Biochemical profile and in vitro biological activities of extracts from seven folk medicinal plants growing wild in southern Tunisia

Abstract

Recently, much attention has been paid to the extracts obtained from plant species in order to analyse their biological activities. Due to the climate diversity in Tunisia, the traditional pharmacopoeia consists of a wide arsenal of medicinal plant species since long used in folk medicine, in foods as spices, and in aromatherapy. Although many of these species are nearly facing extinction, only a small proportion of them have been scientifically studied. Therefore, this study explores the biochemical properties of seven spontaneous plants, which were harvested in the arid Tunisian desert: Marrubium vulgare (L.), Rhus tripartita (Ucria) D.C., Thymelaea hirsute (L.) Endl., Plantago ovata (Forsk.), Herniaria fontanesii (J. Gay.), Ziziphus lotus (L.) and Hyoscyamus albus (L.). Extracts from these plants were found to contain different types of secondary metabolites (polyphenols, flavonoids, condensed tannins, crude saponins, carotenoids and alkaloids) that are involved in important biological activities. The biological activity of the extracts obtained from each Tunisian plant was assessed: first of all, leukaemia and colon cancer cell lines (K-562 and CaCo-2 respectively) were treated with different concentrations of extracts, and then the anti-proliferative activity was observed. The results showed, in particular, how the plant extract from Rhus tripartita significantly inhibits cell proliferation, especially on the K-562 tumour cell line. Subsequently, the anti-inflammatory activity was also assessed, and the results showed that Herniaria fontanesii and Marrubium vulgare possess the highest activity in the group of analysed plants. Finally, the greatest acetylcholinesterase inhibitory effect was exhibited by the extract obtained from Rhus tripartita. In conclusion, all the Tunisian plants we analysed were shown to contain a remarkable amount of different bio-active compounds, thus confirming their involvement in several biological activities. Rhus tripartita and Ziziphus lotus were shown to be particularly effective in anti-proliferative activity, while Herniaria fontanesii were shown to have the best anti-inflammatory activity.

Fig 1. Photos of the plants.

Photos of studied plants collected form Tunisian arid regions.

Fig 2. Cell viability (%).

Anti-proliferative activities of the different ethanol extracts (100 μg/ml) of Tunisian medicinal plants tested on two neoplastic cell lines (K-562 and CaCo-2). Data are presented as mean values ± standard deviation (n = 3). Statistical analysis: unpaired STUDENT T-test. The results were statistically significant compared with the untreated cells (control) (p <0.001).

Fig 3. Inhibition of protein denaturation (%).

Anti-inflammatory activity of the different methanolic extracts (100 μg/ml) of the tested Tunisian medicinal plants. Data are presented as mean values ± standard deviation (n = 3). Statistical analysis: ANOVA test and DUNCAN test. ^a,b,c Different letters above the bars indicate significant differences (p<0.05).

Fig 4. IC₅₀ (mg/ml).

Acetylcholinesterase activity inhibition of ethanol extracts of the tested Tunisian medicinal plants. Data are presented as mean values ± standard deviation (n = 3). Statistical analysis: ANOVA test and DUNCAN test. ^a,b,c Different letters above the bars indicate significant differences (p<0.05).