conditions
(ì > 290 nm). High-performance liquid chromatography (HPLC-UV and HPLC-MS) analyses were
used to identify the degradates and to study the kinetics of photodecomposition and hydrolysis. Five
main products of iodosulfuron-methyl-ester degradation were tentatively identified, and one of them
(4-methoxy-6-methyl-1,3,5-triazin-2-amine) was confirmed using an authentic standard. Among the
phototransformation mechanisms, photosubstitution of the iodide atom by a hydroxyl group,
photodissociation of the N-S bond, and photoassisted hydrolysis were observed. The quantum
efficiencies (multiwavelength quantum yield) of the photodegradation under different conditions were
determined, and values of 0.054 ( 0.02 (pH 9.6), 0.08 ( 0.02 (pH 7), and 0.044 ( 0.008 (pH 5.3)
were obtained
Unusual products of the aqueous chlorination of atenolol
The reaction
of the drug atenolol
with hypochlorite
under conditions
that simulate
wastewater
disinfection
was investigated.
The pharmaceutical
reacted in 1 h yielding
three products
that were
separated
by chromatographic
techniques
and characterized
by spectroscopic
features.
Two unusual
products
2-(4-(3-(chloro(2-chloropropan-
2-yl)amino)-2-hydroxypropoxy)
phenyl) acetamide
and 2-(4-
(3-formamido-
2-hydroxypropoxy)
phenyl) acetamide
were obtained along with 2-(4-hydroxyphenyl)
acetamide.
When the reaction
was stopped at shorter times only 2-(4-(3-amino-2-hydroxypropoxy)
phenyl) acetamide
and the dichlorinated
product
were detected. Tests performed
on the seeds of
Lactuca
sativa
show that chlorinated
products
have phytotoxic
activity
Apteniols A-F, oxyneolignans from the leaves of Aptenia cordifolia.
Abstract—Investigation of the organic extract of Aptenia cordifolia leaves revealed six new oxyneolignans named apteniols A–F. The
structures were determined by means of spectroscopic methods. The C6C3 units are linked by an oxygen atom at C4–C40 or C4–C20 and they are dihydrophenylpropanoid acid units. Their effects on germination and growth of Lactuca sativa L. have been studied in the range concentration 10K4–10K7 M
A mechanistic study on the phototoxicity of atorvastatin: singlet oxygen generation by a phenanthrene-like photoproduct
Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the
adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have
been reported and associated with photosensitivity disorders. Previous work dealing with ATV
photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts
resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative. Laser
flash photolysis of ATV, at both 266 and 308 nm, led to a transient spectrum with two maxima at λ )
360 and λ ) 580 nm (τ ) 41 μs), which was assigned to the primary intermediate of the stilbene-like
photocyclization. On the basis of the absence of a triplet-triplet absorption, the role of the parent drug
as singlet oxygen photosensitizer can be discarded. By contrast, a stable phenanthrene-like photoproduct
would be a good candidate to play this role. Laser flash photolysis of this compound showed a triplet-triplet
transient absorption at λmax ) 460 nm with a lifetime of 26 μs, which was efficiently quenched by
oxygen (kq ) 3 ((0.2) Ă— 109 M-1 s-1). Its potential to photosensitize formation of singlet oxygen was
confirmed by spin trapping experiments, through conversion of TEMP to the stable free radical TEMPO.
The photoreactivity of the phenanthrene-like photoproduct was investigated using Trp as a marker. The
disappearance of the amino acid fluorescence (λmax ) 340 nm) after increasing irradiation times at 355
nm was taken as a measurement of photodynamic oxidation. To confirm the involvement of a type II mechanism, the same experiment was also performed in D2O; this resulted in a significant enhancement of the reaction rate. On the basis of the obtained photophysical and photochemical results, the phototoxicity of atorvastatin can be attributed to singlet oxygen formation with the phenanthrene-like photoproduct as
a photosensitizer
Degradation of lansoprazole and omeprazole in the aquatic environment
Lansoprazole and omeprazole degrade in water leading to sulfides, benzimidazolones and a red complex material.
Degradation is accelerated in acid medium and by solar simulator irradiation. Benzimidazoles, dianilines and pyridines
have also been identified
Photochemical behavior of the drug atorvastatin in water.
Atorvastatin undergoes a self-sensitized photooxygenation by sunlight in water. The main photoproducts, isolated by chromatographic
techniques, have been identified by spectroscopic means. They present a lactam ring arising from an oxidation of pyrrole ring and an
alkyl/aryl shift. A mechanism involving singlet oxygen addition and an epoxide intermediate is suggested
Photooxygenation of furans in water and ionic liquid solutions
Photooxygenation of differently functionalized furans is investigated in aqueous solutions and in
ionic liquids [emim]Br and [bmim]BF4. The reaction is generally selective and the final products
derive from rearrangement of the intermediate endoperoxides, depending mainly on the polarity
and/or nucleophilic nature of the solvent
TOXICITY OF PREDNISOLONE, DEXAMETHASONE AND THEIR PHOTOCHEMICAL DERIVATIVES ON AQUATIC ORGANISMS
Light exposure of aqueous suspensions of prednisolone and dexamethasone causes their partial phototransformation.
The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means.
Prednisolone, dexamethasone and their photoproducts have been tested to evaluate their acute and chronic toxic effects
on some freshwater chain organisms. The rotifer Brachionus calyciflorus and the crustaceans Thamnocephalus platyurus
and Daphnia magna were chosen to perform acute toxicity tests, while the alga Pseudokircheneriella subcapitata (formerly
known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia to perform chronic tests. The
photochemical derivatives are more toxic than the parent compounds. Generally low acute toxicity was found. Chronic
exposure to this class of pharmaceuticals caused inhibition of growth population on the freshwater crustacean C. dubia
while the alga P. subcapitata seems to be less affected by the presence of these drugs
Phototransformation Products of Tamoxifen by Sunlight in Water. Toxicity of the Drug and Its Derivatives on Aquatic Organisms
Transformation of tamoxifen has been observed in water by prolonged sunlight irradiation. The main photoproducts, isolated by
chromatographic techniques, have been identified by spectroscopic means. Photoisomerization, photocyclization and, to a lesser extent,
photooxygenation appear to be involved in the degradation of the drug. The acute and chronic toxicity of the parent drug and its photoproducts
were tested on non-target aquatic organisms (Brachionus calyciflorus, Thamnocephalus platyurus, Daphnia magna and Ceriodaphnia
dubia). Exposure to all the compounds induced mainly chronic effects without significant differences among the parental and
derivative compounds
- …