Date Published: September 17, 2019
Publisher: Public Library of Science
Author(s): Hajer Tlili, Najjaa Hanen, Abdelkerim Ben Arfa, Mohamed Neffati, Abdelbasset Boubakri, Daniela Buonocore, Maurizia Dossena, Manuela Verri, Enrico Doria, Gianfranco Pintus.
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.
Nature has been a source of medicinal agents for thousands of years and an impressive number of modern drugs have been isolated from natural sources, many of them based on their use in traditional medicine. Today it is estimated that more than two thirds of the world’s population relies on plant-derived drugs; some 7,000 medicinal compounds used in the Western pharmacopoeia are derived from plants .
This work offers an overview of some biochemical and biological properties of seven aromatic plants, traditionally used in the Tunisian region in folk medicine. Both biochemical and biological tests were performed to provide a complete framework for each plant examined in this study. All the tested Tunisian plants showed a remarkable presence of secondary metabolites, involved in several biological activities. In particular, Rhus tripartita has a high content of polyphenols and saponins, responsible for the significant anti-proliferative activity. Due to the abundance of bioactive metabolites, all the extracts obtained by the plants were shown to be able to inhibit AChE activity by 50%, at a concentration less than or equal to 1 mg/ml; moreover, these extracts were shown to be efficient, with the exception of Z. lotus, in the prevention of precipitation of the denatured protein aggregates involved in inflammation. In conclusion, all the data confirm the importance of the Tunisian local vegetation as a potential source of various bioactive phytochemical compounds; the investigation is based on the need for different biological agents from natural sources with potent activity and lesser side effects as substitutes for chemical therapeutics.