PEGylated and functionalized polylactide-based nanocapsules: An overview.

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Poly-ɛ-caprolactone nanocapsules loaded with copaiba essential oil reduce inflammation and pain in mice.

Diverse drugs have been used for the management of inflammation disorders and pain. However, they present many side effects and stimulate the search for new pharmacotherapeutic alternatives. Plant-derived products such as copaiba essential oil (CO) offer beneficial pharmacological effects. On the other hand, essential oil's low water solubility and physical instability hinder its in vivo application. Thus, poly-ɛ-caprolactone (PCL)-based nanocarriers have been used to increase their stability and efficacy. This work aimed to encapsulate CO in PCL nanocapsules and evaluate their effect on inflammation models and pain. The polymeric nanocapsules loading CO (CO-NC) were prepared by nanoprecipitation technique, characterized, and analyzed for their anti-inflammatory effect in vitro and in vivo. The results showed that CO-NC presented a spherical shape, 229.3 ± 1.5 nm diameter, and a negative zeta potential (approximately -23 mV). CO and CO-NC presented anti-inflammatory and antioxidant effects by LPS-activated macrophages (J774 cells). In addition, CO-NC significantly reduced TNF-α secretion (3-fold) compared to CO. In vivo, pre-treatment with CO or CO-NC (50, 100, 200 mg/kg, intraperitoneal; i.p) reduced the mechanical allodynia, paw edema, and pro-inflammatory cytokines induced by intraplantar (i.pl) injection of carrageenan in mice. Specifically, CO-NC (200 mg/kg; i.p.) reduced the production of TNF-α similar to the control group. Our results support using polymeric nanocapsules for CO delivery in inflammatory conditions.

The effect of free and encapsulated cisplatin into long-circulating and pH-sensitive liposomes on IEC-6 cells during wound healing in the presence of host-microbiota.

OBJECTIVES: To circumvent cisplatin (CDDP) toxic effects and improve the antitumoural effect, our research group developed long-circulating and pH-sensitive liposomes containing CDDP (SpHL-CDDP). This study aimed to evaluate whether SpHL-CDDP is associated with intestinal protection under in-vitro conditions in the presence of host-microbiota, compared with free CDDP. METHODS: The cytotoxicity of CDDP and SpHL-CDDP were evaluated by colorimetric MTT and sulforhodamine B (SRB) assays. Epithelial proliferation was assessed by using an in-vitro wounding model in the presence of host-microbiota with intestinal epithelial cell line 6 (IEC-6) monolayers. Cytokines were determined by ELISA. KEY FINDINGS: Reduced cytotoxicity of SpHL-CDDP in IEC-6 cells (minimum of 1.3-fold according to the IC50 values) was observed when compared with CDDP. The presence of microbiota or CDDP reduced the wound healing. The association of microbiota and SpHL-CDDP improved the wound healing and cell number in IEC-6 cells when compared with control. These beneficial results can be associated with increased IL-6 and IL-10 levels induced by SpHL-CDDP which were affected by the presence of microbiota. CONCLUSIONS: These results indicate that the presence of microbiota associated with SpHL-CDDP provided less intestinal cellular damages compared with CDDP and constitutes a promising candidate for clinical use.

Lecithin-based nanocapsule loading sucupira (Pterodon emarginatus) oil effects in experimental mucositis.

Intestinal mucositis (IM) is a frequent adverse effect in anticancer therapy without standard treatment. The oil obtained from sucupira (Pterodon emarginatus) has anti-inflammatory properties, and the soybean lecithin reduces the intestinal toxicity of several xenobiotics. However, their water insolubility impairs the in vivo application. For this reason, we evaluated if the nanoencapsulation of sucupira oil (SO) in lecithin-based nanocapsules (SO-NC) could be a therapeutically effective system for the treatment of IM in murine cisplatin (CDDP)-induced intestinal mucositis model. SO was analyzed by LC-HRMS/MS and HPLC. SO-NC was prepared by nanoprecipitation and characterized using DLS, HPLC, and AFM. Mice body weight and food consumption were assessed daily during experimental mucositis induced by CDDP. The animals were euthanized, and intestinal permeability, inflammatory mediators, and intestinal histology were performed. SO-NC demonstrated adequate characteristics for oral administration as size under 300 nm, IP < 0.3, high EE, and spherical shape. In vitro cytotoxicity performed against RAW 264.7 cell lines resulted in cell viability above 80 % confirming the non-cytotoxic profile of SO (IC50 268 µg/mL) and SO-NC (IC50 118.5 µg/mL) up to 117.2 µg/mL. The untreated mice showed intestinal toxicity after i.p. of CDDP, principally weight loss, increased intestinal permeability, and MPO and TNF-α levels. Surprisingly, the administration of SO to CDDP-mucositis animals did not circumvent the CDDP effects and increased intestinal permeability. However, SO-NC proved efficient in mitigating the experimental intestinal mucositis by improving intestinal epithelium architecture, reducing intestinal permeability, and improving the MPO levels. In conclusion, SO-NC can positively impact intestinal mucositis by promoting mucosal recovery. This is a promising strategy for developing a new treatment for intestinal mucositis.

