Biochemical Indices and Life Traits of Loggerhead Turtles (Caretta caretta) from Cape Verde Islands

The loggerhead turtle (Caretta caretta) is an endangered marine reptile for whom assessing population health requires knowledge of demographic parameters such as individual growth rate. In Cape Verde, as within several populations, adult female loggerhead sea turtles show a size-related behavioral and trophic dichotomy. While smaller females are associated with oceanic habitats, larger females tend to feed in neritic habitats, which is reflected in their physiological condition and in their offspring. The ratio of RNA/DNA provides a measure of cellular protein synthesis capacity, which varies depending on changes in environmental conditions such as temperature and food availability. The purpose of this study was to evaluate the combined use of morphometric data and biochemical indices as predictors of the physiological condition of the females of distinct sizes and hatchlings during their nesting season and how temperature may influence the physiological condition on the offspring. Here we employed biochemical indices based on nucleic acid derived indices (standardized RNA/DNA ratio-sRD, RNA concentration and DNA concentration) in skin tissue as a potential predictor of recent growth rate in nesting females and hatchling loggerhead turtles. Our major findings were that the physiological condition of all nesting females (sRD) decreased during the nesting season, but that females associated with neritic habitats had a higher physiological condition than females associated with oceanic habitats. In addition, the amount of time required for a hatchling to right itself was negatively correlated with its physiological condition (sRD) and shaded nests produced hatchlings with lower sRD. Overall, our results showed that nucleic acid concentrations and ratios of RNA to DNA are an important tool as potential biomarkers of recent growth in marine turtles. Hence, as biochemical indices of instantaneous growth are likely temperature-, size- and age-dependent, the utility and validation of these indices on marine turtles stocks deserves further study.     

Growth and IGF-I response of juvenile Nile tilapia (Oreochromis niloticus) to changes in water temperature and dietary protein level

Water temperature and dietary protein level play an important role in influencing the growth and insulin-like growth factor I (IGF-I) in Nile tilapia juveniles. The combined effect of temperature (20–34 °C) and dietary protein level (25–50%) on the specific growth rate (SGR), feed efficiency (FE), serum IGF-I level and hepatic IGF-I mRNA level was examined under laboratory conditions by employing central composite design and response surface method. Results showed that the linear effects of temperature and dietary protein level on the SGR, FE, serum IGF-I and hepatic IGF-I mRNA level were significant (P<0.05); the quadratic effects of temperature and dietary protein level on the FE and serum IGF-I were significant (P<0.05). The interaction of temperature and dietary protein level on the FE, serum IGF-I and hepatic IGF-I mRNA level all proved significant (P<0.05). The optimal temperature/dietary protein level combination was determined, i.e., 29.9 °C/40.3%, at which the greatest SGR (2.748%/d) and FE (0.775) were simultaneously arrived. Both SGR and FE were linearly correlated with serum IGF-I or hepatic IGF-I mRNA level. These results suggested that optimum combination of temperature and dietary protein level would enhance tilapia growth efficiency and IGF-I would regulate growth and FE.     

Alkyl-methylimidazolium ionic liquids affect the growth and fermentative metabolism of Clostridium sp

In this study, the effect of ionic liquids, 1-ethyl-3-methylimidazolium acetate [EMIM][Ac], 1-ethyl-3-methylimidazolium diethylphosphate [EMIM][DEP], and 1-methyl-3-methylimidazolium dimethylphosphate [MMIM][DMP] on the growth and glucose fermentation of Clostridium sp. was investigated. Among the three ionic liquids tested, [MMIM][DMP] was found to be least toxic. Growth of Clostridium sp. was not inhibited up to 2.5, 4 and 4 g L⁻¹ of [EMIM][Ac], [EMIM][DEP] and [MMIM][DMP], respectively. [EMIM][Ac] at <2.5 g L⁻¹, showed hormetic effect and stimulated the growth and fermentation by modulating medium pH. Total organic acid production increased in the presence of 2.5 and 2 g L⁻¹ of [EMIM][Ac] and [MMIM][DMP]. Ionic liquids had no significant influence on alcohol production at <2.5 g L⁻¹. Total gas production was affected by ILs at ?2.5 g L⁻¹ and varied with type of methylimidazolium IL. Overall, the results show that the growth and fermentative metabolism of Clostridium sp. is not impacted by ILs at concentrations below 2.5 g L⁻¹.     

