YEW EXTRACTS - A POSSIBLE SOURCE OF BIOACTIVE COMPOUNDS WITH POTENTIAL ALLELOPATHIC PROPERTIES

Abstract

Representative species of the Taxus genus, known since antiquity for their toxicity, have been an essential plant resource for the production of plant extracts with medicinal properties (anti-inflammatory, antifungal, and antibacterial) and, more recently, for the study of their allelopathic properties with significant implications in organic agriculture (bioherbicidal potential). With a view to the development of this new direction of research, the present work aims: to present a qualitative evaluation of two types of plant extracts (aqueous and alcoholic) of different concentrations (1% and 5%) obtained from various organs (bark, leaves, arils, and seeds) belonging to three Taxus taxa: a spontaneous taxa - Taxus baccata L. (T1) and two cultivated taxa - Taxus baccata (T2) and Taxus baccata 'Robusta' (T3) at different times of the phenological cycle by determining their absorption spectra (of both types of extracts), total amounts of polyphenols and flavonoids, and by evaluating their antioxidant capacity (alcoholic extracts); to investigate, under experimental conditions of cultivation the possible allelopathic effects induced by the aqueous extracts on the germination and development of the seedlings in two test plant species: Amaranthus retroflexus L. (ruderal species) and Lycopersicon esculentum Mill, variety Silvia (crop species). The data indicates the presence of phenolic and compounds, alkaloids, and carotenoid pigments in the alcoholic extracts prepared from the different organs of the studied yew taxa, showing higher amounts of polyphenols and flavonoids in the extracts obtained from the leaves of taxon T2 compared to taxon T1. The effect of 1% and 5% aqueous extracts obtained from the bark of the three investigated yew taxa, as well as 1% aqueous extracts prepared from the leaves of taxon T3 on seed germination and seedling growth was more pronounced in the crop species Lycopersicon esculentum Mill, variety Silvia, compared to the ruderal broadleaf weed Amaranthus retroflexus L., both species having rapid germination stimulated by ambient light. Aqueous extracts of 5% concentration obtained from the arils of plants belonging to the three yew taxa stimulated the elongation of the seedlings’ hypocotyls of both test species.