Ablation of sensory nerves favours melanoma progression.

The tumour mass is composed not only of heterogeneous neoplastic cells, but also a variety of other components that may affect cancer cells behaviour. The lack of detailed knowledge about all the constituents of the tumour microenvironment restricts the design of effective treatments. Nerves have been reported to contribute to the growth and maintenance of numerous tissues. The effects of sensory innervations on tumour growth remain unclear. Here, by using state-of-the-art techniques, including Cre/loxP technologies, confocal microscopy, in vivo-tracing and chemical denervation, we revealed the presence of sensory nerves infiltrating within the melanoma microenvironment, and affecting cancer progression. Strikingly, melanoma growth in vivo was accelerated following genetic ablation or chemical denervation of sensory nerves. In humans, a retrospective analysis of melanoma patients revealed that increased expression of genes related to sensory nerves in tumours was associated with better clinical outcomes. These findings suggest that sensory innervations counteract melanoma progression. The emerging knowledge from this research provides a novel target in the tumour microenvironment for therapeutic benefit in cancer patients.

P1G10, the Proteolytic Fraction from Vasconcellea cundinamarcensis, Stimulates Tissue Repair after Acute Exposure to Ultraviolet B Radiation.

BACKGROUND: P1G10 is a cysteine proteolytic fraction from Vasconcellea cundinamarcensis latex, obtained by chromatographic separation on Sephadex-G10 and ultrafiltration. This fraction enhances healing in different models of skin lesions, and displays a protective/healing effect against gastric ulcers, where it was suggested an antioxidant role. METHODS: We evaluated here the effect of topical treatment with P1G10, in mice lesions induced by UVB. RESULTS: After single exposure to 2.4 J cm-2 UVB, P1G10 reduced erythema, increased cellularity of hypodermis, enhanced MPO activity and IL1ß, and inhibited COX2 levels. These results point to an anti-inflammatory effect by P1G10. This fraction displayed antioxidant activity by reversing the depletion of glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and reducing the catalase activity increased by UVB. These changes may be related to a reduction in MDA observed in groups treated with P1G10. P1G10 also inhibited MMP-9, caspase-3 and pkat while increasing p53 levels.

Cysteine Proteases from V. cundinamarcensis (C. candamarcensis) Inhibit Melanoma Metastasis and Modulate Expression of Proteins Related to Proliferation, Migration and Differentiation.

Previous studies showed that P1G10, a proteolytic fraction from Vasconcellea cundinamarcensis latex, reduced the tumor mass in animals bearing melanoma, increased in vitro DNA fragmentation and decreased cell adhesion. Here, we present some molecular and cellular events related to the antimetastatic effect induced by the CMS-2 fraction derived from P1G10 in metastatic melanoma B16-F10 and melanocyte Melan-a. Using difference gel electrophoresis and mass spectrometry, we identified four proteins overexpressed in tumor cells, all of them related to proliferation, survival, migration and cell invasion, that had their expression normalized upon treatment with CMS-2: nucleophosmin 1, heat shock protein 65, calcyclin binding protein and eukaryotic translation initiation factor 4H. In addition, some antioxidant and glycolytic enzymes show increased expression after exposure to CMS-2, along with an induction of melanogenesis (differentiation marker). The down regulation of cofilin 1, a protein involved in cell motility, may explain the inhibition of cell migration and dendritic-like outgrowth in B16-F10 and Melan-a, observed after CMS-2 treatment. Taken together, it is argued that CMS-2 modulates the expression of proteins related to metastatic development, driving the cell to a more differentiated-like state. These effects support the CMS-2 antimetastatic activity and place this fraction in the category of anticancer agent.

Silver(I) complexes with chromone-derived hydrazones: investigation on the antimicrobial and cytotoxic effects.

