Phytosterol of Potamogeton maackianus and its change under the stress of Microcystis aeruginosa

The phytosterol in Potamogeton maackianus was identified and quantified. From the hexane extracts analysis of unsaponifiable fraction of P. maackianus by gas chromatography-mass spectrometry(GC-MS), campesterol, stigmasterol and β -sitosterol were the main phytosterols in P. maackianus with the contents of 0.368, 1.17 and 0.824 mg·g −1 , respectively. After 7 days’ exposure under M. aeruginosa , the contents of campesterol, stigmasterol and β -sitosterol in P.maackianus increased by 23.1%, 40.4% and 40.8%, respectively. Both the contents of 24-ethyl sterols (sitosterol and stigmasterol) and 24-methyl sterol (campesterol) in macrophytes increased, but the percentage of total sterol composition did not change significantly. This result indicated that the content of 4-demethyl sterols and the second alkylation of the phytosterol side-chain at C-24 in P. maackianus were affected by M. aeruginosa .