Bioactive compounds in Diospyros mafiensis roots inhibit growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus

J. A. Mmongoyo, M. G. Nair, J. E. Linz, F. Wu, J. K. Mugula, A. A. Dissanayake, C. Zhang, D. M. Day, J. M. Wee, G. M. Strasburg

Research output: Contribution to journalArticle

Abstract

Diospyros mafiensis F. White is a medicinal shrub or small tree (6 m tall) widely distributed in the Zanzibar- Inhambane regional mosaic and traditionally used to treat leprosy, diarrhoea, and skin fungal infections in Tanzania and Mozambique. Our objective was to determine the anti-aflatoxigenic properties of compounds from D. mafiensis root bark against vegetative growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus. Bioassay-guided extraction, fractionation, and isolation of bioactive compounds using A. parasiticus B62 were employed. The bioactive compounds were elucidated using 1H and 13CNMR and LC-MS. Growth inhibition was determined by measuring the colony diameter of A. flavus AF3357 and A. parasiticus SU-1 ATCC56775. Inhibitory effects on sporulation were estimated using a haemocytometer. Total aflatoxin was quantified by direct competitive enzyme-linked immunosorbent assay (ELISA). Bioactive compounds diosquinone (DQ) and 3-hydroxydiosquinone (3HDQ) were identified. DQ weakly inhibited A. flavus and A. parasiticus vegetative growth (MIC50 >100 μg/ml) and 3HDQ strongly inhibited A. flavus (MIC50 = 14.9 μg/ml) and A. parasiticus (MIC50 = 39.1 μg/ml). DQ strongly reduced total aflatoxin production by A. flavus from 157 to 36 ng/plate, and by A. parasiticus from 1,145 ng/plate to 45 ng/plate at 100 μg/ml. 3HDQ reduced total aflatoxin production by A. parasiticus from 1,145 to 32 ng/plate; stimulated production by A. flavus from 157 to 872 ng/plate at 12.5 μg/ml but reduced to 45 ng/plate at 100 μg/ ml. In summary, DQ and 3HDQ could be used as natural antifungal compounds to prevent mould growth and aflatoxin accumulation in food and feed.

Original languageEnglish (US)
Pages (from-to)237-248
Number of pages12
JournalWorld Mycotoxin Journal
Volume10
Issue number3
DOIs
StatePublished - Jan 1 2017

All Science Journal Classification (ASJC) codes

  • Food Science
  • Toxicology
  • Public Health, Environmental and Occupational Health

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    Mmongoyo, J. A., Nair, M. G., Linz, J. E., Wu, F., Mugula, J. K., Dissanayake, A. A., Zhang, C., Day, D. M., Wee, J. M., & Strasburg, G. M. (2017). Bioactive compounds in Diospyros mafiensis roots inhibit growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus. World Mycotoxin Journal, 10(3), 237-248. https://doi.org/10.3920/WMJ2016.2107