In vitro biological evaluation of new antimycobacterial salicylanilide-tuftsin conjugates

Abstract

Tuberculosis is caused by Mycobacterium tuberculosis, an intracellular pathogen that can survive in host cells, mainly in macrophages. An increase of multidrug-resistant tuberculosis qualifies this infectious disease as a major public health problem worldwide. The cellular uptake of the antimycobacterial agents by infected host cells is limited. Our approach is to enhance the cellular uptake of the antituberculars by target cell-directed delivery using drug-peptide conjugates to achieve an increased intracellular efficacy. In this study, salicylanilide derivatives (2-hydroxy-N-phenylbenzamides) with remarkable antimycobacterial activity were conjugated to macrophage receptor specific tuftsin based peptide carriers through oxime bond directly or by insertion of a GFLG tetrapeptide spacer. We have found that the in vitro antimycobacterial activity of the salicylanilides against M. tuberculosis HRv is preserved in the conjugates. While the free drug was ineffective on infected macrophage model, the conjugates were active against the intracellular bacteria. The fluorescently labelled peptide carriers that were modified with different fatty acid side chains showed outstanding cellular uptake rate to the macrophage model cells. The conjugation of the salicylanilides to tuftsin based carriers reduced or abolished the in vitro cytostatic activity of the free drugs with the exception of the palmitoylated conjugates. The conjugates degraded in the presence of rat liver lysosomal homogenate leading to the formation of an oxime bond-linked salicylanilide-amino acid fragment as the smallest active metabolite.

Membrane affinity and fluorescent labelling: comparative study of monolayer interaction, cellular uptake and cytotoxicity profile of carboxyfluorescein-conjugated cationic peptides

“…MonoMac6 cell line represents monocytic cells with a closely related pattern of surface, phenotypic, functional features and adhesion properties of mature monocytes and macrophages (Ziegler-Heitbrock et al 1988;Erl et al 1995). In our previous studies these model cells were used to determine uptake profile, cytotoxicity and membrane interactions of promising drug carrier peptides (Horváti et al 2017;Baranyai et al 2017;Horváti et al 2018;Ábrahám et al 2016;Horváti et al 2014). Relative viability of the cells was above 80 % for each peptide except the bee venom Melittin.…”

Nanotechnology‐Based Targeted Drug Delivery: An Emerging Tool to Overcome Tuberculosis

“…Several tuftsin-based carriers were developed [158] and were used for TB targeting as drug-peptide conjugates, these conjugates efficiently inhibited the intracellular bacteria in infected macrophage models. [159,160] Due to its quick biodegradation, the use of this peptide as targeting ligand is more suitable in a nanocarrier-based formulation.…”

Tailoring Uptake Efficacy of HSV-1 gD Tailoring Uptake Efficacy of Hsv-1 GD Derived Carrier Peptides

“…The fluorescence properties of the Cf-peptides were studied at different pH values with fluorescence spectroscopy using Varian Cary Eclipse fluorimeter (the method was first described in [20]). Briefly: peptides were dissolved in 0.1 M citrate phosphate buffer (pH = 4.0, 5.0, 6.0, 7.0); and 0.4 µm peptide concentration was used.…”

“…In Set I, three overlapping 20mer peptides were chosen from the N-terminal of the HSV-1 gD glycoprotein which are only partly visible on the complex structures of either HSV-1 gD -nectin or HSV-1 gD -HVEM. Further two N-terminal peptide sequences based on the structure of the HSV-1 gD -nectin complex (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42), and a sequence based on the structure of the HSV-1 gD -HVEM complex and its N-and C-terminal decamers were prepared and studied for their cellular uptake ( Figure 5A, Figure S16a A series of 20mer peptides (Set II) from the central part of HSV-1 gD (181-216) was found to have very poor internalisation efficiency, with the exception of Cf-(181-200) with mediocre internalisation (UC50 = 36.8 μM), their UC50 values were above 50 μM, in case of Cf-(193-212) and Cf-(197-216) above 100 μM (Figure 5b, Figure S16c,d). Even in c = 250 μM, the percentag...…”

“…Tuftsin is a natural peptide produced by enzymatic cleavage of the Fc-domain of the heavy chain of immunoglobulin G. During the past decade, a new group of sequential oligopeptide carriers with discrete molecular masses has been developed in our laboratory: these oligotuftsin derivatives consisting of tandem pentapeptide repeat unit [TKPKG] n (n = 2, 4, 6 and 8) are based on the canine tuftsin sequence TKPK. These compounds are nontoxic and non-immunogenic and are developed to be effective tuftsin-receptor specific carrier peptides [42,43] to deliver, e.g., antitubercular drug candidates into monocytic host cells [20,44]. In this study, we have compared the internalising ability of Cf-TKPKGTKPKG (Cf-OT10) peptide with that of HSV-1 gD peptides on SH-SY5Y cells (comparison of Set II peptides and OT10 is shown in Figure S19).…”