Diallyl Disulphide, a Beneficial Component of Garlic Oil, Causes a Redistribution of Cell-Cycle Growth Phases, Induces Apoptosis, and Enhances Butyrate-Induced Apoptosis in Colorectal Adenocarcinoma Cells (HT-29)

Potential antitumor activity of garlic against colorectal cancer: focus on the molecular mechanisms of action

PURPOSE

The aim of this review is to highlight the potential of garlic phytoconstituents as antitumor agents in colorectal cancer management based on their molecular mechanisms of action, while asking if their consumption, as part of the human diet, might contribute to the prevention of colorectal cancer.

METHODS

To gather information on appropriate in vitro, in vivo and human observational studies on this topic, the keywords "Allium sativum", "garlic", "colorectal cancer", "antitumor effect", "in vitro", "in vivo", "garlic consumption" and "colorectal cancer risk" were searched in different combinations in the international databases ScienceDirect, PubMed and Google Scholar. After duplicate and reviews removal, 61 research articles and meta-analyses published between 2000 and 2022 in peer-reviewed journals were found and included in this review.

RESULTS

Garlic (Allium sativum) proves to be a rich source of compounds with antitumor potential. Garlic-derived extracts and several of its individual constituents, especially organosulfur compounds such as allicin, diallyl sulfide, diallyl disulfide, diallyl trisulfide, diallyl tetrasulfide, allylmethylsulfide, S-allylmercaptocysteine, Z-ajoene, thiacremonone and Se-methyl-L-selenocysteine were found to possess cytotoxic, cytostatic, antiangiogenic and antimetastatic activities in different in vitro and in vivo models of colorectal cancer. The molecular mechanisms for their antitumor effects are associated with the modulation of several well-known signaling pathways involved in cell cycle progression, especially G1-S and G2-M transitions, as well as both the intrinsic and extrinsic apoptotic pathways. However, even though in various animal models some of these compounds have chemopreventive effects, based on different human observational studies, a diet rich in garlic is not consistently associated with a lower risk of developing colorectal cancer.

CONCLUSION

Independent of the impact of garlic consumption on colorectal cancer initiation and promotion in humans, its constituents might be good candidates for future conventional and/or complementary therapies, based on their diverse mechanisms of action.

Natural essential oils as a new therapeutic tool in colorectal cancer

Colorectal cancer (CRC) is the third most revalent type of cancer in the world and the second most common cause of cancer death (about 1 million per year). Historically, natural compounds and their structural analogues have contributed to the development of new drugs useful in the treatment of various diseases, including cancer. Essential oils are natural odorous products made up of a complex mixture of low molecular weight compounds with recognized biological and pharmacological properties investigated also for the prevention and treatment of cancer. The aim of this paper is to highlight the possible role of essential oils in CRC, their composition and the preclinical studies involving them. It has been reviewed the preclinical pharmacological studies to determine the experimental models used and the anticancer potential mechanisms of action of natural essential oils in CRC. Searches were performed in the following databases PubMed/Medline, Web of science, TRIP database, Scopus, Google Scholar using appropriate MeSH terms. The results of analyzed studies showed that EOs exhibited a wide range of bioactive effects like cytotoxicity, antiproliferative, and antimetastatic effects on cancer cells through various mechanisms of action. This updated review provides a better quality of scientific evidence for the efficacy of EOs as chemotherapeutic/chemopreventive agents in CRC. Future translational clinical studies are needed to establish the effective dose in humans as well as the most suitable route of administration for maximum bioavailability and efficacy. Given the positive anticancer results obtained from preclinical pharmacological studies, EOs can be considered efficient complementary therapies in chemotherapy in CRC.

