Allyl sulfur compounds and cellular detoxification system: effects and perspectives in cancer therapy

Bridging the Gap in Cancer Research: Sulfur Metabolism of Leukemic Cells with a Focus on L-Cysteine Metabolism and Hydrogen Sulfide-Producing Enzymes

Leukemias are cancers of the blood-forming system, representing a significant challenge in medical science. The development of leukemia cells involves substantial disturbances within the cellular machinery, offering hope in the search for effective selective treatments that could improve the 5-year survival rate. Consequently, the pathophysiological processes within leukemia cells are the focus of critical research. Enzymes such as cystathionine beta-synthase and sulfurtransferases like thiosulfate sulfurtransferase, 3-mercaptopyruvate sulfurtransferase, and cystathionine gamma-lyase play a vital role in cellular sulfur metabolism. These enzymes are essential to maintaining cellular homeostasis, providing robust antioxidant defenses, and supporting cell division. Numerous studies have demonstrated that cancerous processes can alter the expression and activity of these enzymes, uncovering potential vulnerabilities or molecular targets for cancer therapy. Recent laboratory research has indicated that certain leukemia cell lines may exhibit significant changes in the expression patterns of these enzymes. Analysis of the scientific literature and online datasets has confirmed variations in sulfur enzyme function in specific leukemic cell lines compared to normal leukocytes. This comprehensive review collects and analyzes available information on sulfur enzymes in normal and leukemic cell lines, providing valuable insights and identifying new research pathways in this field.

Modelling the disease: H2S-sensitivity and drug-resistance of triple negative breast cancer cells can be modulated by embedding in isotropic micro-environment

Three-dimensional (3D) cell culture systems provide more physiologically relevant information, representing more accurately the actual microenvironment where cells reside in tissues. However, the differences between the tissue culture plate (TCP) and 3D culture systems in terms of tumour cell growth, proliferation, migration, differentiation and response to the treatment have not been fully elucidated. Tumoroid microspheres containing the MDA-MB 231 breast cancer cell line were prepared using either tunable PEG-fibrinogen (PFs) or tunable PEG-silk fibroin (PSFs) hydrogels, respectively named MDAPFs and MDAPSFs. The cancer cells in the tumoroids showed changes both in globular morphology and at the protein expression level. A decrease of both Histone H3 acetylation and cyclin D1 expression in all 3D systems, compared to the 2D cell culture, was detected in parallel to changes of the matrix stiffness. The effects of a glutathionylated garlic extract (GSGa), a slow H2S-releasing donor, were investigated on both tumoroid systems. A pro-apoptotic effect of GSGa on tumour cell growth in 2D culture was observed as opposed to a pro-proliferative effect apparent in both MDAPFs and MDAPSFs. A dedicated ad hoc 3D cell migration chip was designed and optimized for studying tumour cell invasion in a gel-in-gel configuration. An anti-cell-invasion effect of the GSGa was observed in the 2D cell culture, whereas a pro-migratory effect in both MDAPFs and MDAPSFs was observed in the 3D cell migration chip assay. An increase of cyclin D1 expression after GSGa treatment was observed in agreement with an increase of the cell invasion index. Our results suggest that the "dimensionality" and the stiffness of the 3D cell culture milieu can change the response to both the gasotransmitter H2S and doxorubicin due to differences in both H2S diffusion and changes in protein expression. Moreover, we uncovered a direct relation between the cyclin D1 expression and the stiffness of the 3D cell culture milieu, suggesting the potential causal involvement of the cyclin D1 as a bio-marker for sensitivity of the tumour cells to their matrix stiffness. Therefore, our hydrogel-based tumoroids represent a valid tunable model for studying the physically induced transdifferentiation (PiT) of cancer cells and as a more reliable and predictive in vitro screening platform to investigate the effects of anti-tumour drugs.

