Bioactive alkaloids produced by Pseudomonas brassicacearum subsp. Neoaurantiaca, an endophytic bacterium from Salvia miltiorrhiza

Abstract

Eleven compounds were isolated from the culture of an endophytic bacterium Pseudomonas brassicacearum subsp. Neoaurantiaca in Salvia miltiorrhiza Bunge. Their structures were elucidated by spectroscopic methods as cyclo-(Gly-L-Ala) (1), cyclo-(L-Ala-L-Ala) (2), cyclo-(L-Pro-Gly) (3), cyclo-(L-Pro-L-Ser) (4), cyclo-(L-Ala-trans-4-hydroxy-L-Pro) (5), cyclo-(L-Val-L-Pro) (6), cyclo-(Gly-L-Tyr) (7), cyclo-(L-Ala-L-Tyr) (8), cyclo-(L-Tyr-trans-4-hydroxy-L-Pro) (9), 3-methylhydantoin (10) and 2-piperidinone (11). All these compounds were isolated from this bacterium for the first time. The brine shrimp lethality, antifungal and antibacterial activities of these compounds were evaluated. The results indicated that some cyclodipeptides may play an important role in plant–bacteria interactions.

Keywords:

• Pseudomonas brassicacearum subsp. Neoaurantiaca
• endophytic bacteria
• cyclodipeptides
• antifungal activity

Acknowledgements

This study was supported by the Program for New Century Excellent Talents in University (NCET-05-0852).