SUPEROXIDE ANION SCAVENGER PROPERTIES OF SPARTEINE, A QUINOLIZIDINE ALKALOID FROM LUPINUS

Peroxidase activity in lupin (Lupinus albus cv. Multolupa) hypocotyls is located, as are quinolizidine-type alkaloids, in epidermal tissues. Since these alkaloids have been shown to suffer a rapid turnover and degradation in lupin tissues, the ability of sparteine (a typical tetr acyclic quinolizidine alkaloid) and cytisine (a typical tricyclic alph a-pyridone quinolizidine alkaloid) to act as peroxidase substrates was studied. However, neither alkaloid was oxidized by a partially purifi ed lupin peroxidase fraction, or by horseradish peroxidase, as was asc ertained by spectrophotometric and GC-MS studies. Likewise, these quin olizidine-type alkaloids were not substrates of a laccase of fungal or igin. However, sparteine, unlike cytisine, acted as a superoxide scave nger, when the superoxide anions were generated in a phenazin methosul phate-NADH system and determined by the superoxide dismutase-sensitive reduction of nitroblue tetrazolium. The IC50 value was 2.0 mmol/L. Th ese results are discussed in the light of a possible protective role a gainst oxidative damage of sparteine in Lupinus.