Isolation of inhibitory RNA aptamers against severe acute respiratory syndrome (SARS) coronavirus NTPase/Helicase

Recent outbreak of Severe Acute Respiratory Syndrome (SARS) that caused almost 800 victims requires a development of efficient inhibitor against SARS coronavirus (SCV). In this study, RNA aptamers against SCV NTPase/Helicase (nsP10) were isolated from RNA library containing random sequences of 40 nts using in vitro selection technique. Nucleotide sequences of enriched RNA aptamer pool (ES15 RNA) contain AG-rich conserved sequence of 10-11 nucleotides [AAAGGR(G)GAAG; R, purine base] and/or additional sequence of 5 nucleotides [GAAAG], which mainly reside at the loop region in all the predicted secondary structures. Isolated RNAs were observed to efficiently inhibit double-stranded DNA unwinding activity of the helicase by up to ∼85% with an IC₅₀ value of 1.2 nM but show a slight effect on ATPase activity of the protein in the presence of cofactor, poly (rU). These results suggest that the pool of selected aptamers might be potentially useful as anti-SCV agents.     

DNA- and RNA-binding and enhanced DNA-photocleavage properties of a ferrocenyl-containing ruthenium(II) complex

The interaction of [Ru(bpy)₂(fip)](PF₆)₂ {bpy = 2,2′-bipyridine, fip = 2-ferrocenyl-1H-imidazo[4,5-f][1,10]-phenanthroline} with calf thymus DNA and yeast tRNA was investigated comparatively by UV-visible absorption and luminescence spectrophotometric titrations, steady-state emission quenching by [Fe(CN)₆]^4 −, ethidium bromide competition experiment, DNA thermal denaturation, viscosity measurements and salt effect studies. The results suggest that the complex binds to the DNA more strongly than to the RNA. The density functional theory calculations were also carried out in order to better understand the nucleic acid binding properties. Agarose gel electrophoresis showed that the complex exhibited enhanced DNA-photocleavage capacity on pUC 18 plasmid DNA under irradiation at 360 nm as compared with a ferrocenyl-free analogous complex.     

Torque generation by one of the motor subunits of heterotrimeric kinesin-2

Heterotrimeric kinesin-2 motors [1] and [2] transport intraflagellar transport (IFT)-particles from the base to the tip of the axoneme to assemble and maintain cilia [3], [4], [5], [6], [7], [8], [9] and [10]. These motors are distinct in containing two non-identical motor subunits together with an accessory subunit [1], [11], [12], [13], [14] and [15]. We evaluated the significance of this organization by comparing purified wild type kinesin-2 holoenzymes that support IFT in vivo, with mutant trimers containing only one type of motor domain that do not support IFT in vivo. In motility assays, wild type kinesin-2 moved microtubules (MTs) at a rate intermediate between the rates supported by the two mutants. Interestingly, one of the mutants, but not the other mutant or the wild type protein, was observed to drive a persistent counter-clock-wise rotation of the gliding MTs. Thus one of the two motor domains of heterotrimeric kinesin-2 exerts torque as well as axial force as it moves along a MT, which may allow kinesin-2 to control its circumferential position around a MT doublet within the cilium.     

Formation of a wrapped DNA-protein interface: experimental characterization and analysis of the large contributions of ions and water to the thermodynamics of binding IHF to H' DNA

To characterize driving forces and driven processes in formation of a large-interface, wrapped protein-DNA complex analogous to the nucleosome, we have investigated the thermodynamics of binding the 34-base pair (bp) H′ DNA sequence to the Escherichia coli DNA-remodeling protein integration host factor (IHF). Isothermal titration calorimetry and fluorescence resonance energy transfer are applied to determine effects of salt concentration [KCl, KF, K glutamate (KGlu)] and of the excluded solute glycine betaine (GB) on the binding thermodynamics at 20 °C. Both the binding constant K_obs and enthalpy ΔH°_obs depend strongly on [salt] and anion identity. Formation of the wrapped complex is enthalpy driven, especially at low [salt] (e.g., ΔH^o_obs = − 20.2 kcal·mol^− 1 in 0.04 M KCl). ΔH°_obs increases linearly with [salt] with a slope (dΔH°_obs/d[salt]), which is much larger in KCl (38 ± 3 kcal·mol^− 1 M^− 1) than in KF or KGlu (11 ± 2 kcal·mol^− 1 M^− 1). At 0.33 M [salt], K_obs is approximately 30-fold larger in KGlu or KF than in KCl, and the [salt] derivative SK_obs = dlnK_obs/dln[salt] is almost twice as large in magnitude in KCl (− 8.8 ± 0.7) as in KF or KGlu (− 4.7 ± 0.6).A novel analysis of the large effects of anion identity on K_obs, SK_obs and on ΔH°_obs dissects coulombic, Hofmeister, and osmotic contributions to these quantities. This analysis attributes anion-specific differences in K_obs, SK_obs, and ΔH°_obs to (i) displacement of a large number of water molecules of hydration [estimated to be 1.0(± 0.2) × 10³] from the 5340 Å² of IHF and H′ DNA surface buried in complex formation, and (ii) significant local exclusion of F⁻ and Glu⁻ from this hydration water, relative to the situation with Cl⁻, which we propose is randomly distributed. To quantify net water release from anionic surface (22% of the surface buried in complexation, mostly from DNA phosphates), we determined the stabilizing effect of GB on K_obs: dlnK_obs/d[GB]  = 2.7 ± 0.4 at constant KCl activity, indicating the net release of ca. 150 H₂O molecules from anionic surface.     

