Estabelecimento in vitro e estudo fitoquímico e biológico dos extratos de folhas, galhos e calos de Duroia longiflora Ducke (Rubiaceae)

Abstract

The species Duroia longiflora Ducke (Rubiaceae) is a non-endemic plant that produces secondary metabolites such as terpenes, flavonoids and alkaloids. This species is included in the genus Duroia, which also includes species such as Duroia macrophylla, from which indole alkaloids and triterpenes with antitumor and antimycobacterial activities were isolated, and Duroia saccifera, known for its antifungal and antiparasitic potential. This work aimed to perform a phytochemical study of the extracts of leaves, twigs and calluses of D. longiflora to identify the metabolites produced, comparing the metabolites produced in natura and in vitro, in addition to evaluating the antioxidant and antimicrobial biological potential of the extracts. The phytochemical study allowed the isolation and identification of several bioactive substances in the extracts of leaves and twigs. β-Sitosterol, lupeol, α-amyrin, β-amyrin acetate, 132-hydroxy-pheophorbide-a and a pheophorbide isomer were isolated, these compounds being described for the first time in the species D. longiflora. The methanolic extracts of leaves and twigs from the 1st collection showed antioxidant activity, while the hexane and methanolic extracts from the 2nd collection did not show this activity. Furthermore, the extracts from both collections showed high inhibition against Staphylococcus aureus and Klebsiella pneumoniae, and moderate inhibition against Aeromonas hydrophila. In the in vitro study performed with leaf explants, callus formation was observed, with the MS medium being more effective in reducing oxidation and root formation, compared to the WPM medium. Phytochemical analysis of the methanolic extract of callus revealed the production of terpenes, flavonoids and iridoids, with emphasis on mussaenoside acid, geniposidic acid and gardenoside. The use of MS medium with 2 mg L⁻¹ of NAA and BAP, in dark conditions, is recommended for large-scale production of the compounds of interest.