Comparison of metabolic profiles and bioactivities of the leaves of three edible Congolese Hibiscus species

Abstract

Methanolic and dichloromethane extracts from the leaves of Congolese Hibiscus species were characterised by chromatographic and spectroscopic techniques and their in vitro biochemical activities against ROS production were evaluated in cellular models and on an enzyme, myeloperoxidase (MPO), involved in inflammation. Hibiscus acetosella has a chemical fingerprint different from Hibiscus cannabinus and Hibiscus sabdariffa both having similar fingerprints. Major compounds were polyphenols, represented mainly by caffeoyl-hydroxycitric acid for H. acetosella and neochlorogenic acid for the two other species. All extracts displayed high cellular antioxidant activity with IC₅₀ values ranging from 0.5 to 3 μg mL⁻¹ using lucigenin on neutrophils. Dichloromethane extracts showed more efficient effects on extracellular ROS production and MPO activity. Antioxidant and anti-inflammatory activities of caffeoyl-hydroxycitric acid were significantly higher than those of neochlorogenic acid. The bioactivities of Hibiscus species were positively correlated with their phytochemical content and could justify their use as local nutraceutical resources and medicines.

Keywords:

• Caffeoyl-hydroxycitric acid
• Hibiscus acetosella
• Hibiscus cannabinus
• Hibiscus sabdariffa
• myeloperoxidase
• neochlorogenic acid

Acknowledgements

The authors thank Dr. P Stofelen and Mrs. B Mato of the National Botanical Garden of Meise, Belgium, and Mr. A Kikufi of the University of Kinshasa for identification of the plants studied. They also thank JN Wauters, J Romainville and A Niesten for their technical advice.