Diallyl trisulfide alleviates chemotherapy sensitivity of ovarian cancer via the AMPK/SIRT1/PGC1α pathway

Platinum-based chemotherapy promotes drug resistance in ovarian cancer. We investigated the antichemoresistance characteristics of diallyl trisulfide (DATS) in cisplatin-resistant ovarian cancer cells, in vitro and in vivo. Previous preclinical studies have revealed that DATS regulates distinct hallmark cancer-signaling pathways. The cell cycle pathway is the most investigated signaling pathway in DATS. Additionally, post-DATS treatment has been found to promote proapoptotic capacity through the regulation of intrinsic and extrinsic apoptotic pathway components. In the present study, we found that treating cisplatin-sensitive and cisplatin-resistant ovarian cell lines with DATS inhibited their proliferation and reduced their IC_50. It induced cell apoptosis and promoted oxidative phosphorylation through the regulation of the AMPK/SIRT1/PGC1α pathway, OXPHOS, and enhanced chemotherapy sensitivity. DATS treatment alleviated glutamine consumption in cisplatin-resistant cells. Our findings highlight the role of DATS in overcoming drug resistance in ovarian cancer in vitro and in vivo. In addition, we elucidated the role of the AMPK/SIRT1/PGC1α signaling pathway as a potential target for the treatment of drug-resistant ovarian cancer.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Anticancer potential of garlic and its bioactive constituents: A systematic and comprehensive review

Vegetables of the Allium genus, such as garlic (Allium sativum L.), onions, shallots, leaks, and chives, have been used for many years for food consumption and for medicinal purposes. Historical medical texts have indicated the therapeutic applications of garlic as an antitumor, laxative, diuretic, antibacterial and antifungal agent. Specifically, garlic's antitumor abilities have been traced back 3500 years as a chemotherapeutic agent used in Egypt. Other beneficial effects of garlic consumption include lowering blood pressure, blood cholesterol, sugar and lipids. The processing and aging of garlic result in the production of non-toxic organosulfur by-products. These sulfur-containing compounds, such as allicin, diallyl sulfide, diallyl disulfide, diallyl trisulfide, alliin, S-allylcysteine, and S-allylmercaptocysteine, impact various stages of carcinogenesis. The anticancer mechanisms of action of these garlic-derived phytochemicals include altering mitochondrial permeability, inhibiting angiogenesis, enhancing antioxidative and proapoptotic properties, and regulating cell proliferation. All these effects of garlic's sulfur-compounds have been demonstrated in various human cancers. The intent of this literature research is to explore the potential of garlic-derived products and bioactive organosulfur compounds as cancer chemopreventive and chemotherapeutic agents. This investigation employs criteria for systematic review and critically analyzes published in vitro, in vivo and clinical studies. Concerns and limitations that have arisen in past studies regarding standards of measurement, bioavailability, and method of delivery are addressed. Overall, it is hoped that through this systematic and comprehensive review, future researchers can be acquainted with the updated data assembled on anticancer properties of garlic and its phytoconstituents.

Prevailing Knowledge on the Bioavailability and Biological Activities of Sulphur Compounds from Alliums: A Potential Drug Candidate

Allium sativum (garlic) is widely known and is consumed as a natural prophylactic worldwide. It produces more than 200 identified chemical compounds, with more than 20 different kinds of sulfide compounds. The sulfide compounds particularly are proven to contribute to its various biological roles and pharmacological properties such as antimicrobial, antithrombotic, hypoglycemic, antitumour, and hypolipidemic. Therefore, it is often referred as disease-preventive food. Sulphur-containing compounds from A. sativum are derivatives of S-alkenyl-l-cysteine sulfoxides, ajoene molecules, thiosulfinates, sulfides, and S-allylcysteine. This review presents an overview of the water-soluble and oil-soluble sulphur based phytochemical compounds present in garlic, highlighting their mechanism of action in treating various health conditions. However, its role as a therapeutic agent should be extensively studied as it depends on factors such as the effective dosage and the suitable method of preparation.