Complexes [Ag(HCrPh)2]NO3·2H2O (1) and [Ag(HCrpClPh)2]NO3 (2) were obtained with 3-formyl-6-methylchromone-phenyl hydrazone (HCrPh, HL1) and 3-formyl-6-methylchromone-para-chloro-phenyl hydrazone (HCrpClPh, HL2). Although the hydrazones were inactive, upon coordination to silver(I) antifungal activity significantly improved against several Candida strains. Complexes (1-2) revealed to be more active than silver nitrate, silver sulfadiazine and the reference drug nystatin against Candida parapsilosis. The cytotoxic activities of the hydrazones and their silver(I) complexes were evaluated in comparison with cisplatin on B16F10 (metastatic melanoma) and Melan-a (non-tumorigenic melanocyte) cells. The hydrazones showed low cytotoxicity against B16F10 cells, reducing only about 20% of cell viability at the concentration of 10 µM. Upon coordination to silver(I) the cytotoxic effect did not appreciably change in complex (1) while complex (2) proved to be as cytotoxic as cisplatin and much more cytotoxic than both the free ligand and silver nitrate at 1 µM. Both complexes (1) and (2) were less active than cisplatin on non-malignant Melan-a cells, indicating that these compounds might promote less damage on normal cells.

Psychotria viridis: Chemical constituents from leaves and biological properties.

The phytochemical study of hexane, chloroform and methanol extracts from leaves of Psychotria viridis resulted in the identification of: the pentacyclic triterpenes, ursolic and oleanolic acid; the steroids, 24-methylene-cycloartanol, stigmasterol and ß-sitosterol; the glycosylated steroids 3-O-ß-D-glucosyl-ß-sitosterol and 3-O-ß-D-glucosyl-stigmasterol; a polyunsaturated triterpene, squalene; the esters of glycerol, 1-palmitoylglycerol and triacylglycerol; a mixture of long chain hydrocarbons; the aldehyde nonacosanal; the long chain fat acids hentriacontanoic, hexadecanoic and heptadenoic acid; the ester methyl heptadecanoate; the 4-methyl-epi-quinate and two indole alkaloids, N,N-dimethyltryptamine (DMT) and N-methyltryptamine. The chemical structures were determined by means of spectroscopic (IR, 1H and 13C NMR, HSQC, HMBC and NOESY) and spectrometric (CG-MS and LCMS-ESI-ITTOF) methods. The study of biologic properties of P. viridis consisted in the evaluation of the acetylcholinesterase inhibition and cytotoxic activities. The hexane, chloroform, ethyl acetate and methanol extracts, the substances 24-methylene-cycloartanol, DMT and a mixture of 3-O-ß-D-glucosyl-ß-sitosterol and 3-O-ß-D-glucosyl-stigmasterol showed cholinesterase inhibiting activity. This activity induced by chloroform and ethyl acetate extracts was higher than 90%. The methanol and ethyl acetate extracts inhibit the growth and/or induce the death of the tumor cells strains B16F10 and 4T1, without damaging the integrity of the normal cells BHK and CHO. DMT also demonstrated a marked activity against tumor cell strains B16F10 and 4T1.

Antiangiogenesis, loss of cell adhesion and apoptosis are involved in the antitumoral activity of Proteases from V. cundinamarcensis (C. candamarcensis) in murine melanoma B16F1.

The proteolytic enzymes from V. cundinamarcensis latex, (P1G10), display healing activity in animal models following various types of lesions. P1G10 or the purified isoforms act as mitogens on fibroblast and epithelial cells by stimulating angiogenesis and wound healing in gastric and cutaneous ulcers models. Based on evidence that plant proteinases act as antitumorals, we verified this effect on a murine melanoma model. The antitumoral effect analyzed mice survival and tumor development after subcutaneous administration of P1G10 into C57BL/6J mice bearing B16F1 low metastatic melanoma. Possible factors involved in the antitumoral action were assessed, i.e., cytotoxicity, cell adhesion and apoptosis in vitro, haemoglobin (Hb), vascular endothelial growth factor (VEGF), tumor growth factor-ß (TGF-ß), tumor necrosis factor-α (TNF-α) content and N-acetyl-glucosaminidase (NAG) activity. We observed that P1G10 inhibited angiogenesis measured by the decline of Hb and VEGF within the tumor, and TGF-ß displayed a non-significant increase and TNF-α showed a minor non-significant reduction. On the other hand, there was an increase in NAG activity. In treated B16F1 cells, apoptosis was induced along with decreased cell binding to extracellular matrix components (ECM) and anchorage, without impairing viability.

