The development of new extraction methods to quantify three lignans in espresso and roast and ground coffee.

Introduction: Lignans, compounds with two phenylpropanoid units, possess various biological activities, i.e., antioxidant, estrogenic and anti-estrogenic [1]. Our aim was to develop an analytical method for the extraction and quantification of three lignans, namely secoisolariciresinol (SECO), matairesinol (MAT) and lariciresinol (LARI) in espresso (EC) and in roast and ground (R&G) coffee. Methods: Various extraction methods, i.e., acid and enzymatic hydrolysis and methanolic extractions, have been evaluated to extract target compounds from liquid (EC) and solid (R&G coffee) matrixes. As analytical instrument an HPLC-MS/MS triple quadrupole equipped with electrospray ionization (ESI) source was used operating in multiple reaction monitoring (MRM) mode. Results: The best lignan recovery values (from 93 to 98%) in EC were found using an enzymatic hydrolysis with clara-diastase at 10% (w/v), carrying out the digestion at 37°C for 3h. For lignan extraction from R&G coffee, the best performing method used again enzymatic digestion, but with taka-diastase 2% (w/v). Our analytical method showed good sensitivity, with limit of quantification (LOQ) ranging from 5 to 10 μg l-1, linearity (R2 ≥0.9944 for any target molecule) and repeatability, with RSDs ranging from 1.75 to 7.34% for intra-day repeatability and from 5.72 to 12.12% for inter-day repeatability. Once validated, the extraction methods have been applied to real EC and R&G coffee samples. We found a concentration of total lignans from 33.2 to 79.1 μg l-1 in EC samples and from 117.7 to 341.4 μg kg-1 in R&G coffee samples. Conclusions: A new analytical method for the extraction and quantification of lignans in EC and R&G coffee has been developed and validated [2]. Comparing the total amount of lignans in ECs with that in R&G coffee, the average of extraction yield was 95%. Lignans are completely extracted during the preparation of espresso coffee. References 1. Ososki A. L., Kennelly E. J., Phytotherapy Research: An International Journal Devoted to Pharmacological and Toxicological Evaluation of Natural Product Derivatives, 17, 845-869 (2003). 2. Angeloni S., Navarini L., Sagratini G., Torregiani E., Vittori S., Caprioli G., Journal of Mass Spectrometry, 1–7 (2018). https://doi.org/10.1002/jms.4251.