In vitro antioxidant, antilipoxygenase and antimicrobial activities of extracts from seven climbing plants belonging to the Bignoniaceae.

This study aimed to evaluate the in vitro antioxidant capacity, to determine the anti-inflammatory effect due to lipoxygenase inhibition and to test the antimicrobial activity of ethanolic extracts from leaves of seven climbing species belonging to the Bignoniaceae family. These species are Adenocalymma marginatum (Cham.) DC., Amphilophium vauthieri DC., Cuspidaria convoluta (Vell.) A. H. Gentry, Dolichandra dentata (K. Schum.) L. G. Lohmann, Fridericia caudigera (S. Moore) L. G. Lohmann, Fridericia chica (Bonpl.) L. G. Lohmann and Tanaecium selloi (Spreng.) L. G. Lohmann.

The antioxidant activity was evaluated using three methods, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power. Lipoxygenase-inhibiting activity was assayed spectrophotometrically; the result was expressed as percent inhibition. The antimicrobial activity was assessed using the agar disk diffusion method. Minimal inhibitory concentration (MIC) and minimal bactericidal/fungicidal concentration were also determined for each extract against 12 pathogenic bacterial strains of Staphylococcus aureus and seven fungal strains of the Candida genus. The identification of the major compounds present in the most promising extract was established by high-performance liquid chromatography-tandem mass spectrometry.

C. convoluta, F. caudigera, and F. chica exhibited the best antioxidant activity by scavenging DPPH and ABTS+ radicals and reducing Fe3+ ion. These extracts showed a notable inhibition of lipoxygenase. F. caudigera was found to have the lower MIC value against S. aureus strains and six Candida species. The extracts of F. caudigera and C. convoluta were active even against methicillin-resistant S. aureus. C. convoluta had higher total phenol content, better antioxidant activity and superior anti-inflammatory and antimicrobial activity. The main phenolic compounds found in this extract were coumaric and hydroxybenzoic acid derivatives and glycosylated and nonglycosylated flavones.

Most of the extracts exhibited antioxidant activity as well as in vitro inhibition of lipoxygenase. The excellent antimicrobial activity of T. selloi and F. chica supports their use in traditional medicine as antiseptic agents. The extracts of F. caudigera and C. convoluta, both with notable biological activities in this study, could be used as herbal remedies for skin care. In addition, this study provides, for the first time, information about phenolic compounds present in C. convoluta.