Determination of naphthoquinones in invasive alien plants Impatiens glandulifera Royle and I. balfourii Hook.f. from Croatia

The study aimed to develop an HPLC method for a simultaneous determination of 2-hydroxy-1,4-naphthoquinone (2-HNQ) and 2methoxy-1,4-naphthoquinone (2-MNQ) in plant material. The method was implemented to determine naphthoquinones (NQs) in leaves and flowers of the invasive alien species Impatiens glandulifera and I. balfourii collected in Croatia. Two NQs extraction methods from plant material were compared: decoction and ultrasonic extraction. Validation parameters indicate that the developed method is reliable for the simultaneous determination of 2-HNQ and 2-MNQ in plant material. The decoction extraction obtained a higher NQs yield than ultrasonic extraction. In the leaves and flowers of I. glandulifera and I. balfourii only 2-MNQ was detected. Both, I. glandulifera and I. balfourii, had higher 2-MNQ concentrations in flowers than in leaves. A significantly higher 2-MNQ concentration was found in I. glandulifera compared to I. balfourii. Therefore, I. glandulifera can be considered a rich source of 2-MNQ whose antitumor potential is established.