Allelopathic effect of the ethanol extract and fractions of the aerial parts of Lippia alba (Verbenaceae).

Lippia alba, belonging to the Verbenaceae family, is one of the most commonly utilized medicinal plants in folk medicine. The allelopathic activity was assessed using seeds of Lactuca sativa (lettuce) and Allium cepa (onion) by assessing the growth of the radicle and hypocotyl. The tests showed allelopathic efficiency in inhibiting the growth of lettuce and onion seeds. The best results for allelopathic activity were presented by the dichloromethane (DCM) fraction of the fresh plant, which inhibited radicle (23.04-100% lettuce and 64.17-66.36% onion) and hypocotyl (16.77-100% lettuce and 65.10-69.43% onion) formation, and as well as the DCM fraction of the dry plant, which also inhibited radicle (30.74-82.83% lettuce and 63.50-93.67% onion) and hypocotyl (24.12-70% lettuce and 69.07-79.95% onion) formation. Based on these results, it was found that the aerial parts of L. alba are rich in bioactive substances, suggesting the possibility of using of L. alba as a natural herbicide.

Phytochemical characterisation and bioprospection for antibacterial and antioxidant activities of Lippia alba Brown ex Britton & Wilson (Verbenaceae).

Ethanol extract and fractions obtained from fresh and dry aerial parts of Lippia alba were examined in order to determine their phytochemical composition, antioxidant capacity and antibacterial activities. The ethanol extracts and fractions exhibited an antioxidant effect by the DPPH assay, especially samples of fresh plant. HPLC analysis of the ethyl acetate fractions identified the presence of phenolic acids and flavonoids. The ethanol extract and fractions showed activity against reference and multidrug-resistant strains of Staphylococcus aureus and Enterococcus faecalis (MIC range 2000-250 µg/mL). The hexane and dichloromethane fractions of fresh plant showed better activity against reference strains of Escherichia coli (MIC of 250 and 125 µg/mL, respectively), but all extracts and fractions were less active against multidrug-resistant strains of all the Gram-negative species evaluated. The results showed that the extract and fractions of L alba aerial parts showed antibacterial activity, even against multidrug-resistant Gram-positive bacteria, and antioxidant effect (DPPH assay).

Antioxidant, antibacterial and cytotoxic potential of the ripe fruits of Solanum lycocarpum A. St. Hil. (Solanaceae).

Ethanol extract (EE) and fractions obtained from the ripe fruits of Solanum lycocarpum were examined in order to determine their phenolic composition, antioxidant capacity, antibacterial activities and cytotoxic potential. High-performance liquid chromatography coupled with DAD analysis indicated that caffeic and chlorogenic acids were the main phenolic compounds present in the EE, dichloromethane (DCM) and ethyl acetate (Ac) fractions. The antioxidant activity assessed by the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radical was significantly more pronounced for DCM and Ac fractions than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). EE and fractions exhibited selective antibacterial activity against Gram-positive bacteria, especially the hexane (Hex) and DCM fractions. EE and fractions exhibited low toxicity towards the LLC-MK2 cell line, especially the Hex, DCM and Ac fractions. This work provides the knowledge of phenolic composition in the extract and fractions from the ripe fruits of S. lycocarpum and their antioxidant, antibacterial and cytotoxic activities.