Occurrence of the C-series fumonisins in maize from the former Transkei region of South Africa

Abstract

Fumonisins are a group of structurally related mycotoxins produced mainly in maize by Fusarium verticillioides and F. proliferatum. The most abundant naturally occurring analogue is fumonisin B1 (FB1), with lesser amounts of fumonisin B2 (FB2) and fumonisin B3 (FB3) occurring. The C-series fumonisins (FCs) are structurally analogous to the B-series but lack the C-1 methyl group. Good and mouldy subsistence-grown maize samples were collected from the Centane and Bizana districts in the former Transkei region of South Africa. After extraction with methanol/water and clean-up on strong anion exchange solid phase extraction cartridges, FB1, FB2, FB3, FC1, FC3 and FC4 were determined by reversed-phase LC–MS/MS using positive ion electrospray ionisation. FB1 levels in both good and mouldy maize from Centane (means (±SD) 2.75 ± 2.24 and 23.4 ± 12.5 mg kg−1, respectively) were higher than the corresponding levels in maize samples from Bizana (means 0.056 ± 0.157 and 3.71 ± 5.01 mg kg−1, respectively). Similarly, FC1 levels in both good and mouldy maize from Centane (means 0.107 ± 0.099 and 0.814 ± 0.391 mg kg−1, respectively) were higher than in Bizana, where FC1 was detected in only one (0.018 mg kg−1) of 19 good maize samples and occurred in mouldy maize with a mean of 0.102 ± 0.135 mg kg−1. A significant correlation (r = 0.982, p < 0.01) was observed between FB1 and FC1 levels in all samples, with FC1 levels at 3.3% of the corresponding FB1 levels. FC4 levels were similar to FC1, whereas only low amounts of FC3 were detected.