Antioxidant and cytoxicity δ-tocotrienol from the fruits of Allophylus africanus

aDepartment of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
bDepartment of chemistry, Higher Teacher Training College, University of Yaoundé I, P.O. Box 47, Yaoundé, Cameroon.
cOrganic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, (P.O. Box 100131, 33501 Bielefeld, Germany.
* Corresponding author: phone: 00 237 673551059; E-mail: jean.chouna@univ-dschang.org
Abstract
Background: The World Health Organization has described traditional herbal medicine as one of the surest ways to achieve total health care coverage for the world’s population. In traditional herbal practice in Africa, indigenous medicinal plants have been employed in the treatment of several important infections. Allophylus africanus belonging to the Sapindaceae family is used in the West Region of Cameroon for the treatment of conjunctivitis, dysentery, malaria, skin inflammation, diarrhoea, cancer and migraine. In our efforts to enrich the chemical compositions of the Allophylus africanus, the present study was undertaken to investigate the chemical constituents of the fruits of this plants who our knowledge was not studies on chemical composition and biological properties.
Aims of the study: In our continuous search of bioactive compounds from Cameroonian medicinal plants, we undertook in the present study the antioxidant and cytotoxicity activities of a new δ-tocotrienol isolated from the fruits of Allophylus africanus.
Results: Chemical investigation led to the isolation of a new δ-tocotrienol: 3α-hydroxy-δ-tocotrienol (1) together with eight known compounds (2-9). Compound (1) was allylated (1a) and prenylated (1b and 1c) to give three new semisynthesized derivatives which were fully characterized as: 6-O-allyl-3α-hydroxy-δ-tocotrienol (1a), 6-O-prenyl-3α-hydroxy-δ-tocotrienol (1b) and 6-O,5-C-diprenyl-3α-hydroxy-δ-tocotrienol (1c). The structures of compounds were established using comprehensive spectroscopic and physics analysis including UV, MS, [α]D, 1D and 2D NMR data. Compound (1) and (1a-c) were tested for their antioxydant activity using DPPH radical scavenging assay and also for their cytotoxicity using human cervix carcinoma KB-3-1 cell lines. The results showed that compound (1) exhibited 100-fold increase antioxidant activity compared to the reference control trolox (26 µM) with IC50 value of 0.25 μM; and very good cytotoxic activity with IC50 values of 97 μM compared to the reference control (+)-griseofulvin (IC50 between 17-21 μM).
Keywords: Allophylus africanus, tocotrienol, antioxidant, cytotoxicty.