The rock oyster, Saccostrea cucullata, native to the Indo-Pacific region, is widely recognized for its nutritional and therapeutic benefits. A sulfated glycosaminoglycan (SCP-2) with β-(1 → 3)-GlcNSp and α-(1 → 4)-GlcAp as recurring units was isolated from S. cucullata. SCP-2 exhibited substantial 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) inhibition potential (IC