Molecular Cytotoxicity Mechanisms of Allyl Alcohol (Acrolein) in Budding Yeast

Unveiling the molecular networks underlying cellular impairment in Saccharomyces cerevisiae: investigating the effects of magnesium oxide nanoparticles on cell wall integrity and endoplasmic reticulum stress response

Nanoparticles, particularly magnesium oxide nanoparticles (MgO-NPs), are increasingly utilized in various fields, yet their potential impact on cellular systems remains a topic of concern. This study aimed to comprehensively investigate the molecular mechanisms underlying MgO-NP-induced cellular impairment in Saccharomyces cerevisiae, with a focus on cell wall integrity, endoplasmic reticulum (ER) stress response, mitochondrial function, lipid metabolism, autophagy, and epigenetic alterations. MgO-NPs were synthesized through a chemical reduction method, characterized for morphology, size distribution, and elemental composition. Concentration-dependent toxicity assays were conducted to evaluate the inhibitory effect on yeast growth, accompanied by propidium iodide (PI) staining to assess membrane damage. Intracellular reactive oxygen species (ROS) accumulation was measured, and chitin synthesis, indicative of cell wall perturbation, was examined along with the expression of chitin synthesis genes. Mitochondrial function was assessed through Psd1 localization, and ER structure was analyzed using dsRed-HDEL marker. The unfolded protein response (UPR) pathway activation was monitored, and lipid droplet formation and autophagy induction were investigated. Results demonstrated a dose-dependent inhibition of yeast growth by MgO-NPs, with concomitant membrane damage and ROS accumulation. Cell wall perturbation was evidenced by increased chitin synthesis and upregulation of chitin synthesis genes. MgO-NPs impaired mitochondrial function, disrupted ER structure, and activated the UPR pathway. Lipid droplet formation and autophagy were induced, indicating cellular stress responses. Additionally, MgO-NPs exhibited differential cytotoxicity on histone mutant strains, implicating specific histone residues in cellular response to nanoparticle stress. Immunoblotting revealed alterations in histone posttranslational modifications, particularly enhanced methylation of H3K4me. This study provides comprehensive insights into the multifaceted effects of MgO-NPs on S. cerevisiae, elucidating key molecular pathways involved in nanoparticle-induced cellular impairment. Understanding these mechanisms is crucial for assessing nanoparticle toxicity and developing strategies for safer nanoparticle applications.

Chavibetol: major and potent phytotoxin in betel (Piper betle L.) leaf essential oil

BACKGROUND

Many essential oils and their constituent volatile organic compounds are known to be phytotoxic and potential bioherbicides. This study aims to investigate the phytotoxicity of propenylbenzene-rich essential oils and identify active molecule(s) therein.

RESULTS

Five commercially available propenylbenzene-rich oils were screened, of which betel (Piper betle L.) oil was identified as a potent natural phytotoxin. It dose-dependently inhibited wheatgrass (Triticum aestivum) seed germination and growth in water and agar medium with half maximal inhibitory concentration (IC50 ) in the range 23.2-122.7 μg mL-1 . Phytotoxicity-guided fractionation and purification revealed chavibetol as the major and most potent phytotoxic constituent of betel oil, followed by chavibetol acetate. A structure-activity relationship study involving 12 propenylbenzenes indicated the structural and positional importance of aromatic substitutions for the activity. Furthermore, the phytotoxic efficacy of chavibetol was established against wheatgrass germination and growth in water (IC50 15.8-53.4 μg mL-1 ), agar (IC50 34.4-53.6 μg mL-1 ) and aerial (IC50 1.7-4.5 mg L-1 ) media with a more pronounced effect on the radicle. Also, in open phytojars, chavibetol efficiently inhibited the growth of 3-7-day-old bermudagrass (Cynodon dactylon) seedlings when sprayed directly (IC50 2.3-3.4 mg jar-1 ) or supplemented in agar (IC50 116.6-139.1 μg mL-1 ). The growth of pre-germinated green amaranth (Amaranthus viridis) was inhibited more effectively in both application modes (1.2-1.4 mg jar-1 and IC50 26.8-31.4 μg mL-1 respectively).

