Abstract
Alternariol (AOH) is a mycotoxin produced by Alternaria species. In vitro studies suggest the genotoxic, mutagenic, and endocrine disruptor effects of AOH, and an increased incidence of esophageal cancer has been reported related to higher AOH exposure. Human serum albumin (HSA) is the most abundant plasma protein in the circulation, it is able to affect toxicokinetic properties of numerous xenobiotics. HSA forms stable complexes with several mycotoxins, however, the interaction of AOH with albumin has not been examined. In this study, the complex formation of AOH with HSA was tested, employing fluorescence spectroscopy, ultrafiltration, and molecular modeling. Each spectroscopic measurement shows the formation of stable AOH-HSA complexes (K = 4 × 105 L/mol). Investigations with site markers (in spectroscopic and ultrafiltration models) as well as modeling studies suggest that AOH occupies Sudlow’s site I as a high-affinity binding site in HSA. The binding affinity of AOH towards bovine, porcine, and rat albumins was also tested, suggesting that AOH binds to rat albumin with considerably higher affinity than other albumins tested. Our results demonstrate the strong interaction of AOH with serum albumins, suggesting the potential in vivo importance of these interactions.
Highlights
Mycotoxins are secondary metabolites of filamentous fungi, exerting adverse effects in humans and animals [1,2]
AOH exerted only relatively low fluorescence at 455 nm without Human serum albumin (HSA); its fluorescence emission signal considerably increased in the presence of albumin
Water molecules are commonly able to partly quench the fluorescence signal of aromatic fluorophores [36], the interaction of AOH with an apolar pocket in albumin leads to the partial decomposition of its hydration shell
Summary
Mycotoxins are secondary metabolites of filamentous fungi, exerting adverse effects in humans and animals [1,2]. Alternariol (AOH; Figure 1) is a dibenzo-α-pyrone mycotoxin produced by Alternaria species, it shows. Fluorescence Spectra of AOH in the Absence and Presence of HSA. In the presence of HSA, a red shift (421 → 455 nm) of the fluorescence emission spectrum was noticed, and the fluorescence signal of AOH was markedly increased (Figure 3A). The HSA preparation (without AOH) showed fluorescence at. SSttaabbiilliittyy ooff AAOOHH--HHSSAA CCoommpplleexx BBaasseedd oonn FFlluuoorreesscceennccee SSppeeccttrroossccooppiicc MMeeaassuurreemmeennttss. EEffffeeccttss ooff SSiittee MMaarrkkeerrss oonn tthhee FFlluuoorreesscceennccee SSiiggnnaall ooff AAOOHH--HHSSAA CCoommpplleexx SSiinnccee HHSSAA iinndduucceess aa ssttrroonngg iinnccrreeaassee iinn tthhee fflluuoorreesscceenncceeooffAAOOHH(F(Figiguurere33),),ititisisreraesaosnoanbalbeleto thoyhpyopthoetshiezseiztehatht atthethedidspislpaclaecmemenetnot fofAAOOHHfrforommHHSSAA lleeaaddss ttoo tthhee ssiiggnniifificcaanntt ddeeccrreeaasseeininththee flfluuoorreesscceennccee ssiiggnnaall aatt 445555 nnmm ((λλeexx ==334455nnmm).).UsUinsgintghitshipsrpinrcinipcliep,lein, cirnecarseiansgincgonccoenncternattrioantisonosf soifte smitaermkearrskoefrsSSoIf, SSSSIII,,SoSrIIH, eomr eHseimteewseitree wadedreedadtodsetdantodasrtdancdoanrcdenctorantcieonntsraotfioAnOsHofaAndOHHSaAnd(1.H0 SaAnd (31..00μaMnd, 3re.0spμeMct,ivreeslyp)e,ctthiveenlyfl)u, othreesncflenucoereesmceisnscieoneminitsesniosnitiienstewnesriteiedsewteermreidneetder(mλeixn=e3d4(5λenxm=, λ34em5 =nm λnemm)=. FFiigguurree66. .FlFuluoroersecsecnecnecemeimssiisosniointeintseitnysiotfyAoOf HA(O1HμM(1) inμMth)e pinresthenecpe roefsHenScAe (o3fμHMS)Aand(3inμcMre)asaingd cinoncrceeanstirnagtioconnsc(e0n.0t,ra0t.i5o,n1s.0(,02.0.0,,04.5.0,,16..00,,2a.n0,d41.0,.06.μ0M, a)nodf 1S0S.I0(AμM), S) SoIfI S(BSI),(aAn)d, SHSIeIm(Be )s,itaen(dCH) memarekseirtse i(nCP) mBSar(kpeHrs7i.n4;PλBeSx (=pH3475.4n;mλe,xλ=em345=n4m55, λnemm ;=*45p5
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