L-Tryptophan, glycyl-L-asparaginyl-L-tryptophyl-L-histidylglycyl-L-threonyl-L-alanyl-L-prolyl-L-alpha-aspartyl-L-tryptophyl-L-phenylalanyl-L-phenylalanyl-L-asparaginyl-L-tyrosyl-L-tyrosyl-, cyclic (9-1)-peptide