Gastrointestinal toxicity, antiinflammatory activity, and superoxide dismutase activity of copper and zinc complexes of the antiinflammatory drug indomethacin

Synthesis, Structure and Biological Activity of Indole-Imidazole Complexes with ZnCl2: Can Coordination Enhance the Functionality of Bioactive Ligands?

The ability of the indole-imidazole hybrid ligands to coordinate with the Zn(II) ion and the resulting structures of this new class of coordination compounds were analyzed in order to determine their structural properties and biological functionalities. For this purpose, six novel Zn(II) complexes, [Zn(InIm)₂Cl₂] (1), [Zn(InMeIm)₂Cl₂] (2), [Zn(IniPrIm)₂Cl₂] (3), [Zn(InEtMeIm)₂Cl₂] (4), [Zn(InPhIm)₂Cl₂] (5) and [Zn₂(InBzIm)₂Cl₂] (6) (where InIm is 3-((1H-imidazol-1-yl)methyl)-1H-indole), were synthesized by the reactions of ZnCl₂ and the corresponding ligand in a 1:2 molar ratio in methanol solvent at an ambient temperature. The structural and spectral characterization of these complexes was performed using NMR, FT-IR and ESI-MS spectrometry and elemental analysis, and the crystal structures of 1-5 were determined using single-crystal X-ray diffraction. Complexes 1-5 form polar supramolecular aggregates by utilizing, for this purpose, the N-H(indole)∙∙∙Cl(chloride) intermolecular hydrogen bonds. The assemblies thus formed differ depending on the distinctive molecular shape, which can be either compact or extended. All complexes were screened for their hemolytic, cytoprotective, antifungal, and antibacterial activities. The results show that the cytoprotective activity of the indole/imidazole ligand significantly increases upon its complexation with ZnCl₂ up to a value comparable with the standard antioxidant Trolox, while the response of its substituted analogues is diverse and less pronounced.

Biological Activity of fac-[Re(CO)3(phen)(aspirin)], fac-[Re(CO)3(phen)(indomethacin)] and Their Original Counterparts against Ishikawa and HEC-1A Endometrial Cancer Cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) are inhibitors of cyclooxygenase enzyme (COX) and were found to have positive effects in reducing the risk of developing gynecological cancers. However, long-term administration of NSAIDs carries the risk of various side effects, including those in the digestive and circulatory systems. Therefore, there is a constant need to develop new NSAID derivatives. In this work, we investigated rhenium NSAIDs, comparing their effects on endometrial cancer cells with original NSAIDs, demonstrating the high activity of aspirin and indomethacin derivatives. The cytotoxic activity of rhenium derivatives against the Ishikawa and HEC-1A cancer cell lines was higher than that of the original NSAIDs. The IC50 after 24-h incubation of Ishikawa and HEC-1A were 188.06 µM and 394.06 µM for rhenium aspirin and 228.6 µM and 1459.3 µM for rhenium indomethacin, respectively. At the same time, IC50 of aspirin and indomethacin were 10,024.42 µM and 3295.3 µM for Ishikawa, and 27,255.8 µM and 5489.3 µM for HEC-1A, respectively. Moreover, these derivatives were found to inhibit the proliferation of both cell lines in a time- and state-dependent manner. The Ishikawa cell proliferation was strongly inhibited by rhenium aspirin and rhenium indomethacin after 72-h incubation (*** = p < 0.001), while the HEC-1A proliferation was inhibited by the same agents already after 24-h incubation (*** = p < 0.001). Furthermore, the ROS level in the mitochondria of the tested cells generated in the presence of rhenium derivatives was higher than the original NSAIDs. That was associated with rhenium indomethacin exclusively, which had a significant effect (*** = p < 0.001) on both Ishikawa and HEC-1A cancer cells. Rhenium aspirin had a significant effect (*** = p < 0.001) on the mitochondrial ROS level of Ishikawa cells only. Overall, the research revealed a high potential of the rhenium derivatives of aspirin and indomethacin against endometrial cancer cells compared with the original NSAIDs.

