Abstract:
This work is devoted to the phytochemical and biological study of two endemic Saharan
medicinal plants, Heliotropium bacciferum Forssk. (Boraginaceae) and Lifago dielsii
Schwein. & Musch. (Asteraceae).
This phytochemical study led the isolation and identification of twenty products, seventeen
of which were monoterpenes megastigans and phenolic type, were obtained from the
chloroform and methanol extracts of the aerial parts of Heliotropium bacciferum Forssk.
While three glycosylated flavonoids were obtained from the ethyl acetate extract of the aerial
parts of Lifago dielsii Schwein & Musch. The structures of the isolated products were
elucidated mainly by the use of NMR techniques (1H, 13C, COSY, HSQC and HMBC), UV
spectrophotometry and by comparison with those reported in the literature.
The quantification of the total phenolic content of the MeOH extract of H. bacciferum was
carried out using the Folin-Ciocalteu method. This step showed a polyphenolic content of
68.0 mgGAE/g extract. This extract was evaluated for its antioxidant activity towards the
free radical DPPH and the radical ABTS. The results showed that this extract exhibited a
significant activity and is dependent on the concentration in vitro with respect to the DPPH
radicals (IC50 70.912 μg/ml), and ABTS (IC50 1.466 μg/ml), related to the presence of the
phenolic derivatives.
Both extracts and some isolated products of H. bacciferum were tested for their cytotoxic
effect in human cancer cell lines (HCT-116, DLD1 and HDFa). Only the chloroform extract
showed a significant and concentration-dependent inhibitory effect on the growth of IC50
treated cancer cell lines of 0.095 mg/ml on HCT116 and 0.062 mg/ml on DLD1.
The quantification of total phenols and total flavonoids contents of the CHCl3, EtOAc, nBuOH extracts and of the methanol insoluble part (MeOH) of the aerial parts of L. dielsii
was carried out using colometric methods. This study showed a phenolic content more
important in the EtOAc extract. However, total flavonoids content was higher in n-BuOH
extract (88.81%). The antioxidant activity of L. dielsii extracts was evaluated by the DPPH
free radical scavenging and the lipid peroxidation inhibition (LPO) assays. The EtOAc
extract has the strongest effect on DPPH with (IC50 = 47.80 ± 2.20 μg/ml) and the inhibition
of lipid peroxidation (IC50 = 113.24 ± 0.65 μg/ml).
