The conversion of triglycerides in edible oils into diacylglycerols (DAGs) is of great significance for obtaining products with health benefits. Camellia seed oil (C-oil), which is rich in oleic acid and linoleic acid, is an excellent raw material for the production of DAGs. In this study, the hydrolysis rate reached 87.14% under optimal hydrolysis conditions (reaction temperature of 60 °C, reaction time 24 h, 30% water content and 4% enzyme addition) with RMIM as catalyst, and camellia seed oil diacylglycerol (C-DAG) with a content of 62.49% was also given under optimal esterification conditions (vacuum system, 3% enzyme addition, 2% water addition, reaction temperature of 50 oC, and substrate molar ratio of free fatty acid to glycerol of 1:1). The high content of DAG was obtained by a coupled method, which eliminated the purification steps and reduced production costs. C-oil, and C-DAG have been characterized by means of GC, TG, DSC, and GC-IMS. Our results showed that the enzymatic coupling method did not affect the structural composition of the substances themselves, but did affect the crystallization and melting properties of the oils. Moreover, the taste of C-DAG was more delicate flavor than that of C-oil. Finally, the reaction mechanism has been analyzed by means of infrared spectroscopy, which showed that C-oil was mostly hydrolyzed to free fatty acids. C-DAG exhibited ester C-O stretching vibrations in the range 1280–1030 cm-1, indicating successful esterification reaction between camellia seed oil free fatty acids (C-FFAs) and glycerol under catalysis by the enzyme.

Background and Purpose: The ionotropic purinergic trimeric receptor P2X3 is a new drug target other than the opioid receptor for the treatment of refractory chronic cough (RCC). However, the only marketed P2X3 antagonist, Gefapixant/AF-219, has a side effect of taste disorders due to simultaneous action on the human P2X2/3 (hP2X2/3) heterotrimer. Therefore, selective molecules with high affinity for the hP2X3 homotrimer and low affinity for the hP2X2/3 heterotrimer have potential in iteration 2.0 RCC drug development, such as Sivopixant/S-600918, a clinical phase II RCC candidate with lower taste disturbance than Gefapixant. S-600918 and its analogue (3-(4-((3-chloro-4-isopropoxyphenyl)amino)-3-(4-methylbenzyl)-2,6-dioxo-3,6-dihydro-1,3,5-triazin-1(2H)-yl)propanoic acid (DDTPA) exhibit both high affinity and high selectivity for hP2X3 homotrimers compared to hP2X2/3 heterotrimer. The mechanism of its druggable site and this high selectivity is not clear. Experimental Approach: Here, we reveal a novel allosteric mechanism that distinguishes this drug candidate from other P2X3 inhibitors through chimera construction, site covalent occupation, metadynamics, mutagenesis, and electrophysiology. Key Results: We suggest that the tri-symmetric site adjacent to the upper vestibule determines the high affinity and selectivity of S-600918/DDTPA for hP2X3. Only four amino acids of the hP2X2 upper body domain swapped with hP2X3, allow the hP2X2/3 heterotrimer to gain comparable affinity for S-600918/DDTPA as the hP2X3 homotrimer. Conclusion and Implications: Thus, we have revealed the molecular basis for the cough suppressive effects and reduced side effects of new RCC clinical candidates from the perspective of receptor-ligand recognition, which may provide information critical for the development of new drugs targeting P2X3 for indications such as RCC, idiopathic pulmonary fibrosis (IPF), and primary hypertension.

The conversion of triglycerides in edible oils into diacylglycerols (DAGs) is of great significance for a healthy lifestyle. Camellia Seed Oil (C-oil), which is rich in oleic acid and linoleic acid, is an excellent raw material for the production of DAG. In this study, the results showed that under the optimum conditions, the hydrolysis rate was 87.14 %, and the content of DAG was 62.49 % after the hydrolysis product was esterified with glycerol. The C-oil, C-FFA, and Camellia Seed Oil diacylglycerol (C-DAG) were characterized using GC, TG, DSC, and GC-IMS. The results showed that the enzymatic coupling method did not affect the structural composition of the substances themselves, but it did affect the crystallization and melting properties of the oils and the taste of C-DAG was more delicate than that of C-oil. Finally, the reaction mechanism was analyzed using infrared spectroscopy, which showed that C-oil had been mostly hydrolyzed into free fatty acids, and C-DAG exhibited ester C-O stretching vibrations at 1280-1030 cm-1, indicated that the esterification reaction between C-FFA and glycerol had successfully occurred under the catalysis of the enzyme.