In vitro studies of the activity of dithiocarbamate organoruthenium complexes against clinically relevant fungal pathogens.

The in vitro antifungal activity of nine dirutheniumpentadithiocarbamate complexes C1-C9 was investigated and assessed for its activity against four different fungal species with clinical interest and related to invasive fungal infections (IFIs), such as Candida spp. [C. albicans (two clinical isolates), C. glabrata, C. krusei, C. parapsolisis, C. tropicalis, C.dubliniensis (six clinical isolates)], Paracoccidioides brasiliensis (seven clinical isolates), Cryptococcus neoformans and Sporothrix schenckii. All synthesized complexes C1-C9 and also the free ligands L1-L9 were submitted to in vitro tests against those fungi and the results are very promising, since some of the obtained MIC (minimal inhibitory concentration) values were very low (from 10-6 mol mL-1 to 10-8 mol mL-1) against all investigated clinically relevant fungal pathogens, except for C. glabrata, that the MIC values are close to the ones obtained for fluconazole, the standard antifungal agent tested. Preliminary structure-activity relations (SAR) might be suggested and a strong influence from steric and lipophilic parameters in the antifungal activity can be noticed. Cytotoxicity assays (IC50) showed that the complexes are not as toxic (IC50 values are much higher-30 to 200 fold-than MIC values). These ruthenium complexes are very promising lead compounds for novel antifungal drug development, especially in IFIs, one of most harmful emerging infection diseases (EIDs).

Improved pharmacological profile of the lipophilic antitumor dichloro-(N-dodecyl)-propanediamine-platinum(II) complex after incorporation into pegylated liposomes.

Liposome encapsulation of platinum (Pt) drugs has emerged as a promising strategy to overcome their toxicity and cellular Pt resistance. The aim of the present work was to examine the impact of liposome encapsulation of a novel antitumor lipophilic Pt complex, dichloro-(N-dodecyl)-propanediamine-platinum(II) complex (DDPP), on its pharmacological profile as an antitumor agent. Biological assays included acute toxicity and histopathological evaluations, pharmacokinetics, and growth inhibition of B16-F1 tumor cells in C57Bl/6 mice. Comparison was made with cisplatin and free DDPP dissolved in castor oil. DDPP encapsulated in pegylated liposomes showed reduced acute toxicity in mice following intraperitoneal administration, compared with the free complex. Free DDPP at 5 mg Pt/kg induced histopathological alterations in the liver, in contrast to liposomal DDPP and cisplatin. Interestingly, the marked loss of body weight following the treatment of mice with cisplatin was not observed after liposomal DDPP at the same Pt dose. Liposomal DDPP was found to inhibit tumor growth significantly, when administered at 5 mg Pt/kg/day for 3 days, similar to cisplatin, but in contrast to the free complex. Pharmacokinetic studies after intraperitoneal and intravenous administrations at 5 mg Pt/kg indicated greater and more prolonged Pt levels in the plasma, liver, spleen, and kidneys from liposomal DDPP, compared with free DDPP or cisplatin. The tumor concentration of Pt increased after liposomal DDPP over the 24-h period, whereas it decreased after cisplatin. In conclusion, the encapsulation of DDPP in pegylated liposomes reduced the drug toxicity and enhanced its antitumoral activity in mice, as a result of improved drug pharmacokinetics.

