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Two series of 2,3-disubstituted 5,8-dimethoxy-6-[N- (omega-dimethylaminoalkyl) amino] quinoxalines were prepared: the first series with identical 2,3-substituents H, CH3, C6H5, C6H4-4-Cl, and CH2C6H5; and the second with identical styryl groups CH=CHC6H5, CH=CHC6H4-4-Cl, CH=CHC6H3-3,4-C12, CH=CHC6H4-4-F, CH=CHC6H4-4-CF3, and CH=CHC6H4-4-NO2. None of the substances possessed antimalarial activity; several were toxic at highest dosage levels.

The 600-MHz proton nuclear magnetic resonance spectra of bradykinin, [2-dehydroproline]bradykinin, [7-dehydroproline]bradykinin, and [5-tyrosine]bradykinin in aqueous solution have been recorded and completely assigned by means of pH variation, spin-spin decoupling, and chemical shift correlations. Analysis of the spin-spin coupling constants in the main chain and in the side chains suggests that bradykinin is in rapid equilibrium among many conformers and does not show any persistent structural features such as beta turns or internal hydrogen bonds. Addition of lipids or lipid-like materials [such as sodium (trimethylsilyl)propionate] in high concentration causes changes in the spectra, indicating specific interactions with proline-7 and phenylalanine-8, as well as a change in side-chain rotameric preference.

[Tyr8]-substance P, an undecapeptide having the structure Arg-Pro-Lys-Pro-Gln-Gln-Phe-Tyr-Gly-Leu-Met-NH2, has been synthesized by the solid-phase technique on a Beckman automatic peptide synthesizer, appropriately purified and biologically characterized. At twice the dosage, [Tyr8]-substance P showed the same biological activity response as synthetic substance P for stimulation of contraction of the isolated guinea pig ileum and for decrease in the systemic blood pressure of dogs. On the dog's blood pressure, no qualitative differences were observed, but on the isolated gut, the Tyr8 analog gave a more gradual increase in the muscle tone than synthetic substance P. [Tyr8]-substance P released, in vitro, the luteinizing and follicle-stimulating hormones at a very high dosage but did not release growth hormone, prolactin, or thyrotropin.