Ac-LIVKHH-NH 2 (P1) and Fmoc-LIVKHH-NH 2 (P2) peptides were synthesized based on Fmoc/Boc solid phase peptide chemistry. In brief, Fmoc-rink amide AM resin (0.78 mmol g -1 ) was weighed out, and the beads were allowed to swell for 1h in DMF. Fmoc deprotection was achieved with a mixture of 20% v/v piperidine in DMF, which was added to the resin and left to agitate for 15 min. After thorough washing with DMF, 2 equiv. of HOBt and HBTU were dissolved in DMF and combined. Another 2 equiv. of the initial protected amino acid, pre-dissolved in DMF, were introduced to the mixture, followed by the addition of 2 equiv. of DIPEA to the same solution, allowing 20 seconds for activation. Subsequently, this solution was added to the resin and left to agitate for 45 minutes. The resin was washed with DMF and subjected to a series of deprotection and coupling reactions with the desired amino acids. All the reactions were performed at 25°C, and the couplings were monitored via Kaiser test. After a though washing with DMF, a DMF solution of 12 equiv. of Ac 2 O and DIPEA was added (capping) to prevent side reactions of the side-groups, and the mixture was incubated for 30 minutes. To obtain the P1, the Fmoc group of the final amino acid was deprotected. Then, the N-terminus of P1 was acetylated using a 5-times excess of Ac 2 O and DIPEA. In case of P2 the N-terminus remained intact with the Fmoc group still attached. The resin was subsequently washed with DMF and DCM and allowed to dry before the peptide cleavage step using a mixture of 94% TFA, 3% Milli-Q water and 3% TIS. The solvents were reduced under an argon atmosphere, and Et 2 O was added to precipitate the peptide. The peptides were isolated through several centrifugations, washed with Et 2 O, and dried under reduced pressure. The peptides were then lyophilized in Milli-Q water with the presence of 0.01% TFA and analyzed by high-performance liquid chromatography system coupled to a mass spectrometer (HPLC-MS, Thermo scientific, Ultimate 3000 HPLC system coupled with maXis UHR-TOF). The purity of the desired peptides ranged between 95 and 99%, therefore, no further purification was necessary. ESI-MS spectra were measured on a Brucker maXis UHR-TOF equipped with ESI electrospray ionization chamber in positive mode. Yield: P1: 287 mg (57.4%); P2: 379 mg (