CONCLUSION

The study concluded betel oil as a potent phytotoxic herbal extract and its major constituent chavibetol as a promising volatile phytotoxin for the future management of weeds in their early phase of emergence. © 2023 Society of Chemical Industry.

Unbalance between Pyridine Nucleotide Cofactors in The SOD1 Deficient Yeast Saccharomyces cerevisiae Causes Hypersensitivity to Alcohols and Aldehydes

Alcohol and aldehyde dehydrogenases are especially relevant enzymes involved in metabolic and detoxification reactions that occur in living cells. The comparison between the gene expression, protein content, and enzymatic activities of cytosolic alcohol and aldehyde dehydrogenases of the wild-type strain and the Δsod1 mutant lacking superoxide dismutase 1, which is hypersensitive to alcohols and aldehydes, shows that the activity of these enzymes is significantly higher in the Δsod1 mutant, but this is not a mere consequence of differences in the enzymatic protein content nor in the expression levels of genes. The analysis of the NAD(H) and NADP(H) content showed that the higher activity of alcohol and aldehyde dehydrogenases in the Δsod1 mutant could be a result of the increased availability of pyridine nucleotide cofactors. The higher level of NAD⁺ in the Δsod1 mutant is not related to the higher level of tryptophan; in turn, a higher generation of NADPH is associated with the upregulation of the pentose phosphate pathway. It is concluded that the increased sensitivity of the Δsod1 mutant to alcohols and aldehydes is not only a result of the disorder of redox homeostasis caused by the induction of oxidative stress but also a consequence of the unbalance between pyridine nucleotide cofactors.

A "push-pull-restrain" strategy to improve citronellol production in Saccharomyces cerevisiae

Microbial production of monoterpenes has attracted increasing attention in recent years. Up to date, there are only few reports on the biosynthesis of the monoterpene alcohol citronellol that is widely used as fragrant and pharmaceutical intermediates. Here, we engineered Saccharomyces cerevisiae by employing a "push-pull-restrain" strategy to improve citronellol production based on the reduction of geraniol. Starting from a engineered geraniol-producing strain, different reductases were investigated and the best performing iridoid synthase from Catharanthus roseus (CrIS) resulted in 285.89 mg/L enantiomerically pure S-citronellol in shake flasks. Geranyl diphosphate (GPP), the most important precursor for monoterpenes, was enhanced by replacing the wild farnesyl diphosphate synthase (Erg20) with the mutant Erg20^F96W, increasing the citronellol titer to 406.01 mg/L without negative influence on cell growth. Moreover, we employed synthetic protein scaffolds and protein fusion to colocalize four sequential enzymes to achieve better substrate channeling along with the deletion of an intermediate degradation pathway gene ATF1, which elevated the citronellol titer to 972.02 mg/L with the proportion of 97.8% of total monoterpenes in YPD medium. Finally, the engineered strain with complemented auxotrophic markers produced 8.30 g/L of citronellol by fed-batch fermentation, which was the highest citronellol titer reported to date. The multi-level engineering strategies developed here demonstrate the potential of monoterpenes overproduction in yeast, which can serve as a generally applicable platform for overproduction of other monoterpenes.

