Bitter flavours act as nature’s warning signs, evolved over hundreds of millions of years to steer us away from potentially toxic compounds.

New research published this week in the Journal of Agricultural and Food Chemistry has just identified the most potent natural bitter compounds known to date and with it insights into why bitterness is so important. 

The star of this discovery is the mushroom Amaropostia stiptica, a non-toxic fungus renowned among foragers for its relentless, mouth-puckering bitterness. 

By guiding their isolation efforts with taste assays, the researchers extracted and characterised three previously unknown triterpene glucosides from this mushroom. 

Among the trio of new compounds, oligoporin D stole the show. In cell-based assays, oligoporin D activated the human bitter taste receptor TAS2R46 at astonishingly low concentrations of around 63 millionths of a gram per litre (roughly one gram dissolved in the volume of a million bathtubs) 

Why does this matter? 

Most entries in BitterDB hail from plants or human-made chemicals. Adding fungal compounds like oligoporin D enriches our chemical map of bitterness, revealing new scaffolds that challenge existing predictive models of taste receptor activation 

Bitter taste receptors predate flowering plants by some 300 million years. By discovering a potent fungal bitterant, researchers gain clues about ancient ecological interactions, did early vertebrates encounter fungi that drove the diversification of their taste receptors? 

Bitter receptors aren’t confined to our mouths - they’re sprinkled throughout the gut, lungs, heart, and even on blood cells. Understanding how natural bitterants like oligoporin D engage these extraoral receptors could unlock new avenues in digestion, immunity, and respiratory health 

The discovery of oligoporin D opens doors to practical innovations including the development of a natural, ultra-bitter coating for household chemicals or pharmaceuticals to prevent accidental ingestion. 

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