X-ray crystal structure of CMS1MS2: a high proteolytic activity cysteine proteinase from Carica candamarcensis.

CMS1MS2 (CC-Ib) from Carica candamarcensis (Vasconcellea cundinamarcensis) is a cysteine proteinase found as a single polypeptide containing 213 residues of 22,991 Da. The enzyme was purified by three chromatographic steps, two of them involving cationic exchange. Crystals of CMS1MS2 complexed with E-64 were obtained by the hanging drop vapor-diffusion method at 291 K using ammonium sulfate and polyethylene glycol 4000/8000 as precipitant. The complex CMS1MS2-E-64 crystallized in the tetragonal space group P4(1)2(1)2 with unit-cell parameters; a = b = 73.64, c = 118.79 Å. The structure was determined by Molecular Replacement and refined at 1.87 Å resolution to a final R factor of 16.2 % (R (free) = 19.3 %). Based on the model, the structure of CMS1MS2 (PDB 3IOQ) ranks as one of the least basic cysteine isoforms from C. candamarcensis, is structurally closer to papain, caricain, chymopapain and mexicain than to the other cysteine proteinases, while its activity is twice the activity of papain towards BAPNA substrate. Two differences, one in the S2 subsite and another in the S3 subsite of CMS1MS2 may contribute to the enhanced activity relative to papain. In addition, the model provides a structural basis for the sensitivity of CMS1MS2 to inhibition by cystatin, not shown by other enzymes of the group, e.g., glycyl endopeptidase and CMS2MS2.

Nanohydroxyapatite/Titanate Nanotube Composites for Bone Tissue Regeneration.

Strategies for the production of new nanocomposites that promote bone tissue regeneration are important, particularly those that enhance the osteoinduction of hydroxyapatite in situ. Here, we studied and report the synthesis of nanohydroxyapatite and titanate nanotube (nHAp/TiNT) composites formulated at different concentrations (1, 2, 3, and 10 wt % TiNT) by means of a wet aqueous chemical reaction. The addition of TiNT affects the morphology of the nanocomposites, decreasing the average crystallite size from 54 nm (nHAp) to 34 nm (nHAp/TiNT10%), while confirming its interaction with the nanocomposite. The crystallinity index (CI) calculated by Raman spectroscopy and XRD showed that the values decreased according to the increase in TiNT concentration, which confirmed their addition to the structure of the nanocomposite. SEM images showed the presence of TiNTs in the nanocomposite. We further verified the potential cytotoxicity of murine fibroblast cell line L929, revealing that there was no remarkable cell death at any of the concentrations tested. In vivo regenerative activity was performed using oophorectomized animal (rat) models organized into seven groups containing five animals each over two experimental periods (15 and 30 days), with bone regeneration occurring in all groups tested within 30 days; however, the nHAp/TiNT10% group showed statistically greater tissue repair, compared to the untreated control group. Thus, the results of this study demonstrate that the presently formulated nHAp/TiNT nanocomposites are promising for numerous improved bone tissue regeneration applications.

Skin-healing activity and toxicological evaluation of a proteinase fraction from Carica candamarcensis.

Previous studies demonstrated that proteinases from latex of C. candamarcensis act as mitogens on fibroblast and epithelial cells and a subsequent report showed their protective, angiogenic and wound healing effects on gastric ulcers. In this study, we present evidence of skin healing activity by the group of proteinases known as P1G10. By using a hairless mouse model, we compared the healing effect following topical application of various concentrations of P1G10. The data confirm that healing actions take place between 0.1 and 1%, without adverse local irritation or systemic toxicological action after a prolonged period of use. The wound healing effect is unaltered when P1G10 is previously inhibited with iodoacetamide. The low permeation of the hydrosoluble formulation Polawax(®) supports the maintenance of the drug at the site of application. These results extend the healing properties of these groups of enzymes in situations of dermatological trauma and open the way to future clinical applications.