Macromolecular crowding effects on the kinetics of opposing reactions catalyzed by alcohol dehydrogenase

In order to better understand how the complex, densely packed, heterogeneous milieu of a cell influences enzyme kinetics, we exposed opposing reactions catalyzed by yeast alcohol dehydrogenase (YADH) to both synthetic and protein crowders ranging from 10 to 550 kDa. The results reveal that the effects from macromolecular crowding depend on the direction of the reaction. The presence of the synthetic polymers, Ficoll and dextran, decrease V_max and K_m for ethanol oxidation. In contrast, these crowders have little effect or even increase these kinetic parameters for acetaldehyde reduction. This increase in V_max is likely due to excluded volume effects, which are partially counteracted by viscosity hindering release of the NAD⁺ product. Macromolecular crowding is further complicated by the presence of a depletion layer in solutions of dextran larger than YADH, which diminishes the hindrance from viscosity. The disparate effects from 25 g/L dextran or glucose compared to 25 g/L Ficoll or sucrose reveals that soft interactions must also be considered. Data from binary mixtures of glucose, dextran, and Ficoll support this “tuning” of opposing factors. While macromolecular crowding was originally proposed to influence proteins mainly through excluded volume effects, this work compliments the growing body of evidence revealing that other factors, such as preferential hydration, chemical interactions, and the presence of a depletion layer also contribute to the overall effect of crowding.

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Yeast alcohol dehydrogenase reduction of acetaldehyde is enhanced by crowding.

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Crowding effects on YADH kinetics depend on the direction of the reaction.

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Crowders like dextran can be used as a tool to elucidate enzyme mechanism.

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Excluded volume optimizes YADH hydride transfer; viscosity hinders product release.

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The presence of a depletion layer with large crowders mitigates their effects.

Study of the controversial resveratrol that interact with the endogenous glutathione thiyl radical in cancer cells

Found in various natural food products, many in vitro evidence indicated that resveratrol (RES) has been linked to neuroprotective and cardioprotective effects and prevent cancer development. However, human clinical trials have been conducted with varying results, making the usage of RES controversial. In this paper, we demonstrated that the drug RES could be conjugated with the high levels of endogenous GS^• in cancer cells. 5,5-Dimethyl-1-Pyrroline-N-Oxide (DMPO) was employed to capture the GS^•. The molecular mechanism of the reaction between RES and GS^• was further studied by UV-Vis spectrometry, mass spectrometry and Density Functional Theory (DFT) calculations. Besides, the formation of the adduct GS-RES in cancer cell was obtained when RES was added during incubation. Further study indicated that over 77.6% of the RES was consumed in cancer cells. This study suggested that endogenous GS^• may be one of the important factors to cause the depletion of anti-tumour drugs during chemotherapy, which should be paid special attention in clinical therapeutics and drug development.

Engineered mitochondrial production of monoterpenes in Saccharomyces cerevisiae

Monoterpene indole alkaloids (MIAs) from plants encompass a broad class of structurally complex and medicinally valuable natural products. MIAs are biologically derived from the universal precursor strictosidine. Although the strictosidine biosynthetic pathway has been identified and reconstituted, extensive work is required to optimize production of strictosidine and its precursors in yeast. In this study, we engineered a fully integrated and plasmid-free yeast strain with enhanced production of the monoterpene precursor geraniol. The geraniol biosynthetic pathway was targeted to the mitochondria to protect the GPP pool from consumption by the cytosolic ergosterol pathway. The mitochondrial geraniol producer showed a 6-fold increase in geraniol production compared to cytosolic producing strains. We further engineered the monoterpene-producing strain to synthesize the next intermediates in the strictosidine pathway: 8-hydroxygeraniol and nepetalactol. Integration of geraniol hydroxylase (G8H) from Catharanthus roseus led to essentially quantitative conversion of geraniol to 8-hydroxygeraniol at a titer of 227 mg/L in a fed-batch fermentation. Further introduction of geraniol oxidoreductase (GOR) and iridoid synthase (ISY) from C. roseus and tuning of the relative expression levels resulted in the first de novo nepetalactol production. The strategies developed in this work can facilitate future strain engineering for yeast production of later intermediates in the strictosidine biosynthetic pathway.

