OBJECTIVE To optimize the formulation for sustained-release particles of matrine(MAT) and paeonol(PAE) and to primarily evaluate their quality. METHODS The sustained-release particles were fabricated by the extrusion-spheronization method. Single factor analysis was conducted on the main sustained-release materials and their dosage, auxiliary sustained-release materials, and the total amount and proportion of mixed sustained-release materials, using the cumulative release rates of MAT and PAE in vitro as evaluation indicators. By combining central composition design-response surface methodology, the formulation of sustained-release materials was optimized, and the effects of the total amount and mass ratio of ethyl cellulose(EC) and chitosan(CS) on the cumulative release rate and release synchronization of MAT and PAE were investigated. The formulation characteristics, in vitro release, and preliminary stability tests of MAT-PAE-SRPs were evaluated, and the release process kinetic equation was fitted. RESULTS The optimized formulation contained 23.5% EC and 17.1% CS as sustained-release materials. The yield, repose angle, bulk density and friability of final particles were 97.23%, 38.1°, 0.74 g·mL−1 and 0.74%, respectively. The particles showed sustained release pattern in various media and released faster in acidic media with its release percentage >90% at 12 h. The release profile of MAT was fitted best with first order equation, and that of paeonol with Higuchi equation. The formation of SRPs improved the stability of both drugs. CONCLUSION The sustained-release effect of MAT-PAE-SRPs prepared by sustained-release materials EC and CS is significant, and the cumulative release rate and release synchronization of MAT and PAE are good, which can provide reference for the research of dual loaded sustained-release formulations.

Objective: To explore the protective effects of anthrahydroquinone-2,6-disulfonate (AH 2 QDS) on the kidneys of paraquat (PQ) poisoned rats via the apelin-APJ pathway. Methods: Male Sprague Dawley rats were divided into four experimental groups: control, PQ, PQ+sivelestat, and PQ+AH 2 QDS. The PQ+sivelestat group served as the positive control group. The model of poisoning was established via intragastric treatment with a 20% PQ pesticide solution at 200 mg/kg. Two hours after poisoning, the PQ+sivelestat group was treated with sivelestat, while the PQ+AH 2 QDS group was given AH 2 QDS. Six rats were selected from each group on the first, third, and seventh days after poisoning and dissected after anesthesia. The PQ content of the kidneys was measured using the sodium disulfite method. Hematoxylin-eosin staining of renal tissues was performed to detect pathological changes. Apelin expression in the renal tissues was detected using immunofluorescence. Western blotting was used to detect the expression levels of the following proteins in the kidney tissues: IL-6, TNF-α, apelin-APJ (the apelin-Angiotensin receptor), NF-κB p65, caspase-1, caspase-8, glucose-regulated protein 78 (GRP78), and the C/EBP homologous protein (CHOP). In in vitro study, a PQ toxicity model was established using human tubular epithelial cells treated with standard PQ. Twenty-four hours after poisoning, sivelestat and AH 2 QDS were administered. The levels of oxidative stress in human renal tubular epithelial cells were assessed using a reactive oxygen species fluorescence probe. Results: The PQ content in the kidney tissues of the PQ group was higher than that of the PQ+AH 2 QDS group. Hematoxylin-eosin staining showed extensive hemorrhage and congestion in the renal parenchyma of the PQ group. Vacuolar degeneration of the renal tubule epithelial cells, deposition of crescent-like red staining material in renal follicles, infiltration by a few inflammatory cells, and a small number of cast formation were also observed. However, these pathological changes were less severe in the PQ+sivelestat group and the PQ+AH 2 QDS group (P<0.05). On the third day after poisoning, immunofluorescence assay showed that the level of apelin in the renal tissues was significantly higher in the PQ+AH 2 QDS group than in the PQ group. Western blotting analysis results showed that IL-6, TNF-α, NF-κB p65, caspase-1, caspase-8, GRP78, and CHOP protein levels in the PQ group were higher than in the PQ+AH 2 QDS group (P<0.05). The expression of apelin-APJ proteins in the PQ+AH 2 QDS group was higher than in the PQ+sivelestat and PQ groups (P<0.05); this difference was significant on Day 3 and Day 7. The level of oxidative stress in the renal tubular epithelial cells of the PQ+AH 2 QDS group and the PQ+sivelestat group was significantly lower than in the PQ group (P<0.05). Conclusions: This study confirms that AH 2 QDS has a protective effect on PQ-poisoned kidneys and its positive effect is superior to that of sivelestat. The mechanism of the protective effects of AH 2 QDS may be linked to reduction in cellular oxidative stress, PQ content of renal tissue, inflammatory injury, endoplasmic reticulum stress, and apoptosis. AH 2 QDS may play a role in the treatment of PQ poisoning by upregulating the expression of the apelin-APJ.