Determination of rosmarinic acid and its N-substituted analog A1 in rat plasma by high-performance liquid chromatography-tandem mass spectrometry and its application in pharmacokinetics
Shujie Fu1, Qinglang Zhang2, Shiyu Zhang2, Weizhe Jiang1, Minjie Jiang2*
1 School of Pharmaceutical, Guangxi Medical University, Nanning 530021, China, 2 Guangxi University of Chinese Medicine, Nanning 530001, China
* Corresponding author. Tel.: +86 13768509293; fax: +86 07713137535.
E-mail address: jiangminjietp@me.com (M. Jiang).
Introduction
Caffeic acid esters, rosmarinic acid (RA, Fig. 1a), exhibit different biological properties, such as antiviral, antibacterial, anti-inflammatory, and antioxidant properties[1,2]. It has been recently noted that RA pharmacology is important[2–5], but very few papers have evaluated its pharmacokinetics and pharmacodynamics [6–11]using high-performance liquid chromatography-tandem mass spectrometry. In order to investigate the pharmacodynamic mechanisms of RA in more depth, we synthesized many analogs based on RA, including (E)-3-(3,4-dihydroxyphenyl)-2-(3-(3,4-dihydroxyphenyl)acrylamido)propanoic acid (A1, Fig. 1b). Previous studies have shown that A1 has higher pharmacological activity against tumors than RA[12]. Thus, in order to simultaneously determine A1 and RA, pharmacokinetics (PK) must be studied using a sensitive and precise method. Recently, researchers have expressed concern about RA absorption and metabolism, but few papers have used HPLC-MS to study the pharmacokinetics and pharmacodynamics of RA. By avoiding the need to fully analyze the chromatograms, this method guarantees high sensitivity and speedy quantification. The majority of previous studies, however, only focused on administering one substance at a time; thus, no one has conducted a simultaneous study on RA and other compounds and their pharmacokinetics. The objective of this study was to implement and validate a new method for estimating RA and A1 in plasma samples collected from rats. Therefore, this method is very useful for pharmacokinetics studies.
2. Experimental section
2.1. Reagents and chemicals
RA (batch number 111871) with a purity above 99% and pseudoephedrine hydrochloride (PPD, batch number 171237-201510) were obtained from the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China) (Fig. 1c) and used as standards. A1 (99.8% purity) was synthesized at the School of Pharmaceutical, Guangxi Medical University (Nanning, China). Ethyl acetate was obtained from Dikma Technologies, Inc. (Richmond Hill, ON, Canada). The methanol and acetonitrile used were obtained from Sigma-Aldrich Chemicals (St. Louis, MO, USA). Deionized water was purified with an Alpha-Q water purification system and then filtered with 0.20-μm membranes.