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.

Keywords:

• chromatography, HPLC
• fumonisins
• cereals

Acknowledgements

This material is based upon work supported financially by the National Research Foundation (NRF). Any opinion, findings and conclusions or recommendations expressed in this material are those of the authors and therefore the NRF does not accept any liability in regard thereto. The authors would like to thank Professor Yin-Won Lee (Seoul National University, South Korea) for the provision of FC standards.