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Molecular acidity is an important physiochemical property essential in many fields of molecular studies, but an efficient and reliable computational approach to make accurate predictions is still missing. In this work, based on our previous studies to use gas phase electronic properties such as molecular electrostatic potential and valence natural atomic orbitals of the acidic atom and leaving proton, we demonstrate here that different approaches can be employed to tackle this problem. To that end, we employ 196 singly, doubly, and triply substituted benzoic acids for the study. We show that two different approaches are possible, one focusing on the carboxyl group through its localized electronic properties and the other on the substituting groups via Hammett constants and their additivity rule. Our present results clearly exhibit that with the linear models built from the singly substituted species, one can accurately predict the pK(a) values for the doubly and triply substituted species with both of these two approaches. The predictions from these approaches are consistent with each other and agree well with the experimental data. These intrinsically different approaches are the two manifestations of the same molecular acidity property, both valid and complementary to each other.

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Background: The ABC phenomenon is described as a syndrome of accelerated clearance of polyethylene glycol (PEG)-modified liposomes from the bloodstream when repeatedly injected, with their increased accumulation in the liver and spleen. Methods: To clarify this immune response phenomenon, we evaluated a novel modified pH-sensitive liposome with a cleavable double smart PEG-lipid derivative (mPEG-Hz-CHEMS). Results: The ABC phenomenon in mice was brought about by repeated injection of conventional PEG-PE liposomes and was accompanied by a greatly increased uptake in the liver. However, a slight ABC phenomenon was brought about by repeated injection of mPEG-CHEMS liposomes and was accompanied by only a slightly increased uptake in the liver, and repeated injection of mPEG-Hz-CHEMS liposomes did not induce the ABC phenomenon and there was no increase in liver accumulation. This finding indicates that the cleavable mPEG-Hz-CHEMS derivative could lessen or eliminate the ABC phenomenon induced by repeated injection of PEGylated liposomes. Conclusion: This research has shed some light on a solution to the ABC phenomenon using a cleavable PEG-Hz-CHEMS derivative encapsulated in nanoparticles.

Diaphragma juglandis fructus is the dry wooden diaphragm inside walnuts and a byproduct in food processing of walnut kernels. The purpose of our research is to enrich the information on compounds in Diaphragma juglandis fructus to further discover and exploit its potential nutritional value. In this study, new quali–quantitative analytical approaches were developed to identify and determine bioactive compounds in Diaphragma juglandis fructus. Two-hundred compounds, including hydrolyzable tannins, flavonoids, phenolic acids, and quinones, were identified by UHPLC-Q-Orbitrap HRMS, more than 150 of which were first discovered in Diaphragma juglandis fructus. Among them, 21 major dietary polyphenols with health-promoting effects were successfully quantified using UHPLC-MS/MS, with total contents of 2.88–6.18 mg/g. This successful characterization and quantification of bioactive compounds in Diaphragma juglandis fructus gives a better understanding of its potential nutritional value and supports efficiently developing and reusing it instead of discarding it as agrofood waste.