- The Cooperative Effect of Both Molecular and Supramolecular Chirality on Cell Adhesion
-
Although helical nanofibrous structures have great influence on cell adhesion, the role played by chiral molecules in these structures on cells behavior has usually been ignored. The chirality of helical nanofibers is inverted by the odd–even effect of methylene units from homochiral l-phenylalanine derivative during assembly. An increase in cell adhesion on left-handed nanofibers and weak influence of cell behaviors on right-handed nanofibers are observed, even though both were derived from l-phenylalanine derivatives. Weak and negative influences on cell behavior was also observed for left- and right-handed nanofibers derived from d-phenylalanine, respectively. The effect on cell adhesion of single chiral molecules and helical nanofibers may be mutually offset.
- Liu, Jinying,Yuan, Feng,Ma, Xiaoyu,Auphedeous, Dang-i Y.,Zhao, Changli,Liu, Chuntai,Shen, Changyu,Feng, Chuanliang
-
supporting information
p. 6475 - 6479
(2018/05/08)
-
- An efficient and cost-effective approach to kahalalide F N-terminal modifications using a nuisance algal bloom of Bryopsis pennata
-
Background: Kahalalide F (KF) and its isomer iso-kahalalide F (isoKF), both of which can be isolated from the mollusk Elysia rufescens and its diet alga Bryopsis pennata, are potent cytotoxic agents that have advanced through five clinical trials. Due to a short half-life, narrow spectrum of activity, and a modest response in patients, further efforts to modify the molecule are required to address its limitations. In addition, due to the high cost in producing KF analogues using solid phase peptide synthesis (SPPS), a degradation and reconstruction approach was employed using natural KF from a seasonal algal bloom to generate KF analogues. Methods: N-protected KF was carefully hydrolyzed at the amide linkage between L-Thr12 and D-Val13 using dilute HCl. The synthesis of the C-terminal fragment began with the formation of hexanoic succinimide ester, followed by a reaction with dipeptides. The final coupling reaction was performed between the semisynthesized Fmoc-KF hydrolysis product and the C-terminal fragment, followed by the deprotection of the Fmoc group. Results: Six KF analogues with an addition of an amino acid residue on the N-terminal chain, D-Val14-isoKF (2), Val13-Val14-isoKF (3), D-Leu14-isoKF (4), D-Pro14-isoKF (5), D-Phe14-isoKF (6), and 3,4-2F-D-Phe14-isoKF (7) were prepared using semisynthesis at the exposed N-terminal chain. Conclusions: The overall yield of the medication was 45%. This approach is economical, efficient and amendable to large-scale production while eliminated a nuisance algal bloom. General significance: B. pennata blooms are capable of producing KF in good yields. The semisynthesis from the natural product produced N-terminal modifications for the construction of inexpensive semisynthetic KF libraries.
- Wang, Bin,Waters, Amanda L.,Valeriote, Frederick A.,Hamann, Mark T.
-
p. 1849 - 1854
(2015/06/08)
-
- LE CHLOROFORMIATE D'ISOPROPENYLE (IPCF) EN CHIMIE DES AMINO-ACIDES ET DES PEPTIDES - III SYNTHESE D'ESTERS ACTIFS D'AMINO ACIDES N-PROTEGES
-
Isopropenyl chloroformate (IPCF) was used for preparation of mixed carbonates (Aryl and isopropenyl) which are very suitable reagents for active ester synthesis of amino acid derivatives (Boc derivatives in particular).
- Jaouadi, M.,Selve, C.,Dormoy, J. R.,Castro, B.,Martinez, J.
-
p. 1721 - 1722
(2007/10/02)
-
- Collagenase-sensitive peptidyl-nitrogen mustards as potential antitumor agents.
-
Attempts to design an agent which would release cytotoxic nitrogen mustards within collagenase-producing tumors led to the synthesis of Cbz-L-Pro-L-Leu-Gly-L-Pro-Gly-NHC6H4N(CH2CH2Cl)2 (10). 10 was cleaved in vitro by bacterial and tumor-associated collagenase as expected at the peptide bond joining L-leucine and glycine to give Gly-L-Pro-Gly-NHC6H4N(CH2CH2Cl)2 which was over six times more toxic, on a molar basis, than 10. In vivo tests of 10 against well-advanced Sarcoma-180 gave disappointing results. The lack of specific antitumor activity may be accounted for by the presence of competing cleavage reactions by collagenases in certain normal tissues.
- Marquisee,Kauer
-
p. 1188,1191
(2007/10/08)
-