[Syntheses and preliminary bioassays of inhibin segments]

Six segments within the subunit beta-A of the follicular inhibin have been synthesized by an improved solid phase procedure on p-methyl-benzhydrylamine (1% divinylbenzene) resin. The courses of the syntheses were monitored by quantitative ninhydrin assays and amino acid analyses. Following the cleavage by HF-p-cresol (9:1 V/V), the peptides were extracted with anhydrous trifluoroacetic acid containing 1% dithiothreitol and precipitated with dry ethyl ether. The purification was achieved uniquely by reverse phase HPLC and final products were characterized by several TLC systems, analytical HPLC and amino acid analyses. Pituitary cell culture bioassays were performed to ascertain their biological activities. However, among these synthetic peptides, the small peptides Ib-beta A (37-39)NH2(I), Ib-beta A(34-39)NH2(II), and Ib-beta A(30-39)NH2(III) showed no significant suppression on the LHRH-induced FSH secretion; the large peptides Ib-beta A(23-39)NH2(IV), Ib-beta A(16-39)NH2(V), and Ib-beta A(14-39)NH2(VI) lack adequate solubility in neutral media, and other methods are to be sought to test their bioactivities.