Phenylpyrrole fungicides act on triosephosphate isomerase to induce methylglyoxal stress and alter hybrid histidine kinase activity

Fludioxonil, a natural product of pyrrolnitrin, is a potent fungicide used on crops worldwide. Drug action requires the presence of a group III hybrid histidine kinase (HHK) and the high osmolarity glycerol (HOG) pathway. We have reported that the drug does not act directly on HHK, but triggers the conversion of the kinase to a phosphatase, which dephosphorylates Ypd1 to constitutively activate HOG signaling. Still, the direct drug target remains unknown and mode of action ill defined. Here, we heterologously expressed a group III HHK, dimorphism-regulating kinase 1 (Drk1) in Saccharomyces cerevisae to delineate fludioxonil’s target and action. We show that the drug interferes with triosephosphate isomerase (TPI) causing release of methylglyoxal (MG). MG activates the group III HHK and thus the HOG pathway. Drug action involved Drk1 cysteine 392, as a C392S substitution increased drug resistance in vivo. Drug sensitivity was reversed by dimedone treatment, indicating Drk1 responds in vivo to an aldehydic stress. Fludioxonil treatment triggered elevated cytosolic methylglyoxal. Likewise, methylglyoxal treatment of Drk1-expressing yeast phenocopied treatment with fludioxonil. Fludioxonil directly inhibited TPI and also caused it to release methylglyoxal in vitro. Thus, TPI is a drug target of the phenylpyrrole class of fungicides, inducing elevated MG which alters HHK activity, likely converting the kinase to a phosphatase that acts on Ypd1 to trigger HOG pathway activation and fungal cell death.

Acrolein-stressed threshold adaptation alters the molecular and metabolic bases of an engineered Saccharomyces cerevisiae to improve glutathione production

Acrolein (Acr) was used as a selection agent to improve the glutathione (GSH) overproduction of the prototrophic strain W303-1b/FGP^PT. After two rounds of adaptive laboratory evolution (ALE), an unexpected result was obtained wherein identical GSH production was observed in the selected isolates. Then, a threshold selection mechanism of Acr-stressed adaption was clarified based on the formation of an Acr-GSH adduct, and a diffusion coefficient (0.36 ± 0.02 μmol·min⁻¹·OD₆₀₀⁻¹) was calculated. Metabolomic analysis was carried out to reveal the molecular bases that triggered GSH overproduction. The results indicated that all three precursors (glutamic acid (Glu), glycine (Gly) and cysteine (Cys)) needed for GSH synthesis were at a relativity higher concentration in the evolved strain and that the accumulation of homocysteine (Hcy) and cystathionine might promote Cys synthesis and then improve GSH production. In addition to GSH and Cys, it was observed that other non-protein thiols and molecules related to ATP generation were at obviously different levels. To divert the accumulated thiols to GSH biosynthesis, combinatorial strategies, including deletion of cystathionine β-lyase (STR3), overexpression of cystathionine γ-lyase (CYS3) and cystathionine β-synthase (CYS4), and reduction of the unfolded protein response (UPR) through up-regulation of protein disulphide isomerase (PDI), were also investigated.

Saccharomyces cerevisiae lipid droplet associated enzyme Ypr147cp shows both TAG lipase and ester hydrolase activities

Saccharomyces cerevisiae Ypr147cp was found localized to lipid droplets but the physiological role of Ypr147cp remains unknown. Sequence analysis of Ypr147cp revealed an α/β hydrolase domain along with the conserved GXSXG lipase motif. Recombinant Ypr147cp showed both triacylglycerol lipase and ester hydrolase activities. Knock out of YPR147C led to accumulation of TAG in ypr147cΔ when compared to wild type (WT). In addition, transmission electron microscopic analysis of ypr147cΔ cells revealed a greater number of lipid bodies, justifying the increase in TAG content, and the phenotype was rescued upon overexpression of YPR147C in ypr147cΔ. Moreover, the lipid profiling confirmed the accumulation of fatty acids derived from neutral and phospholipids in ypr147cΔ cells. Based on these results, Ypr147cp is identified as a lipid droplet associated triacylglycerol lipase along with an ester hydrolyzing capacity.

