Litchi chinensis Sonn.: estudos microbiológicos e fitoquímicos.

Abstract

The species Litchi chinensis Sonn., popularly known as litchi, originated in China and has medicinal applications in many countries, particularly in traditional chinese medicine. The aim of this study was to evaluate leaf extract and fractions of this species both chemically and biologically. The hydroethanolic leaf extract was prepared, and from the liquid-liquid partition, the fractions hexane, ethyl acetate, butanol and aqueous acetate were obtained. The technique of mass spectrometry ESI -IT-MSn was used to determine the profile the extract and fractions. The quantification of total phenolic content, total flavonoid, the scavenging power of DPPH radical and the reducing power of leaf extracts and fractions was carried out. In addition, the following in vitro biological activities were also evaluated: antimicrobial for bacteria and fungi (agar diffusion method and minimum inhibitory concentration), leishmanicidal and cytotoxicity. The leaf extract and fractions showed phenolic compounds as major chemical constituents, such as flavonoids (aglycones and glycosides) and condensed tannins. The results of the determination of total phenolics and flavonoids have shown that there is a higher concentration of these compounds in the ethyl acetate fraction compared to the leaf extract and other fractions and evaluation of scavenging power of DPPH radical and reducing power demonstrates that this fraction also showed higher antioxidant activity in vitro compared to the leaf extract and other fractions. Thus, there is evidence of a possible correlation between these compounds and antioxidant activity. The leaf extract of L. chinensis and fractions tested in this work had the following antimicrobial activity against gram-positive bacteria: Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Enterococcus faecalis, and Staphylococcus aureus and against the gram-negative bacteria Proteus mirabilis. The leaf extract of L. chinensis and fractions showed no activity against L. amazonensis tested up to a concentration of 40 mg/mL, nor were toxic to murine macrophages in the concentration tested (160 mg/mL). The ethyl acetate fraction (FrAcOEt) of leaf extracts showed the best results on the content of total phenolics, total flavonoids, the best antioxidant activity and the lowest values of minimum inhibitory concentration, thus demonstrating the viability of this fraction of the leaf extract as a potential source of bioactive compounds.