Analytical and chromatographic parameters used to quantify flavonols and chlorogenic acid in Solidago raw extracts

Species in the Solidago genus are used worldwide due to the therapeutic activities of their flavonoids and terpenoids. Its anti-inflammatory, vulnerary, antirheumatic, analgesic, diuretic, aquaretic, wound-healing properties, as well as its ability to relieve the burn and insect bites, allow use in a variety of situations. (Oliveira et al., 2017). This study was carried out to determine the comparative chemical profile, flavonols and chlorogenic acid contents between Solidago chilensis (SCMI) and Solidago canadensis (SCAI) inflorescence extracts and also the biological potential, comparing with the others Solidago species used in North America and Europe. SCM was cultivated (dedicated cultivation) in Tapera Quilombo’s (Itaipava-RJ) (22°23'10.19''S; 43°3'27.14''W), by Sérgio Monteiro (Itaboraí Forum - FIT / Fiocruz) (SCM-FIT) (UFRJ exsiccate, RFA 39.930) and the Agroecological Platform of Phytomedicines (PAF/Farmanguinhos/Fiocruz) (22.9407°S 43.4046° W) by Valério Morelli (SCM-PAF) (UFRJ exsiccate, RFA 32,689). SCAI was acquired at RJ, in a popular market. The extracts were obtained by dynamic maceration with Ether:Ethanol 1:1 v/v (T0118 and SCAI), and with Ethanol:Water 66ºGL (tinctures T0116 and TB0116). The HPLC-UV-PDA revealed mainly flavonols (FLV) such as quercetin, glycosides as well as chlorogenic acid (CA). They both contain the same flavonoid aglycones, and their glycosides are important chemical and biological markers for extracts and products based on species of the genus Solidago. HPLC-UV-PDA also characterizes the extracts and improve the quality control of raw plant materials and commercialized phytotherapeutics and also contributes to the development of new products and phytomedicines. The extracts will be quantified and standardized by HPLC analytical methodology in relation to the levels of the FLV reference standard and CA content and expressed in µg/mL for quantification, using the selectivity analytical parameters, linearity, limit of detection and quantification, accuracy, precision and robustness as defined by RDC 166/2017 (ANVISA). Primary reference standards of chlorogenic acid and five flavonoids (hyperoside, isoquercitrin, quercetin, and quercitrin) were used to analyze sample extracts of SCMI and SCAI by HPLC. Reversed-phase was carried out at 25°C using a Hibar-Lichrospher 100-RP 18 - 5µm column (250mm x 4.0mm). The column was eluted at a flow rate of 1mL.min-1 in gradient mode, with a mixture of (i) acetic acid and water 1:40 (v/v) and (ii) acetonitrile. (APÁTI et al., 2002) The gradient method allowed good separation of flavonols and CA and also was used to investigate the extract's specific composition. For the analysis of flavonoids, the chromatographic peaks were confirmed by comparing their retention times and UV spectra with those of the reference standards at an absorbance of 310 nm. At this wavelength, a 10 – 100 µg/mL linear analytical curve (r2 > 0,998) was obtained for each flavonoid and CA standards. The SCAI presented the highest concentrations of quercetin (114.46 ± 0.114 µg/mL) and quercitrin (54.40 ± 2.014 µg/mL) but did not present isoquercitrin. However, the SCMI TT0116 presented the highest amount of CA (96.06 ± 2.365 µg/mL) and isoquercitrin (143.88 ± 4.219 µg/mL), and the samples of TB0116 presented the highest amount of hyperoside (227.79 ± 3.333 µg/mL and 153.49 ± 4.200 µg/mL). The data presented in this study indicate that there are significant variations in the contents of CA and FLV in raw extracts of two species of Solidago. These differences are important for evaluating the biological activity of each species.
REFERENCES
OLIVEIRA, T.B.; SILVA, F.C.; KELLY, A.M.; VALVERDE, S.S. Rev. Bras. Pl. Med., São Paulo, v.19, n.2, p.304-310, 2017.
APÁTI, P.; SZENTMIHÁLYI, K.; BALÁZS, A.; BAUMANN, D.; HAMBURGER, M.; KRISTON, T.S.Z.; SZOKE E.; KERY, A. Chromatographia Supp., v.56, p. S-65-S-68. USA. 2002.