Synthesis and characterization of chemical engineered PLGA nanosphere: Triggering mechanism of Catechol-O-methyltransferase inhibition on in vivo neurodegeneration

Chemically engineered PLGA nanospheres are one of the emerging technologies for treating neurodegenerative disorders by inhibiting Catechol-O-methyltransferase (COMT). PLGA-MATPM nanospheres were chemically synthesized using PLGA and MATPM (N-allyl-N-(3-(m-tolyloxy)propyl) methioninate). The tailored PLGA nanospheres induce dose-dependent COMT inhibition in competitive kinetic mode. The interactions between COMT and PLGA nanosphere are explained by spectroscopic and molecular dynamics analysis. PLGA-MATPM NPs suppressed the growth of neuroblastoma cells due to the neurodegenerative toxicity of MPTP induction, demonstrating its potency as a cure for neurological disorders. PLGA-MATPM NPs cross the blood-brain barrier more effectively than those in the blood. Furthermore, PLGA nanospheres showed the most neurodegenerative recovery against MPTP-induced C57BL/6 mice. Using magnetic resonance imaging (MRI), it was validated for quality images of cerebral blood flow (CBF).

Engineered graphene quantum dot nanocomposite triggers α-synuclein defibrillation: Therapeutics against Parkinson's disease

Emerging clinically required α-synuclein (α-syn) inhibitor which acts as a neuroprotective nanocomposite drug is in increased demand as a patient-safe central nervous system therapeutic. This inhibitor is intended to chemically engineer graphene quantum dot (GQD) with blue luminescence, and stands to be a potential cure for Parkinson's disease. It has been theorized that α-syn aggregation is a critical step in the development of Parkinson's. Hence narrow the target by α-syn inhibition, through chemically synthesize methyl N-allyl N-benzoylmethioninate (MABM) and functionally engineer the surface of GQD to target the brain delivery on C57BL/6 mice. Spectroscopic and simulation studies confirm defibrillation through the interaction between N-terminal amino acids and MABM-GQD nanoparticles, which makes nontoxic α-syn. Therefore, this drug's ability to cross the blood-brain barrier in vitro functionally prevents neuronal loss in neuroblastoma cells. Thus, in vivo cerebral blood flow analysis using magnetic resonance imaging illustrates, how this nanocomposite can possibly treat Parkinson's.

Activity-Based Proteomic Identification of the S-Thiolation Targets of Ajoene in MDA-MB-231 Breast Cancer Cells

Garlic is a medicinal plant and spice that has been used for millennia for its health-promoting effects. These medicinal properties are associated with low molecular weight organosulfur compounds, produced following the crushing of garlic cloves. One of these compounds, ajoene, is proposed to act by S-thioallylating cysteine residues on target proteins whose identification in cancer cells holds great promise for understanding mechanistic aspects of ajoene's cancer cell cytotoxicity. To this end, an ajoene analogue (called biotin-ajoene, BA), containing a biotin affinity tag, was designed as an activity-based probe specific for the protein targets of ajoene in MDA-MB-231 breast cancer cells. BA was synthesized via a convergent "click" strategy and found to retain its cytotoxicity against MDA-MB-231 cells compared to ajoene. Widespread biotinylation of proteins was found to occur via disulfide bond formation in a dose-dependent manner, and the biotin-ajoene probe was found to share the same protein targets as its parent compound, ajoene. The biotinylated proteins were affinity-purified from the treated MDA-MB-231 cell lysate using streptavidin-coated magnetic beads followed by an on-bead reduction, alkylation, and digestion to liberate the peptide fragments, which were analyzed by liquid chromatography tandem mass chromatography. A total of 600 protein targets were identified, among which 91% overlapped with proteins with known protein cysteine modification (PCM) sites. The specific sites were enriched for those susceptible to S-glutathionylation (-SSG) (16%), S-sulfhydration (-SSH) (20%), S-sulfenylation (-SOH) (22%), and S-nitrosylation (-SNO) (31%). As target validation, both ajoene and a dansylated ajoene (DP) were found to S-thiolate the pure recombinant forms of glutathione S-transferase pi 1 (GSTP1) and protein disulfide isomerase (PDI), and the ajoene analogue DP was found to be a more potent inhibitor than 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB). Pathway analysis elucidated that ajoene targets functional and signaling pathways that are implicated in cancer cell survival, specifically cellular processes, metabolism, and genetic information processing pathways. The results of this study provide mechanistic insights into the character of the anti-cancer activity of the natural dietary compound ajoene.

