Isolation, characterisation and biological evaluation of a phenoxazine, a natural dyestuff isolated from leaves of Peristrophe bivalvis

Abstract

Peristrophe bivalvis (L.) Merr. (Acanthaceae) is a wild growing and cultivated plant used for dyeing of foods by the ethnic minorities of Vietnam. The major component of the colour aqueous extract (CAE) of its leaves was identified as peristrophine by spectral analysis, especially the 2D NMR spectra (HSQC, HMBC and NOESY). Considering the widespread utilisation of the decoction of this plant for food dyeing, we evaluated the acute oral toxicity of the CAE. Based on the results in an acute toxicity study in mice, the LD₅₀ value of the CAE was determined as 9100 ± 290 mg kg⁻¹ body weight. Additionally, in vitro cytotoxic assay showed an inhibition of peristrophine against Hepatocellular carcinoma (HepG2, IC₅₀3.90 µg mL⁻¹). CAE and peristrophine (1) have also been tested for their ability to affect the cell number of the OCI acute myeloid leukaemia cell line. CAE and peristrophine significantly decreased the OCI cell number at different concentrations and times of treatment.

Keywords:

• Peristrophe bivalvis
• P. roxburghiana
• natural dyestuff phenoxazine
• peristrophine

Acknowledgements

The authors acknowledge the financial support for this work by National Foundation for Science & Technology Development (NAFOSTED, reference code 104.01.130.09). We thank Dr Ninh Khac Ban, VAST, for identifying the plant and Dr Nicola Pozzesi, University of Perugia, for biotest on tumour cell line growth.