Garlic and its Active Compounds: A Potential Candidate in The Prevention of Cancer by Modulating Various Cell Signalling Pathways

BACKGROUND

Cancer is a multi-factorial disease including alterations in the cell signalling pathways. Currently, several drugs are in use to treat cancer but such drugs show negative side effects on normal cells and cause severe toxicity.

METHODS

The current research is mainly focused on medicinal plants with potential therapeutic efficacy in the treatment of cancer without any adverse effects on normal cells. In this regard, garlic and its active compounds including diallyl sulfide, diallyl trisulfide, ajoene, and allicin have been established to suppress the growth of cancer and killing of cancer cells.

RESULT

The review focuses on garlic and its active compounds chemopreventive effect through modulating various cell signalling pathways. Additionally, garlic and its active compound were established to induce cell cycle arrest at the G0/G1 phase and G2/M phases in cancer cells, increase the expression of tumor suppressor genes, inhibit the angiogenesis process, induction of apoptosis and modulation of various other genetic pathways.

CONCLUSION

This review sketches the diverse chemopreventive activities of garlic and their active ingredients in the management of cancer mainly focusing on cell signalling pathways.

Garlic intake and the risk of colorectal cancer: A meta-analysis

This was a meta-analysis of epidemiological articles that aimed to estimate the association of garlic intake with the risk of colorectal cancer (CRC).Electronic databases, including the Cochrane Database of Systematic Reviews, PubMed, and EMBASE, were systemically searched from inception to May 2019 to identify related articles. In addition, a random model was used to pool the included evidence based on heterogeneity. Additionally, subgroup analyses were carried out to examine the differences between different groups. The stability of our findings was tested through sensitivity analyses. Publication bias was also assessed by Egger and Begg tests. Moreover, all enrolled studies were ordered according to the publication year for a cumulative meta-analysis.A total of 11 studies (involving 12,558 cases) were included in the current meta-analysis. Our integrated relative risk (RR) of CRC was 0.80 (95% confidence interval [CI], 0.69-0.91) for the highest versus the lowest garlic consumption categories (RR: 0.71 [95% CI, 0.60-0.84] for controls and RR: 0.99 [95% CI, 0.80-1.23] for cohorts). There was significant heterogeneity across all enrolled studies (I = 68.3%, P < .01). The sensitivity analysis revealed no notable alterations of the integrated results. According to the funnel plot regarding garlic intake and the risk of CRC, together with the Egger test (P = .1) and Begg test (P = .064) results, there was no notable evidence of publication bias. The cumulative meta-analysis suggested that the 95% CIs became narrower with the increase in sample size.Based on the existing evidence, garlic intake could reduce the risk of CRC.

Response surface methodology and artificial neural network approach for the optimization of ultrasound-assisted extraction of polyphenols from garlic

This paper aimed to establish the optimal conditions for ultrasound-assisted extraction of polyphenols from domestic garlic (Allium sativum L.) using response surface methodology (RSM) and artificial neural network (ANN) approach. A 4-factor-3-level central composite design was used to optimize ultrasound-assisted extraction (UAE) to obtain a maximum yield of target responses. Maximum values of the two output parameters: 19.498 mg GAE/g fresh weight of sample total phenolic content and 1.422 mg RUT/g fresh weight of sample total flavonoid content were obtained under optimum extraction conditions: 13.50 min X₁, 59.00 °C X₂, 71.00% X₃ and 20.00 mL/g X₄. Root mean square error for training, validation, and testing were 0.0209, 3.6819 and 1.8341, respectively. The correlation coefficient between experimentally obtained total phenolic content and total flavonoid content and values predicted by ANN were 0.9998 for training, 0.9733 for validation, and 0.9821 for testing, indicating the good predictive ability of the model. The ANN model had a higher prediction efficiency than the RSM model. Hence, RSM can demonstrate the interaction effects of basic inherent UAE parameters on target responses, whereas ANN can reliably model the UAE process with better predictive and estimation capabilities.

