Terfezia boudieri: A Desert Truffle With Anticancer and Immunomodulatory Activities

Morphological and molecular development of Terfezia claveryi ectendomycorrhizae exhibits three well-defined stages

The normal development of mycorrhizal symbiosis is a dynamic process, requiring elaborately regulated interactions between plant roots and compatible fungi, mandatory for both partners´ survival. In the present study, we further elucidated the mycorrhizal development of the desert truffles Terfezia claveryi with the host plant Helianthemum almeriense as an ectendomycorrhizal symbiosis model under greenhouse conditions. To investigate this, we evaluated the morphology of mycorrhizal colonization, concomitantly with the dynamic expression of selected marker genes (6 fungal and 11 plant genes) measured every week until mycorrhiza maturation (three months). We were able to determine 3 main stages in the mycorrhization process, 1) pre-symbiosis stage where mycelium is growing in the soil with no direct interaction with roots, 2) early symbiosis stage when the fungus spreads along the roots intercellularly and plant-fungal signaling is proceeding, and 3) late symbiosis stage where the fungus consolidates and matures with intracellular hyphal colonization; this is characterized by the regulation of cell-wall remodeling processes.

Identification of immunostimulatory activities and active compounds from sequentially extracted fractions of rhizosphere fungal fermentation broth of Atractylodes macrocephala Koidz. rhizomes

Introduction

Pharmacological studies have shown that the rhizome of Atractylodes macrocephala Koidz. (Compositae), commonly known as atractylodes macrocephala rhizome (AMR), can modulate immunity. Nevertheless, its resources have been largely depleted, and the pharmacological activity of artificial AMR is relatively modest. We hypothesized that the fermented crude extracts of the rhizosphere fungi of AMR would have similar immunomodulatory effects since the metabolites generated by these fungi are similar to those of the host plant given their long-term synergistic evolution.

Methods

Rhizosphere fungi were isolated from the rhizosphere soil of AMR and cultured to produce the secondary metabolites. These metabolites were then sequentially extracted with four solvents of increasing polarities (petroleum ether, ethyl acetate, n-butanol, and water). The in vitro immunomodulatory activities of the metabolite extracts were evaluated by cell proliferation capacity, cell phagocytosis activity, NO secretion capacity, cell morphology changes, and cytokine (TNF-α, IL-1β and IL-6) secretion capacity in RAW264.7 macrophage cells. The biologically active secondary metabolites produced by the rhizosphere fungi were identified using ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS).

Results

Three rhizosphere fungi, namely Penicillium (MK-1), Penicillium glaucoroseum (MN-1), and Purpureocillium lilalium (MG-1), were isolated from the rhizosphere soil of AMR. The assays for cell proliferation capacity, cell phagocytosis activity, and NO secretion capacity showed that all metabolite extracts exhibited in vitro immunomodulatory activities. The crude extracts of MG-1 exhibited the highest levels of in vitro immunomodulatory activities compared to the other extracts. Furthermore, it was demonstrated that the fermented extracts of MG-1 could facilitate immunological enhancement in vitro by altering the cellular morphology in the resting state and increasing the secretions of TNF-α, IL-1β, and IL-6. Meanwhile, there was no observable endotoxin contamination. The metabolite profiling of MG-1 by UHPLC-Q-TOFMS revealed the presence of several compounds with established immunoreactive activities, including L-arginine, prostaglandin I2, deoxyguanosine, bestatin, and osthole.

Discussion

The present study demonstrated that the metabolite extracts of the rhizosphere fungi isolated from the rhizosphere soil of AMR exhibited in vitro immunoreactive activities and that these rhizosphere fungi could produce several bioactive metabolites. The crude extracts of the rhizosphere fungi may hence extend the medicinal utility of AMR and provide a basis for further development of natural plant-based immunomodulators.