Single-molecule real-time sequencing of the full-length transcriptome of purple garlic (Allium sativum L. cv. Leduzipi) and identification of serine O-acetyltransferase family proteins involved in cysteine biosynthesis

BACKGROUND

Garlic (Allium sativum L.), whose bioactive components are mainly organosulfur compounds (OSCs), is a herbaceous perennial widely consumed as a green vegetable and a condiment. Yet, the metabolic enzymes involved in the biosynthesis of OSCs are not identified in garlic.

RESULTS

Here, a full-length transcriptome of purple garlic was generated via PacBio and Illumina sequencing, to characterize the garlic transcriptome and identify key proteins mediating the biosynthesis of OSCs. Overall, 22.56 Gb of clean data were generated, resulting in 454 698 circular consensus sequence (CCS) reads, of which 83.4% (379 206) were identified as being full-length non-chimeric reads - their further transcript clustering facilitated identification of 36 571 high-quality consensus reads. Once corrected, their genome-wide mapping revealed that 6140 reads were novel isoforms of known genes, and 2186 reads were novel isoforms from novel genes. We detected 1677 alternative splicing events, finding 2902 genes possessing either two or more poly(A) sites. Given the importance of serine O-acetyltransferase (SERAT) in cysteine biosynthesis, we investigated the five SERAT homologs in garlic. Phylogenetic analysis revealed a three-tier classification of SERAT proteins, each featuring a serine acetyltransferase domain (N-terminal) and one or two hexapeptide transferase motifs. Template-based modeling showed that garlic SERATs shared a common homo-trimeric structure with homologs from bacteria and other plants. The residues responsible for substrate recognition and catalysis were highly conserved, implying a similar reaction mechanism. In profiling the five SERAT genes' transcript levels, their expression pattern varied significantly among different tissues.

CONCLUSION

This study's findings deepen our knowledge of SERAT proteins, and provide timely genetic resources that could advance future exploration into garlic's genetic improvement and breeding. © 2021 Society of Chemical Industry.

Exhaled volatile organic compounds for diagnosis of hepatocellular carcinoma

Volatile organic compounds (VOCs) profile for diagnosis and monitoring therapeutic response of hepatocellular carcinoma (HCC) has not been well studied. We determined VOCs profile in exhaled breath of 97 HCC patients and 111 controls using gas chromatography–mass spectrometry and Support Vector Machine algorithm. The combination of acetone, 1,4-pentadiene, methylene chloride, benzene, phenol and allyl methyl sulfide provided the highest accuracy of 79.6%, with 76.5% sensitivity and 82.7% specificity in the training set; and 55.4% accuracy, 44.0% sensitivity, and 75.0% specificity in the test set. This combination was correlated with the HCC stages demonstrating by the increased distance from the classification boundary when the stage advanced. For early HCC detection, d-limonene provided a 62.8% sensitivity, 51.8% specificity and 54.9% accuracy. The levels of acetone, butane and dimethyl sulfide were significantly altered after treatment. Patients with complete response had a greater decreased acetone level than those with remaining tumor post-treatment (73.38 ± 56.76 vs. 17.11 ± 58.86 (× 10⁶ AU, p = 0.006). Using a cutoff of 35.9 × 10⁶ AU, the reduction in acetone level predicted treatment response with 77.3% sensitivity, 83.3% specificity, 79.4%, accuracy, and AUC of 0.784. This study demonstrates the feasibility of exhaled VOCs as a non-invasive tool for diagnosis, monitoring of HCC progression and treatment response.

Epigenetic "Drivers" of Cancer

Genetics is at the basis of cancer initiation and evolution, but emerging evidence indicates that mutations are not sufficient to produce cancer, indicating a role for epigenetic contributions to the different stages of tumorigenesis. While the genetic tracks of cancer have been widely investigated, the epigenetic "drivers" remain a vague definition. Gene-environment interactions can produce gene-regulatory programs that dictate pathogenesis; this implies a reciprocal relationship where environmental factors contribute to genetic mechanisms of tumorigenesis (i.e. mutagenesis) and genetic factors influence the cellular response to extrinsic stress. In this review article, we attempt to summarise the most remarkable findings demonstrating a contribution of epigenetic factors as proper "drivers" of tumorigenesis. We also try to pose attention on the relevance of epigenetic mechanisms as downstream consequences of genes versus environment interaction.