The relationship between the structures of periphery ligands and the DNA binding mode of [Ru(II)(1,10-phenanthroline)(L1L2)dipyrido[3,2-a:2',3'-c]phenazine](n+) (L1=Cl or pyridine and L2=pyridine, n=1,2)

The binding modes of the [Ru(II)(1,10-phenanthroline)(L₁L₂) dipyrido[3,2-a:2′,3′-c]phenazine]²⁺ {[Ru(phen)(py) Cl dppz]⁺ (L₁ = Cl, L₂ = pyridine) and ([Ru(phen)(py)₂dppz]²⁺ (L₁ = L₂ = pyridine)} to native DNA is compared to that of the [Ru(II)(1,10-phenanthroline)₂dipyrido[3,2-a:2′,3′-c]phenazine]²⁺ complex ([Ru(phen)₂dppz]²⁺) by various spectroscopic and hydrodynamic methods including electric absorption, linear dichroism (LD), fluorescence spectroscopy, and viscometric titration. All measured properties, including red-shift and hypochromism in the dppz absorption band, nearly perpendicular molecular plane of the dppz ligand with respect to the local DNA helix axis, prohibition of the ethidium binding, the light switch effect and binding stoichiometry, increase in the viscosity upon binding to DNA, increase in the melting temperature are in agreement with classical intercalation of dppz ligand of the [Ru(phen)₂dppz]²⁺ complex, in which both phenanthroline ligand anchored to the DNA phosphate groups by electrostatic interaction. [Ru(phen)(py)₂ dppz]²⁺ and [Ru(phen)(py) Cl dppz]⁺ complexes had one of the phenanthroline ligand replaced by either two pyridine ligands or one pyridine plus a chlorine ion. They exhibited similar protection from water molecules, interaction with DNA bases, and occupying site that is common with ethidium. The dppz ligand of these two Ru(II) complex were greatly tilted relative to the DNA helix axis, suggesting that the dppz ligand resides inside the DNA and is not perpendicular relative to the DNA helix axis. These observation suggest that anchoring the [Ru(phen)₂dppz]²⁺complex by both phenanthroline is essential for the dppz ligand to be classically intercalated between DNA base-pairs.     

Synthesis, DNA-binding and photocleavage studies of ruthenium complexes [Ru(bpy)2(mitatp)] and [Ru(bpy)2(nitatp)]

Two new ruthenium complexes [Ru(bpy)₂(mitatp)](ClO₄)₂1 and [Ru(bpy)₂(nitatp)](ClO₄)₂2 (bpy = 2,2′-bipyridine, mitatp = 5-methoxy-isatino[1,2-b]-1,4,8,9-tetraazatriphenylene, nitatp = 5-nitro-isatino[1,2-b]-1,4,8,9-tetraazatriphenylene) have been synthesized and characterized by elemental analysis, ¹H NMR, mass spectrometry and cyclic voltammetry. Spectroscopic and viscosity measurements proved that the two Ru(II) complexes intercalate DNA with larger binding constants than that of [Ru(bpy)₂(dppz)]²⁺ (dppz = dipyrido[3,2-a:2′,3′-c]phenazine) and possess the excited lifetime of microsecond scale upon binding to DNA. Both complexes can efficiently photocleave pBR322 DNA in vitro under irradiation. Singlet oxygen (¹O₂) was proved to contribute to the DNA photocleavage process, the ¹O₂ quantum yields was determined to be 0.43 and 0.36 for 1 and 2, respectively. Moreover, a photoinduced electron transfer mechanism was also found to be involved in the DNA cleavage process.     

