Myricetin from Plinia cauliflora (Mart.) Kausel and activity against Candida albicans

The aim of this work was to obtain a pure compound from P. cauliflora leaves extract and to evaluate its anti-Candida activity. The leaves extract was obtained with 70% ethanol by percolation. After partition with ethyl acetate and water, the ethyl acetate fraction was chromatographed through a Sephadex LH-20 gel column eluted with methanol. Fractions (8 mL each) were collected and analyzed by TLC (silicagel plate, 025µm thickness) eluted with chloroform:methanol:n-propanol:water (5:6:1:4; v/v; organic phase) and sprayed with sulphuric anisaldehyde. Spots with similar Rf and colour were assembled The isolated compound was identified by its spectral data (¹H-NMR, ¹³C-NMR, HMQC, COSY, HMBC, 1D-TOCSY) and compared to those reported in the literature [1,2]. Determination of Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) was performed according NCCLS M27-A2 [3]. The identified fraction sample was diluted to 500µg/mL and the Candida albicans (ATCC 64548) final inoculum was 2.5–5.0×10³ cells/mL. The spectroscopic data of the isolated compound were in complete agreement with the flavonoid myricetin-3-O-β-allopyranoside. This compound showed MIC and MFC of 250µg/mL and 500µg/mL, respectively. This was the first flavonol isolated from the leaves of P. cauliflora and it was possible to determine for the first time its good activity against the pathogen C. albicans.

Support: PADC-UNESP and FAPESP

References: [1] Agrawal, P.K. (1989) Carbon 13 NMR of Flavonoids, Elsevier, Amsterdam.

[2] Harborne, J.B., Willians, C.A. (2000) Phytochemistry 55: 481–504.

[3] NCCLS. National Committee For Clinical Laboratory Standards (2002). Approved standard M27-A2, 2nd ed. National Committee for Clinical Laboratory Standards, Wayne, PA.