Estudo químico de Piper Peltatum l. (Piperaceae) e Commelina Erecta l. (Commelinaceae)

Abstract

Piper peltatum L. and Commelina erecta L. are tropical species widely distributed in the Amazon region and heavily used by provincials Amazon, for its hardiness, ease of collection and cultivation, to curing several diseases, especially inflammatory. In this work has been performed phytochemical studies and evaluations of antioxidant activity of these species, aiming to contribute to it chemical knowledge, adding value to traditional knowledges. Essential oils from the leaves and hexane, ethyl acetate and ethanol extracts of the leaves, stems and inflorescences of P. peltatum were investigated. Similarly, were studied extracts of leaves and stems of C. erecta and also analyzed its hydro-alcoholic extract (30%) of its flowers. The essential oils of P. peltatum presented as main constituents β-caryophyllene (19.9 to 36.9%), germacrene D (5.8 to 18.8%), α-humulene (4.9 to 6.3%), bicyclogermacrene (3.3 to 10.8), caryophyllene oxide - (3.3-8.3%), E-nerolidol (2.9 to 6.1%) and phytol (1.7 to 8.4%). From the leaves extracts of P. peltatum were isolated, diterpene phytol, a mixture of steroid sitosterol, stigmasterol and campesterol, the flavonoid 5-hydroxy-4 ',7-dimethoxyflavone and identified the 4-nerolidylcatechol, the A, B, and C peltatols; from inflorescence were isolated 4-nerolidylcatechol and peltatol A, as well as identified the B and C peltatols and p-hydroxybenzoic acid; In the stems have been identified cinnamic acid, the uridine and adenosine nucleosides,the uracil base, 4-nerolidylcatechol and A, B and C peltatols. From the ethyl acetate extract of C. erecta stems were isolated the flavonoid luteolin and a mixture of steroids glycosides. In ethyl acetate and ethanol extracts from stems of C. erecta were identified saccharinic acid lactone, shikimic acid, flavonoids luteolin, quercitrin, isoquercitrin, the uridine nucleoside. In the ethyl acetate and ethanol extracts from stems, the saccharinic acid lactone and shikimic acid are major constituents, respectively. In the ethanol leaf extract were identified shikimic acid, 5-cafeoilshikimic acid, the flavonoids orientin, isoschaftoside, 8-C-pentosyl-luteolin, the base uracil and uridine and adenosine nucleosides, and in the hydroalcoholic extract of flowers were identified the isovitexin and vitexin flavonoids C-glycosides. The compounds structures were determined by extensive studies by nuclear magnetic resonance spectroscopy, one-dimensional (1D) and two dimensional (2D) and/or mass spectrometry. The most effective extracts as the scavenging activity of DPPH and ABTS radicals were the ethanol 96% of the inflorescence of P. peltatum (IC50 37.8 and 34.1 μg/mL) and leaves of C. erecta (IC50 50.0 and 65.0 μg/mL). The constitution of these extracts presents phenolic compounds that contribute to antioxidant activity, as 4-nerolidylcatechol for P. peltatum, orientin and luteolin for C. erecta, compatible with the popular use of the species, stimulating the continuation of their investigations.