Catalyzes 8-hydroxy-alpha-humulene into zerumbone in presence of NAD. Also converts borneol to camphor in vitro. Zerumbone is a highly promising multi-anticancer agent. 10-hydroxy-alpha-humulene + NAD(+) = H(+) + NADH + zerumbone kcat is 3.8 sec(-1) with NAD as substrate. kcat is 1.3 sec(-1) with 8-hydroxy-alpha-humulene as substrate. kcat is 4.1 sec(-1) with borneol as substrate. Expressed in leaves, stems and rhizomes. Belongs to the short-chain dehydrogenases/reductases (SDR) family.