Seasonal Chemical Evaluation of Miconia chamissois Naudin from Brazilian Savanna

Abstract

Miconia chamissois Naudin is a species from the Cerrado, which is being increasingly researched for its therapeutic potential. The aim of this study was to obtain a standardized extract and to evaluate seasonal chemical variations. Seven batches of aqueous extracts from leaves were produced for the standardization. These extracts were evaluated for total solids, polyphenol (TPC) and flavonoid content (TFC), vitexin derivative content, antioxidant activity; thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC) profiles were generated. For the seasonal study, leaves were collected from five different periods (May 2017 to August 2018). The results were correlated with meteorological data (global radiation, temperature, and rainfall index). Using chromatographic and spectroscopic techniques, apigenin C-glycosides (vitexin/isovitexin) and derivatives, luteolin C-glycosides (orientin/isoorientin) and derivatives, a quercetin glycoside, miconioside B, matteucinol-7-O-β-apiofuranosyl (1 → 6) -β-glucopyranoside, and farrerol were identified. Quality parameters, including chemical marker quantification by HPLC, and biological activity, are described. In the extract standardization process, all the evaluated parameters showed low variability. The seasonality study revealed no significant correlations (p < 0.05) between TPC or TFC content and meteorological data. These results showed that it is possible to obtain extracts from M. chamissois at any time of the year without significant differences in composition.

Keywords: Cerrado; Miconia chamissois Naudin; seasonality; standardized extract.

Figure 1

Thin-layer Chromatography from seven batches of aqueous extract of M. chamissois Naudin (AEMC). Each column represents one extraction batch. The leaves were collected in May 2017. The stationary phase was silica gel, and the mobile phase was a mixture of ethyl acetate, formic acid, acetic acid, and deionized water (100:11:11:26). Chromatographic spots were visualized using an ultraviolet lamp at 254 nm and the NP/PEG reagent. 1: R_f 0.17, 2: R_f 0.33, 3: R_f 0.43, 4: R_f 0.54 and 5: R_f 0.61.

Figure 2

Chromatographic profile of aqueous extract M. chamissois Naudin leaves (B4) by HPLC/DAD at 354 nm. Detection at 354 nm, C18 column, flow rate of 0.6 mL/min, eluent: phosphoric acid 1%, and acetonitrile in gradient system. (A) similarity of peak 6 (t_R 24.89 min, λmax: 270, 336) and vitexin standard compound (similarity index: 0.9959); (B) similarity of peak 6 (t_R 24.89 min) and isovitexin standard compound (similarity index: 0.9951), (C) peak 6 (t_R 24.89 min, λmax: 270, 336); strongly suggestive a vitexin or isovitexin related compound (D) peak 11 (t_R 41.27 min; λmax: 282, 363) miconioside B; (E) peak 12 (t_R 50.76 min; λmax: 282, 363) matteucinol-7-O-β-apiofuranosyl (1 → 6)-β-glucopyranoside.

Figure 3

Chromatogram profile of M. chamissois Naudin aqueous extract from leaves (AEMC) analyzed UHPLC/UV/MS/MS at 354 nm. Detection at 354 nm, C18 column, flow rate of 0.3 mL/min, eluent: formic acid 1%, and acetonitrile in gradient system. The mass spectrometer was operated in several different modes for separate injections. The ion source temperature was 130 °C, the desolvation gas was nitrogen at 950 L/h, the desolvation temperature was 450 °C, and the capillary voltage was 2.7 KV.