6-Hydroxy-5-nitrobenzo[d]oxazol-2(3H)-one—A degradable derivative of natural 6-Hydroxybenzoxazolin-2(3H)-one produced by Pantoea ananatis

• Main Authors: Margot Schulz, Dieter Sicker, Oliver Schackow, Lothar Hennig, Diana Hofmann, Ulrich Disko, Marina Ventura, Kateryna Basyuk
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2017-05-01
• Series: Communicative & Integrative Biology
• Subjects: Abutilon theophrasti L.; allelopathy; nitro-aromatic compound; Pantoea ananatis; peroxidase; root surface; 6-hydroxybenzoxazolin-2(3H)-one
• Online Access: http://dx.doi.org/10.1080/19420889.2017.1302633

Pantoea ananatis is a bacterium associated with other microorganisms on Abutilon theophrasti Medik. roots. It converts 6-hydroxybenzoxazolin-2(3H)-one (BOA-6-OH), a hydroxylated derivative of the allelochemical benzoxazolin-2(3H)-one, into 6-hydroxy-5-nitrobenzo[d]oxazol-2(3H)-one. The compound was identified by NMR and mass spectrometric methods. In vitro synthesis succeeded with Pantoea protein, with isolated proteins from the Abutilon root surface or with horseradish peroxidase in the presence of nitrite and H2O2. Nitro-BOA-6-OH is completely degraded further by Pantoea ananatis and Abutilon root surface proteins. Under laboratory conditions, 6-hydroxy-5-nitrobenzo[d]oxazol-2(3H)-one inhibits Lepidium sativum seedling growth whereas Abutilon theophrasti is much less affected. Although biodegradable, an agricultural use of 6-hydroxy-5-nitrobenzo[d]oxazol-2(3H)-one is undesirable because of the high toxicity of nitro aromatic compounds to mammals.