A Comparative Phytochemical and Biological Study between Different Solvent Extracts of Leaves and Stems Extracts of Erica arborea L. and Viburnum tinus L. Plants Growing in Tunisia

Abstract

Background: Many Tunisian medicinal plants are widespread and are used in modern ethnomedecin due to their interesting biological activities. Considering natural products of plant origin, this study was conceived to evaluate the allelopathic effect of leaf and stem extracts of Erica arborea and Viburnum tinus on the seed germination and seedling development of Avena sativa. We identified the secondary metabolites that were responsible. Methods: Total phenols, flavonoids, tannins contents and antioxidant activity were evaluated using the Folin ciocalteux, Aluminum trichloride, vanillin and scavenging activity on 2, 2-diphenyl- 1picrylhydrazyl (DPPH) radicals methods, respectively. Leaf powders (5, 20, 40, 60 and 100 g) were macerated each with 1000 ml of distilled water for 24 h. The extracts were filtered through Whatman N°1 filter paper, pooled and concentrated under vacuum. Allelopathic bioassays were conducted using the obtained supernatant. Results: The obtained results indicated that acetonic extracts of the Viburnum leaves had the highest levels of total phenols (36.82 mg / g), flavonoïds (11.99 mg / g) and tannins (7.93 mg / g) and recorded a high antioxidant activity (0.054 mg / ml). Both test species showed that all organs had significant inhibitory effect on the development of Avena sativa. The leaves of Viburnum are best from the point of view inhibition of root length (-85.45%) and height of the aerial part (-78.95%). Conclusion: The inhibitory effects of these extracts were manifested much more on the development of seedlings. Extracts from Viburnum tinus leaves were the best inhibitors and could be regarded as promising candidates for natural plant source of antioxidant and herbicide agents.