Two new allatostatins from the brains of Diploptera punctata

Allatostatins VI and VII have been isolated from saline extracts of the brain of the viviparous cockroach Diploptera punctata. Active fractions, obtained by successive reverse-phase high pressure liquid chromatography separations, inhibited juvenile hormone (JH) III production by corpora allata (CA) in vitro. The primary structures, Y-P-Q-E-H-R-F-S-F-G-L-amide (VI) and D-G-R-M-Y-S-F-G-L-amide (VII), clearly identify them as members of a family of D. punctata allatostatins, five of which have been identified previously and shown to have F-G-L-amide at the C terminus. Synthetic allatostatins VI and VII coeluted with the native allatostatins on two successive high pressure liquid chromatography separations. Allatostatins VI and VII have the same capacity to inhibit JH production by CA of 2 day virgin females as does allatostatin I, previously shown to be a potent inhibitor similar in activity to allatostatin V. Allatostatins VI and VII also resemble the other allatostatins in their ability to affect both larval and adult CA, in the reversibility of their effect, and in the abolition of their effect by addition of farnesoic acid (a late precursor of JH) to CA in vitro.