Assessing the anticancer effects associated with food products and/or nutraceuticals using in vitro and in vivo preclinical development-related pharmacological tests

This review is part of a special issue entitled "Role of dietary pattern, foods, nutrients and nutraceuticals in supporting cancer prevention and treatment" and describes a pharmacological strategy to determine the potential contribution of food-related components as anticancer agents against established cancer. Therefore, this review does not relate to chemoprevention, which is analysed in several other reviews in the current special issue, but rather focuses on the following: i) the biological events that currently represent barriers against the treatment of certain types of cancers, primarily metastatic cancers; ii) the in vitro and in vivo pharmacological pre-clinical tests that can be used to analyse the potential anticancer effects of food-related components; and iii) several examples of food-related components with anticancer effects. This review does not represent a catalogue-based listing of food-related components with more or less anticancer activity. By contrast, this review proposes an original pharmacological strategy that researchers can use to analyse the potential anticancer activity of any food-related component-e.g., by considering the crucial characteristics of cancer biological aggressiveness. This review also highlights that cancer patients undergoing chemotherapy should restrict the use of "food complements" without supervision by a medical nutritionist. By contrast, an equilibrated diet that includes the food-related components listed herein would be beneficial for cancer patients who are not undergoing chemotherapy.

Natural Compounds As Modulators of Non-apoptotic Cell Death in Cancer Cells

Cell death is an innate capability of cells to be removed from microenvironment, if and when they are damaged by multiple stresses. Cell death is often regulated by multiple molecular pathways and mechanism, including apoptosis, autophagy, and necroptosis. The molecular network underlying these processes is often intertwined and one pathway can dynamically shift to another one acquiring certain protein components, in particular upon treatment with various drugs. The strategy to treat human cancer ultimately relies on the ability of anticancer therapeutics to induce tumor-specific cell death, while leaving normal adjacent cells undamaged. However, tumor cells often develop the resistance to the drug-induced cell death, thus representing a great challenge for the anticancer approaches. Numerous compounds originated from the natural sources and biopharmaceutical industries are applied today in clinics showing advantageous results. However, some exhibit serious toxic side effects. Thus, novel effective therapeutic approaches in treating cancers are continued to be developed. Natural compounds with anticancer activity have gained a great interest among researchers and clinicians alike since they have shown more favorable safety and efficacy then the synthetic marketed drugs. Numerous studies in vitro and in vivo have found that several natural compounds display promising anticancer potentials. This review underlines certain information regarding the role of natural compounds from plants, microorganisms and sea life forms, which are able to induce non-apoptotic cell death in tumor cells, namely autophagy and necroptosis.

[The role of the PI3K/AKT signaling pathway in DADS-induced apoptosis of K562 cells]

OBJECTIVE

To study the role of the PI3K/AKT signaling pathway in the diallyl disulfide (DADS)-induced apoptosis of K562 cells.

METHODS

K562 cells in the logarithmic growth phase were treated with 10, 20, 40, or 80 mg/L DADS for 48 hours, then fixed and stained with acridine orange/ethidium bromide (AO/EB), and examined for cellular morphological changes under an inverted microscope. Annexin V-FITC/PI staining was used for determining the apoptotic rates, and Western blot for measuring the expression of AKT, p-AKT, and Caspase-3. Two control groups, blank and solvent, were used as references.

RESULTS

K562 cells treated with DADS for 48 hours exhibited the characteristic morphological features of apoptosis including cell shrinkage, irregular cell shape, and membrane blebbing. AO/EB staining results demonstrated that the number of apoptotic cells with cell shrinkage, pyknotic or bead-like nuclei, chromatin condensation, and orange staining increased with the increasing DADS concentration, and 40 mg/L DADS had the most significant effect. The apoptotic rates of cells treated with 10, 20, 40, and 80 mg/L DADS were all significantly higher than those in the control groups (P<0.05). There were no significant differences in AKT protein expression between the K562 cells treated with different concentrations of DADS; the p-AKT protein expression decreased with the increasing DADS concentration, while the Caspases-3 protein expression increased with the increasing DADS concentration (P<0.05).