A systematic assessment of chemical, genetic, and epigenetic factors influencing the activity of anticancer drug KP1019 (FFC14A)

KP1019 ([trans-RuCl₄(1H-indazole)₂]; FFC14A) is one of the promising ruthenium-based anticancer drugs undergoing clinical trials. Despite the pre-clinical and clinical success of KP1019, the mode of action and various factors capable of modulating its effects are largely unknown. Here, we used transcriptomics and genetic screening approaches in budding yeast model and deciphered various genetic targets and plethora of cellular pathways including cellular signaling, metal homeostasis, vacuolar transport, and lipid homeostasis that are primarily targeted by KP1019. We also demonstrated that KP1019 modulates the effects of TOR (target of rapamycin) signaling pathway and induces accumulation of neutral lipids (lipid droplets) in both yeast and HeLa cells. Interestingly, KP1019-mediated effects were found augmented with metal ions (Al³⁺/Ca²⁺/Cd²⁺/Cu²⁺/Mn²⁺/Na⁺/Zn²⁺), and neutralized by Fe²⁺, antioxidants, osmotic stabilizer, and ethanolamine. Additionally, our comprehensive screening of yeast histone H3/H4 mutant library revealed several histone residues that could significantly modulate the KP1019-induced toxicity. Altogether, our findings in both the yeast and HeLa cells provide molecular insights into mechanisms of action of KP1019 and various factors (chemical/genetic/epigenetic) that can alter the therapeutic efficiency of this clinically important anticancer drug.

Engineering the biocatalytic selectivity of iridoid production in Saccharomyces cerevisiae

Monoterpene indole alkaloids (MIAs) represent a structurally diverse, medicinally essential class of plant derived natural products. The universal MIA building block strictosidine was recently produced in the yeast Saccharomyces cerevisiae, setting the stage for optimization of microbial production. However, the irreversible reduction of pathway intermediates by yeast enzymes results in a non-recoverable loss of carbon, which has a strong negative impact on metabolic flux. In this study, we identified and engineered the determinants of biocatalytic selectivity which control flux towards the iridoid scaffold from which all MIAs are derived. Development of a bioconversion based production platform enabled analysis of the metabolic flux and interference around two critical steps in generating the iridoid scaffold: oxidation of 8-hydroxygeraniol to the dialdehyde 8-oxogeranial followed by reductive cyclization to form nepetalactol. In vitro reconstitution of previously uncharacterized shunt pathways enabled the identification of two distinct routes to a reduced shunt product including endogenous 'ene'-reduction and non-productive reduction by iridoid synthase when interfaced with endogenous alcohol dehydrogenases. Deletion of five genes involved in α,β-unsaturated carbonyl metabolism resulted in a 5.2-fold increase in biocatalytic selectivity of the desired iridoid over reduced shunt product. We anticipate that our engineering strategies will play an important role in the development of S. cerevisiae for sustainable production of iridoids and MIAs.

A Pyridoindole-Based Multifunctional Bioprobe: pH-Induced Fluorescence Switching and Specific Targeting of Lipid Droplets

A versatile fluorescent probe, PITE, based on alkyl-substituted pyridoindole (PI) and tetraphenylethylene (TE), which exhibits facile pH-induced fluorescence switching in solution, as nanoparticles, and in the solid state, is presented. Strong fluorescence in the solid state, as well as in solution and the aggregated state, allow sensing of toxic acid vapors. Fluorescence "off-on" switching of PITE through exposure to trifluoroacetic acid and triethylamine vapor is visualized by the naked eye. A unified picture of the switchable fluorescence of PITE is obtained by comprehensive spectroscopic investigations coupled with quantum mechanical calculations. Strong fluorescence, a large Stokes shift, high photostability, and biocompatibility of PITE make it a viable probe for subcellular imaging. Extensive fluorescence microscopic studies by employing organisms including lower and higher eukaryotes reveal specific localization of PITE to lipid droplets (LDs). LDs are dynamic subcellular organelles linked to various physiological processes and human diseases. Hence, the specific detection of LDs in diverse organisms is important to biomedical research and healthcare. Isolation of LDs and subsequent colocalization studies ascertain selective targeting of LDs by the easily affordable, lipophilic bioprobe, PITE. Thus, PITE is a promising multifunctional probe for chemosensing and the selective tracking of LDs.