In vitro susceptibility of Aspergillus spp. to dithiocarbamate organoruthenium compounds.

The in vitro antifungal activity of ruthenium dithiocarbamate compounds (1-5) was investigated and assessed for its activity against seven different species of Aspergillus (Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus nomius, Aspergillus tamarii and Aspergillus terreus). Analysis of in vitro susceptibility was performed using broth microdilution assay following the Clinical and Laboratory Standards Institute guidelines for filamentous fungi. The cytotoxicity was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Aspergillus clavatus and A. fumigatus were more susceptible species for complexes 1 and 2. Other complexes showed excellent minimum inhibitory concentration (4-64 µg ml(-1)) against most microorganisms. Complexes 1 and 2 are respectively 180- and 95-fold more active than the corresponding free ligands against A. clavatus and the complex 5 is 46-fold more active than free ligand against A. niger. Aspergillus niger was more susceptible to the action of the complexes 1 and 5 (16 µg ml(-1)). A low cytotoxic activity (IC(50) > 10(-6) mol l(-1) ) on normal mammalian cells (BHK-21) to the evaluated complexes was measured. Ruthenium complexes are promising antifungal agents against the development of novel effective drug against different species of Aspergillus; however, for A. nomius and A. terreus, they were not active in the highest concentration tested.

Cenostigma macrophyllum Tul. var. acuminata Teles Freire Fraction Leaves Stimulate Gastric Healing in Rats and Human Cell Cultures.

Cenostigma macrophyllum Tul. var. acuminata Teles Freire (Leguminosae-Caesalpinioideae) is a medicinal plant traditionally used for treatment of gastric ulcer. This study evaluated the ulcer-healing activity of the hydroalcoholic fraction of C. macrophyllum Tul. var. acuminata Teles Freire leaves (Cm-FHA) and the tea of the leaves of C. macrophyllum (Cm-tea), as well as the possible action of Cm-FHA, through in vitro models. Leaves of C. macrophyllum were dried and powdered to obtain the Cm-FHA. Subsequently, the Cm-FHA was characterized phytochemically and biologically. Besides, Cm-tea was prepared. The gastric healing effects of Cm-tea and Cm-FHA were analyzed using the model of acetic acid-induced gastric ulcer in rats. The human gastric adenocarcinoma (AGS) cell line was employed as an in vitro model. Cm-tea promoted a protective effect against gastric ulcers induced by absolute ethanol. Cm-FHA or Cm-tea (100 mg/kg/7 days) exhibited a significant healing effect on ulcers induced by acetic acid. In the histological analysis, gastric mucosa treated with Cm-FHA or Cm-tea advanced restoration of the mucosal epithelium. In vitro, lower concentrations of Cm-FHA stimulated cell proliferation in the BrdU assay and cell migration. Cm-tea and Cm-FHA present a significant gastric healing effect in in vivo and in vitro models.

Stimulation of fibroblast proliferation by the plant cysteine protease CMS2MS2 is independent of its proteolytic activity and requires ERK activation.

The cysteine protease CMS2MS2 from Carica candamarcensis latex has been shown to enhance proliferation of L929 fibroblast and to activate the extracellular signal-regulated protein kinase (ERK). In experiments with CMS2MS2 irreversibly inhibited by E-64, the proliferative effect on fibroblasts remains unaffected. ERK phosphorylation mediated by CMS2MS2 was abolished in the presence of PD 98059 or U0126, both MAPK cascade inhibitors. In addition, these inhibitors suppress the mitogenic activity of intact CMS2MS2 or CMS2MS2-E-64. Furthermore, ERK phosphorylation and the mitogenic effect are partially suppressed by a phospholipase C (PLC) inhibitor. These data suggest that the mitogenic effect of CMS2MS2 on fibroblasts is independent of its proteolytic activity, requires ERK phosphorylation, and involves activation of PLC.

