Thursday, 26 November 2015

Phenolic composition and antioxidant activity of kenaf leaves

Volume 78, December 30, 2015, Pages 116-123

MEtRiCS, Departamento de Ciências e Tecnologia da Biomassa, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, Campus de Caparica, Caparica, Portugal
Department of Analytical Chemistry, Faculty of Sciences, University of Granada, c/Fuentenueva s/n, Granada, Spain
Functional Food Research and Development Center (CIDAF), Health Science Technological Park, Avenida del Conocimiento s/n, Granada, Spain


Kenaf (. Hibiscus cannabinus L.) is a short day, annual, herbaceous plant producing high quality cellulose. Kenaf is a valuable fiber crop that is cultivated for its fibrous stem. Recently, seeds and leaves have been also considered as a source of industrial products, such as biopharmaceuticals. However, their pharmacological effects and chemical composition are still poorly studied.In this context, the aim of this work was to identify the phenolic compounds and to evaluate the antioxidant activity of kenaf leaves extracts, comparing two varieties, Everglades 41 and Tainung 2, produced in Portugal. The identification of the phenolic compounds in the leaves was done using advanced analytical techniques such as high-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). Parallel to this, in vitro antioxidant activity and total phenolic content of extracts were also determined. The antioxidant activity was evaluated with the use of two assays (oxygen radical absorbance capacity assay-ORAC and DPPH assay) and the total phenolic content by the Folin-Ciocalteu method.HPLC-ESI-QTOF-MS analyses enabled to tentatively identify 29 compounds in both varieties, mainly chlorogenic acids and quercetin and kaempferol derivatives. Some of the compounds found in the kenaf leaves were related before to the Hibiscus genus. Results of Folin-Ciocalteu, DPPH and ORAC assays showed that Everglades 41 leaves were richer in phenolic compounds presenting a higher antioxidant potential than Tainung 2 leaves. This study indicates that kenaf leaves can be considered as potentially new source of antioxidants but its future use in food and nutraceutical matrices still need to be tested and evaluated. © 2015 Elsevier B.V.

Author keywords

Antioxidant capacity; HPLC-ESI-QTOF-MS; Kenaf; Kenaf leaves; Phenolic compounds

Indexed keywords

Engineering controlled terms: Agents; Antioxidants; Assays; Chemical compounds; Chromatography; Electrospray ionization; Flavonoids; Hemp; High performance liquid chromatography; Ionization of liquids; Liquid chromatography; Mass spectrometry; Phenols
Antioxidant capacity; ESI-QTOF-MS; Kenaf; Kenaf leaves; Phenolic compounds
Engineering main heading: Plants (botany)
Species Index: Hibiscus; Hibiscus cannabinus