Structure and synthesis of copper-based Schiff base and reduced Schiff base complexes: a combined experimental and theoretical investigation of biomimetic catalytic activity

Three copper(ii) complexes, [Cu(L1)(NCS)]n (1), [Cu(L1)(N3)]n (2) and [Cu(L2)(N3)] (3) were synthesized from one Schiff base ligand and one reduced Schiff base ligand, (E)-4-chloro-2-[(2-propylaminoethylimino)methyl]phenol (HL1) and 4-chloro-2-[(2-(propylaminoethylamino) methyl]phenol (HL2), respectively. All complexes were characterized by various physicochemical studies, such as FT-IR, UV-Vis, ESI-MS, EPR and single crystal X-ray diffraction. Complexes 1 and 2 have 1D polymeric chain-like structures bridging through thiocyanate and azide anions, whereas complex 3 has a mononuclear structure in the solid state. All the complexes are active towards mimicking two well-known proteins, phosphatase and phenoxazinone synthase, using the disodium salt of 4-nitrophenylphosphate (4-NPP) and 2-aminophenol (OAP) as the substrate in DMF medium. Complexes 2 and 3 show the highest activity towards phosphatase and phenoxazinone synthase activity with kcat values of 22.6 s-1 and 134.4 h-1, respectively. EPR studies confirmed that for complex 1, the OAP oxidation goes through the generation of an organic radical at g = 1.99, which is due to an imine radical formation, whereas the metal center redox pathway is followed for complex 3. Extensive DFT calculations have been performed for both catalytic studies to put forward the most probable mechanistic pathways.

Thermodynamics of inclusion within cyclodextrins and structural evidence of Cu(indomethacin)2 and Zn(indomethacin)2 complexes in aqueous solutions

Cu(IMC)₂ and Zn(IMC)₂ inclusion within cyclodextrins is spontaneous, the former driven by entropic and the last by enthalpic contributions.

Varying structural motifs, unusual X-band electron paramagnetic spectra, DFT studies and superoxide dismutase enzymatic activity of copper(ii) complexes with N′-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide

A diverse set of new copper(ii) complexes synthesized as possible models for antioxidant superoxide dismutase mimics.

Sponge like microparticles for drug delivery and cosmeto-textile use: Formulation and human skin penetration

This unique work is targeted to achieve three main goals: i) to enhance the aqueous solubility of three specifically selected hydrophobic active agents, ii) to prepare such polymeric biodegradable microparticles which can encapsulate actives-cyclodextrin complexes and iii) to functionalize a polyamide base textile with active loaded microparticles and active-cyclodextrin loaded microparticles. To achieve this objective, biodegradable cationic microparticles were prepared via double emulsion solvent evaporation process and were loaded with hydroxypropyl-beta-cyclodextrin based complexes of Indomethacin, α-tocopheroland Lauryl Isoquinolinium Bromide during the formulation process. Inclusion complex based particles were evaluated for their morphology, size distribution, zeta potential, skin penetration aptitude and adsorption onto a selected textile. It was observed that active-cyclodextrin complex encapsulation do not affect the morphology, size and zeta potential of the microparticles as well as adsorption of the microparticles onto textile remains unaltered. However such active-cyclodextrin complex encapsulated particles provided the enhancement in the aqueous solubility of hydrophobic agents and also provided prolonged release formulations.

Evaluation of anti-inflammatory and ulcerogenic potential of zinc-ibuprofen and zinc-naproxen complexes in rats

Because of numerous indications and high availability, non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed and used medicines in the world. However, long-term therapy with and improper use of NSAIDs may lead to gastrointestinal damage. Therefore, improving the therapeutic index of the existing drugs has become a priority over the past decades. Considerable attention in the field has been concentrated on metal complexes of non-steroidal anti-inflammatory drugs. The aim of this study is to evaluate the effect of complexation with zinc on the anti-inflammatory and ulcerogenic effects of ibuprofen and naproxen after single and triple intragastric administration to rats. The anti-inflammatory effect was assessed in carrageenan-induced inflammatory edema in the hind paw of male albino Wistar rats. The mucosal lesions were inspected and evaluated for gross pathology. Single administration of both the investigated complexes, namely zinc-ibuprofen and zinc-naproxen (20 mg/kg equivalent to ibuprofen and naproxen, respectively) and their parent drugs and physical mixtures with zinc hydroaspartate (ZHA doses: 16.05 and 14.37 mg/kg), caused a significant reduction of the edema after the same time from the carrageenan injection in comparison to the control groups. However, no statistically significant differences between the investigated drugs were observed after their single administration. The mean ulceration score for the mixture of ibuprofen and ZHA was statistically lower than the mean score achieved in rats after treatment with ibuprofen alone. On the other hand, triple intragastric administration of the ZHA-ibuprofen and ZHA-naproxen combination showed substantial enhancement of the anti-inflammatory activity against control groups, as well as against the parent NSAIDs. The most potent anti-inflammatory activity was demonstrated after 2 h from the carrageenan injection in animals receiving ZHA together with naproxen. The edema growth was reduced in these animals by 80.9% as compared to the control group. This result was significantly higher than the results achieved in animals receiving zinc-naproxen (50.2%) or naproxen alone (47.9%). Both NSAID complexes with zinc and mixtures with ZHA alleviated ulcerations caused by parent NSAIDs; however, the mixtures of both ibuprofen and naproxen with ZHA after triple administration were the least damaging. In view of the above results, zinc supplementation during NSAID therapy may have a beneficial effect on ulcer prevention and healing by reducing the effective dose of the parent drug and increasing its potency.

