“…Conversely, calcium and lanthanum ions are hard metals and show a preference for hard bases such as carboxylate anions and dissociated hydroxyl groups. In fact, in addition to its interaction with chelators such as EDTA, lanthanum ion forms complexes with citrate, flavonoids and other products containing oxygen and nitrogen ligands [24,25,51,52]. Interestingly, classical chelators such as EDTA do not modify the inhibitory action exerted by the soft noble metals on TrxR [33] further supporting the previous considerations.…”