Data Views Plants (>= 1 Chemical): 356 All Chemicals: 21 CSV Excel PDF Previous12 Show all rows. Paginate rows. Click on column headings to sort table by that column Chemical Dosage References TRYPTOPHAN --Martindale's 29th *Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.