CONCLUSIONS

DADS induces the apoptosis of K562 cells, probably through inhibiting the protein expression in the PI3K/AKT signaling pathway.

Effect of diallyl trisulfide on human ovarian cancer SKOV- 3/DDP cell apoptosis

AIM

To investigate the effects of diallyl trisulfide (DT) on apoptosis of cisplatin (DDP)-resistant human epithelial ovarian cancer SKOV-3 cells (SKOV-3/DDP), and the role of p53 upregulated modulator of apoptosis (PUMA).

METHODS

SKOV-3/DDP cells were randomly divided into control, DT, DPP and DPP+DT groups, which were treated with DT or combined DT and DDP. All cells were incubated for 48 h. and apoptosis rates were assessed by flow cytometry. mRNA and protein expression of PUMA, Bax and Bcl-2 was determined by RT-PCR and Western blot assays, respectively.

RESULTS

Compared with control group, the apoptosis rates of SKOV-3/DDP cells in DT groups were obviously increased, with dose-dependence (P < 0.05), the mRNA and protein expressions of PUMA, Bax also being up-regulated (P < 0.05), while those of Bcl-2 were down-regulated (P < 0.05). Compared with DT groups, the apoptosis rate in the DDP+DT group was significantly increased (P < 0.05). After knockdown of PUMA with specific siRNA, the apoptosis rate of SKOV-3/DDP cells was obviously decreased (P < 0.05).

CONCLUSION

DT can promote the apoptosis of SKOV-3/DDP cells with PUMA playing a critical role.

Allium vegetables and garlic supplements do not reduce risk of colorectal cancer, based on meta-analysis of prospective studies

BACKGROUND & AIMS

Laboratory studies have provided evidence that allium vegetables and garlic supplements might protect against colorectal cancer (CRC), but epidemiologic studies have produced inconsistent findings.

METHODS

We conducted a meta-analysis of prospective studies evaluating the associations between allium vegetables, garlic supplements, and CRC risk. We pooled effect measures using fixed- or random-effect models, assessing the highest vs the lowest intakes. We used a dose-response regression model to evaluate the relationship between allium vegetable intake and CRC risk.

RESULTS

Our analysis included 8 studies with 20 reports of the effects of allium vegetables (5458 patients with CRC including 7,125,067 person-years) and 5 studies with 11 reports of the effects of garlic supplements (2685 patients with CRC including 2,304,439 person-years). We found no association between higher intake of allium vegetables and CRC risk (relative risk [RR], 1.06; 95% confidence interval [CI], 0.96-1.17; P = .26). Intake of allium vegetables did not correspond to CRC risk (P for nonlinear = .24, P for linear = .20). In subgroup analysis, a higher consumption of allium vegetables was associated marginally with increased risk of colon cancer among women (RR, 1.23; 95% CI, 1.01-1.50; P = .05). Use of garlic supplements was associated significantly with an increased risk of CRC (RR, 1.18; 95% CI, 1.02-1.36; P = .03).

CONCLUSIONS

In a meta-analysis, we found no evidence that higher intake of allium vegetables reduced the risk for CRC. We observed that garlic supplements increased the risk for CRC, but this finding requires external validation.

Effects of garlic oil on pancreatic cancer cells

BACKGROUND

To investigate the preventive and therapeutic potential of garlic oil on human pancreatic carcinoma cells.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was performed to study the effects of garlic oil on three human pancreatic cancer cell lines, AsPC-1, Mia PaCa-2 and PANC-1. Cell cycle progression and apoptosis were detected by flow cytometry (FCM), staining with PI and annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI), respectively. Morphologic changes of pancreatic cancer cells were observed under transmission electron microscopy (TEM) after treatment with garlic oil at low inhibitory concentrations (2.5 μM and 10 μM) for 24 hours.