Effects of maternal acrolein exposure during pregnancy on testicular testosterone production in fetal rats

Acrolein has been reported to have diverse toxic effects on various organs, including the reproductive system. However, little is known regarding the effects of maternal acrolein exposure on testicular steroidogenesis in male offspring. The present study investigated the effects of acrolein on fetal testosterone production and associated genes. Pregnant Sprague-Dawley rats were intraperitoneally injected with vehicle (normal saline) or 1, 2 or 5 mg/kg acrolein from gestational day (GD) 14–20, and fetal testes were examined on GD 21. Fetal body and testicular weights were markedly reduced in pups following exposure to high doses of acrolein (5 mg/kg) in late pregnancy. Notably, in utero exposure of 5 mg/kg acrolein significantly decreased the testicular testosterone level and downregulated the expression levels of steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD), whereas the levels of other steroidogenic enzymes, including scavenger receptor class B, cholesterol side-chain cleavage enzyme and steroid 17 alpha-hydroxylase/17,20 lyase, were unaffected. Furthermore, the 3β-HSD immunoreactive area in the interstitial region of the fetal testes was reduced at a 5 mg/kg dose, whereas the protein expression levels of 4-hydroxynonenalwere dose-dependently increased following maternal exposure to acrolein. mRNA expression levels of insulin-like factor 3, a critical gene involved in testicular descent, were unaltered following maternal acrolein exposure. Taken together, the results of the present study suggested that maternal exposure to high doses of acrolein inhibited fetal testosterone synthesis, and abnormal expression of StAR and 3β-HSD may be associated with impairment of the steroidogenic capacity.

NapA Mediates a Redox Regulation of the Antioxidant Response, Carbon Utilization and Development in Aspergillus nidulans

The redox-regulated transcription factors (TFs) of the bZIP AP1 family, such as yeast Yap1 and fission yeast Pap1, are activated by peroxiredoxin proteins (Prxs) to regulate the antioxidant response. Previously, Aspergillus nidulans mutants lacking the Yap1 ortholog NapA have been characterized as sensitive to H₂O₂ and menadione. Here we study NapA roles in relation to TFs SrrA and AtfA, also involved in oxidant detoxification, showing that these TFs play different roles in oxidative stress resistance, catalase gene regulation and development, during A. nidulans life cycle. We also uncover novel NapA roles in repression of sexual development, normal conidiation, conidial mRNA accumulation, and carbon utilization. The phenotypic characterization of ΔgpxA, ΔtpxA, and ΔtpxB single, double and triple peroxiredoxin mutants in wild type or ΔnapA backgrounds shows that none of these Prxs is required for NapA function in H₂O₂ and menadione resistance. However, these Prxs participate in a minor NapA-independent H₂O₂ resistance pathway and NapA and TpxA appear to regulate conidiation along the same route. Using transcriptomic analysis we show that during conidial development NapA-dependent gene expression pattern is different from canonical oxidative stress patterns. In the course of conidiation, NapA is required for regulation of at least 214 genes, including ethanol utilization genes alcR, alcA and aldA, and large sets of genes encoding proteins involved in transcriptional regulation, drug detoxification, carbohydrate utilization and secondary metabolism, comprising multiple oxidoreductases, membrane transporters and hydrolases. In agreement with this, ΔnapA mutants fail to grow or grow very poorly in ethanol, arabinose or fructose as sole carbon sources. Moreover, we show that NapA nuclear localization is induced not only by oxidative stress but also by growth in ethanol and by carbon starvation. Together with our previous work, these results show that SakA-AtfA, SrrA and NapA oxidative stress-sensing pathways regulate essential aspects of spore physiology (i.e., cell cycle arrest, dormancy, drug production and detoxification, and carbohydrate utilization).

