Screening and selection of marker(s) of Passiflora Foetida extract by high performance liquid chromatography and dopamine receptors/transporter binding assay

Abstract

Passiflora Foetida has long been used in traditional medicine for several purposes such as analgesic, sedative and anxiolytic effect. Preliminary studies showed that the dichloromethane fraction of P. foetida (PF003) potentially bound to dopamine receptor. Therefore, this study aimed to further screen for constituents in this extract that could bind with dopamine D1, D2 receptors or dopamine transporter (DAT) and to select marker(s) for using in quality control. High-performance liquid chromatography–diode array detection (HPLC–DAD) method has been developed for the components analysis and characterization. From preliminarily study, six major peaks were present in the PF003 chromatogram. Later, PF003 was fractionated to fraction A-F by preparative HPLC and six fractions were further studied for the affinity to dopamine D1, D2 and DAT by radioligand receptor binding assay. The results showed that only fraction D was able to bind to dopamine D1 and D2 receptor with 12 ± 1.2 and 61 ±2.6 % inhibition, respectively. The main component in fraction D was identified by HPLC based on retention time and UV adsorption spectra, and compared with standard. Main compound which could bind to dopamine D1 and D2 receptors was luteolin. The affinity of luteolin to dopamine D2 receptor was confirmed with an IC50 value of 14 µg/ml (48.9 µM). Luteolin showed potentially to be a biomarker. Moreover, vitexin and apigenin were also found in PF003 chromatogram. They were the dominant compounds described in this genus and were served as the chemical markers as well. The detection of the markers would be applied for the herbal medicine quality control for PF003.