Sesquiterpene lactones from Polydora serratuloides and their quorum sensing inhibitory activity

Abstract

The leaves of Polydora serratuloides, with the synonym Vernonia perrottetii are widely used as purgative agents for gastrointestinal problems, and other members of Vernonieae have been used in African traditional medicine for decades. A new sesquiterpene lactone of the keto-hirsutinolide type, 13-acetoxy-1(4β),5(6)β-diepoxy-8α-(senecioyloxy)−3-oxo-1,7(11)-germacradiene-12,6-olide 1, was isolated from the hexane extract of its leaves, in addition to the known 13-acetoxy-1,4β-epoxy-8α-(senecioyloxy)−3-oxo-1,5,7(11)-germacratriene-12,6-olide 2. Three common flavonoids (apigenin 3, luteolin 4 and velutin 5) were also isolated. The antibacterial and quorum sensing inhibitory activities of compounds 1 and 2 and crudes extracts showed limited activity on Bacillus subtilis and Staphylococcus aureus, with no activity on Gram negative bacteria. However, quorum sensing (QSI) experiments indicated that 1 and 2, and the four crude extracts had interesting inhibitory activity on the biosensor organism, Chromobacterium violaceum ATCC 12472 in the range of 0.33–5.25 mg mL⁻¹, with compound 1 being the most effective at 0.33 mg mL⁻¹.

Graphical Abstract

Keywords:

• Polydora serratuloides
• Vernonia perrottetii
• sesquiterpene lactones
• keto-hirsutinolides
• quorum sensing inhibition

Acknowledgments

This work was supported by the National Research Foundation South Africa by a Competitive Grant for Rated Researchers (Grant No. 118534) and Incentive Funding for Rated Researchers (Grant No. 114817), Ahmadu Bello University, Zaria, and the Tertiary Education Trust Fund (TETFUND) in Nigeria for a study Fellowship. Zohra Kajee is acknowledged for her technical assistance during antimicrobial and quorum sensing inhibition studies.

Disclosure statement

No potential conflict of interest was reported by the authors and they have no financial interest or benefit from the direct applications of this research.

Additional information

Funding

This work was supported by the National Research Foundation, South Africa by a Competitive Grant for Rated Researchers (Grant No. 118534) and Incentive Funding for Rated Researchers (Grant No. 114817).