Citric acid improves growth performance and phosphorus digestibility in Beluga (Huso huso) fed diets where soybean meal partly replaced fish meal

A 2 × 3 factorial experiment was conducted to evaluate the effect of partial substitution of dietary fish meal with soybean meal and citric acid (CA) supplementation on growth, food utilization, muscle composition and nutrient digestibility of Beluga, Huso huso. Three isonitrogenic and isoenergetic diets, as SBM₁ (soybean meal protein (SBP):fishmeal protein (FP) = 1:3), SBM₂ (SBP:FP = 2:3) and SBM₃ (SBP:FP = 1:1) containing two levels of CA (0 and 30 g kg⁻¹) were fed to triplicate groups of fish for 8 weeks. The results revealed that adding CA increased (P<0.05) the weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) and decreased (P<0.05) food conversion rate (FCR) whereas partial substitution of fishmeal with soybean meal decreased (P<0.05) growth performance. Partial replacement of fishmeal with SBM (P=0.021) as well as CA supplementation (P=0.019) and their interaction (P<0.001) affected hepatosomatic index (HSI). No differences (P>0.05) were observed for viscerosomatic index (VSI) among treatments (P>0.05). No differences (P>0.05) were detected in moisture, protein of muscle sample among treatments, but lipid content was reduced (P<0.05) while ash content increased (P=0.035) by CA. Soybean meal decreased (P<0.05) nutrient digestibility, whereas CA improved apparent protein and phosphorus (P) digestibility (P=0.011 and P<0.001 respectively). No interaction (P<0.05) between levels of SBM and CA was found on these parameters. Results of the present study indicate that Beluga has a limited ability to utilize SBM as a protein source in practical diets whereas CA can improve growth and nutrient utilization in Beluga.     

Synthesis, DNA binding, photo-induced DNA cleavage, cytotoxicity and apoptosis studies of copper(II) complexes

Two new Cu(II) complexes, [Cu(acac)(dpq)Cl] () and [Cu(acac)(dppz)Cl] () (acac = acetylacetonate, dpq = dipyrido[3,2-d:20,30-f]quinoxaline, dppz = dipyrido[3,2-a:20,30-c] phenazine), have been synthesized and their DNA binding, photo-induced DNA cleavage activity and cell cytotoxicity are studied. The complexes show good binding propensity to calf thymus DNA in the order: 2(dppz) > 1(dpq). Furthermore, two complexes exhibit efficient DNA cleavage activity on natural light or UV-A (365 nm) irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. The photo-induced DNA cleavage activity of the dppz complex 2 is found to be more efficient than its dpq analogue. In vitro study of the photocytotoxicity of two complexes on HeLa cells indicate that both of them have the potential to act as effective anticancer drugs, with IC₅₀ values of 5.25 ± 0.83 μM (1) and 4.40 ± 0.52 μM (2) in the natural light, and 2.57 ± 0.92 μM (1) and 2.18 ± 0.52 μM (2) in UV-A light. In addition, to detect an apoptotic HeLa body, cells were stained with Hoechst 33342 dye.     

Synthesis, characterization and equilibrium study of the dinuclear adducts formation between nickel(II) Salen-type complexes with diorganotin(IV) dichlorides in chloroform

Adduct formation between R₂SnCl₂ (R = methyl and n-butyl) as acceptors, and nickel(II) complexes of tetradentate Schiff base ligands ([NiL]) where L = [3-methoxysalen, N,N′-bis(3-methoxysalicylidene)ethylenediamine], [4-methoxysalen, N,N′-bis(4-methoxysalicylidene)ethylenediamine], [5-methoxysalen, N,N′-bis(5-methoxysalicylidene)ethylenediamine], [salen, N,N′-bis(salicylaldehydo)ethylenediamine], [5-chlorosalen, N,N′-bis(5-chlorosalicylidene)ethylenediamine] and [5-bromosalen, N,N′-bis(5-bromosalicylidene)ethylenediamine] as donors have been investigated in chloroform as a solvent by means of UV-Vis spectrophotometeric analysis. Adducts have been characterized by ¹H NMR, IR and electronic spectroscopy. The formation constants and the thermodynamic free energies were measured using UV-Vis spectrophotometry titration for 1:1 adduct formation at various temperatures (T = 278-308 K). The trend of the adduct formation of the nickel Schiff base complexes with a given tin acceptor decreases as follow:

