Oleuropein Degradation Kinetics in Olive Leaf and Its Aqueous Extracts

Although olives leaves are currently considered a waste material from oil mills, they have great potential to be transformed into by-products due to their high oleuropein content. Oleuropein is a glycoside precursor of hydroxytyrosol, which is the phenolic compound with the highest antioxidant capacity in nature and which is associated with multiple health benefits. For this reason, the demand for oleuropein is growing in the pharmaceutical, cosmetic and food sectors. The objective of this study is to determine the stability of oleuropein in olive leaves from oil mills in solid and aqueous forms under different conditions of temperature, relative humidity and lighting. The results indicate that the degradation of oleuropein conforms well to first-order kinetics. The rate constants at the temperatures tested in the aqueous extracts indicate activation energies from RTl to 80 °C and from 7 °C to 14 °C, as the degradation reactions were different in these ranges. Furthermore, olive leaf powder stored at any temperature with an RH ≥ 57% showed greater stability after six months, which is an encouraging result for the storage and transformation of this waste in oil mills.

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Evaluation of degradation kinetics for abamectin in formulations using a stability indicating method

Acta Pharmaceutica ◽

10.2478/acph-2013-0007 ◽

2013 ◽

Vol 63 (1) ◽

pp. 59-69 ◽

Cited By ~ 2

Author(s):

Atul Awasthi ◽

Majid Razzak ◽

Raida Al-Kassas ◽

Joanne Harvey ◽

Sanjay Garg

Keyword(s):

Degradation Kinetics ◽

Hplc Method ◽

Degradation Behavior ◽

Ph Change ◽

Stability Indicating ◽

First Order ◽

Stability Indicating Method ◽

First Order Kinetics ◽

Maximum Stability ◽

The Stability

The aim of this study was to evaluate stability characteristics and kinetics behavior of abamectin (ABM) as a 1 % (m/V) topical veterinary solution. During the study, samples stressed at 55 and 70 °C were regularly analyzed for several parameters over 8 weeks on a chromatographic (HPLC) system, using a Prodigy C18, 250 x 4.6 mm, 5-μm, column eluting with 15 : 34 : 51 (V/V/V) water/methanol/ acetonitrile as mobile phase. The HPLC method was validated for precision, accuracy, linearity and specificity, and was found to be stability indicating. The results showed that degradation of ABM followed first-order kinetics and data on loss in kobs (s-1) and half life (t1/2, days) demonstrated ABM showing the maximum stability in glycerol formal. The degradation behavior of ABM varies from solvent to solvent. The effect of added alkali on pH change and loss of ABM was studied and found to be unique for all solvents and very distinct from typical hydrolysis degradation. The present study may serve as a platform to design and develop topical non-aqueous solutions of ABM for veterinary use given no such comprehensive efforts have been published to date on the stability profile of ABM in non-aqueous solvents.

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Determination of Chemical Stability of Two Oral Antidiabetics, Metformin and Repaglinide in the Solid State and Solutions Using LC-UV, LC-MS, and FT-IR Methods

Molecules ◽

10.3390/molecules24244430 ◽

2019 ◽

Vol 24 (24) ◽

pp. 4430

Author(s):

Anna Gumieniczek ◽

Anna Berecka-Rycerz ◽

Tomasz Mroczek ◽

Krzysztof Wojtanowski

Keyword(s):

High Temperature ◽

Degradation Products ◽

Degradation Kinetics ◽

Magnesium Stearate ◽

Oral Antidiabetics ◽

First Order ◽

First Order Kinetics ◽

Ft Ir ◽

The Stability

Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV method was examined, as to whether it validly determined these drugs in the presence of their degradation products and whether it is suitable for estimating degradation kinetics. Finally, the respective LC-MS method was used to identify the degradation products. In addition, using FT-IR method, the stability of metformin and repaglinide was scrutinized in the presence of polyvinylpyrrolidone (PVP), mannitol, magnesium stearate, and lactose. Significant degradation of metformin, following the first order kinetics, was observed in alkaline medium. In the case of repaglinide, the most significant and quickest degradation, following the first order kinetics, was observed in acidic and oxidative media (0.1 M HCl and 3% H2O2). Two new degradation products of metformin and nine new degradation products of repaglinide were detected and identified when the stressed samples were examined by our LC-MS method. What is more, the presence of PVP, mannitol, and magnesium stearate proved to affect the stability of metformin, while repaglinide stability was affected in the presence of PVP and magnesium stearate.

