Four crystalline constituents have been isolated from the leaves of Shih-chun-tze,Quisqualis indica L.They are identified to be nicotinic acid methylbetaine (Trigonelline),L-proline,L-asparagine and potassium quisqualate by direct comparison of the physical constants including R_f values on paper strips of the compounds with those of the authentic samples.The original molecular formula of potassium quisqualate,C₁₆H₁₆O₁₀N₆K₃,is revised to C₅H₆O₅N₃K,according to molecular weight determination of the quisqualic acid and of the potassium salt,as well as the analyses of its crystalline potassium salt and dinitrophenyl derivative.