2937.90 - Other:

Category 2937.90, "Other," serves as a residual classification within the broader group of hormones, prostaglandins, thromboxanes, leukotrienes, and their synthetic derivatives and analogues. It encompasses substances that fulfill the primary function of hormones but do not fit into the more specific subcategories of polypeptide, protein, glycoprotein, or steroidal hormones, nor are they prostaglandins, thromboxanes, or leukotrienes. This category is intended for hormonal compounds and their related structures that possess distinct chemical properties or applications not adequately described by the preceding enumerations.

This residual category distinguishes itself from its siblings by its catch-all nature. Unlike the explicitly defined polypeptide, protein, and glycoprotein hormones (which are typically large biomolecules), steroidal hormones (characterized by their specific ring structures), and prostaglandins, thromboxanes, and leukotrienes (eicosanoids with distinct physiological roles), 2937.90 is for hormonal agents that fall outside these defined chemical families or structural types. It captures compounds that function as hormones but are not structurally aligned with the previously listed major classes.

The subcategories under 2937.90 further refine this residual classification. The "Catecholamine hormones, their derivatives and structural analogues" cover compounds like epinephrine and norepinephrine, which are distinct from the broader hormonal categories. Similarly, "Amino-acid derivatives" addresses hormonal substances derived from amino acids that do not fall under the protein or polypeptide hormone classifications. Finally, "Other" at 2937.90.90.00 is a further residual category for any remaining hormonal compounds and their analogues not otherwise specified.