Biological activity and ESI MS study of oxaalkyl and hydroksyoxaalkyl lasalocid esters

Eight lasalocid esters (Las1)–(Las8) have been synthesised and their complex formation with Mg2+ and Ca2+ cations has been studied by ESI MS and PM5 semiempirical method. The ESI MS spectra of the complexes have shown that Las1–8 forms stable 1:1 complexes with Mg2+ and Ca2+ cations. The ESI MS spectra at higher cone voltage values have revealed the m/z peaks characteristic of the abstraction of one proton from the complex molecule. The calculated structures of Las1–8 with Mg2+ and Ca2+ cations are compared with those of the respective 1:1 complexes with monovalent cations. The biological activity of the esters on pathogenic bacteria Ervinia carotovora and fungus Fusarium oxysporum has been studied in vitro and some biological active compounds have been identified. This result can be very important for future applications in agriculture.