Synthesis, Spectroscopic, and Thermal Investigations of Metal Complexes with Mefenamic Acid

The novel metal complexes with empirical formulae M(mef)2·nH2O (where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); mef is the mefenamic ligand) were synthesized and characterized by elemental analysis, molar conductance, FTIR-spectroscopy, and thermal decomposition techniques. All IR spectra revealed absorption bands related to the asymmetric (νas) and symmetric (νs) vibrations of carboxylate group. The Nakamoto criteria clearly indicate that this group is bonded in a bidentate chelate mode. The thermal behavior of complexes was studied by TGA methods under non-isothermal condition in air. Upon heating, all compounds decompose progressively to metal oxides, which are the final products of pyrolysis. Cu(II), Zn(II), and Cd(II) complexes were also characterized by the coupled TG-FTIR technique, which finally proved the path and gaseous products of thermal decomposition. Additionally, the coupled TG-MS system was used to determine the principal volatile products of thermolysis and fragmentation processes of Mn(mef)2·3H2O and Co(mef)2·2H2O.

Anti-ulcer mechanisms of polyphenols extract of Euphorbia umbellata (Pax) Bruyns (Euphorbiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia umbellata (leitosinha) is used in southern Brazilian folk medicine to treat gastric problems, as well as for its analgesic and anti-inflammatory properties.

AIM OF STUDY

To evaluate the anti-ulcer effects of methanolic bark fraction (MF) against in vivo and in vitro assays, as well as an antioxidant, antibacterial and chromatographic study of this fraction.

MATERIALS AND METHODS

In vivo anti-ulcer activity was performed using ethanol and indomethacin models with different MF concentrations (50, 100 or 200mg/Kg). The stomachs of the animals were applied to histological evaluation, and the serum to evaluate the ABTS(•+) radical capture. The 200mg/Kg dose was used to analyze the mechanisms involved in antiulcerogenic properties of methanolic fraction. The in vitro activity was performed using several different antioxidant assays, in addition to anti-Helicobacter pylori and anti-urease experiments. The chromatographic study was carried out by LC-MS analysis.

RESULTS

Pharmacological investigation of the MF showed an anti-ulcer potential in ethanol and indomethacin in vivo assays. The material presented a high antioxidant activity for several oxidant in vitro systems (DPPH(•), ABTS(•+), O2(•-), HOCl, TauCl and HRP), as well as an ABTS(•+) capture increasing (7.5%) by the treated animals serum (when compared to the negative control). Prostaglandins, nitric oxide/ cyclic guanosine monophosphate pathway and involvement of the protein components of the glutathione complex are some of the mechanisms related with this potential anti-ulcer action. The histological examination of the stomachs of the animals showed that the MF also prevents local action of offensive agents. Chemical analysis using LC-QTOF-MS revealed the presence of ellagic and gallic acid derivatives and flavonols.

CONCLUSION

The findings provide scientific basis to the ethnopharmacological purpose of the studied plant and the biological activities of MF of E. umbellata stem bark may be due to the presence of phenolic compounds.

A novel class of copper(II)- and zinc(II)-bound non-steroidal anti-inflammatory drugs that inhibits acute inflammation in vivo

Background

The ability of Zn(II) and Cu(II) metal complexes of non-steroidal anti-inflammatory drugs (NSAIDs) to inhibit acute arterial inflammation in vivo has been studied.

