Boc-Phe-D-Phe-OH

Mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes [HM(III){Pc(alpha-3-OC(5)H(11))(4)}{TOAPP}] [Pc(alpha-3-OC(5)H(11))(4) = 1,8,15,22-tetrakis(3-pentyloxy)-phthalocyaninate; TOAPP = meso-tetrakis(4-octylamino-phenyl)porphyrinate; M = Y (1), Ho (2)] were prepared as a racemic mixture by treating metal-free phthalocyanine H(2)Pc(alpha-3-OC(5)H(11))(4) with half-sandwich complexes [M(III)(acac)(TOAPP)], generated in situ from M(acac)(3).nH(2)O and H(2)TAPP [TAPP = meso-tetrakis(4-amino-phenyl)porphyrinate], in refluxing 1-octanol. The obtained double-deckers were characterized by elemental analysis and various spectroscopic methods. The molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction analysis. The compounds crystallize in the triclinic system with a pair of enantiomeric double-deckers per unit cell. Resolution of 1 and 2 was achieved using a chiral HPLC technique combined with the formation of their diastereomeric mixture using L-Boc-Phe-OH as the chiral resolving agent, yielding for the first time the pure diastereoisomers of chiral mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes with C(4) symmetry.

The chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) induces peptide leukotriene release at concentrations of 20-25 pmol/ml 3 min after the start of FMLP infusion. FMLP-induced leukotriene release in rabbit hearts is not blocked by the leukotriene receptor antagonist FPL-55712 at concentrations that totally antagonize the hemodynamic effects of exogenously infused peptide leukotrienes. Moreover, propyl gallate, a lipoxygenase inhibitor, does not block FMLP-induced leukotriene release. However, the chemotactic peptide antagonist (Boc-Phe-Leu-Phe-Leu-Phe-OH) totally antagonized FMLP-induced leukotriene release suggesting that the release is via a different mechanism, possibly a receptor mediated event.

A competitive reaction of activated Boc-Ala-OH and Boc-Phe-OH with H-Leu-resin has been developed for assessing the relative efficiencies of different carbodiimides. This allowed a comparison of the efficiency of the carbodiimides N,N'-dicyclohexylcarbodiimide,N,N'-diisopropylcarbodiimide, N-tert-butyl-N'-methylcarbodiimide and N-tert-butyl-N'-ethylcarbodiimide. Comparable results were obtained when these reagents were used for the preformation of symmetrical anhydrides or of 1-hydroxybenzotriazole esters in situ. Differential incorporation was observed when asymmetrical carbodiimides were used for peptide bond formation by the direct carbodiimide procedure.

The present work reports the synthesis of a plant-originated cyclooctapeptide--psammosilenin A 8--by cyclization of linear peptide fragment phe-pro-phe-phe-ala-pro-leu-pro-Opfp which was prepared by coupling of tetrapeptide units Boc-phe-pro-phe-phe-OH and ala-pro-leu-pro-OMe followed by proper deprotection of terminal groups and activation of the acid functionality. During synthesis, dicyclohexylcarbodiimide (DCC) and N,N-diisopropylcarbodiimide (DIPC) were used as the coupling agents and N-methylmorpholine (NMM)/triethylamine (TEA) were used as bases. Structure of the synthesized peptide was elucidated by spectral as well as elemental data. The newly synthesized peptide was subjected to biological screening and found to possess potent cytotoxic activity against DLA and EAC cell lines with IC(50) value of 7.93 and 17.06 microM, respectively. Furthermore, good anthelmintic activity against earthworms M. konkanensis and Eudrilus species at 1 and 2 mg/mL was also observed for the synthesized cyclic peptide.