Bispecific antibodies come to the aid of cancer immunotherapy

Three collaborative studies published by the groups of Vogelstein, Gabelli, and Zhou report the development of specially designed bispecific antibodies that may help in overcoming the limitations of current immunotherapies. The bispecific antibodies have been designed to couple cells harboring HLA-presented tumor-specific antigens from Tp53 mutant or Ras mutant with CD4 and CD8 T cells, thus facilitating immune-mediated clearance of the cancer cells.

Allicin, the Odor of Freshly Crushed Garlic: A Review of Recent Progress in Understanding Allicin's Effects on Cells

The volatile organic sulfur compound allicin (diallyl thiosulfinate) is produced as a defense substance when garlic (Allium sativum) tissues are damaged, for example by the activities of pathogens or pests. Allicin gives crushed garlic its characteristic odor, is membrane permeable and readily taken up by exposed cells. It is a reactive thiol-trapping sulfur compound that S-thioallylates accessible cysteine residues in proteins and low molecular weight thiols including the cellular redox buffer glutathione (GSH) in eukaryotes and Gram-negative bacteria, as well as bacillithiol (BSH) in Gram-positive firmicutes. Allicin shows dose-dependent antimicrobial activity. At higher doses in eukaryotes allicin can induce apoptosis or necrosis, whereas lower, biocompatible amounts can modulate the activity of redox-sensitive proteins and affect cellular signaling. This review summarizes our current knowledge of how bacterial and eukaryotic cells are specifically affected by, and respond to, allicin.

Health Benefits of Plant-Derived Sulfur Compounds, Glucosinolates, and Organosulfur Compounds

The broad spectrum of the mechanism of action of immune-boosting natural compounds as well as the complex nature of the food matrices make researching the health benefits of various food products a complicated task. Moreover, many routes are involved in the action of most natural compounds that lead to the inhibition of chronic inflammation, which results in a decrease in the ability to remove a pathogen asymptomatically and is connected to various pathological events, such as cancer. A number of cancers have been associated with inflammatory processes. The current review strives to answer the question of whether plant-derived sulfur compounds could be beneficial in cancer prevention and therapy. This review focuses on the two main sources of natural sulfur compounds: alliaceous and cruciferous vegetables. Through the presentation of scientific data which deal with the study of the chosen compounds in cancer (cell lines, animal models, and human studies), the discussion of food processing’s influence on immune-boosting food content is presented. Additionally, it is demonstrated that there is still a need to precisely demonstrate the bioavailability of sulfur-containing compounds from various types of functional food, since the inappropriate preparation of vegetables can significantly reduce the content of beneficial sulfur compounds. Additionally, there is an urgent need to carry out more epidemiological studies to reveal the benefits of several natural compounds in cancer prevention and therapy.

Rapid SERS Detection of Thiol-Containing Natural Products in Culturing Complex

Thiol-containing natural products possess a wide range of bioactivities. The burst of synthetic biology technology facilitates the discovery of new thiol-containing active ingredients. Herein, we report a sensitive, quick, and robust surface-enhanced Raman scattering technology for specific and multiplex detection of thiol-containing compounds without purification requirements and also indicating the thiols with different chemical environments. Using this platform, we successfully demonstrated the simultaneous detection of thiol-containing compounds from as low as 1 μM of analytes spiked in complex culture matrices.

Curcumin may reverse 5-fluorouracil resistance on colonic cancer cells by regulating TET1-NKD-Wnt signal pathway to inhibit the EMT progress

BACKGROUND AND PURPOSE

Colorectal cancer is a kind of gastrointestinal tumor with rising morbidity and mortality. 5-fluorouracil is one of the most effective chemotherapy drugs for the treatment of CRC. However, clinical data reported dramatic resistance on the treatment for CRC with 5-fluorouracil. Present study aims to explore the anti-resistant effect of curcumin and its mechanism.

METHODS

MTT assay was used to evaluate the proliferation of rHCT-116 cells. Flow cytometry was used to determine the apoptosis and cell cycle of rHCT-116 cells. Western Blot was performed to detect the expression level of TET1, NKD2, E-cadherin, Vimentin, β-catenin, TCF4 and Axin in transfected rHCT-116 cells.