Recent progress in micro and nano-encapsulation of bioactive derivatives of the Brazilian genus Pterodon.

In the last few decades, utilization of medicinal plants by the pharmaceutical industry has led to the identification of many new bioactive compounds. The genus Pterodon, native of the Brazilian Flora, is known for the therapeutic properties attributed to its species, which are widely used in popular medicine for their anti-inflammatory, anti-rheumatic, tonic, and depurative properties. The intrinsic low water solubility of the plant derivatives from the genus, including diterpenes with vouacapane skeletons that are partially associated with the pharmacological activities, impairs the bioavailability of these bioactive compounds. Recent studies have aimed to encapsulate Pterodon products to improve their water solubility, achieve stability, increase their efficacy, and allow clinical applications. The purpose of this paper is to review recent research on the use of nanotechnology for the development of new products from plant derivatives of the Pterodon genus in different types of micro- and nanocarriers. Therapeutic properties of their different products are also presented. Finally, an update about the current and future applications of encapsulated formulations is provided.

Nano-emulsification Enhances the Larvicidal Potential of the Essential Oil of Siparuna guianensis (Laurales: Siparunaceae) Against Aedes (Stegomyia) aegypti (Diptera: Culicidae).

Siparuna guianensis (Laurales: Siparunaceae) has a terpene-rich essential oil with great potential for larvicides. The poor water miscibility of their compounds makes nano-emulsions of great interest for novel bioactive systems, including for control of Aedes aegypti (Diptera: Culicidae). This species is adapted to urban environments with important role in the epidemiology of some arboviruses such as dengue, chikungunya fever, zika, and urban yellow fever. The aim of the present study was to evaluate the feasibility of nano-emulsification to affect Ae. aegypti larvae. An optimal system was achieved by using a nonionic single surfactant, highlighted by its satisfactory size distribution profile. Moreover, improved larvicidal activity in comparison to bulk essential oil can be observed for the nano-emulsions. The estimated LC50 and LC90 values after 24 h of treatment of larvae with the essential oil were, respectively, 86.5232 and 134.814 µg/ml, while the estimated LC50 and LC90 value after treatment with the nano-emulsion were 24.7572 and 75.2452 µg/ml, respectively. The utilization of a simple technique to produce a fine nano-emulsion opens perspective for further integrative practices of mosquito control and giving value to this Amazon plant species may encourage its sustainable use and contribute to conservation policies.

Cloxacillin benzathine-loaded polymeric nanocapsules: Physicochemical characterization, cell uptake, and intramammary antimicrobial effect.

The present work shows the development and evaluation of the veterinary antibiotic cloxacillin benzathine (CLOXB) loaded into poly-ε-caprolactone (PCL) nanocapsules (NC), as a potential new treatment strategy to manage bovine intramammary infections, such as mastitis. Staphylococcus aureus-induced mastitis is often a recurrent disease due to the persistence of bacteria within infected cells. CLOXB-PCL NC were prepared by interfacial deposition of preformed biodegradable polymer followed by solvent displacement method. The mean diameter of NC varied from 241 to 428 nm and from 326 to 375 nm, when determined by dynamic light scattering and by atomic force microscopy, respectively. The zeta potential of NC was negative and varied from -28 to -51 mV. In vitro release studies from the NC were performed in two media under sink conditions: PBS with 1% polyethylene glycol or milk. A reversed-phase HPLC method was developed to determine the NC entrapment efficiency and kinetics of CLOXB release from the NC. Free CLOXB dissolution occurred very fast in both media, while drug release from the NC was slower and incomplete (below 50%) after 9 h. CLOXB release kinetics from polymeric NC was fitted with the Korsmeyer-Peppas model indicating that CLOXB release is governed by diffusion following Fick's law. The fluorescence confocal microscopy images of macrophage-like J774A.1 cells reveal NC uptake and internalization in vitro. In addition, antimicrobial effect of the intramammary administration of CLOXB-PCL NC in cows with mastitis resulted in no clinical signs of toxicity and allowed complete pathogen elimination after treatment. The in vivo results obtained in this work suggest that CLOXB-PCL NC could be a promising formulation for the treatment of intramammary infections in cattle, considering their physicochemical properties, release profiles and effects on bovine mastitis control.

