[D-Pro4,D-Trp7,9,10,Val8]-Substance P (4-11) is a heavily modified eight-residue Substance P fragment developed as a peptide antagonist for peripheral and central tachykinin studies.

In addition to D-Pro4 and three D-Trp substitutions, the peptide replaces Phe8 with Val. This additional aromatic-to-aliphatic substitution was investigated as a strategy for reducing unwanted agonist activity.

Product Information

Val8 Reduces Aromatic Character in the Antagonist Scaffold

Native Substance P contains Phe at position 8. This analog replaces that aromatic side chain with the smaller aliphatic residue Val while maintaining D-Trp substitutions at positions 7, 9 and 10.

In early spinal pharmacology studies, both this Val8 analog and the corresponding Phe8 compound inhibited Substance P-associated responses. The Val8 analog showed approximately threefold less agonistic activity in that experimental comparison.

This makes the Phe8 → Val substitution particularly interesting when the experimental objective is to separate antagonist behavior from residual intrinsic activity.

Research Applications

The peptide can support Substance P antagonist studies, spinal tachykinin pharmacology, peptide agonist–antagonist SAR and investigation of aromatic versus aliphatic residue requirements at position 8.

We recommend including the corresponding non-Val8 antagonist as a comparator when the specific effect of the position-8 substitution is being investigated.

Frequently Asked Questions

What is unique about this analog?

In addition to several D-amino-acid substitutions, Phe8 is replaced by Val.

Why is Val8 experimentally important?

Historical comparative studies found lower residual agonistic activity for the Val8 analog than for the corresponding Phe8 antagonist.

Does the peptide contain Met11?

Yes. The C-terminal methionine remains present and can undergo oxidation.

Research Use Only.