RESULTS

5-fluorouracil resistant HCT-116 cells were successfully established. Curcumin was found to be effective in the inhibition of proliferation, inducement of apoptosis and block of G0/G1 phase on 5-fluorouracil treated HCT-116 cells. The expression of TET1 and NKD2 was greatly inhibited by high dosage of curcumin. The WNT signal pathway and EMT progress were suppressed in rHCT-116 cells by high dosage of curcumin. The inhibitory effects of curcumin on WNT signal pathway and EMT progress were verified to be consistent with Pax-6, TET1 and NKD2.

CONCLUSION

Curcumin might exert anti-resistant effect of 5-FU on HCT-116 cells by regulating the TET1-NKD2-WNT signal pathway to inhibit the EMT progress.

In vitro protective effects of plants frequently used traditionally in cancer prevention in Thai traditional medicine: An ethnopharmacological study

ETHNOPHARMACOLOGICAL RELEVANCE

Thai traditional medicine (TTM) has been used widely in cancer management in Thailand. Although several Thai medicinal plants were screened for pharmacological activities related to cancer treatment, such evidence still suffers from the lack of linking with TTM knowledge.

AIM OF THE STUDY

To document knowledge and species used in cancer prevention in TTM and to preliminary investigate pharmacological activities related to the documented knowledge of twenty-six herbal drugs used in cancer/mareng prevention.

METHODS

Fieldwork gathering data on TTM concept and herbal medicines used in cancer prevention was performed with TTM practitioners across Thailand. Later, water and ethanol extracts from twenty-six herbal drugs mentioned as being used in cancer prevention were screened for their protective effect against tert-butyl hydroperoxide-induced cell death in HepG2 cells. Then active extracts were investigated for their effects on NQO1 activity, glutathione level, and safety in normal rat hepatocytes.

RESULTS

The fieldwork helped in the development of TTM cancer prevention strategy and possible experimental models to test the pharmacological activities of selected medicinal plants. Fifteen plant extracts showed significant protective effect by restoring the cell viability to 40-59.3%, which were comparable or better than the positive control EGCG. Among them, ethanol extracts from S. rugata and T. laurifolia showed the most promising chemopreventive properties by significantly increased NQO1 activity, restored GSH level from oxidative damage, as well as showed non-toxic effect in normal rat hepatocytes.

CONCLUSION

TTM knowledge in cancer prevention was documented and used in the planning of pharmacological experiment to study herbal medicines, especially in cancer, inflammation, and other chronic diseases. The proposed strategy should be applied to in vivo and clinical studies in order to further confirm the validity of such a strategy. Other traditional medical systems that use integrated approaches could also apply our strategy to develop evidence that supports a more rational uses in traditional medicine.

Enhanced Allicin Cytotoxicity on HEPG-2 Cells Using Glycyrrhetinic Acid Surface-Decorated Gelatin Nanoparticles

The cytotoxic potential of allicin was evaluated on different cancer cell lines, particularly, hepatic (HepG-2), breast (MCF-7), lung (A-549), and prostatic (PC-3), where allicin scored an IC₅₀ score of 19.26 μM on HepG-2. In order to increase the cell uptake, optimized allicin-loaded gelatin nanoparticles (GNPs) were prepared where the optimum formulation was surface-conjugated to glycyrrhetinic acid. GNPs were optimized using a D-optimal design. The optimum formulation had a particle size of 370.7 ± 6.78 nm and polydispersity index of 0.0363 ± 0.009 and 39.13 ± 2.38% of drug entrapment. The conjugation of the ligand, glycyrrhetinic acid with allicin-loaded GNPs, was confirmed utilizing ¹H NMR. Drug release profiles in the presence/absence of collagenase were obtained. Finally, a cytotoxicity study on HepG-2 was performed for the unconjugated and conjugated allicin-loaded GNPs scoring IC₅₀ of 10.95 and 5.046 μM, revealing two- and fourfold enhancements in allicin cytotoxicity, respectively. To our knowledge, the ligand-carrier pair, glycyrrhetinic acid-gelatin, was not explored before, and the developed system poses a successful liver cancer therapy.