Antioxidant and cytotoxic activities of Centella asiatica (L) Urb.

In the present study, the phenolic (Folin-Dennis) and flavonoid (colorimetric assay) constituents, antioxidant [2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay] and cytotoxic activities of an aqueous extract (AE) of Centella asiatica leaves were investigated. The aqueous extract (50 g/L) was obtained by infusion followed by cold maceration for 24 h. The levels of phenolic and flavonoid compounds were 2.86 g/100 g and 0.361 g/100 g, respectively. The AE showed elevated DPPH scavenging activity, with an IC(50) value of 31.25 microg/mL. The AE had a promising activity against mouse melanoma (B(16)F(1)), human breast cancer (MDA MB-231) and rat glioma (C(6)) cell lines, with IC(50) values of 698.0, 648.0 and 1000.0 microg/mL, respectively. A positive correlation was established between the level of flavonoids, antioxidant and antitumor activities.

Plant cysteine proteinases: evaluation of the pharmacological activity.

Cysteine proteinases are involved in virtually every aspect of plant physiology and development. They play a role in development, senescence, programmed cell death, storage and mobilization of germinal proteins, and in response to various types of environmental stress. In this review, we focus on a group of plant defensive enzymes occurring in germinal tissue of Caricaceae. These enzymes elicit a protective response in the unripe fruit after physical stress. We propose that these enzymes follow a strategy similar to mammalian serine proteinases involved in blood clotting and wound healing. We show evidence for the pharmacological role of plant cysteine proteinases in mammalian wound healing, immunomodulation, digestive conditions, and neoplastic alterations.

The proteolytic activities in latex from Carica candamarcensis.

Prior evidence suggests that proteinases in latex from Caricaceae protect against injuries induced by physical wounding. While the proteolytic enzymes from Carica papaya are well characterized, the homologues from Carica candamarcensis were not given similar attention, probably because its distribution is restricted to South American regions. We describe the chromatographic steps to fractionate 14 components from C. candamarcensis, 12 of them displaying amidase activity. The mass of these proteins plus two others isolated by HPLC rank between 23,943 and 22,991Da, and their N-terminal sequences showed similarities or identities with the enzymes described earlier in this species. Following CM-Sephadex chromatography two major peaks containing proteolytic activity were resolved. Each of these peaks was further resolved by Mono S chromatography yielding several purified fractions. The kinetic parameters of two of the Mono S purified enzymes originated from each of the CMS-Sephadex peaks were determined. While the Km with (Pyr-Phe-Leu-pNA), is similar in both enzymes, the kcat for one of them is 10-fold lower than the other. Based on these differences it is proposed that two groups of proteinases exist in latex of C. candamarcensis.

Amifostine protection against mitomycin-induced chromosomal breakage in fanconi anaemia lymphocytes.

Fanconi anaemia (FA) is a rare genetic chromosomal instability syndrome caused by impairment of DNA repair and reactive oxygen species (ROS) imbalance. This disease is also related to bone marrow failure and cancer. Treatment of these complications with radiation and alkylating agents may enhance chromosomal breakage. We have evaluated the effect of amifostine (AMF) on basal and mitomycin C (MMC)-induced chromosomal breakage in FA blood cells using the micronucleus assay. The basal micronuclei count was higher among FA patients than healthy subjects. Pre-treatment with AMF significantly inhibited micronucleation induced by MMC in healthy subjects (23.4 +/- 4.0 - MMC vs 12.3 2.9 - AMF --> MMC) MN/1000CB, p < 0.01, one way ANOVA) as well as in FA patients (80.0 +/- 5.8 - MMC vs 40.1 +/- 5.8 - AMF --> MMC) MN/1000CB, p < 0.01, ANOVA). Release of ROS by peripheral blood mononuclear cells treated with AMF -> MMC and measured by chemoluminometry showed that AMF-protection was statistically higher among FA patients than in healthy individuals. Based on these results we suggest that AMF prevents chromosomal breakage induced by MMC, probably by its antioxidant effect.

