synthesis of [ half-cys4 , half-cys10 ] -alpha-msh , a cyclic , conformationally restricted , `` '' isosteric '' '' analogue of alpha-msh , provided a melanotropin with a potency greater than 10,000 times that of the native hormone in stimulating frog ( rana pipiens ) skin darkening .
C0002302
f alpha-m
C0026667
a melanotrop