Malformin A1 Research Articles

Structure of malformin B, phytotoxic metabolites produced by Aspergillus niger

Malformin B, produced by Aspergillus niger, was separated on HPLC and six peaks were detected. Amino acid analyses and mass spectra suggested that all of them are structurally related to cyclic pentapeptide malformin A1. The structures of malformin Bs were deduced by two dimensional NMR experiments and MS/MS experimentas as cyclo-D-cysteinyl-D-cysteinyl-L-valyl-D-leucyl-L-alloisoleucyl for B1a, cyclo-D-cysteinyl-D-cysteinyl-L-valyl-D-leucyl-L-leucyl for B1b, and cyclo-D-cysteinyl-D-cysteinyl-L-valyl-D-valyl-L-leucyl for B2.

Malformin A1 as a mammalian toxicant from Aspergillus niger.

Malformin A1 as a mammalian toxicant from Aspergillus niger.

Production of Malformin by Aspergillus awamori

The malformins constitute a small family of biologically active cyclic pentapeptides produced by the fungus, Aspergillus niger. These plant growth regulators induce malformations in stems and petioles of Phaseolus vulgaris and curvatures in roots of Zea mays (R. W. Curtis, Science 128:661, 1958). Four malformins have been isolated from culture filtrates of A. niger, malformin A1 and A2 from strain 58-883, and B1 and B2 from strain 56-30 (S. Takeuchi, M. Senn, R. W. Curtis, and F. W. McLafferty, Phytochemistry 6:287, 1967). They are most readily isolated as their respective mixtures, malformin A and B. We report here the isolation of malformin A from culture filtrates of A. awamori, and evidence for the presence of compounds with malforminlike activity in the culture filtrates of other fungi including members of the A. niger group of aspergilli. The fungi were grown in shake-flask culture for 7 days on corn steep-glucose medium as described earlier (R. W. Curtis, Plant Physiol. 33:17, 1958), and were then filtered. The filtrates were adjusted to pH 8.3 with NaHCO3, were extracted three times with equal volumes of ethyl ether, and the ether was evaporated on a steam bath. The residues, containing ether-soluble neutral and basic compounds, were treated with water containing Tween 80 (2 drops/100 ml). They were mixed, and the water-soluble compounds were tested for malformin activity by treating the apical buds of seedlings of P. vulgaris var. Black Valentine and the roots of Z. mays, the single-cross WF9 x 38-11, as described in earlier reports. The concentrations of the test solutions ranged from 20 to 1/1,024 times that of the original culture filtrate. Similar extracts from uninoculated culture medium that served as controls were inactive. The fungi tested and the biological activity of their ether extracts are summarized in Table 1. If both induction of corn root curvatures and malformations in bean seedlings are used as criteria for malformin activity, extracts from 7 of 31 fungi contained compounds with malformin-like

Production of Malformin by Aspergillus awamori1

The malformins constitute a small family of biologically active cyclic pentapeptides produced by the fungus, Aspergillus niger. These plant growth regulators induce malformations in stems and petioles of Phaseolus vulgaris and curvatures in roots of Zea mays (R. W. Curtis, Science 128:661, 1958). Four malformins have been isolated from culture filtrates of A. niger, malformin A1 and A2 from strain 58-883, and B1 and B2 from strain 56-30 (S. Takeuchi, M. Senn, R. W. Curtis, and F. W. McLafferty, Phytochemistry 6:287, 1967). They are most readily isolated as their respective mixtures, malformin A and B. We report here the isolation of malformin A from culture filtrates of A. awamori, and evidence for the presence of compounds with malforminlike activity in the culture filtrates of other fungi including members of the A. niger group of aspergilli. The fungi were grown in shake-flask culture for 7 days on corn steep-glucose medium as described earlier (R. W. Curtis, Plant Physiol. 33:17, 1958), and were then filtered. The filtrates were adjusted to pH 8.3 with NaHCO3, were extracted three times with equal volumes of ethyl ether, and the ether was evaporated on a steam bath. The residues, containing ether-soluble neutral and basic compounds, were treated with water containing Tween 80 (2 drops/100 ml). They were mixed, and the water-soluble compounds were tested for malformin activity by treating the apical buds of seedlings of P. vulgaris var. Black Valentine and the roots of Z. mays, the single-cross WF9 x 38-11, as described in earlier reports. The concentrations of the test solutions ranged from 20 to 1/1,024 times that of the original culture filtrate. Similar extracts from uninoculated culture medium that served as controls were inactive. The fungi tested and the biological activity of their ether extracts are summarized in Table 1. If both induction of corn root curvatures and malformations in bean seedlings are used as criteria for malformin activity, extracts from 7 of 31 fungi contained compounds with malformin-like