Results

When acute vascular inflammation was induced in normocholesterolemic New Zealand White rabbits by inserting a non-occlusive silastic collar around the common carotid artery, a single oral dose of Cu(II)-indomethacin (Cu(II)Indo, 3 mg/kg) administered by laparotomy achieved a 67 % (8.2 ± 1.7 vs. 2.7 ± 0.4 image units, p < 0.05) reduction in endothelial expression of vascular cell adhesion molecule-1 (VCAM-1) but did not inhibit endothelial intercellular adhesion molecule (ICAM-1) expression significantly. Treatment with Cu(II)-acemetacin (Cu(II)ACM, 3 mg/kg) led to a profound 88 % (8.2 ± 1.7 vs. 1.0 ± 0.5 image units, p < 0.01) reduction in endothelial VCAM-1 expression but did not inhibit ICAM-1 expression, while treatment with Zn(II)-acemetacin (Zn(II)ACM, 3 mg/kg) led to an 84 % (19.3 ± 1.0 vs. 3.1 ± 1.2 image units, p < 0.01) reduction in endothelial ICAM-1 expression and did not inhibit VCAM-1 expression. No adverse gastric, hepatic or renal effects were observed in treated animals.

Conclusion

These findings provide the “proof of concept” that this novel class of drug, where there is complexation of NSAIDs with metal ions, has substantial anti-inflammatory effects in an animal model of acute vascular inflammation with the possibility of low rates of adverse effects.

Enhanced analgesic activity by cyclodextrins - a systematic review and meta-analysis

INTRODUCTION

Analgesics can be ineffective in treating some types of pain, hence, improved drug delivery systems could optimize their efficacy.

AREA COVERED

The authors conducted a systematic review to evaluate the analgesic activity of compounds complexed in cyclodextrins, analyzing whether these complexes improved analgesic efficacy. The search terms 'analgesics', 'cyclodextrins' and 'drug effects' were used to retrieve articles in SCOPUS, PUBMED and EMBASE. A total of 22 papers were identified. In the clinical studies, there was greater efficacy in the complexed drug when compared with control groups, with differences ranging from 25 to 83%. Through a meta-analysis, the preclinical studies showed that the complexed drug had a significantly (p < 0.01) greater effect than the non-complexed drug.

EXPERT OPINION

The use of cyclodextrins can improve the efficacy of analgesic compounds, and they are an important tool in the search for greater analgesic effect. They may also be a way to reduce the therapeutic doses, and hence increasing the potential of the drug.

Vanadium(V) and -(IV) complexes of anionic polysaccharides: Controlled release pharmaceutical formulations and models of vanadium biotransformation products

Uncontrolled reactions in biological media are a main obstacle for clinical translation of V-based anti-diabetic or anti-cancer pro-drugs. We investigated the use of controlled-release pharmaceutical formulations to ameliorate this issue with a series of V(V) and (IV) complexes of anionic polysaccharides. Carboxymethyl cellulose, xanthan gum, or alginic acid formulations were prepared by the reactions of [VO4](3-) with one or two molar equivalents of biological reductants, L-ascorbic acid (AA) or L-cysteine (Cys), in the presence of excess polysaccharide at pH~7 or pH~4. XANES studies with the use of a previously developed library of model V(V), V(IV) and V(III) complexes showed that reactions in the presence of AA led mostly to the mixtures of five- and six-coordinate V(IV) species, while the reactions in the presence of Cys led predominantly to the mixtures of five- and six-coordinate V(V) species. The XANES spectra of some of these samples closely matched those reported previously for [VO4](3-) biotransformation products in isolated blood plasma, red blood cells, or cultured adipocytes, which supports the hypothesis that modified polysaccharides are major binders of V(V) and V(IV) in biological systems. Studies by EPR spectroscopy suggested predominant V(IV)-carboxylato binding in complexes with polysaccharides. One of the isolated products (a V(IV)-alginato complex) showed selective release of low-molecular-mass V species at pH~8, but not at pH~2, which makes it a promising lead for the development of V-containing formulations for oral administration that are stable in the stomach, but release the active ingredient in the intestines.

Synthesis, crystal structure, fluorescence and antimicrobial activity of a series of rare-earth complexes based on indolebutyric acid

The antimicrobial activity of a series of rare earth complexes was investigated in detail.