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Bleaching of chlorophylls by UV irradiation in vitro: The effects on chlorophyll organization in acetone and n-hexane

Journal of the Serbian Chemical Society ◽

10.2298/jsc0803271z ◽

2008 ◽

Vol 73 (3) ◽

pp. 271-282 ◽

Cited By ~ 12

Author(s):

Jelena Zvezdanovic ◽

Dejan Markovic

Keyword(s):

Uv Irradiation ◽

Photosynthetic Pigments ◽

Energy Input ◽

First Order ◽

First Order Kinetics ◽

Uv Photons ◽

The Stability ◽

Major Factors

The stability of chlorophylls toward UV irradiation was studied by Vis spectrophotometry in extracts containing mixtures of photosynthetic pigments in acetone and n-hexane. The chlorophylls underwent destruction (bleaching) obeying first-order kinetics. The bleaching was governed by three major factors: the energy input of the UV photons, the concentration of the chlorophylls and the polarity of the solvent, implying different molecular organizations of the chlorophylls in the two solvents.

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Influence of Oxygen-Containing Sulfur Flavor Molecules on the Stability of β-Carotene under UVA Irradiation

Molecules ◽

10.3390/molecules24020318 ◽

2019 ◽

Vol 24 (2) ◽

pp. 318 ◽

Cited By ~ 1

Author(s):

Gong-Liang Zhang ◽

Hong-Yan Wu ◽

Ying Liang ◽

Jie Song ◽

Wei-Qi Gan ◽

...

Keyword(s):

Sulfur Atom ◽

Critical Role ◽

Oxidation Products ◽

First Order ◽

Uva Irradiation ◽

First Order Kinetics ◽

Dynamic Degradation ◽

The Stability ◽

Ethanol System ◽

Β Carotene

The influence of 11 kinds of oxygen-containing sulfur flavor molecules was examined on β-carotene stability under UVA irradiation in ethanol system. Both the effects of sulfides on dynamic degradation of β-carotene and the relation between structure and effect were investigated. The oxidation products of β-carotene accelerated by sulfides under UVA irradiation were also identified. The results indicated that the disulfides had more obvious accelerative effects on the photodegradation of β-carotene than mono sulfides. The degradation of β-carotene after methyl (2-methyl-3-furyl) disulfide (MMFDS), methyl furfuryl disulfide (MFDS) and bis(2-methyl-3-furyl) disulfide (BMFDS) exposure followed first-order kinetics. Furan-containing sulfides such as MMFDS and BMFDS showed more pronounced accelerative effects than their corresponding isomers. The oxidation products were identified as 13-cis-β-carotene, 9,13-di-cis-β-carotene and all-trans-5,6-epoxy-β-carotene. These results suggest that both the sulfur atom numbers and the furan group in oxygen-containing sulfides play a critical role in the photooxidation of β-carotene.

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Use of purified lyophilized human lactate dehydrogenase isoenzyme 5 in a study of measuring lactate dehydrogenase activity.

Clinical Chemistry ◽

10.1093/clinchem/35.8.1774 ◽

1989 ◽

Vol 35 (8) ◽

pp. 1774-1776 ◽

Cited By ~ 1

Author(s):

D A Smith ◽

G C Moses ◽

A R Henderson

Keyword(s):

Lactate Dehydrogenase ◽

Half Life ◽

Specific Activity ◽

Lactate Dehydrogenase Activity ◽

Bovine Albumin ◽

First Order ◽

First Order Kinetics ◽

The Stability ◽

Lactate Dehydrogenase Isoenzymes ◽

Excellent Stability

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27) isoenzyme 5--purified to a specific activity of about 400 kU/g--when lyophilized in a buffered, stabilized matrix of bovine albumin. This isoenzyme was prepared with a final activity of about 500 U/L and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. This isoenzyme decayed with approximate first-order kinetics, with an estimated half-life at -20 degrees C of about 475 years. Stability of reconstituted samples stored at 20 or 4 degrees C was poor, suggesting that the reconstituted material should be used without delay; material stored at -20 degrees C showed excellent stability for 15 days. We propose that such preparations might be further investigated as standards for use in electrophoresis of lactate dehydrogenase isoenzymes.

