Allelopathic Potential and Cytotoxic, Genotoxic, and Antigenotoxic Effects of Tecoma stans Flowers (Bignoniaceae)

Weed control is mainly carried out using synthetic herbicides, which represent 62.6% of the total pesticides sold. However, some plants produce allelochemicals that inhibit the growth of other plants, and these substances can be isolated and used as natural herbicides. This study aimed to evaluate the allelopathic, cytotoxic, genotoxic, and antigenotoxic potential of the ethanol extract (EE), hexane (HEX), dichloromethane (DCM), ethyl acetate (EA) and hydroethanol (HE) fractions obtained from Tecoma stans flowers. Nuclear magnetic resonance (NMR) was used to characterize the compounds present in the samples. The allelopathic activity was tested using Allium cepa and Lactuca sativa seeds, and the cytotoxicity, genotoxicity and antigenotoxicity were evaluated using A. cepa seeds. The saturated and unsaturated fatty acids ω-3 and ω-6, terpenes, flavonoids, and phenolic acids with coumaroyl or glycosyl derivatives were characterized in the samples. The HEX and DCM fractions significantly inhibited germination and root growth, effects associated with fatty acids and phenolic compounds. The EA fraction exhibits genotoxic potential at higher concentrations tested. The extract and fractions reduced the genotoxicity induced by glyphosate and atrazine, reversing chromosomal abnormalities. These results demonstrate the possible use of the extract and fractions as natural sources of allelochemicals, but safe dosage validation is required.