Antimicrobial peptide, compositions, and uses therefor
The invention refers to small peptides with low hemolytic activity, presenting similar antiparasitic, antifungal and antibacterial activities. More specifically, it refers to a peptide called gomesin, with 18 amino acid residues, configured as a hairpin structure consisting of two anti-parallel beta-folded sheets joined by a beta turn, containing four invariable residues of cysteine forming two disulphide bridges, configurable as a cyclic chain with open or closed ends.
1. An isolated peptide of the general formula:
in which: Z 1 is:
in the absence of X 19 , pyroglutamic acid;
when X 19 is present, glutamine with a free amino end group available to close the ends of the molecule;
P 1 and P 2 are disulphide bridges from C 2 to C 15 and from C 6 to C 11 , respectively, either one or both bridges being present;
R 18 is:
in the absence of X 19 : an arginine bearing a free carboxyl group end or forming an acceptable salt, or amidated with an amine of the formula NH 3 or RNH 2 or R 2 NH, in which R is independently a saturated or unsaturated hydrocarbyl with one to six carbons;
when X 19 is present: an arginine whose free carboxyl end is involved with the closing of peptide molecule ends;
X 19 may be absent or present; if present, it is a chemical link between Z 1 and R 18 or a chemical structure or molecule present between Z 1 and R 18 and linked to both, closing the amino acid chain ends of the peptide of the invention, wherein, in the absence of X 19 , R 18 , said peptide is amidated (SEQ ID NO: 1).
2. The peptide of claim 1 in which, when X 19 is present R 18 is non-amidated (SEQ ID NO: 2).
3. The peptide of claim 1 in which, when X 19 is present R 18 is non-amidated and Z 1 is Q (SEQ ID NO: 3).
4. A pharmaceutical, botanical or veterinary composition comprising the peptide of claim 1 in admixture with at least one carrier, diluent, or excipient.
5. A method for treating an infection associated with a human, animal or plant disease, said disease being selected from the group consisting of a bacterial infection, a fungal infection, a yeast infection and a parasitic infection, comprising administering to said human, animal or plant an effective amount of the peptide of any one of claims 1 , 2 and 3 .
6. A method for treating an infection associated with a human, animal or plant disease, said disease being selected from the group consisting of a bacterial infection, a fungal infection, a yeast infection and a parasitic infection, comprising administering to said human, animal or plant the composition of claim 4 .
7. A method of inhibiting the development of parasites, fungi or bacteria associated with an infection, comprising contacting said parasites, fungi or bacteria with an effective amount of a peptide of any one of claims 1 , 2 and 3 .
8. The method of claim 7 , in which the parasite is a protozoary.
9. The method of claim 7 , in which the parasite is a Leishmania or T. cruzi.
10. A method to inactivate the endotoxin from Gram-negative bacteria, in which said endotoxin is contacted with an amount of a peptide of any one of claims 1 , 2 and 4 , which is effective to inactivate said endotoxin.