Protective and Restorative Effects of Nutrients and Phytochemicals

Intoroduction:

Dietary intake fundamentally provides reintegration of energy and essential nutrients to human organisms. However, its qualitative and quantitative composition strongly affects individual’s health, possibly being either a preventive or a risk factor. It was shown that nutritional status resulting from long-term exposition to specific diet formulations can outstandingly reduce incidences of most common and most important diseases of the developed world, such as cardiovascular and neoplastic diseases. Diet formulations result from different food combinations which bring specific nutrient molecules. Numerous molecules, mostly but not exclusively from vegetal foods, have been characterized among nutritional components as being particularly responsible for diet capabilities to exert risk reduction. These “bioactive nutrients” are able to produce effects which go beyond basic reintegration tasks, i.e. energetic and/or structural, but are specifically pharmacologically active within pathophysiological pathways related to many diseases, being able to selectively affect processes such as cell proliferation, apoptosis, inflammation, differentiation, angiogenesis, DNA repair and carcinogens activation.

Conclusion:

The present review was aimed to know the molecular mechanisms and pathways of activity of bioactive molecules; which will firstly allow search for optimal food composition and intake, and then use them as possible therapeutical targets and/or diagnostics. Also, the present review discussed the therapeutic effect of both nutrients and phytochemicals.

Potential Mechanisms of Action of Dietary Phytochemicals for Cancer Prevention by Targeting Cellular Signaling Transduction Pathways

Cancer is a severe health problem that significantly undermines life span and quality. Dietary approach helps provide preventive, nontoxic, and economical strategies against cancer. Increased intake of fruits, vegetables, and whole grains are linked to reduced risk of cancer and other chronic diseases. The anticancer activities of plant-based foods are related to the actions of phytochemicals. One potential mechanism of action of anticancer phytochemicals is that they regulate cellular signal transduction pathways and hence affects cancer cell behaviors such as proliferation, apoptosis, and invasion. Recent publications have reported phytochemicals to have anticancer activities through targeting a wide variety of cell signaling pathways at different levels, such as transcriptional or post-transcriptional regulation, protein activation and intercellular messaging. In this review, we discuss major groups of phytochemicals and their regulation on cell signaling transduction against carcinogenesis via key participators, such as Nrf2, CYP450, MAPK, Akt, JAK/STAT, Wnt/β-catenin, p53, NF-κB, and cancer-related miRNAs.

Synthesis and Biological Evaluation of S-Substituted Perhalo-2-nitrobuta-1,3-dienes as Novel Xanthine Oxidase, Tyrosinase, Elastase, and Neuraminidase Inhibitors

S-substituted perhalo-2-nitrobuta-1,3-dienes 3a, b were synthesized by the reaction of polyhalo-2-nitrobuta-1,3-dienes 1a, b with allyl mercaptan. 1-(2,3-Dibromopropanethio)-4-bromo-1,3,4-trichloro-2-nitrobuta-1,3-diene 4 was obtained from the addition of bromine to S-substituted polyhalo-2-nitrobuta-1,3-diene 3b in carbon tetrachloride. Sulfoxides 5a, b, and 6 were obtained from the reaction of thiosubstituted polyhalonitrobutadienes 3a, b, and 4 with m-CPBA in CHCl3. The structures of the new compounds were determined by spectroscopic data (FTIR, 1H NMR, 13C NMR, MS). These compounds exhibited antixanthine oxidase, antityrosinase, antielastase, and antineuraminidase activities.

The Effects of Allicin, a Reactive Sulfur Species from Garlic, on a Selection of Mammalian Cell Lines

Garlic (Allium sativum L.) has been used as a spice and medicinal plant since ancient times. Garlic produces the thiol-reactive defence substance, allicin, upon wounding. The effects of allicin on human lung epithelium carcinoma (A549), mouse fibroblast (3T3), human umbilical vein endothelial cell (HUVEC), human colon carcinoma (HT29) and human breast cancer (MCF7) cell lines were tested. To estimate toxic effects of allicin, we used a standard MTT-test (methylthiazoltetrazolium) for cell viability and ³H-thymidine incorporation for cell proliferation. The glutathione pool was measured using monobromobimane and the formation of reactive species was identified using 2',7'-dichlorofluoresceine-diacetate. The YO-PRO-1 iodide staining procedure was used to estimate apoptosis. Allicin reduced cell viability and cell proliferation in a concentration dependent manner. In the bimane test, it was observed that cells treated with allicin showed reduced fluorescence, suggesting glutathione oxidation. The cell lines tested differed in sensitivity to allicin in regard to viability, cell proliferation and glutathione oxidation. The 3T3 and MCF-7 cells showed a higher proportion of apoptosis compared to the other cell types. These data show that mammalian cell lines differ in their sensitivity and responses to allicin.