Biodistribution of free and encapsulated 99mTc-fluconazole in an infection model induced by Candida albicans.

BACKGROUND: Candida spp is an etiologic agent of fungal infections in hospitals and resistance to treatment with antifungals has been extensively reported. Thus, it is very important to develop formulations that increase effectiveness with low toxicity. In this sense, nanocarriers have been investigated, once they modify drug biodistribution profile. Thus, this study aimed to evaluate the biodistribution of free and encapsulated 99mTc-fluconazole into nanocapsules (NCs) in an experimental immunosuppressed murine model of Candida albicans infection. METHODS: Fluconazole was radiolabeled with technetium-99 metastable (99mTc) and encapsulated into conventional (99mTc-Fluconazole-PLA-POLOX) and surface-modified (99mTc-Fluconazole-PLA-PEG) NCs by the interfacial deposition of the preformed biodegradable polymer [poly (D,L-lactic acid) (PLA) and PLA-PEG (polyethyleneglycol)] followed by solvent evaporation. The size distribution and zeta potential of the NCs preparations were determined in a Zetasizer by photon correlation spectroscopy and laser Doppler anemometry, respectively. Free and encapsulated 99mTc-fluconazole were administered intravenously in immunosuppressed mice bearing a local infection induced by Candida Albicans inoculation in the right thigh muscle. At pre-established time intervals, tissues and organs of interest were removed and radioactivity was measured in an automatic gamma radiation counter. RESULTS: The NCs diameter was between 200 and 400 nm with negative zeta potential values. Free 99mTc-fluconazole was more rapidly eliminated by the renal system compared to the encapsulated drug in NCs, which remained longer in blood circulation. The uptake of conventional NCs by mononuclear phagocyte system organs was higher than the one demonstrated by the surface-modified NCs. Both NCs remained longer in the infectious focus when compared to free 99mTc-fluconazole, but the results did not show a significant difference between NC formulations. CONCLUSION: These data indicate that these NCs might represent a therapeutic alternative for the treatment of candidiasis, once they remain more time in the infectious focus, allowing high retention of 99mTc-fluconazole at this site.

Intestinal toxicity evaluation of long-circulating and pH-sensitive liposomes loaded with cisplatin.

Cisplatin (CDDP) is a chemotherapeutic agent widely used in several anticancer protocols for instance head and neck, testicle, ovarian, lung and peritoneal carcinomatosis. According to the literature, the use of CDDP is associated with several side effects; among them, we highlighted the mucositis. CDDP, when administered by IP, promoted significant intestinal epithelium alterations in an experimental model. Our research group has proposed that the incorporation of CDDP into long-circulating and pH-sensitive liposomes (SpHL-CDDP) could help to overcome some side effects induced by this drug. Thus, we evaluated signs of intestinal toxicity 24h and 72h after the administration of a single i.p dose of free CDDP or SpHL-CDDP to healthy Swiss mice. Twenty-four hours after administration of free CDDP, the mice showed signs of intestinal toxicity, principally weight loss, increased intestinal permeability associated with a decrease in expression of tight junctions, and histological damage with the presence of inflammatory infiltrates and activation of ERK1/2 and NF-κB. These changes persisted after 72h. While signs of intestinal toxicity were also observed 24h after administration of SpHL-CDDP, after 72h body weight and intestinal permeability of mice in this group were similar to those of mice in the control group. In comparison with the free CDDP treatment group, 72h after treatment mice in the SpHL-CDDP group showed better histological parameters, lower levels of inflammatory infiltrate with increased IL-10 and IgA levels, and less activation of caspase-3, ERK1/2 and NF-κB. These differences could account for the recovery of the intestinal epithelium observed in mice treated with SpHL-CDDP but not in mice treated with free CDDP. In conclusion, here we show that encapsulation of CDDP in SpHL lessens intestinal damage and that, as such, SpHL-CDDP is a promising candidate for clinical use.