Ni(3-MeOSalen)>Ni(5-MeOSalen)>Ni(4-MeOSalen)     

DNA binding mode transitions of Escherichia coli HU(alphabeta): evidence for formation of a bent DNA--protein complex on intact, linear duplex DNA

Escherichia coli HU_αβ, a major nucleoid-associated protein, organizes chromosomal DNA and facilitates numerous DNA transactions. Using isothermal titration calorimetry, fluorescence resonance energy transfer and a series of DNA lengths (8 bp, 15 bp, 34 bp, 38 bp and 160 bp) we established that HU_αβ interacts with duplex DNA using three different nonspecific binding modes. Both the HU to DNA molar ratio ([HU]/[DNA]) and DNA length dictate the dominant HU binding mode. On sufficiently long DNA (≥ 34 bp), at low [HU]/[DNA], HU populates a noncooperative 34 bp binding mode with a binding constant of 2.1 ± 0.4 × 10⁶ M^− 1, and a binding enthalpy of + 7.7 ± 0.6 kcal/mol at 15 °C and 0.15 M Na⁺. With increasing [HU]/[DNA], HU bound in the noncooperative 34 bp mode progressively converts to two cooperative (ω∼20) modes with site sizes of 10 bp and 6 bp. These latter modes exhibit smaller binding constants (1.1 ± 0.2 × 10⁵ M^− 1 for the 10 bp mode, 3.5 ± 1.4 × 10⁴ M^− 1 for the 6 bp mode) and binding enthalpies (4.2 ± 0.3 kcal/mol for the 10 bp mode, − 1.6 ± 0.3 kcal/mol for the 6 bp mode). As DNA length increases to 34 bp or more at low [HU]/[DNA], the small modes are replaced by the 34 bp binding mode. Fluorescence resonance energy transfer data demonstrate that the 34 bp mode bends DNA by 143 ± 6° whereas the 6 bp and 10 bp modes do not. The model proposed in this study provides a novel quantitative and comprehensive framework for reconciling previous structural and solution studies of HU, including single molecule (force extension measurement), fluorescence, and electrophoretic gel mobility-shift assays. In particular, it explains how HU condenses or extends DNA depending on the relative concentrations of HU and DNA.     

Deceptively simple but simply deceptive - Caenorhabditis elegans lifespan studies: Considerations for aging and antioxidant effects

The nematode worm Caenorhabditis elegans (C. elegans) is increasingly popular as a model organism for aging studies as well as for testing antioxidants and other compounds for effects on longevity. However, results in the literature are sometimes confusing and contradictory [1], [2], [3] and [4]. This review introduces C. elegans as a model organism, discusses aspects that make it attractive for aging and antioxidant research, and addresses some problems and potential artifacts.     

The stability of DNA-porphyrin complexes in the presence of Mn(II) ions

The complex formation of porphyrins with DNA leads to changes of stability of DNA. In the present study we investigated binding properties and the thermodynamic parameters of a water-soluble, cationic planar Cu(II)-containing meso-tetrakis(4-N-butyl-pyridiniumyl)porphyrin [CuTButPyP4] and nonplanar Co(II)-containing meso-tetrakis(4-N-butyl-pyridiniumyl)porphyrin [CoButPyP4] with calf thymus DNA in the presence of divalent manganese ions. For displaying the changes of thermodynamic parameters (T_m and ΔT) the melting curves of DNA-porphyrin complexes in the presence of Mn²⁺ ions have been obtained. The enthalpy (ΔH) of helix-coil transition has been also evaluated. It was shown that the binding of ions to DNA proceeds in two stages depending on the manganese/DNA phosphates molar ratio [Mn]/[P]. At the first stage (0.001 < [Mn]/[P] < 1), the interaction of manganese ions with DNA phosphates occurs, causing an additional screening of their negative charge and the stabilization of the double helix. As a result, the best conditions for intercalation of CuTButPyP4 or of peripheral rings of CoButPyP4 occur. The significant increase of T_m, but less changes of ΔT were observed. At the second stage (1 < [Mn]/[P] < 4), the ions interact with both the phosphates and the nitrogen bases of DNA. At this stage, it is possible for the manganese ion to coordinate simultaneously to the oxygen atom of the phosphate and the neighboring base of DNA. At a higher [Mn]/[P] ratio, the destabilization of the double helix begins, and partial breakage of the hydrogen bonds between the nitrogen bases occurs. Respectively the destabilization of DNA in the presence of both porphyrins takes place.     

