Mycotoxin and cyanogenic glycoside assessment of the traditional leafy vegetables <i>mutete</i> and <i>omboga</i> from Namibia

Abstract

Sixty traditional leafy vegetables, comprising of <i>mutete (Hibiscus sabdariffa)</i> (<i>n</i> = 20) and <i>omboga</i> (<i>Cleome gynandra</i>) (<i>n</i> = 40) were analysed for fungal, plant and bacterial metabolites using liquid-chromatography-tandem mass spectrometry. No European Union legislated mycotoxins were quantified and no vegetables contained levels above the FAO/WHO limit of 10 mg/kg for cyanogenic potential, suggesting comparative safety regarding regulated mycotoxins and cyanogenic glycosides. Quantified fungal metabolites included averufin and 3-Nitropropionic acid from <i>Aspergillus flavus</i>, beauvericin and equisetin from <i>Fusarium</i>, citrinin and curvularin from <i>Penicillium</i> and altertoxin -1 and tentoxin from <i>Alternaria</i>. Of the plant cyanogenic glycosides, linamarin was quantifiable in 65% of <i>mutete</i> at a maximum of 398 µg/kg but not in <i>omboga</i>, while lotaustralin was quantifiable in both <i>omboga</i> and <i>mutete</i>. The bacterial metabolite nonactin was detected in 27.5% of <i>omboga</i> samples (range: 0.2-7.3 μg/kg). Minimal variation in metabolite patterns was recorded for <i>omboga</i> samples from Oshana and Oshikoto regions.