Cytotoxicity of citrinin, sterigmatocystin and 5-methoxysterigmatocystin to human lung cells

Mikotoksini su sekundarni metaboliti plijesni koji predstavljaju rizik za zdravlje ljudi i životinja uzrokujući mikotoksikoze. Iako se mikotoksini češće povezuju s kontaminiranom hranom ne smije se zanemariti izloženost preko respiratornog sustava. Kronična izloženost može dovesti do ozbiljnih zdravstvenih problema, uključujući rak i imunodeficijencije. Citrinin (CTN) se najčešće pronalazi na žitaricama na kojima je provedeno i najviše istraživanja. Poznat je po kontaminaciji pripravaka crvene riže koja služi kao alternativna terapija hiperlipidemije. Spada u nefrotoksične mikotoksine i 3. skupinu kancerogenih spojeva prema IARC (International Agency for Research on Cancer) klasifikaciji. Sterigmatocistin (STC) je klasificiran kao karcinogen 2B skupine (IARC), a kao sekundarni metabolit Aspergillus vrsta iz sekcije Versicolores nalazi se u prašini vlažnih zatvorenih prostora gdje je detektiran zajedno sa svojim derivatom, 5-metoksistergmatocistinom (5-MET-STC). Sva tri mikotoksina detektirana u prašini poplavljenih kuća u Gunji. Cilj ovog rada bio je odrediti citotoksične koncentracije CTN, STC, 5-MET-STC te njihovih kombinacija na ljudske stanice adenokarcinoma pluća A549. Za određivanje vijabilnosti stanica 24 sata nakon izloženosti mikotoksinima korišten je MTT test. Koncentracije CTN, STC i 5-MET-STC koje su smanjile vijabilnost A549 stanica za 50 % iznosile se redom: 127,7 1,5 μM, 60,6 1,8 μM, 7,1 1,2 μM. 5-MET-STC pokazao se najtoksičnijim mikotoksinom od ispitivanih. Kombinacije mikotoksina priređene su u omjerima 1:1, 1:2 i 2:1 pojedinačnih IC50. IC50 CTN+STC iznosile su 0,3 – 0,5 μM, a za CTN+5-MET-STC 0,2 – 1,5 μM. Kombinacije mikotoksina pokazale su veću citotoksičnost od pojedinačnih. Citotoksične interacije binarnih kombinacija mikotoksina opisane su CI-izobologramom s korekcijom za neparalelne krivulje doza-učinak. Binarne kombinacije pokazale su većinom aditivan učinak. Iznimku su predstavljali CTN+5-MET-STC i CTN+STC omjera 2:1 pri niskim koncentracijama i CTN+STC omjera 1:1 u području IC25-IC50 koji su pokazali antagonistički učinak.Mycotoxins are secondary metabolites of moulds that represent a health risk for people and animals because they cause mycotoxicosis. Although they are often connected to the contaminated food, exposure through respiratory system should not be dismissed. Chronic exposure can lead to serious health risks, including cancer and immunodeficiency. Citrinin (CTN) is often found on grains on which most of the research is done. It is known for its contamination of red rice which is used as alternative therapy for hyperlipidemia. It is a nephrotoxic mycotoxin and classified as group 3 carcinogen according to IARC classification (International Agency for Research on Cancer classification). Sterigmatocystin (STC) is classified as group 2B carcinogen (IARC) and as the secondary metabolite of Aspergillus species from Versicolores section it has been detected in the dust of damp indoor spaces with its derivate, 5-methoxysterigmatocystin (5-MET-STC). All three mycotoxins were detected in dust of flooded houses in Gunja. The aim of this study was to determine cytotoxic concentrations of CTN, STC, 5-MET-STC and its combinations in human adenocarcinoma cells A549. The MTT assay was performed to measure the viability of cells after 24 h treatment. Concentrations of CTN, STC and 5-MET-STC that lowered the viability of treated A549 cells to 50% were: 127.7 1.5 μM, 60.6 1.8 μM, 7.1 1.2 μM, respectively. 5-MET-STC turned out to be more toxic than other mycotoxins. Mycotoxin combinations were prepared in 1:1, 1:2 and 2:1 of IC50 concentration ratios. IC50 of CTN+STC ranged from 0.3 to 0.5 μM and for CTN+5-MET-STC from 0.2 to 1.5 μM. Combinations of mycotoxins showed more cytotoxicity than single mycotoxins. Cytotoxic interactions of binary combinations were described by applying CI-isobologram with correction for unparalleled dose-response curves. Binary combinations showed mostly additive effect. The exceptions were CTN+5-MET-STC and 2:1 CTN+STC in low affected areas and 1:1 CTN+STC between IC25-IC50 which showed antagonistic effect