Distributional Prototypical Methods for Reliable Explanation Space Construction

As deep learning has been successfully deployed in diverse applications, there is an ever increasing need to explain its decision. To explain decisions, case-based reasoning has proved to be effective in many areas. The prototype-based explanation is a method that provides an explanation of the model’s prediction using the distance between an input and learned prototypes to effectively perform case-based reasoning. However, existing methods are less reliable because distance is not always consistent with human perception. In this study, we construct a latent space which we call an $explanation space$ with distributional embedding and latent space regularization. This explanation space ensures that similar (in terms of human-interpretable features) images share similar latent representations, and therefore provides a reliable explanation for the consistency between distance-based explanation and human perception. The explanation space also provides additional explanation by transition, allowing the user to understand the factors that affect the distance. Throughout extensive experiments including human evaluation, we have shown that the explanation space provides a more human-understandable explanation

Synthesis and structure–activity relationship study of saponin-based membrane fusion inhibitors against SARS-CoV-2

© 2022 Elsevier Inc.We previously discovered that triterpenoid saponin platycodin D inhibits the SARS-CoV-2 entry to the host cell. Herein, we synthesized various saponin derivatives and established a structure–activity relationship of saponin-based antiviral agents against SARS-CoV-2. We discovered that the C3-glucose, the C28-oligosaccharide moiety that consist of (→3)-β-D-Xyl-(1 → 4)-α-L-Rham-(1 → 2)-β-D-Ara-(1 → ) as the last three sugar units, and the C16-hydroxyl group were critical components of saponin-based coronavirus cell entry inhibitors. These findings enabled us to develop minimal saponin-based antiviral agents that are equipotent to the originally discovered platycodin D. We found that our saponin-based antiviral agents inhibited both the endosomal and transmembrane protease serine 2-mediated cell surface viral entries. Cell fusion assay experiment revealed that our newly developed compounds inhibit the SARS-CoV-2 entry by blocking the fusion between the viral and host cell membranes. The effectiveness of the newly developed antiviral agents over various SARS-CoV-2 variants hints at the broad-spectrum antiviral efficacy of saponin-based therapeutics against future coronavirus variants.11Nsciescopu