RESUMO
In attempt to evaluate the effects of cyclodextrins (CDs) on enantioselectivity of chiral pesticides toxicity, this study investigated effects of three kinds of cyclodextrins including α-CD, ß-CD and randomly methylated ß-CD (RAMEB) on toxicity of four enantiomers of isomalathion including (1R, 3R)-isomalathion, (1S, 3S)-isomalathion, (1S, 3R)-isomalathion and (1R, 3S)-isomalathion. Generally, the addition of α-CD and RAMEB (1.5 g/L to 3.5 g/L concentration) could lead to reduction of isomalathion toxicity in most cases, while the presence of ß-CD (0.3 g/L to 1.5 g/L concentration) enhanced the toxicity of isomalathion. It was speculated that higher electronic cloud density and lower water solubility of ß-CD than α-CD and RAMEB might favor to combination between acetylcholinesterase (AChE) and isomalathion included by ß-CD. With respect for α-CD and RAMEB, isomalathion included by them could be easily dissolved in water because of high water solubility of the two CDs. Therefore, α-CD and RAMEB can be used as remediation regent for the pollution of isomalathion, and ß-CD can act as an additive in improving bioactivity of such pesticides. In addition, the presence of CDs can alter enantioselectivity of chiral pesticides. The differences on the extent of enantioselectivity variation of isomalathion induced by α-CD, RAMEB and ß-CD might be ascribe to the different cavity, electron cloud density and solubility among the three CDs. In conclusion, the above results gave researchers a possibility to change enantioselectivity of chiral pesticides from undesirable outcomes to desirable ones.
Assuntos
Acetilcolinesterase/química , Inibidores da Colinesterase/química , Ciclodextrinas/química , Proteínas de Peixes/química , Malation/química , Praguicidas/química , Animais , Electrophorus , EstereoisomerismoRESUMO
Proteoglycan aggregate is the primary component in articular cartilage responsible for resisting compressive loading. It consists of a core molecule of hyaluronan and a number of side chains of aggrecan bound to hyaluronan non-covalently. The loss of aggrecan from articular cartilage is considered to be a major factor in the development of osteoarthritis. Though enzymatic digestion of aggrecan is believed to be responsible for the release of aggrecan from osteoarthritic cartilage, other mechanisms, such as direct force-mediated detachment of aggrecan from hyaluronan may also be involved. In this study, the rupture force of the single bond between hyaluronan and aggrecan in articular cartilage was directly quantified using experimental measurement and Monte Carlo simulation. Low rupture force of this bond, as determined in this study suggested a possible direct force-mediated detachment of aggrecan from proteoglycan aggregate in osteoarthritic cartilage.
Assuntos
Cartilagem Articular/química , Proteoglicanas/química , Agrecanas , Animais , Fenômenos Biomecânicos , Fenômenos Químicos , Físico-Química , Proteoglicanas de Sulfatos de Condroitina/química , Proteínas da Matriz Extracelular/química , Ácido Hialurônico/química , Lectinas Tipo C/química , Modelos Químicos , Método de Monte Carlo , Nanotecnologia/métodos , Ligação ProteicaRESUMO
The non-covalent bond between aggrecan and hyaluronan is critical for maintaining the normal structure and function of the extracellular matrix in articular cartilage. The failure of this bond can cause the loss of aggrecan and destruction of the extracellular matrix of articular cartilage. In this study, the rupture force of the single bond between hyaluronan and hyaluronan binding protein - the complex of the hyaluronan binding region of aggrecan and link protein - was directly measured with a nanomechanical testing system as 40+/-11 pN. The results were compared to a theoretical prediction based on a smart version of the Monte Carlo simulation.