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Reaction of Glutathione with Conjugated Carbonyls

Zeitschrift für Naturforschung C ◽

10.1515/znc-1975-7-808 ◽

1975 ◽

Vol 30 (7-8) ◽

pp. 466-473 ◽

Cited By ~ 177

Author(s):

Hermann Esterbauer ◽

Helmward Zöllner ◽

Norbert Scholz

Keyword(s):

Catalytic Effect ◽

Biological Activities ◽

Equilibrium Constants ◽

Reverse Reaction ◽

Mesityl Oxide ◽

Forward Reaction ◽

First Order ◽

First Order Kinetics ◽

Proton Donors ◽

The Stability

Abstract 1. GSH reacts with conjugated carbonyls according to the equation: G SH+R-CH=CH-COR⇆R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with αSH. Besides OH- ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter preted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (kt = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.

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PERSISTENCIA DEL ENDOSULFÁN EN MEDIO ACUOSO ESTÁTICO

Pesticidas Revista de Ecotoxicologia e Meio Ambiente ◽

10.5380/pes.v11i0.3140 ◽

2001 ◽

Vol 11 ◽

Author(s):

ARGELIA M. L. LENARDÓN ◽

PATRICIA M. DE LA SIERRA ◽

FERNANDA MARINO

Keyword(s):

River Water ◽

Degradation Kinetics ◽

Water Type ◽

Ultrapure Water ◽

First Order ◽

First Order Kinetics ◽

Predominant Factor ◽

Two Temperatures ◽

In The Beginning ◽

Kinetics Of

Estudou-se a cinética de degradação da mistura dos isômeros alfa e beta Endosulfan em diferentes condições de trabalho. Os compostos foram adicionados em água ultrapura, água do rio, água de rio filtrada e água ultrapura com sais (salinidade similar à agua do rio utilizada). As condições de degradação escolhidas foram: escuridão e duas temperaturas (14+1 ºC e 26+1 ºC). As amostragens foram programadas de modo a se obter dados periódicos mais freqüentes no início da experiência e posteriormente mais espaçados até o seu final (230 dias). As amostras foram submetidas à microextração e analisadas por cromatografia em fase gasosa com detector de Ni63 e coluna Megabore DB-5. A degradação foi descrita de acordo com a cinética de primeira ordem, determinando-se os tempos de meia vida (t1/2) e as energias de ativação (Ea). Os dados obtidos evidenciaram que a temperatura é o fator preponderante, sendo possível deduzir que o alfaendosulfan, exceto para água ultrapura (AU), é mais influenciado pela temperatura do que o beta-endosulfan. O segundo efeito mais importante refere-se ao tipo de água utilizada como matriz, devido à influência da salinidade. PERSISTANCE OF ENDOSULFAN IN STATIC AQUEOUS MEDIUM Abstract Degradation kinetics of a mixture of alpha- and beta-Endosulfan isomers was studied under different conditions. The compounds were spiked in ultrapure water, river water, filtered water and ultrapure water with salts (similar salinity condition to that of the river water used). The degradation conditions chosen were: darkness, two temperatures (14+1 ºC e 26+1 ºC). Samplings were programmed in order to obtain more frequent periodical data in the beginning of the experience and after more spaced until its end (230 days). The samples were submitted to microextraction and then analyzed by gas chromatography through a Ni63 detector equipped with a Megabore DB-5 column. Degradation was described using first-order kinetics to determine half-life times (t1/2) and activation energies (Ea). The data obtained evidenced that temperature is the predominant factor, it can possibly be inferred that alfa-endosulfan is much more influenced than beta-endosulfan except for ultrapure water (UW). The second important effect is the water type used as matrix, due to the influence of salinity.

