2937.23.10 - Obtained directly or indirectly from animal or vegetable materials

This HTS category, 2937.23.10, encompasses hormones, prostaglandins, thromboxanes, and leukotrienes, whether of natural origin or synthesized. It specifically includes derivatives and structural analogues of these compounds, with a particular emphasis on chain-modified polypeptides that primarily function as hormones. The key criterion for inclusion is their hormonal application.

While the broader category covers various hormonal substances, this particular subdivision focuses on steroidal hormones, their derivatives, and structural analogues. This distinguishes it from other sections within the 2937 heading that might cover non-steroidal hormones or other classes of related compounds. The classification here is specifically tied to the steroidal chemical structure.

Within this steroidal hormone classification, further subcategories exist to refine the classification based on specific hormonal types. For instance, 2937.23.10.10 specifically details "Estrogens," differentiating them from other steroidal hormones like progestins, which are also covered under this parent category but likely fall into a separate, albeit related, subclassification. This allows for precise tariff application based on the distinct biological function and chemical makeup of the hormone.