Acyl lipidation of a peptide: effects on activity and epidermal permeability in vitro

Figures & data

Figure 1 Structures of the parent peptide and the lipopeptide derivatives tested.

Notes: (A) L-AAPV; MWt =356.42. (B) L-C₇-AAPV; MWt =468.59. (C) L-AAPV-C₇; MWt =453.62. (D) L-C₈-AAPV; MWt =482.61. (E) L-C₈LAA-AAPV or D-C₈LAA-AAPV; MWt =497.63. The structure in black is the common portion (tetrapeptide) and in blue are the different (modified) side chains and functional groups.
Abbreviations: L-AAPV, L-Ala-L-Ala-L-Pro-L-Val; MWt, molecular weight; L-C₇-AAPV, C₇-L-Ala-L-Ala-L-Pro-L-Val; L-AAPV-C₇, L-Ala-L-Ala-L-Pro-L-Val-C₇; L-C₈-AAPV, C₈-L-Ala-L-Ala-L-Pro-L-Val; L-C₈LAA-AAPV, L-octylglycine-L-Ala-L-Ala-L-Pro-L-Val; D-C₈LAA-AAPV, D-octylglycine-L-Ala-L-Ala-L-Pro-L-Val.

Figure 2 Cumulative amounts of parent peptide “L-AAPV (●)” and N- or C-acyl lipidated peptide derivatives “L-C₇-AAPV (■) and L-AAPV-C₇ (○)” in the receptor compartment after 24 hours.

Notes: Results shown are the mean (± SD) of five separate experiments, each conducted in triplicate. Each experiment utilized triplicate skin sections from a different skin donor.
Abbreviations: L-AAPV, L-Ala-L-Ala-L-Pro-L-Val; L-C₇-AAPV, C₇-L-Ala-L-Ala-L-Pro-L-Val; L-AAPV-C₇, L-Ala-L-Ala-L-Pro-L-Val-C₇; SD, standard deviation.

Table 1 Permeation parameters of the parent tetrapeptide and its N-terminal and C-terminal C₇-acyl lipid conjugates

Compound	Cumulative amount in receptor after 24 hours (µg ± SEM)	Epidermal flux (µg⋅cm^−2·h^−1)	Estimated log P using ChemAxon^®	Observed log P	Observed log D
L-AAPV	Undetectable	Undetectable	−1.25	N/A	−2.96 (pH 4.5), −2.92 (pH 9)
L-C7-AAPV	115.53±26.06	8.11	1.06	0.30 (pH 4.5)	−0.79 (pH 9)
L-AAPV-C7	116.02±27.9	8.36	0.86	0.37 (pH 9)	0.13 (pH 4.5)

Note: Partition coefficient data are of observed experimental results versus those estimated using a computer software program.

Abbreviations: SEM, standard error of the mean; L-AAPV, L-Ala-L-Ala-L-Pro-L-Val; N/A, not available; L-C₇-AAPV, C₇-L-Ala-L-Ala-L-Pro-L-Val; L-AAPV-C₇, L-Ala-L-Ala-L-Pro-L-Val-C₇.

Figure 3 Percent inhibition of elastase by L-AAPV, acyl conjugate (L-C₈-AAPV), or lipoaminoacid (D- or L-C₈LAA-AAPV) conjugates in vitro.

Notes: Inhibition was calculated as a percentage of uninhibited reactions carried out concurrently. All reactions were incubated with elastase (0.02 U/mL) for 20 minutes with 25 μg/mL of DQ elastin substrate in the presence or absence of L-AAPV or one of its lipid conjugates. (A) Percent inhibition by L-AAPV, L-C₇-AAPV, or L-AAPV-C₇; results are expressed as the mean (± SEM) of five separate experiments, each conducted, at least, in duplicate. ANOVA: ^αP<0.005 and ^βP<0.001. (B) Percent inhibition by L-AAPV, L-C₈-AAPV, L-C₈LAA-AAPV, or D-C₈LAA-AAPV; results are expressed as the mean (± SEM) of three independent experiments each conducted, at least, in duplicate. t-test: a,bL-AAPV and L-C₈-LAA-AAPV are significantly (P<0.05) different. L-C₈-AAPV and L-C₈-LAA-AAPV are significantly different. Letters a and b are used to help identify which ones are significantly different from each other, without ambiguity.
Abbreviations: L-AAPV, L-Ala-L-Ala-L-Pro-L-Val; L-C₈-AAPV, C₈-L-Ala-L-Ala-L-Pro-L-Val; D-C₈LAA-AAPV, D-octylglycine-L-Ala-L-Ala-L-Pro-L-Val; L-C₈LAA-AAPV, L-octylglycine-L-Ala-L-Ala-L-Pro-L-Val; L-C₇-AAPV, C₇-L-Ala-L-Ala-L-Pro-L-Val; L-AAPV-C₇, L-Ala-L-Ala-L-Pro-L-Val-C₇; SEM, standard error of the mean; ANOVA, analysis of variance.