Manganese-mefenamic acid complexes exhibit high lipoxygenase inhibitory activity

The coordination of non-steroidal anti-inflammatory drugs (NSAIDs) to metal ions could improve the pharmaceutical efficacy of NSAIDs due to the unique characteristics of metal complexes.

Synthesis, biochemical evaluation and molecular modeling studies of novel rhodium complexes with nanomolar activity against Platelet Activating Factor

Two square planar Rh(I) organometallic complexes namely [Rh(L(1))(cod)]Cl (cod = cycloocta-1,5-diene, L(1)=2,2'-pyridylquinoxaline (1-Cl), [Rh(L1)(cod)](NO3) (1-NO(3)) and a series of novel octahedral rhodium(III) complexes of the general formulae mer-[Rh(L(1))Cl(3)(MeOH)] (2) and cis-[Rh(L(2))(2)Cl(2)]Cl (L(2)=4 carboxy 2 (2' pyridyl)quinoline (3), L(3)=2,2' bipyridine 4,4' dicarboxylic acid (4) were synthesized and characterized spectroscopically. All the synthesized compounds including the previously prepared cis-[Rh(L(1))(2)Cl(2)]Cl complex (5) were biologically evaluated as potential inhibitors of the Platelet Activation Factor (PAF) and thrombin induced aggregation. In particular compounds 1-Cl and 1-NO(3) were found to be strong inhibitors of PAF with IC(50) values in the range of 16 nM and 15 nM rendering them good candidates for further investigation. Their potency is comparable to that of the widely used PAF receptor antagonists WEB2170, BN52021, and Rupatadine (IC(50) of 20, 30 and 260 nM respectively). Molecular docking calculations suggest that 1-Cl, 1-NO3 and 2 can be accommodated within the ligand-binding site of PAF receptor and block the activity of PAF. On the other hand, the octahedral rhodium(III) complexes 3-5 that cannot fit the ligand-binding domain, could potentially exhibit their activity at the extracellular domain of the receptor.

Binding of Cu(II) complexes of oxicam NSAIDs to alternating AT and homopolymeric AT sequences: differential response to variation in backbone structure

Besides their principal functions as painkillers and anti-inflammatory agents, drugs belonging to the nonsteroidal anti-inflammatory drug (NSAID) group also have anticancer properties. Cu(II) complexes of these drugs enhance the anticancer effect. How they exert this effect is not clear. As a possible molecular mechanism, our group has already shown that the Cu(II) complexes of two oxicam NSAIDs with anticancer properties, viz. piroxicam and meloxicam, can directly bind to the DNA backbone. AT stretches are abundant in the eukaryotic genome. These stretches are more accessible to binding of different ligands, resulting in expression of different functions. AT stretches containing both alternating base pairs and homopolymeric bases in individual strands show subtle differences in backbone structures. It is therefore of interest to see how the Cu(II)-NSAID complexes respond to such differences in backbone structure. Binding studies of these complexes with alternating polydA-dT and homopolymeric polydA-polydT have been conducted using UV-vis absorption titration studies, UV melting studies and circular dichroism spectroscopy. Competitive binding with the standard intercalator ethidium bromide and the minor groove binder 4',6-diamidino-2-phenylindole was monitored using fluorescence to identify the possible binding mode. Our results show that Cu(II)-NSAID complexes are highly sensitive to the subtle differences in backbone structures of polydA-dT and polydA-polydT and respond to them by exhibiting different binding properties, such as binding constants, effect on duplex stability and binding modes. Both complexes have a similar binding mode with polydA-dT, which is intercalative, but for polydA-polydT, the results point to a mixed mode of binding.

Copper complexes as therapeutic agents

The importance of transition metals in biological processes has been well established. Copper (Cu) is a transition metal that can exist in oxidised and reduced states. This allows it to participate in redox and catalytic chemistry, making it a suitable cofactor for a diverse range of enzymes and molecules. Cu deficiency or toxicity is implicated in a variety of pathological conditions; therefore inorganic complexes of Cu have been investigated for their therapeutic and diagnostic potential. These Cu complexes have been shown to be effective in cancer treatment due to their cytotoxic action on tumour cells. Alternatively, Cu complexes can also modulate Cu homeostasis in the brain, resulting in protective effects in several models of neurodegeneration. In other diseases such as coronary heart disease and skin disease, the success of Cu complexes as potential therapeutics will most likely be due to their ability to increase SOD activity, leading to relief of oxidative stress. This review seeks to provide a broad insight into some of the diverse actions of Cu complexes and demonstrate the strong future for these compounds as potential therapeutic agents.

