Doctor s Best - Glucosamine Chondroitin MSM with OptiMSM - 240 Capsules Glucosamine Chondroitin MSM contains pure glucosamine sulfate as confirmed by HPLC testing. Glucosamine sulfate consists of glucosamine an amino sugar extracted from chitin a component of shellfish skeletons. ( Chitin the resilient polysaccharide that forms the structural framework of animal shells is a long-chain polymer consisting of many glucosamine molecules linked together.