The Proteolytic Fraction from Latex of Vasconcellea cundinamarcensis (P1G10) Enhances Wound Healing of Diabetic Foot Ulcers: A Double-Blind Randomized Pilot Study.

INTRODUCTION: The aim of the study was to investigate the role of the proteolytic fraction from Vasconcellea cundinamarcensis, designated as P1G10, on the healing of chronic foot ulcers in neuropathic patients with diabetes 2. METHODS: Fifty patients were enrolled in a prospective, randomized, double-blind trial, to verify the efficacy and safety of a topical dressing formulated with 0.1% P1G10, intended for wound healing, versus a hydrogel (control) protocol. Upon completion of the intervention, the outcome evaluated the number of patients attaining full epithelization (100%), or at least 80% healing. Statistical analysis compared the data on each group for the significance of the differences. RESULTS: Collection of data was finished in week 16, and the results were analyzed by intention to treat. The results showed that, in the control group, 5 patients attained 100% ulcer healing, 3 patients ≥ 80% healing and 11 experienced ulcer changes ≤ 80%, and the remainder showed no changes or their wounds became worse. Meanwhile, in the P1G10 group, 11 patients experienced full healing, 4 had healing ≥ 80% and 5 had ulcer changes ≤ lower than 80%, and the remainder showed no changes or their wounds became worse. The healing incidence for the first endpoint (100% healing) showed that the P1G10 group was 2.95-fold more efficacious than the control group (CI 95%) and 2.52-fold (CI, 95%) higher than its control for the second endpoint (80% healing). CONCLUSIONS: These data support the hypothesis that topical application of the proteolytic fraction identified as P1G10 significantly enhances foot ulcer healing compared to hydrogel treatment.

[Ag(L)NO3] Complexes with 2-Benzoylpyridine-Derived Hydrazones: Cytotoxic Activity and Interaction with Biomolecules.

Complexes [Ag(H2BzPh)NO3] (1), [Ag(H2BzpCH3Ph)NO3] (2), [Ag(H2BzpClPh)NO3] (3), and [Ag(H2BzpNO2Ph)NO3] (4) were synthesized with 2-benzoylpyridine benzoylhydrazone (H2BzPh) and its para-methyl-benzoylhydrazone (H2BzpCH3Ph), para-chloro-benzoylhydrazone (H2BzpClPh), and para-nitro-benzoylhydrazone (H2BzpNO2Ph) derivatives. Experimental data indicate that the nitrate ligand binds more strongly to the silver center through one of the oxygen atoms, whereas the second oxygen atom from nitrate and the hydrazone oxygen makes much weaker interactions with the metal. Dissociation of nitrate most probably occurs in solution and in biological media. Interestingly, theoretical calculations suggested that when dissociation of the nitrate takes place, all bond orders involving the metal and the atoms from the hydrazone ligand increase significantly, showing that the bonding of nitrate results in the weakening of all other interactions in the metal coordination sphere. Upon complexation of the hydrazones to silver(I), cytotoxicity against B16F10 metastatic murine melanoma cells increased in all cases. Complexes (1-3) proved to be more cytotoxic than cisplatin. All compounds were more cytotoxic to B16F10 cells than to nontumorigenic murine Melan-A melanocyte cells. Interestingly, the selectivity index (SI = IC50 non-malignant cells/IC50 tumor cells) of complex (1), SI = 23, was much higher than that of the parent hydrazone ligand, SI = 9.5. Studies on the interactions of complexes (1-3) with DNA suggested that although (1-3) interact with calf thymus DNA by an intercalative mode, direct covalent binding of silver(I) to DNA probably does not occur. Complexes (1-3) interact in vitro with human serum albumin indicating that these compounds could be transported by albumin.