Phytochemical analysis and hypotensive activity of Ipomoea pes-caprae on blood pressure of normotensive rats

Abstract Ipomoea pes-caprae (Convolvulaceae), popularly known as “salsa-da-praia”, is used in folk medicine for the treatment of several diseases, including hypertension. The aim of this research was to evaluate hypotensive activity attributed to this species and identify the bioactive compounds responsible for this effect. Hydroalcoholic extract of aerial parts of Ipomoea pes-caprae (PIEA) was fractionated by column chromatography with Amberlite XAD-2, thus achieving a methanolic fraction (PIEA-M). The chemical profile investigation of PIEA-M was conducted by Ultra Performance Liquid Chromatography coupled to Mass Spectrometry (UPLC-MS) and compound isolation through High Performance Countercurrent Chromatography (HPCCC). Hemodynamic evaluations of PIEA, PIEA-M and isolated compounds were carried out on normotensive rats. The locomotor activity of PIEA and PIEA-M were performed by Rota Rod test using Swiss mice. UPLC-MS analysis of PIEA-M led to the identification of 11 compounds corresponding to seven phenolic acids and four flavonoids. By means of HPCCC, quercetin 6”-O-acetyl-3-O- glucoside (1), a mixture of quercetin-3-O-galactoside and quercetin-3-O- glucoside (2) and quercetin 3-O-glucoside (3) were isolated. PIEA, PIEA-M and the obtained compounds (1 and 2) significantly reduced blood pressure. Also, PIEA and PIEA-M caused significant impairment on mice locomotor activity. These results indicate the potential of Ipomoea pes-caprae as a source of hypotensive agents suggesting that phenolic compounds present in the species are responsible for its hypotensive activity.

Differentiation of the phenolic chemical profiles of Cecropia pachystachya and Cecropia hololeuca

INTRODUCTION

Cecropia pachystachya and C. hololeuca are common species in Brazil, popularly used to treat respiratory diseases. Phytochemical studies indicate that their leaves are rich in phenolic compounds, mainly C-glycosilated flavonoids. Orientin and isoorientin are reported in both species, while vitexina and isovitexina were reported in C. pachystachya. In addition, both are rich in chlorogenic acid and have some procyanidins. In some cases, syrups and teas are prepared from leaf blends from different species, which may affect the efficacy and safety of this natural medication. This problem motivated the investigation of the chemical profile of leaves of these species.

OBJECTIVE

The phenolic chemical profiles from C. pachystachya and C. hololeuca methanolic extracts were analysed by ultra-high performance liquid chromatography coupled with a diode array detector and mass spectrometry (UPLC-DAD-MS), to investigate possible differences in their metabolite production.

MATERIAL AND METHODS

The methanolic extracts of both species were analysed by UPLC-DAD-MS using a C-18 reverse phase column, DAD at 190-400 nm and electrospray ionisation quadruple time-of-flight (ESI-Q-TOF) mass spectrometer. The separation methodology was validated and most of the flavones present in the extracts were quantified.

RESULTS

Thirty-seven compounds were tentatively identified, including flavonoids, phenolic acids, flavan-3-ols, condensed tannins (procyanidins) and iridoids, through UV analysis and tandem mass spectrometry (MS/MS) spectra obtained in the negative mode. Chlorogenic acid, orientin and isoorientin were observed as the major constituents in both extracts.

CONCLUSIONS

Cecropia pachystachya presented a more diverse chemical profile than C. hololeuca. The methodology developed herein could be an important tool to analyse commercial Cecropia (embaúba) products.