Tephrosia toxicaria Pers. e Stemodia maritima Linn.: Estudo químico e atividades biológicas

Abstract

This work describes the chemical and biological study of the species Tephrosia toxicaria Pers. and Stemodia maritima Linn. The specie T. toxicaria Pers. is a tropical fish-poisoning plant, popularly known as “timbó de caiena” and known in the chemical literature as a source of rotenoids. Also it is commonly used in organics crops as pesticide. The chemical study of roots of T. toxicaria led to the isolation of flavonoid compounds, characteristics of the genus. For extract of the roots of T. toxicaria and the isolated compounds, obovatin, deguelin and 12a-hydroxy-α-toxicarol, the antinociceptive and anti-inflammatory activities were evaluated in a experimental model of zymosan inflammation in the temporomandibular joint in rats. In this study, all compounds reverted the zymosan inflammatory effects. In the evaluation of antibacterial activity for the same compounds and extract it was verified that the deguelin and 12a-hydroxy-α-toxicarol showed considerable inhibitory activity against gram-positive and gram-negative strains. Stemodia maritima Linn. is popularly known in nordheastern Brazil as “melosa” and occurs mainly in salinized areas, growing like a forest. It is used in popular medicine to treat venereal diseases. The chemical study of leaves of S. maritima provided four estemodane diterpenes: stemodin, stemodinol, stemodin-α-L-arabinopyranoside and stemodin-α-L-arabinofuranoside. The anti-inflammatory and antinociceptive activities were also evaluated, where the extract and the compound stemodin demonstrated efficacy in the reduction of formalin-induced nociception. Neuropharmacological effects and behavioral changes were investigated in the ethanolic extract from leaves of S. maritima, having shown activity in the central nervous system, without altering the physiological activity of the animals, exhibiting antidepressant activity like the antidepressant Imipramine. The diterpene stemodin, majority in S. maritima, was used as a substrate for biotransformation by fourteen fungi of Lasiodiplodia genus. The biotransformation by the fungus L. pontae led to the production of two hydroxylated derivatives: 7β-hydroxystemodin and 18-hydroxystemodin. The substances isolated were identified by spectrometric methods (IR, EM, H1 NMR and C13 NMR), including two-dimensional NMR (HMBC, HSQC, NOESY and COSY) and by comparison with literature data.