Studies on synthesis, characterization, and G-quadruplex binding of Ru(II) complexes containing two dppz ligands

In this work, the interaction between the guanine-rich single-strand oligomer AG₃(T₂AG₃)₃ quadruplex and two Ru(II) complexes, [Ru(L¹)(dppz)₂](PF₆)₄ (1) and [Ru(L²)(dppz)₂](PF₆)₄ (2) (L¹ = 5,5′-di(1-(trimethylammonio)methyl)-2,2′-dipyridyl cation, L² = 5,5′-di(1-(triethylammonio)methyl)-2,2′-dipyridyl cation, dppz = dipyrido[3,2-a:2′,3′-c] phenazine), has been studied by UV-Visible, fluorescence, DNA melting, and circular dichroism in K⁺ buffer. The two complexes after binding to G-quadruplex have shown different DNA stability and fluorescence enhancement. The results show that both complexes can induce the stabilization of quadruplex DNA. ΔT_m values of complexes 1 and 2 at [Ru]/[DNA] ratio of 1:1 were 9.4 and 7.0, respectively. Binding stoichiometry along with the quadruplex was investigated through a luminescence-based Job plot. The major inflection points for complexes 1 and 2 were 0.49 and 0.46, respectively. The data were consistent with the binding mode at a [quadruplex]/[complex] ratio of 1:1. In addition, the conformation of G-quadruplex was not changed by the complexes at the high ionic strength of K⁺ buffer.     

DNA-binding and photocleavage studies of mixed polypyridyl ruthenium(II) complexes with calf thymus DNA

New mixed polypyridyl {NMIP = 2′-(2″-nitro-3″,4″-methylenedioxyphenyl)imidazo-[4′,5′-f][1,10]-phenanthroline, dmb = 4,4′-dimethyl-2,2′-bipyridine, bpy = 2,2′-bipyridine} ruthenium(II) complexes [Ru(dmb)₂(NMIP)]²⁺ (1) and [Ru(bpy)₂(NMIP)]²⁺ (2) have been synthesized and characterized. The binding of these complexes to calf thymus DNA (CT-DNA) has been investigated with spectroscopic methods, viscosity and electrophoresis measurements. The experimental results indicate that both complexes could bind to DNA via partial intercalation from the minor/major groove. In addition, both complexes have been found to promote the single-stranded cleavage of plasmid pBR 322 DNA upon irradiation. Under comparable experimental conditions compared with [Ru(phen)₂(NMIP)]²⁺, during the course of the dialysis at intervals of time, the CD signals of both complexes started from none, increased to the maximum magnitude, then no longer changed, and the activity of effective DNA cleavage dependence upon concentration degree lies in the following order: [Ru(phen)₂NMIP]²⁺ > complex 2 > complex 1.     

Side-on binding of p-sulphonatocalix[4]arene to the dinuclear platinum complex trans-[{PtCl(NH3)2}2μ-dpzm] and its implications for anticancer drug delivery

The utility of p-sulphonatocalix[4]arene (s-CX[4]) as a drug delivery vehicle for multinuclear platinum anticancer agents, using trans-[{PtCl(NH₃)₂}₂μ-dpzm]²⁺ (di-Pt; where dpzm = 4,4′-dipyrazolylmethane) as a model complex, has been examined using ¹H nuclear magnetic resonance, electrospray ionisation mass spectrometry, molecular modelling and in vitro growth inhibition assays. s-CX[4] binds di-Pt in a side-on fashion in a ratio of 1:1, with the dpzm ligand of the metal complex located within the s-CX[4] cavity with binding further stabilised by ion-ion interactions and hydrogen bonding between the metal complex am(m)ine groups and the s-CX[4] sulphate groups. Partial encapsulation of di-Pt within the cavity does not prevent binding of 5′-guanosine monophosphate to the metal complex. When bound to two individual guanosine molecules, di-Pt also remains partially bound by s-CX[4]. The cytotoxicity of free di-Pt and s-CX[4] and their host guest complex was examined using in vitro growth inhibition assays in the A2780 and A2780cis human ovarian cancer cell lines. Free di-Pt has an IC₅₀ of 100 and 60 μM, respectively, in the cell lines, which is significantly less active than cisplatin (1.9 and 8.1 μM, respectively). s-CX[4] displays no cytotoxicity at concentrations up to 1.5 mM and does not affect the cytotoxicity of di-Pt, probably because its low binding constant to the metal complex (6.8 × 10⁴ M⁻¹) means the host-guest complex is mostly disassociated at biologically relevant concentrations.