A scent of therapy: Synthetic polysulfanes with improved physico-chemical properties induce apoptosis in human cancer cells

Diallyl sulfanes derived from edible plants are highly potent compounds which at sub-millimolar concentrations are able to induce the formation of reactive oxygen species (ROS) in a variety of different cells, where they often cause an altered redox status. The loss of cellular thiols and/or formation of ROS subsequently triggers a range of cellular responses, including the induction of apoptosis. A great disadvantage of natural diallyl mono- and polysulfanes, however, is their inherent insolubility in water and the extremely bad odour which limits their practical use in humans. Here, we present the synthesis and biological evaluation of two new, especially designed polysulfanes, namely the trisulfide 1-Allyl-3-(2-ethoxyethyl)trisulfide (ATSEE) and the tetrasulfide Allyl-4-benzyltetrasulfide (ATTSB), which are nearly odourless. Both compounds produce O2•- radicals in HCT116 cells and both induce an oxidative defence signalling. Cell viability is especially reduced by the tetrasulfane ATTSB, with an arrest of the cell cycle in the G2-phase. In contrast, the trisulfane ATSEE does not inhibit the cell cycle. In agreement with these findings, treatment of HCT116 cells with ATTSB ultimately results in apoptosis whereas only limited induction of apoptosis has been detected for cells treated with ATSEE. We further show that antioxidative defence mechanisms and death response signalling run in parallel and the dominant pathway decides the fate of the cell. Thus, our results not only illuminate the intricate mode of action of certain polysulfanes; they also demonstrate that the new odourless tri- and tetrasulfanes exhibit a similar activity compared to their natural counterparts, yet are easier to handle and also deprived of the offensive odour which so far has prevented most practical applications of such polysulfanes, at least in the context of medicine.

Glutathione-garlic sulfur conjugates: slow hydrogen sulfide releasing agents for therapeutic applications

Natural organosulfur compounds (OSCs) from Allium sativum L. display antioxidant and chemo-sensitization properties, including the in vitro inhibition of tumor cell proliferation through the induction of apoptosis. Garlic water- and oil-soluble allyl sulfur compounds show distinct properties and the capability to inhibit the proliferation of tumor cells. In the present study, we optimized a new protocol for the extraction of water-soluble compounds from garlic at low temperatures and the production of glutathionyl-OSC conjugates during the extraction. Spontaneously, Cys/GSH-mixed-disulfide conjugates are produced by in vivo metabolism of OSCs and represent active molecules able to affect cellular metabolism. Water-soluble extracts, with (GSGaWS) or without (GaWS) glutathione conjugates, were here produced and tested for their ability to release hydrogen sulfide (H₂S), also in the presence of reductants and of thiosulfate:cyanide sulfurtransferase (TST) enzyme. Thus, the TST catalysis of the H₂S-release from garlic OSCs and their conjugates has been investigated by molecular in vitro experiments. The antiproliferative properties of these extracts on the human T-cell lymphoma cell line, HuT 78, were observed and related to histone hyperacetylation and downregulation of GAPDH expression. Altogether, the results presented here pave the way for the production of a GSGaWS as new, slowly-releasing hydrogen sulfide extract for potential therapeutic applications.

Cancer Preventive Potential of Kimchi Lactic Acid Bacteria (Weissella cibaria, Lactobacillus plantarum)

The number of death due to cancer has been increasing in Korea. Chemotherapy is known to cause side effects because it damages not only cancerous cells but healthy cells. Recently, attention has focused on food-derived chemopreventive and anti-tumor agents or formulations with fewer side effects. Kimchi, most popular and widely consumed in Korea, contains high levels of lactic acid bacteria and has been shown to possess chemopreventive effects. This review focuses on Weissella cibaria and Lactobacillus plantarum, the representatives of kimchi lactic acid bacteria, in terms of their abilities to prevent cancer. Further studies are needed to understand the mechanisms by which lactic acid bacteria in kimchi prevent carcinogenic processes and improve immune functions.