ABSTRACT
Headspace-solid phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) were used to analyze the interaction between the β-lactoglobulin (β-LG) and the botany volatile organic compounds (BVOCs) from pomelo peel to screen out the pharmacodynamic active BVOCs substance group. The selective binding effect between β-LG and BVOCs was analyzed by quantitative recovery of BVOCs, and the binding parameters were calculated. Then, the molecular model of BVOCs binding with β-LG was established by molecular docking and spectroscopic method, and the molecular mechanism of interaction between pharmacodynamic active BVOCs and β-LG was discussed from the perspective of omics. The results showed that dipentene (Dt), linalylacetate (La) and nootkatone (Nt) of BVOCs were selected by HS-SPME/GC-MS by the interaction of β-LG and BVOCs substance group. Parameter calculation showed that β-LG had the strongest affinity with Nt, but the binding force was not strong, and the affinity for La was the weakest. The affinity of β-LG to Dt was weak, but the binding force was the strongest, with a binding rate of 54. 66%, indicating that the selective binding strength of β-LG with the pharmacodynamic active BVOCs depended on the chemical structure of BVOCs molecules. The β-LG preferred to bind to the aldehyde and ketone BVOCs molecules containing carbonyl oxygen structure. The molecular model of β-LG and BVOCs group (Dt, La, Nt) was established to evaluate the binding position of BVOCs group (Dt, La, Nt) on β-LG. The loosening, extension and conformational change of β-LG secondary structure caused by the introduction of BVOCs are the result of van der Waals force, hydro-phobicity and hydrogen bonding. This study provides a new method for screening pharmacodynamic active BVOCs from the perspective of whole substance group of BVOCs, and provides a useful reference for investigating the binding mechanism between pharmacodynamic active BVOCs and functional protein molecules from the perspective of omics.
ABSTRACT
Objective To study the essential oil components in herbal pair (HP) of Radix Angelica dahurica-Ligusticum chuanxiong Hort. (RAD-LCH) and its single herb, and to investigate the influence of HP on the components of the volatile oil. Methods Essential oil was extracted from Radix Angelica dahurica and Ligusticum chuanxiong Hort. by steam distillation. Identification of extracted componentswas accomplished using GC-MS technique combined with library searching and literature comparison. Chromatography analysiswas carried out on a TR5-MS capillary column (30 m × 0. 25 mm, 0. 25 μm); the carrier gas was high-purity helium; the inlet temperature was 250°C; the injection volume was 1 μL, the split ratio 50: 1; constant current mode, the flow rate of carrier gas was 1. 00 mL/min; the temperature program was as follows: 50C for one minute, rose to 240C at 5°C/min and maintained for one minute, then rose to 280C at 5°C/min and maintained for one minute. MS condition was as follows: electron impact (El) ion source, electron energy 70 eV, ion source temperature 200°C, transmission line temperature 280°C, mass scan range m/z: 50-650 amu, data acquisition scan mode for full scan, and solvent delay five minutes. Results There were 69, 59, 59, 60 and 78 volatile constituents in RAD, LCH, HP (1:1), HP (4: 1) and essential oil of mixture of equal concentration from RAD and LCH (EOEC), and 19 common volatilecomponents were identified. Conclusion Regarding the volatile oil constituents and content, the volatile oil compositions of different HP proportions vary greatly, accompanied by changed contents of volatile oil components of single herb in HP.