Synthesis and antimicrobial evaluation of two peptide LyeTx I derivatives modified with the chelating agent HYNIC for radiolabeling with technetium-99m.

BACKGROUND: Current diagnostic methods and imaging techniques are not able to differentiate septic and aseptic inflammation. Thus, reliable methods are sought to provide this distinction and scintigraphic imaging is an interesting option, since it is based on physiological changes. In this context, radiolabeled antimicrobial peptides have been investigated as they accumulate in infectious sites instead of aseptic inflammation. The peptide LyeTx I, from the venom of Lycosa erythrognatha, has potent antimicrobial activity. Therefore, this study aimed to synthesize LyeTx I derivatives with the chelating compound HYNIC, to evaluate their antimicrobial activity and to radiolabel them with (99m)Tc. METHODS: Two LyeTx I derivatives, HYNIC-LyeTx I (N-terminal modification) and LyeTx I-K-HYNIC (C-terminal modification), were synthesized by Fmoc strategy and purified by RP-HPLC. The purified products were assessed by RP-HPLC and MALDI-ToF-MS analysis. Microbiological assays were performed against S. aureus (ATCC® 6538) and E. coli (ATCC® 10536) in liquid medium to calculate the MIC. The radiolabeling procedure of LyeTx I-K-HYNIC with (99m)Tc was performed in the presence of co-ligands (tricine and EDDA) and reducing agent (SnCl2 (.) 2H2O), and standardized taking into account the amount of peptide, reducing agent, pH and heating. Radiochemical purity analysis was performed by thin-layer chromatography on silica gel strips and the radiolabeled compound was assessed by RP-HPLC and radioactivity measurement of the collected fractions. Data were analyzed by ANOVA, followed by Tukey test (p-values < 0.05). RESULTS: Both LyeTx I derivatives were suitably synthesized and purified, as shown by RP-HPLC and MALDI-ToF-MS analysis. The microbiological test showed that HYNIC-LyeTx I (N-terminal modification) did not inhibit bacterial growth, whereas LyeTx I-K-HYNIC (C-terminal modification) showed a MIC of 5.05 µmol(.)L(-1) (S. aureus) and 10.10 µmol(.)L(-1) (E. coli). Thus, only the latter was radiolabeled with (99m)Tc. The radiochemical purity analysis of LyeTx I-K-HYNIC-(99m)Tc showed that the optimal radiolabeling conditions (10 µg of LyeTx I-K-HYNIC; 250 µg of SnCl2 (.) 2H2O; pH = 7; heating for 15 min) yielded a radiochemical purity of 87 ± 1 % (n = 3). However, RP-HPLC data suggested (99m)Tc transchelation from LyeTx I-K-HYNIC to the co-ligands (tricine and EDDA). CONCLUSIONS: The binding of HYNIC to the N-terminal portion of LyeTx I seems to affect its activity against bacteria. Nevertheless, the radiolabeling of the C-terminal derivative, LyeTx I-K-HYNIC, must be better investigated to optimize the radiolabeled compound, in order to use it as a specific imaging agent to distinguish septic and aseptic inflammation.

The role of immunomodulators on intestinal barrier homeostasis in experimental models.

The intestinal epithelium is composed of specialized epithelial cells that form a physical and biochemical barrier to commensal and pathogenic microorganisms. However, dysregulation of the epithelial barrier function can lead to increased intestinal permeability and bacterial translocation across the intestinal mucosa, which contributes to local and systemic immune activation. The increase in these parameters is associated with inflammatory bowel disease, physical exercise under heat stress, intestinal obstruction, ischemia, and mucositis, among other conditions. Lately, there has been growing interest in immunomodulatory nutrients and probiotics that can regulate host immune and inflammatory responses and possibly restore the intestinal barrier. Immunomodulators such as amino acids (glutamine, arginine, tryptophan, and citrulline), fatty acids (short-chain and omega-3 fatty acids and conjugated linoleic acids), and probiotics (Bifidobacterium, Saccharomyces, and Lactobacillus) have been reported in the literature. Here, we review the critical roles of immunomodulatory nutrients in supporting gut barrier integrity and function.

