The conifer biomarkers dehydroabietic and abietic acids are widespread in Cyanobacteria

Maria Sofia Costa,Vitor Ramos,Marco Preto,Catarina Magalhães,Vitor Vasconcelos,Viviana Lopes,Pedro N Leão,Sara Freitas,Adriana Rego,Tiago B Afonso

doi:10.1038/srep23436

Abstract

Terpenes, a large family of natural products with important applications, are commonly associated with plants and fungi. The diterpenoids dehydroabietic and abietic acids are defense metabolites abundant in resin, and are used as biomarkers for conifer plants. We report here for the first time that the two diterpenoid acids are produced by members of several genera of cyanobacteria. Dehydroabietic acid was isolated from two cyanobacterial strains and its identity was confirmed spectroscopically. One or both of the diterpenoids were detected in the cells of phylogenetically diverse cyanobacteria belonging to four cyanobacterial ‘botanical orders’, from marine, estuarine and inland environments. Dehydroabietic acid was additionally found in culture supernatants. We investigated the natural role of the two resin acids in cyanobacteria using ecologically-relevant bioassays and found that the compounds inhibited the growth of a small coccoid cyanobacterium. The unexpected discovery of dehydroabietic and abietic acids in a wide range of cyanobacteria has implications for their use as plant biomarkers.

Highlights

We report the NMR (Nuclear Magnetic Resonance)-guided isolation of 1 in two marine strains and the LC-HRESIMS (Liquid Chromatography coupled to High Resolution Electrospray Ionization Mass Spectrometry) detection of 1 and 2 in an extended group of cyanobacteria, indicating that the diterpenoids are widely distributed among this group of organisms
Our findings indicate that 1–and most likely 2–are widespread in cyanobacteria
The cyanobacterial origin for the two diterpenoids needs to be taken into account especially when important extrapolation is based on the detection of these metabolites

Summary

Introduction

The recent recognition that bacterial genomes (including those from cyanobacteria) are rich in terpene synthases[20,21] suggests that a large diversity of terpenes is yet to be discovered from the bacterial kingdom. As part of our ongoing studies on cyanobacterial secondary metabolite diversity, we have been exploring diverse strains of cyanobacteria from our in-house collection (LEGE Culture Collection) for their small-molecule constituents. We report the NMR (Nuclear Magnetic Resonance)-guided isolation of 1 in two marine strains and the LC-HRESIMS (Liquid Chromatography coupled to High Resolution Electrospray Ionization Mass Spectrometry) detection of 1 and 2 in an extended group of cyanobacteria, indicating that the diterpenoids are widely distributed among this group of organisms

Methods

Results

Conclusion