The chemistry of Vernonanthura nudiflora (Less.) H. Rob. flowers and its antimicrobial activities

Abstract

Twenty-one known specialised metabolites were isolated from the flowers of Vernonanthura nudiflora (Less.) H. Rob., the structures of the compounds were established based on 1 D and 2 D NMR spectroscopic experiments. Others 28 compounds were putatively identified using the dereplication technique by UHPLC-HRMS/MS. Twenty-three of the compounds are being reported for the first time in this species. The mixture of sesquiterpene lactones piptocarphins A and B (17 + 18), and the flavone velutin (14) were tested against several microorganisms and showed promising activity against Mycobacterium tuberculosis with MIC of 15.6 μg/mL and 31.2 μg/mL, respectively. Furthermore, 17 + 18 showed greater cytotoxicity against VERO cells (IC₅₀ = 7.0 ± 1.73) compared to compound 14 (IC₅₀ 85.0 ± 10.6 µg/mL). These findings reveal the feasibility of using the UHPLC-ESI-HRMS/MS-based dereplication strategy in complex fractions to identify specialised metabolites, moreover to V. nudiflora flowers being a source of compounds with antimycobacterial potential.

Keywords:

• Sesquiterpene lactones
• piptocarphins
• velutin
• UHPLC-HRMS/MS
• Mycobacterium tuberculosis
• antimicrobial activity

Acknowledgments

The authors would like to thank CAPES - Finance Code 001, CNPq and INCT BioNat (CNPq 465637/2014-0) for financial support. This work was supported by the Complexo de Central de Apoio à Pesquisa (COMCAP) from the Universidade Estadual de Maringá.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.