A herbal oil in water nano-emulsion prepared through an ecofriendly approach affects two tropical disease vectors

ABSTRACT Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson, Verbenaceae, is considered a great source of a bioactive volatile oil. Due to the wide range of known chemotypes, its chemical analysis is very important. Among the several activities of this volatile oil, a potential larvicidal action against Culicidae species is highlighted. However, the low water miscibility of volatile oils limits their application in aqueous media. Oil in water nano-emulsions are in the spotlight of novelty to solve this main problem. Thus, the aim of the present study was to obtain this nanostructured system with L. alba volatile oil (citral chemotype) and evaluate its larvicidal activity against Aedes aegypti and Culex quinquefasciatus larvae. The major compounds were geranial (30.02%) and neral (25.26%). Low mean droplet size (117.0 ± 1.0 nm) and low polydispersity index (0.231 ± 0.004) were observed and no major changes were observed after seven days of storage. LC50 values against C. quinquefasciatus and A. aegypti third-instar larvae were respectively 38.22 and 31.02 ppm, while LC90 values were, respectively, 59.42 and 47.19 ppm. The present study makes use of a low energy, solvent-free and ecofriendly method with reduced costs. Thus, this paper contributes significantly to phyto-nanobiotechnology of larvicidal agents, opening perspectives for the utilization of L. alba volatile oil in integrated practices of vector control.

Nanosuspension of quercetin: preparation, characterization and effects against Aedes aegypti larvae

Abstract Aedes aegypti (Diptera: Culicidae) is the main vector of some neglected diseases, including dengue. It is very important to develop formulations that increase effectiveness of vector control with low toxicity. Quercetin is a plant-derived flavonoid that modulates the development of some insects. The low water solubility of quercetin impairs the development of water-dispersible commercial products. To circumvent this problem, the preparation of nanoformulations is considered promising. Thus, this study aimed to evaluate the effect of bulk and quercetin nanosuspension against A. aegypti larvae and also to investigate their ecotoxicity. Quercetin nanosuspension was produced by a solvent displacement method followed by solvent evaporation and was maintained in two different temperatures (4 and 25 ºC). Its size distribution and zeta potential were monitored along 30 days. The influence of quercetin nanosuspension and bulk-quercetin was investigated at various concentrations against A. aegypti and the green algae Chlorella vulgaris. The quercetin nanosuspension presented higher stability at 4 ºC and negative zeta potential values. Quercetin nanosuspension and bulk-quercetin adversely affected the larvae development, especially at the highest concentrations. Larvae mortality was between 44% and 100% (48 h) for quercetin nanosuspension at 100 and 500 ppm, respectively. The bulk-quercetin induced around 50% mortality regardless the concentration used at this same time-period. Absence of emerging mosquitoes from water was observed on the survival larvae of all the treated groups. Quercetin nanosuspension was less toxic than bulk-quercetin against C. vulgaris, especially at higher concentrations. These data indicate that quercetin nanosuspension may represent a potential larvicide for A. aegypti control, once they induced larvae death and inhibited the survival ones to emerge from water. In addition, it did not demonstrated ecotoxicity against a non-target organism, highlighting its better properties, when compared to the bulk-quercetin.

Synthesis and antimicrobial evaluation of two peptide LyeTx I derivatives modified with the chelating agent HYNIC for radiolabeling with technetium-99m

