The determinants of chemoreception as evidenced by gradient boosting machines in broad molecular fingerprint spaces

Abstract

The ability to identify and reject bitter molecules may determine evolutionary fitness. These molecules might be in potentially toxic or contaminated food. Surprisingly, the ability to identify but tolerate or even enjoy bitter foods and medicines may be beneficial. For example, the tolerance of bitterness as a spice or as a medicine may lead to better nutritional, immunological and health outcomes. More recently the ability of intensely bitter compounds to induce innate immune responses to counter infection has inspired the screening of new drugs and the repurposing of safe, known drugs to new uses. These avenues of study may also help to address long-standing questions regarding unexpected side-effects and placebo/nocebo effects. Therefore, to distinguish all these effects ranging from desire to aversion, there is a need to quantitatively determine the concentration thresholds and to position these bitter substances on a unified taste threshold spectrum. Such an understanding may help elucidate the concentration-based molecular drivers for the chemoreceptive response to bitter substances. This article reports the development of a gradient boosting machine (GBM) that enables a direct interrogation of molecular structure with no intermediary chemical properties. Using molecularly engineered simulations, it is shown that potassium acesulfame has a hidden bitterness motif that is centered on the chemoreceptive spectrum uniting bitterness and sweetness molecular motifs. The resultant shifted perception from a touchstone bitterness sensation to a bitter after-taste is attributable to this cached molecular motif.