Toxic indole alkaloids avrainvillamide and stephacidin B produced by a biocide tolerant indoor mold Aspergillus westerdijkiae

Raimo Mikkola, Maria Andersson, Maria Hautaniemi, Mirja Sinikka Salkinoja-Salonen

Research output: Contribution to journalArticleScientificpeer-review


Toxic Aspergillus westerdijkiae were present in house dust and indoor air fall-out from a residence and a kindergarten where the occupants suffered from building related ill health. The A. westerdijkiae isolates produced indole alkaloids avrainvillamide (445 Da) and its dimer stephacidin B (890 Da). It grew and sporulated in presence of high concentrations of boron or polyguanidine (PHMB, PHMG) based antimicrobial biocides used to remediate mold infested buildings. The sperm cells were used as sensor cells to purify toxins from HPLC fractions of the fungal biomass. Submicromolar concentrations (EC50 0.3 – 0.4 μM) blocked boar spermatozoan motility and killed porcine kidney tubular epithelial cells (PK-15). Plate grown hyphal mass of the A. westerdijkiae isolates contained 300 - 750 ng of avrainvillamide and 30 - 300 ng of stephacidin B
per mg (wet weight). The toxins induced rapid (30 min) loss of sperm motility, followed (24 h) by loss of mitochondrial membrane potential (Ψm). Apoptotic cell death was observed in PK-15 cell monolayers, prior to cessation of glucose uptake or loss of Ψm. Avrainvillamide and stephacidin B were 100-fold more potent towards the porcine cells than the mycotoxins stephacidin A, ochratoxin A, sterigmatocystin and citrinin. The high toxicity stephacidin B indicates a role of nitrone group in the mechanism of toxicity. Avrainvillamide and stephacidin B represent a new class of toxins with possible a threat to human health in buildings. The use of biocides highly enhanced the growth of toxigenic A. westerdijkiae.
Original languageEnglish
Issue number1
Pages (from-to)58 - 67
Number of pages10
Publication statusPublished - 21 Mar 2015
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1184 Genetics, developmental biology, physiology
  • microbiology
  • Aspergillus
  • Aspergillus westerdijkiae
  • PHMB
  • polyhexamethylene biguanide
  • polyhexamethylene guanidine chloride
  • sterigmatocystin
  • ochratoxin A
  • citrinin
  • emodin
  • enniatin B
  • valinomycin
  • triclosan
  • sick building
  • indoor air
  • indole alkaloid
  • nitrone
  • biocide tolerance

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