Development and validation of qualitative and quantitative high performance thin-layer chromatographic methods for analysis of marker compounds in Matricaria recutita L. and Cynara scolymus L. extracts

TLC methods have long been used in the pharmacopoeias such as European Pharmacopoeia for qualitative analysis of marker compounds in plant materials. Recent advances led to the utilization of HPTLC methods which enable both qualitative and quantitative analyses concurrently. However, there has not yet stated an HPTLC method in the European Pharmacopoeia. Therefore, HPTLC methods for qualitative and quantitative analysis of marker compounds in Matricaria recutita L. and Cynara scolymus L. (Asteraceae) extracts were developed and validated in this study. In M. recutita flower extract, apigenin 7-O-glucoside was separated from the other constituents on silica gel 60 NH2 F254s HPTLC plate using a developing solvent system of ethyl acetate-formic acid-acetic acid-water (30:1.5:1.5:3, v/v/v/v). The developed method was subsequently validated and applied both for qualitative and quantitative analyses of apigenin 7-O-glucoside in extracts of M. recutita, M. recutita-like flowers and numerous commercial M. recutita products. According to C. scolymus leaf extract, chlorogenic acid and luteolin 7-O-glucoside were separated on silica gel 60 F254 HPTLC plate using a developing solvent system of ethyl acetate-formic acid-acetic acid-water (35:2:2:5, v/v/v/v). Moreover, HPTLC-bioautography experiment with DPPH˙ radical was performed for C. scolymus leaf extract and the result revealed that chlorogenic acid and cynarin significantly contributed to antioxidant activity of C. scolymus leaf extract. However, due to decomposition of phenolic compounds on the plate during the chromatography, an alternative HPLC technique was used to quantify chlorogenic acid and cynarin contents. Consequently, both HPTLC and HPLC methods were used to analyze extracts of C. scolymus leaf, bract, receptacle, stem and C. scolymus food supplements sold on market.