Bis(2,2'-bipyridine-κN,N')bis-(1H-indole-2-carboxyl-ato-κO,O')cadmium-2,2'-bipyridine-water (1/0.5/2)

The asymmetric unit of title compound, [Cd(C₉H₆NO₂)₂(C₁₀H₈N₂)₂]·0.5C₁₀H₈N₂·2H₂O, consists of one complex mol­ecule, one half of an uncoordinated 2,2′-bipyridine mol­ecule and two solvent water mol­ecules. The uncoordinated 2,2′-bipyridine mol­ecule is located on a center of symmetry. Within the complex mol­ecule, the Cd^II atom is coordinated by four N atoms from two 2,2′-bipyridine ligands and three O atoms from two 1H-indole-2-carboxyl­ate anion ligands, completing a distorted CdN₄O₃ penta­gonal bipyra­mid. The mol­ecules are assembled into one-dimensional chains along the [100] direction through classical hydrogen bonds (O—H⋯N, N—H⋯O and O—H⋯O). The resulting chains are further connected into two-dimensional supra­molecular layers parallel to the (110) direction by inter­molecular classical hydrogen bonds (N—H⋯O and O—H⋯O) from adjacent chains. A three-dimensional supra­molecular network is formed via interlayer and O—H⋯O hydrogen bonds.

Structurally diverse metal coordination compounds, bearing imidodiphosphinate and diphosphinoamine ligands, as potential inhibitors of the platelet activating factor

Metal complexes bearing dichalcogenated imidodiphosphinate [R₂P(E)NP(E)R₂′]⁻ ligands (E = O, S, Se, Te), which act as (E,E) chelates, exhibit a remarkable variety of three-dimensional structures. A series of such complexes, namely, square-planar [Cu{(OPPh₂)(OPPh₂)N-O, O}₂], tetrahedral [Zn{(EPPh₂)(EPPh₂)N-E,E}₂], E = O, S, and octahedral [Ga{(OPPh₂)(OPPh₂)N-O,O}₃], were tested as potential inhibitors of either the platelet activating factor (PAF)- or thrombin-induced aggregation in both washed rabbit platelets and rabbit platelet rich plasma. For comparison, square-planar [Ni{(Ph₂P)₂N-S-CHMePh-P, P}X₂], X = Cl, Br, the corresponding metal salts of all complexes and the (OPPh₂)(OPPh₂)NH ligand were also investigated. Ga(O,O)₃ showed the highest anti-PAF activity but did not inhibit the thrombin-related pathway, whereas Zn(S,S)₂, with also a significant PAF inhibitory effect, exhibited the highest thrombin-related inhibition. Zn(O,O)₂ and Cu(O,O)₂ inhibited moderately both PAF and thrombin, being more effective towards PAF. This work shows that the PAF-inhibitory action depends on the structure of the complexes studied, with the bulkier Ga(O,O)₃ being the most efficient and selective inhibitor.

Vibrational spectroscopic studies of indolecarboxylic acids and their metal complexes part VIII. 5-methoxyindole-2-carboxylic acid and its Zn(II) complex

The complex of 5-methoxyindole-2-carboxylic acid with Zn(II) has been synthesized and characterized by the infrared and Raman spectroscopic methods. Moreover, the infrared and Raman spectra of 5-methoxyindole-2-carboxylic acid (5-MeOI2CAH) and the infrared spectrum of deuterated derivative of 5-metoxyindole-2-carboxylic acid (5-MeOI2CA-d2) are recorded in the solid phase. The theoretical wavenumbers, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-311++G(df,p) basis set for 5-MeOI2CAH and 5-MeOI2CA-d2 and with the 6-311++G(df,p)/LanL2DZ basis sets for the theoretical model of [Zn(5-MeOI2CA)(2)(H(2)O)(2)](n). The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution for 5-MeOI2CAH, 5-MeOI2CA-d2 and [Zn(5-MeOI2CA)(2)(H(2)O)(2)](n). The results from natural bond orbitals (NBO) analyses for indole-2-carboxylic acid (I2CAH) and 5-MeOI2CAH are discussed.