RESULTS

Proliferation of the AsPC-1, PANC-1, and Mia PaCa-2 cells was obviously inhibited in the first 24 hours with the MTT assay. The inhibition effect was more significant after 48 hours. When cells were exposed to garlic oil at higher concentrations, an early change of the apoptotic tendency was detected by FCM and TEM.

CONCLUSION

Garlic oil could inhibit the proliferation of AsPC-1, PANC-1, and Mia PaCa-2 cells in this study. Moreover, due to programmed cell death, cell cycle arrest, or both, pro-apoptosis effects on AsPC-1 cells were induced by garlic oil in a dose and time dependent manner in vitro.

Immunity: plants as effective mediators

In the domain of nutrition, exploring the diet-health linkages is major area of research. The outcomes of such interventions led to widespread acceptance of functional and nutraceutical foods; however, augmenting immunity is a major concern of dietary regimens. Indeed, the immune system is incredible arrangement of specific organs and cells that enabled humans to carry out defense against undesired responses. Its proper functionality is essential to maintain the body homeostasis. Array of plants and their components hold immunomodulating properties. Their possible inclusion in diets could explore new therapeutic avenues to enhanced immunity against diseases. The review intended to highlight the importance of garlic (Allium sativum), green tea (Camellia sinensis), ginger (Zingiber officinale), purple coneflower (Echinacea), black cumin (Nigella sativa), licorice (Glycyrrhiza glabra), Astragalus and St. John's wort (Hypericum perforatum) as natural immune boosters. These plants are bestowed with functional ingredients that may provide protection against various menaces. Modes of their actions include boosting and functioning of immune system, activation and suppression of immune specialized cells, interfering in several pathways that eventually led to improvement in immune responses and defense system. In addition, some of these plants carry free radical scavenging and anti-inflammatory activities that are helpful against cancer insurgence. Nevertheless, interaction between drugs and herbs/botanicals should be well investigated before recommended for their safe use, and such information must be disseminated to the allied stakeholders.

Autophagy therapeutic potential of garlic in human cancer therapy

Cancer is one of the deadliest diseases against humans. To tackle this menace, humans have developed several high-technology therapies, such as chemotherapy, tomotherapy, targeted therapy, and antibody therapy. However, all these therapies have their own adverse side effects. Therefore, recent years have seen increased attention being given to the natural food for complementary therapy, which have less side effects. Garlic (Dà Suàn; Allium sativum), is one of most powerful food used in many of the civilizations for both culinary and medicinal purpose. In general, these foods induce cancer cell death by apoptosis, autophagy, or necrosis. Studies have discussed how natural food factors regulate cell survival or death by autophagy in cancer cells. From many literature reviews, garlic could not only induce apoptosis but also autophagy in cancer cells. Autophagy, which is called type-II programmed cell death, provides new strategy in cancer therapy. In conclusion, we wish that garlic could be the pioneer food of complementary therapy in clinical cancer treatment and increase the life quality of cancer patients.

No association between garlic intake and risk of colorectal cancer

BACKGROUND

Although experimental studies suggested beneficial role of garlic intake on colorectal carcinogenesis, limited prospective cohort studies have evaluated garlic intake in relation to colorectal cancer (CRC) incidence.

METHODS

We followed 76,208 women in the Nurses' Health Study and 45,592 men in the Health Professionals Follow-up Study for up to 24 years and examined garlic intake and garlic supplement use in relation to CRC risk. Information on garlic intake and supplement use was assessed using a validated food frequency questionnaire and a Cox proportional hazard regression model was used to estimate the multivariable hazard ratio (MV-HR) and 95% confidence intervals (95% CIs).

