Two phenanthrene derivatives, characterized as erianthridin (9,10-dihydro-2,7-dihydroxy-3,4-dimethoxyphenanthrene) and gymnopusin (2,7-dihydroxy-3,4,9-trimethoxyphenanthrene), were isolated from an extract of the orchid Maxillaria densa, using phytotoxicity with amaranth (Amaranthus hypochondriacus) to guide fractionation. Gymnopusin and erianthridin inhibited radicle elongation of A. hypochondriacus seedlings with IC50 values of 330 and 58.2 μM, respectively, The phytoxicity of the two phenanthrene derivatives was also assessed on duckweed (Lemna pausicostata), and compared with mammalian toxicity estimated in vitro with four mammalian cell lines. On duckweed, both phenanthrene derivatives caused electrolyte leakage, chlorophyll loss and photobleaching. Ultrastructural examination of duckweed frond and root tissues treated with gymnopusin (100 μM) revealed membrane damage to the tonoplast after 12 h of exposure. Effects on membrane integrity followed a time course similar to that of electrolyte leakage. Both phenanthrene derivatives exhibited moderate cytotoxicity to all mammalian cells tested, which precludes their use as a bioherbicide.
Bibliographical noteFunding Information:
This investigation was partially supported by grants from DGAPA-UNAM IN-207300 (awarded to R. Mata) and DGEP-UNAM. N.V. acknowledges the fellowship awarded by CONACyT and DGEP-UNAM to carry out graduate studies.
Copyright 2008 Elsevier B.V., All rights reserved.
- Lemna pausicostata
- Mammalian cytotoxicity
- Membrane leakage
- Phenanthrene derivatives