Current diagnostic methods and imaging techniques are not able to differentiate septic and aseptic inflammation. Thus, reliable methods are sought to provide this distinction and scintigraphic imaging is an interesting option, since it is based on physiological changes. In this context, radiolabeled antimicrobial peptides have been investigated as they accumulate in infectious sites instead of aseptic inflammation. The peptide LyeTx I, from the venom of Lycosa erythrognatha, has potent antimicrobial activity. Therefore, this study aimed to synthesize LyeTx I derivatives with the chelating compound HYNIC, to evaluate their antimicrobial activity and to radiolabel them with 99mTc. Methods Two LyeTx I derivatives, HYNIC-LyeTx I (N-terminal modification) and LyeTx I-K-HYNIC (C-terminal modification), were synthesized by Fmoc strategy and purified by RP-HPLC. The purified products were assessed by RP-HPLC and MALDI-ToF-MS analysis. Microbiological assays were performed against S. aureus (ATCC® 6538) and E. coli (ATCC® 10536) in liquid medium to calculate the MIC. The radiolabeling procedure of LyeTx I-K-HYNIC with 99mTc was performed in the presence of co-ligands (tricine and EDDA) and reducing agent (SnCl2. 2H2O), and standardized taking into account the amount of peptide, reducing agent, pH and heating. Radiochemical purity analysis was performed by thin-layer chromatography on silica gel strips and the radiolabeled compound was assessed by RP-HPLC and radioactivity measurement of the collected fractions. Data were analyzed by ANOVA, followed by Tukey test (p-values 0.05). Results Both LyeTx I derivatives were suitably synthesized and purified, as shown by RP-HPLC and MALDI-ToF-MS analysis. The microbiological test showed that HYNIC-LyeTx I (N-terminal modification) did not inhibit bacterial growth, whereas LyeTx I-K-HYNIC (C-terminal modification) showed a MIC of 5.05 mol.L1 (S. aureus) and 10.10 mol.L1 (E. coli). Thus, only the latter was radiolabeled with 99mTc. The radiochemical purity analysis of LyeTx I-K-HYNIC-99mTc showed that the optimal radiolabeling conditions (10 g of LyeTx I-K-HYNIC; 250 g of SnCl2. 2H2O; pH = 7; heating for 15 min) yielded a radiochemical purity of 87 ± 1 % (n= 3). However, RP-HPLC data suggested 99mTc transchelation from LyeTx I-K-HYNIC to the co-ligands (tricine and EDDA). Conclusions The binding of HYNIC to the N-terminal portion of LyeTx I seems to affect its activity against bacteria. Nevertheless, the radiolabeling of the C-terminal derivative, LyeTx I-K-HYNIC, must be better investigated to optimize the radiolabeled compound, in order to use it as a specific imaging agent to distinguish septic and aseptic inflammation.

Synthesis and antimicrobial evaluation of two peptide LyeTx I derivatives modified with the chelating agent HYNIC for radiolabeling with technetium-99m

Background Current diagnostic methods and imaging techniques are not able to differentiate septic and aseptic inflammation. Thus, reliable methods are sought to provide this distinction and scintigraphic imaging is an interesting option, since it is based on physiological changes. In this context, radiolabeled antimicrobial peptides have been investigated as they accumulate in infectious sites instead of aseptic inflammation. The peptide LyeTx I, from the venom of Lycosa erythrognatha, has potent antimicrobial activity. Therefore, this study aimed to synthesize LyeTx I derivatives with the chelating compound HYNIC, to evaluate their antimicrobial activity and to radiolabel them with 99mTc. Methods Two LyeTx I derivatives, HYNIC-LyeTx I (N-terminal modification) and LyeTx I-K-HYNIC (C-terminal modification), were synthesized by Fmoc strategy and purified by RP-HPLC. The purified products were assessed by RP-HPLC and MALDI-ToF-MS analysis. Microbiological assays were performed against S. aureus (ATCC® 6538) and E. coli (ATCC® 10536) in liquid medium to calculate the MIC. The radiolabeling procedure of LyeTx I-K-HYNIC with 99mTc was performed in the presence of co-ligands (tricine and EDDA) and reducing agent (SnCl2. 2H2O), and standardized taking into account the amount of peptide, reducing agent, pH and heating. Radiochemical purity analysis was performed by thin-layer chromatography on silica gel strips and the radiolabeled compound was assessed by RP-HPLC and radioactivity measurement of the collected fractions. Data were analyzed by ANOVA, followed by Tukey test (p-values < 0.05). Results Both LyeTx I derivatives were suitably synthesized and purified, as shown by RP-HPLC and MALDI-ToF-MS analysis. The microbiological test showed that HYNIC-LyeTx I (N-terminal modification) did not inhibit bacterial growth, whereas LyeTx I-K-HYNIC (C-terminal modification) showed a MIC of 5.05 μmol.L−1 (S. aureus) and 10.10 μmol.L−1 (E. coli). Thus, only the latter was radiolabeled with 99mTc. The radiochemical purity analysis of LyeTx I-K-HYNIC-99mTc showed that the optimal radiolabeling conditions (10 μg of LyeTx I-K-HYNIC; 250 μg of SnCl2. 2H2O; pH = 7; heating for 15 min) yielded a radiochemical purity of 87 ± 1 % (n= 3). However, RP-HPLC data suggested 99mTc transchelation from LyeTx I-K-HYNIC to the co-ligands (tricine and EDDA). Conclusions The binding of HYNIC to the N-terminal portion of LyeTx I seems to affect its activity against bacteria. Nevertheless, the radiolabeling of the C-terminal derivative, LyeTx I-K-HYNIC, must be better investigated to optimize the radiolabeled compound, in order to use it as a specific imaging agent to distinguish septic and aseptic inflammation.(AU)