2009 - Gisely Cristiny Lopes
Ph.D. Thesis
Author: Gisely Cristiny Lopes
Postgraduate Program in Pharmaceutical Sciences - State University of Maringá
Area of Knowledge: Pharmacognosy
Date of Defense: March 20, 2009
Advisor: Prof. Dr. João Carlos Palazzo de Mello
Examination Board: Prof. Dr. Cid Aimbiré de Moraes Santos
Prof. Dra. Maria Raquel Marçal Natali
Prof. Dr. Marcos Luciano Bruschi
Prof. Dra. Marli Mirian de Souza Lima
Title: Chemical study , Analytical Methodology Development and Evaluation of stability of Guazuma ulmifolia Lam. (Sterculiaceae) extracts.
Abstract: Guazuma ulmifolia Lam. (Sterculiaceae), popularly known as “Mutamba”, is a tropical-American plant found from Mexico to southern South America. In the popular medicine of several Latin-American countries, it is used for the treatment of burns, diarrhea, inflammations and alopecia. From the bark of G. ulmifolia, nine compounds were isolated and identified: ent-catechin, epicatechin, ent-gallocatechin, epigallocatechin, epiafzelechin-(4β→8)-epicatechin, procyanidins B1 and B2, epicatechin-(4β→8)-epigallocatechin, and the new compound 4′-O-methyl-epiafzelechin. Its structure was elucidated on the basis of spectral and literature data. HPLC analysis of the semipurified extract was performed using a Phenomenex® Gemini RP C18 column (5 µm) as stationary phase, at 30 ºC, with a flow rate of 0.8 mL min-1, at a wavelength of 210 nm for detection and determination. The main validation parameters of the method were also determined. Calibration curves were found to be linear, with ranges of 20.00–150.00 µg mL−1 procyanidin B2 (PB2) and 10.00–110.00 µg mL−1 epicatechin (EP). The correlation coefficients of linear regression analysis were between 0.9981–0.9988, and the detection limits were between 2.89 and 2.54 µg mL-1. The contents of PB2 and EP were successfully determined, with satisfactory reproducibility and recovery. Recoveries of the PB2 and EP were 103.00 and 104.01%, respectively. The method was successfully applied to the determination of procyanidins in bark of G. ulmifolia. The preliminary stability of the dried extracts from bark of G. ulmifolia containing or not colloidal silicon dioxide (CSD) was evaluated. The physical–chemical properties and compatibility of CSD in the extract were evaluated for 21 days of storage under stress conditions of temperature (45±2 °C) and humidity (75±5%). Thermal analysis (TG) was supplemented using a selective high-performance liquid chromatography (HPLC) for determination of stability of the characteristic constituents (chemical markers), namely PB2 and EP. The results showed that PB2 is an appropriate compound to use as chemical marker in control quality of dried extracts of G. ulmifolia. The stress study showed that there was no significant difference between the two extracts. On the other hand, considering the TG data and the high temperatures involved, the results suggest that CSD would be increase the stability of dried extracts of G. ulmifolia.
Keywords: Guazuma ulmifolia, Sterculiaceae, proanthocyanidins, HPLC, validation method, stability test, thermal analysis.
Thesis PDF: Gisely Cristiny Lopes
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