TY - JOUR
T1 - Biomedicine in the environment
T2 - cyclotides constitute potent natural toxins in plants and soil bacteria
AU - Ovesen, Rikke Gleerup
AU - Brandt, Kristian Koefoed
AU - Göransson, Ulf
AU - Nielsen, John
AU - Hansen, Hans Chr. Bruun
AU - Cedergreen, Nina
PY - 2011/5
Y1 - 2011/5
N2 - Bioactive compounds produced by plants are easily transferred to soil and water and may cause adverse ecosystem effects. Cyclotides are gene-encoded, circular, cystine-rich mini-proteins produced in Violaceae and Rubiaceae in high amounts. Based on their biological activity and stability, cyclotides have promising pharmaceutical and agricultural applications. We report the toxicity of the cyclotides: kalata B1, kalata B2, and cycloviolacin O2 extracted from plants to green algae (Pseudokirchneriella subcapitata), duckweed (Lemna minor L.), lettuce (Lactuca sativa L.), and bacteria extracted from soil measured as [3H]leucine incorporation. Quantification by liquid chromatography-mass spectrometry demonstrated up to 98% loss of cyclotides from aqueous solutions because of sorption to test vials. Sorption was prevented by adding bovine serum albumin (BSA) to the aqueous media. Cyclotides were toxic to all test organisms with EC50 values of 12 through 140μM (algae), 9 through 40μM (duckweed), 4 through 54μM (lettuce), and 7 through 26μM (bacteria). Cycloviolacin O2 was the most potent cyclotide in all assays examined. This report is the first to document toxic effects of cyclotides in plants and soil bacteria and to demonstrate that cyclotides are as toxic as commonly used herbicides and biocides. Hence, cyclotides may adversely affect soil and aquatic environments, which needs to be taken into account in future risk assessment of cropping systems for production of these highly bioactive compounds.
AB - Bioactive compounds produced by plants are easily transferred to soil and water and may cause adverse ecosystem effects. Cyclotides are gene-encoded, circular, cystine-rich mini-proteins produced in Violaceae and Rubiaceae in high amounts. Based on their biological activity and stability, cyclotides have promising pharmaceutical and agricultural applications. We report the toxicity of the cyclotides: kalata B1, kalata B2, and cycloviolacin O2 extracted from plants to green algae (Pseudokirchneriella subcapitata), duckweed (Lemna minor L.), lettuce (Lactuca sativa L.), and bacteria extracted from soil measured as [3H]leucine incorporation. Quantification by liquid chromatography-mass spectrometry demonstrated up to 98% loss of cyclotides from aqueous solutions because of sorption to test vials. Sorption was prevented by adding bovine serum albumin (BSA) to the aqueous media. Cyclotides were toxic to all test organisms with EC50 values of 12 through 140μM (algae), 9 through 40μM (duckweed), 4 through 54μM (lettuce), and 7 through 26μM (bacteria). Cycloviolacin O2 was the most potent cyclotide in all assays examined. This report is the first to document toxic effects of cyclotides in plants and soil bacteria and to demonstrate that cyclotides are as toxic as commonly used herbicides and biocides. Hence, cyclotides may adversely affect soil and aquatic environments, which needs to be taken into account in future risk assessment of cropping systems for production of these highly bioactive compounds.
U2 - 10.1002/etc.496
DO - 10.1002/etc.496
M3 - Journal article
C2 - 21337607
SN - 0730-7268
VL - 30
SP - 1190
EP - 1196
JO - Environmental Toxicology and Chemistry
JF - Environmental Toxicology and Chemistry
IS - 5
ER -