High-performance thin-layer chromatographic determination of trigonelline content in various extracts and different varieties of some commercial coffees available in the Saudi Arabian market

The proposed research study was undertaken to establish a simple, rapid and sensitive high-performance thin-layer chromatography (HPTLC) method for the quantification of trigonelline (TGN) in methanolic, aqueous and hydroalcoholic extracts of different brands of coffee samples with different colours due to roasting time. The proposed HPTLC methodology was carried out using glass coated silica gel 60 F254 plates. The mobile phase used was quaternary mixture of ethyl acetate:methanol:water:formic acid 5.4:2.3:1.5:0.8 (%, v/v) which furnished a compact spot of TGN at Rf 0.24 ± 0.01. The developed plate was scanned and quantified densitometrically at 267 nm. Linear regression analysis presented a good relationship between peak area and amount of TGN in the range of 100–700 ng/band. The method was validated as per the International Conference on Harmonization (ICH) recommendations. The maximum amount of TGN was recorded in roasted Arabic coffee among different brands studied. The amounts of TGN in methanolic, aqueous and hydroalcoholic extract of roasted Arabic coffee were obtained as 0.74, 0.80 and 0.79% w/w, respectively. The proposed analytical methodology will be useful to enumerate the therapeutic dose of TGN in different herbal products.