Glucosamine hydrochloride does not prevent conjugated diene formation by calcium ionophore-stimulated chondrocytes (a) or by copper-catalyzed oxidation of low-density lipoprotein (b). (a) A washed monolayer of primary articular chondrocytes in 60-mm Petri dishes was stimulated in the presence or absence of A23187 (20 μm) with or without glucosamine (50 mM) or Vitamin E (250 μM) in phenol-free Earl's balanced salt solution. The media were monitored for conjugated diene formation at 234 nm at different time points. Delta absorbance shown is absorbance at different time points minus the absorbance at 0 hours. A representative of four experiments is shown. (b) Low-density lipoprotein (0.25 mg/ml) was incubated at 30°C in phosphate-buffered saline alone (open circles) or in the presence of 5 μM Cu2+ (closed circles) or with 5 μM Cu2+ and 25 mM (open triangles) or 0.25 mM (closed triangles) glucosamine. A conjugated diene formation was monitored at 234 nm. Ca Iono, calcium ionophore; Cu, copper; Glu, glucosamine; LDL, low-density lipoprotein; Vit E, vitamin E.