A novel molecular imprinting polymer (MIP) was prepared by bulk polymerization using sulpiride as the template molecule, itaconic acid (ITA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. The formation of the MIP was determined as the molar ratio of sulpiride-ITA-EGDMA of 1:4:15 by single-factor experiments. The MIP showed good adsorption property with imprinting factor α of 5.36 and maximum adsorption capacity of 61.13 μmol/g, and was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and surface area analysis. With the structural analogs (amisulpride, tiapride, lidocaine and cisapride) and small molecules containing a mono-functional group (p-toluenesulfonamide, formamide and 1-methylpyrrolidine) as substrates, static adsorption, kinetic adsorption, and rebinding experiments were also performed to investigate the selective adsorption ability, kinetic characteristic, and recognition mechanism of the MIP. A serial study suggested that the highly selective recognition ability of the MIP mainly depended on binding sites provided by N-functional groups of amide and amine. Moreover, the MIP as solid-phase extractant was successfully applied to extraction of sulpiride from the mixed solution (consisted of p-toluenesulfonamide, sulfamethoxazole, sulfanilamide, p-nitroaniline, acetanilide and trimethoprim) and serum sample, and extraction recoveries ranged from 81.57% to 86.63%. The tentative tests of drug release in stimulated intestinal fluid (pH 6.8) demonstrated that the tablet with the MIP–sulpiride could obviously inhibit sulpiride release rate. Thus, ITA-based MIP is an efficient and promising alternative to solid-phase adsorbent for extraction of sulpiride and removal of interferences in biosample analysis, and could be used as a potential carrier for controlled drug release.

The ultrasonic-assisted aqueous two-phase extraction (UAATPE) of flavonoid glycosides from Malvaviscus arboreous Cav. flower (MACF) was developed using ethanol/ammonia sulfate systems, followed by the ultrasonic-assisted acid hydrolysis (UAAH) of the top extract with HCl solution. The optimization of UAATPE and UAAH processes was accomplished by single-factor experiments and response surface methodology. As a result, the flavonoid glycosides enriched in the top phase could achieve a maximum yield of 35.9 ± 1.1 mg/g by UAATPE and were completely hydrolyzed by UAAH deglycosylation. The flavonoid glycosides and their hydrolyzates were separated and characterized by high-performance liquid chromatography and ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Ultrasonic enhancement of the extraction and hydrolysis was explored by comparative study. Furthermore, the in vitro activity of the flavonoid glycosides and the aglycones were comprehensively evaluated by antioxidant activity assays, including ferric-reducing antioxidant power and scavenging DPPH, hydroxyl, and superoxide radicals. All of the IC₅₀ values suggest that the antioxidant activity of flavonoid aglycones was stronger than that of their glucosides and even vitamin C, revealing that the deglycosylated flavonoids from MACF were the more powerful antioxidants. This study provided an effective and eco-friendly strategy for the extraction, separation, and purification of flavonoids from MACF, as well as for the development of the potential flavonoid antioxidants.

Using a polyethylene glycol (PEG)/ammonium sulfate system, a novel approach for one-step extraction and separation of the flavonoid aglycones from Malvaviscus arboreus Cav. flower (MACF) was developed by combining ultrasonic-assisted extraction (UAE) with acidified aqueous two-phase extraction (AATPE). Under the optimized UAE-AATPE conditions of PEG 600 of 22.8 % (w/w), ammonium sulfate of 22.5 % (w/w), 1.5 mol/L HCl, hydrolysis temperature of 85 ℃, and reaction time of 60 min, MACF flavonoid glycosides were not only fully extracted but also completely hydrolyzed, and the produced aglycones were purified by biphasic separation with a yield of 35.90 ± 0.96 mg/g. The mechanism in the UAE-AATPE process including UAE and ultrasonic-assisted acid hydrolysis (UAAH), was explored by investigating the different procedures and chemical composition under an ultrasonic field. The deglycosylated/glycosylated flavonoids were identified and quantified by high-resolution ultrahigh-performance liquid chromatography with quadrupole orbitrap mass spectrometry (UHPLC-Q/Orbitrap-MS) and UHPLC-DAD, revealing that MACF flavonoids were mainly composed of pelargonidin, kaempferol, catechin, cyanidin and quercetin in descending order of their content. The inhibitory assay on pancreatic lipase (PL) confirmed that the activity of the extracted aglycones with IC₅₀ of 563.01 ± 280.63 μg/mL was stronger than their glycosides. Kinetic and molecular docking analyses further explored and validated the PL inhibitory mechanism. The above results proved that UAE-AATPE integrating the multiple procedures, including extraction, hydrolysis and separation, greatly simplified the complex procedures and significantly improved extraction efficiency, providing a simple, rapid and efficient alternative for direct obtainment of the flavonoid aglycones from MACF.