endobiotic

adj

1. living within the tissues of a host.
2. Originating within an organ or biological system.

   “Even though PXR was initially identified as a xenobiotic receptor, emerging evidence has pointed to an equally important role of PXR as an endobiotic receptor that responds to a wide array of endogenous chemicals (endobiotics), such as bile acids and their intermediates, as well as certain steroid hormones.”

noun

1. An endogenous substance that influences the functioning of an organ or biological process.

   “ADME and chemical reactivity-related toxicity is low, while biological receptor activity is of higher dimension in chemistry space, and this is partly explainable by evolutionary pressures on ADME to deal with endobiotics and exobiotics.”

   “Even though PXR was initially identified as a xenobiotic receptor, emerging evidence has pointed to an equally important role of PXR as an endobiotic receptor that responds to a wide array of endogenous chemicals (endobiotics), such as bile acids and their intermediates, as well as certain steroid hormones.”