Combined Transcriptomics and Chemical-Genetics Reveal Molecular Mode of Action of Valproic acid, an Anticancer Molecule using Budding Yeast Model

Valproic acid (VA) is a pharmacologically important histone deacetylase inhibitor that recently garnered attention as an anticancer agent. Since the molecular mechanisms behind the multiple effects of VA are unclear, this study was aimed to unravel the comprehensive cellular processes affected by VA and its molecular targets in vivo using budding yeast as a model organism. Interestingly, genome-wide transcriptome analysis of cells treated with VA showed differential regulation of 30% of the genome. Functional enrichment analysis of VA transcriptome evidenced alteration of various cellular processes including cell cycle, cell wall biogenesis, DNA repair, ion homeostasis, metabolism, stress response, transport and ribosomal biogenesis, etc. Moreover, our genetic screening analysis revealed VA molecular targets belonging to oxidative and osmotic stress, DNA repair, cell wall integrity, and iron homeostasis. Further, our results demonstrated the activation of mitogen-activated protein kinases (MAPKs) Hog1 (p38) and Slt2 (p44/42) upon VA treatment. Our results also exhibited that VA acts through alteration of mitochondrial, ER architecture and functions. Especially, VA effects were neutralized in cells lacking lipid particles. Altogether, our results deciphered the novel molecular insights and mechanistic links to strengthen our knowledge on diverse cellular effects of VA along with its probable therapeutic targets and detoxification approaches.

Synthesis, structure, magnetic and biological activity studies of bis-hydrazone derived Cu(ii) and Co(ii) coordination compounds

Four coordination compounds of formulae [Cu(II)2(H2L(1))(HL(1))](ClO4)3·H2O (1), [Cu(II)2(H2L(2))(CH3OH)2](ClO4)2·2CH3OH (2), [Co(II)2(H2L(1))2](ClO4)4 (3) and [Co(II)2(H2L(2))2]·2H2O (4) were synthesized via self-assembly of succinohydrazone derived ligands (H2L(1) = N',N'-4-bis(2-pyridyl)succinohydrazide, H4L(2) = N',N'-4-bis(2-hydroxybenzylidene)succinohydrazide) and Cu(2+) and Co(2+) ions, respectively. The compounds were characterized by crystal structure determination, magnetic measurements and biological activities. Compounds 1, 3 and 4 have discrete double helicate structures, whereas compound 2 is a one-dimensional chain. Magnetic studies show antiferromagnetic exchange interactions in 2 with a J value of -67.1 cm(-1) and antiferromagnetic spin-canting in compound 3 originates through supramolecular H-bonding. For compound 3, a clear bifurcation was observed in zero field cooled (ZFC) and field cooled (FC) measurement at a temperature of 3.5 K and field of 0.1 T, implying long range magnetic ordering below this temperature. Interestingly, all of compounds 1-4 show significant changes in their absorption (hypo- and hyperchromism) in the presence of SS-DNA, inferring interaction between the compounds and DNA. In addition, compounds 1-4 significantly exhibited nuclease activities on both RNA and pUC19 plasmid DNA. Moreover, the nuclease activity was further enhanced in the presence of oxidant (H2O2) and suggests the possible role of reactive oxygen species in DNA nicking ability of compounds 1-4. Furthermore, compounds 1, 2 and 4 exhibited significant cytotoxicity against mammalian cancer cell lines (HeLa, A549 and MDAMB-231). In addition, our results from Annexin/PI staining and DNA fragmentation assays revealed that these compounds are capable of inducing apoptosis and have potential to act as anticancer drugs.