RESULTS

We documented 2368 (1339 women and 1029 men) incident CRC cases and fo und no association between garlic intake and CRC risk; the MV-HRs (95% CIs) associated with garlic (1 clove or 4 shakes per serving) intake ≥ 1/day compared with < 1/month were 1.21 (0.94-1.57; p-trend = 0.14) for women and 1.00 (0.71-1.42; p-trend = 0.89) for men. The MV-HRs (95% CIs) of CRC for garlic supplement use, which was used in 6% of the participants in each study, were 0.72 (0.48-1.07) for women and 1.22 (0.83-1.78) for men.

CONCLUSION

Our prospective data do not support an important role of garlic intake or garlic supplement use in colorectal carcinogenesis.

Prospective of colon cancer treatments and scope for combinatorial approach to enhanced cancer cell apoptosis

Colorectal cancer is the leading cause of cancer-related mortality in the western world. It is also the third most common cancer diagnosed in both men and women in the United States with a recent estimate for new cases of colorectal cancer in the year 2012 being around 103,170. Various risk factors for colorectal cancer include life-style, diet, age, personal and family history, and racial and ethnic background. While a few cancers are certainly preventable but this does not hold true for colon cancer as it is often detected in its advanced stage and generally not diagnosed until symptoms become apparent. Despite the fact that several options are available for treating this cancer through surgery, chemotherapy, radiation therapy, immunotherapy, and nutritional-supplement therapy, but the success rates are not very encouraging when used alone where secondary complications appear in almost all these therapies. To maximize the therapeutic-effects in patients, combinatorial approaches are essential. In this review we have discussed the therapies previously and currently available to patients diagnosed with colorectal-cancer, focus on some recent developments in basic research that has shaded lights on new therapeutic-concepts utilizing macrophages/dendritic cells, natural killer cells, gene delivery, siRNA-, and microRNA-technology, and specific-targeting of tyrosine kinases that are either mutated or over-expressed in the cancerous cell to treat these cancer. Potential strategies are discussed where these concepts could be applied to the existing therapies under a comprehensive approach to enhance the therapeutic effects.

Recent Research Progress on Garlic ( dà suàn) as a Potential Anticarcinogenic Agent Against Major Digestive Cancers

Garlic ( dà suàn; the bulb of Allium sativum), bestowed with an array of organosulfur compounds finds its application in treating many ailments including cardiovascular problems, common cold, bacterial and fungal infections and cancer. Numerous epidemiological evidences document the beneficial effects of various bioactive organosulfur compounds of garlic against different types of cancer. Studies involving the animal and cell models indicate garlic bioactive compounds could be effective in treating all the stages of cancer. This review gives an update on the recent pre-clinical and clinical trials, carried out to evaluate the efficacy of various garlic bioactive compounds along with the mechanism of action pertaining to major digestive cancers including liver, gastric and colorectal cancers. The major anti-carcinogenic mechanisms are caspase dependent and/or independent induction of apoptosis, anti-proliferative, anti-metastasis, anti-oxidant and immunomodulative properties. Form the clinical trials an increase in the garlic consumption of 20 g/day reduced the risk of gastric and colorectal cancer. In summary, increased uptake of garlic in diet may prevent the incidence of digestive cancers.

The emerging harm of antioxidants in carcinogenesis

Early epidemiologic studies have hinted at an anticancer role for multiple antioxidant compounds that are present in fresh produce. These substances target reactive oxygen and nitrogen species and potentially reduce oxidative damage to DNA that results in mutagenic change and potentially the initiation of cancer, disease and aging. It is tempting to believe that these compounds, through their in vitro actions as observed in cancer cell lines and certain animal experiments, may have the same anticarcinogenic role in humans. This article summarizes the relationship between fresh produce and antioxidant supplements and cancer risks from recent epidemiologic studies as well as identifying worrying trends and future directions for research into this most controversial field. Recent molecular data suggest that certain antioxidants may contribute towards oncogenesis.