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The In Vitro Degradation Kinetics of Polyurethane Prodrug Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.399-401.1067 ◽

2011 ◽

Vol 399-401 ◽

pp. 1067-1070

Author(s):

Chun Yan Li ◽

Cong Cong Hu ◽

Zhi Guo Wen ◽

Sheng Xiong Dong

Keyword(s):

Drug Release ◽

High Performance ◽

Degradation Kinetics ◽

Hplc Method ◽

In Vitro Degradation ◽

Erosion Mechanism ◽

First Order ◽

First Order Kinetics ◽

Kinetics Of

The method of high performance liquid chromatography (HPLC) is established to determine the content of antibacterial agent — ciprofloxacin (CF) in the degradation solution of ciprofloxacin-polyurethane (CFPU) and investigate the in vitro degradation kinetics by plotting and fitting the cumulative release curves to inspect the effects of different medium and different concentrations on drug release. The results showed that the HPLC method is accurate, reliable and simple. The drug-release of CFPU was bioresponsive and could be accorded with first order kinetics. It was observed that CF was released from CFPU by a combination of diffusion and erosion mechanism, mainly in the manner of diffusion in the absence of infection while erosion mechanism in the presence of infection.

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Interactions of natural antioxidants with red grape pomace anthocyanins in a liquid model matrix: Stability and copigmentation effects

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq100701055s ◽

2011 ◽

Vol 17 (1) ◽

pp. 59-66 ◽

Cited By ~ 7

Author(s):

Badherdine Sidani ◽

Dimitris Makris

Keyword(s):

Ascorbic Acid ◽

Natural Antioxidants ◽

Grape Pomace ◽

First Order ◽

First Order Kinetics ◽

Model Matrix ◽

Liquid Model ◽

Matrix Stability ◽

The Stability ◽

Red Grape

The purpose of this study was an examination on the stability and colour enhancement of red grape pomace anthocyanins in a juice model matrix, and the effect of the addition of natural antioxidants. The approach was based on a juice-like liquid medium (10.1?Brix, pH 3.48), which was used as the model matrix to test the effect of the addition of natural antioxidants (L-cysteine, ascorbic acid, catechin and quercetin) on the degradability of anthocyanin pigments, extracted from grape pomace. It was found that treatment of the model solutions at 80?C induced anthocyanin decomposition, which obeyed first order kinetics. Addition of increasing amounts of antioxidants, including L-cysteine, ascorbic acid, catechin and quercetin, did not provoke a proportional impact, either positive or negative, with regard to anthocyanin stability. The best stabilising effect was seen after addition of ascorbic acid and catechin at concentrations of 4 and 2 mg L-1, respectively (P < 0.001). Quercetin, however, was demonstrated a very efficient co-pigment, inducing an increase in A520 by 63%, at pH 5.6 and a copigment-to-pigment ratio of 10.

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Stability of dicyclohexylcarbodiimide in an aqueous medium. The effect of mitochondrial phospholipids

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19830662 ◽

1983 ◽

Vol 48 (2) ◽

pp. 662-667 ◽

Cited By ~ 1

Author(s):

Jan Kopecký ◽

Stanislav Pavelka ◽

Jiří Dědina ◽

Věra Siglerová ◽

Karel Vereš

Keyword(s):

Test Tube ◽

Chemical Modifier ◽

Specific Chemical ◽

First Order ◽

First Order Kinetics ◽

Membrane Bound ◽

Pseudo First Order ◽

Ph Dependent ◽

The Stability ◽

Membrane Bound Enzymes

The stability of N,N'-dicyclohexylcarbodiimide (DCCD) was analyzed with respect to the use of DCCD as a specific chemical modifier of membrane-bound enzymes. The disappearance of DCCD from the sucrose-Tris medium obeyes the pseudo-first-order kinetics the rate constant (kd) of which is pH-dependent (kd = 12.0 . 10-3 min-1 at pH 6.0, and kd = 1.6 . 10-3 min-1 at pH 9.0, respectively). However, the rate of the total [14C]DCCD binding to mitochondrial membrane proteins is not markedly influenced by the change of pH (6.0-9.0). The rate of DCCD disappearance is enhanced in the presence of mitochondrial phospholipids. It is concluded that the rapid equilibration of DCCD between the phospholipid and water phase, the reactivity of DCCD with phospholipids, H+-stimulated hydration of DCCD to dicyclohexylurea and the sorption of DCCD to the test tube must be considered when studying the interaction of DCCD with membrane-bound enzymes.

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