Toxicity, Antibacterial, Antioxidant, Antidiabetic, and DNA Cleavage Effects of Dextran-Graft-Polyacrylamide/Zinc Oxide Nanosystems

Synthesis of metal oxide nanoparticles-polymer nanocomposites is an emerging strategy in nanotechnology to improve targeted delivery and reduce the toxicity of nanoparticles. In this study, we report biological effects of previously described hybrid nanocomposites containing dextran-graft-polyacrylamide/zinc oxide nanoparticles (D-PAA/ZnO NPs) prepared from zinc sulfate (D-PAA/ZnONPs(SO42-)) and zinc acetate (D-PAA/ZnONPs(-OAc)) focusing primarily on their antimicrobial activity. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems were tested in a complex way to assess their antioxidant activity (DPPH assay), antidiabetic potential (α-amylase inhibition), DNA cleavage activity, antimicrobial, and antibiofilm activity. In addition, the toxicity of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems against primary murine splenocytes was tested using MTT assay. The studied nanosystems inhibited E.coli growth. For all the investigated strains, minimum inhibitory concentrations (MICs) of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) were in the range of 8 mg/L-128 mg/L and 16 mg/L-128 mg/L, respectively. The nanocomposites demonstrated effective antibiofilm properties as 94.27% and 86.43%. The compounds showed good antioxidant, anti-α-amylase, and DNA cleavage activities. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems reduced cell viability and promoted cell death of primary murine spleen cells at concentrations higher than those that proved to be antibacterial indicating the presence of therapeutic window. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems show antioxidant, antidiabetic, DNA cleavage, antimicrobial, and antibiofilm activity against the background of good biocompatibility suggesting the presence of therapeutic potential, which should be further investigated in vivo.

Phytol from Scoparia dulcis prevents NF-κB-mediated inflammatory responses during macrophage polarization

Macrophages are primary immune cells that mediate a wide range of inflammatory diseases through their polarization potential. In this study, phytol isolated from Scoparia dulcis has been explored against 7-ketocholesterol and bacterial lipopolysaccharide-induced macrophage polarization in IC-21 cells. Isolated phytol has been characterized using GC-MS, TLC, HPTLC, FTIR, 1H-NMR, and HPLC analyses. The immunomodulatory effects of viable concentrations of phytol were tested on oxidative stress, arginase activity, nuclear and mitochondrial membrane potentials in IC-21 cells in addition to the modulation of calcium and lipids. Further, gene and protein expression of atherogenic markers were studied. Results showed that the isolated phytol at a viable concentration of 400 µg/ml effectively reduced the production of nitric oxide, superoxide anion (ROS generation), calcium and lipid accumulation, stabilized nuclear and mitochondrial membranes, and increased arginase activity. The atherogenic markers including iNOS, COX-2, IL-6, IL-1β, MMP-9, CD36, and NF-κB were significantly downregulated at the levels of gene and protein expression, while macrophage surface and nuclear receptor markers (CD206, CD163, and PPAR-γ) were significantly upregulated by phytol pre-treatment in macrophages. Therefore, the present pharmacognostic study supports the role of phytol isolated from Scoparia dulcis in preventing M2-M1 macrophage polarization under inflammatory conditions, making it a promising compound.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03924-9.

Sitosterol-rich Digera muricata against 7-ketocholesterol and lipopolysaccharide-mediated atherogenic responses by modulating NF-ΚB/iNOS signalling pathway in macrophages

Digera muricata L., commonly known as Tartara, is an edible herb used as traditional medicine in many countries of Africa and Asia. This study aimed to elucidate the effect of a phytosterol-rich extract of D. muricata on 7-ketocholesterol-mediated atherosclerosis in macrophages. The extract was examined by phytochemical analyses, GC-MS, TLC, DPPH scavenging and hRBC membrane stabilization assays. Macrophage polarization was studied with experimental groups framed based on alamar blue cell viability and griess assays. Regulations of arginase enzyme activity, ROS generation, mitochondrial membrane potential, cell membrane integrity, pinocytosis, lipid uptake and peroxidation, as well as, intracellular calcium deposition were determined. In addition, expressions of atherogenic mediators were analysed using PCR, ELISA and immunocytochemistry techniques. Diverse phytochemicals with higher free radical scavenging activity and anti-inflammatory potential have been detected in the D. muricata. Co-treatment with D. muricata markedly reduced the atherogenic responses induced by 7KCh in the presence of LPS such as ROS, especially, NO and O2- along with lipid peroxidation. Furthermore, D. muricata significantly normalized mitochondrial membrane potential, cell membrane integrity, pinocytic activity, intracellular lipid accumulation and calcium deposition. These results provided us with the potentiality of D. muricata in ameliorating atherogenesis. Additionally, it decreased the expression of pro-atherogenic mediators (iNOS, COX-2, MMP9, IL-6, IL-1β, CD36, CD163 and TGFβ1) and increased anti-atherogenic mediators (MRC1 and PPARγ) with high cellular expressions of NF-κB and iNOS. Results showed the potential of sitosterol-rich D. muricata as a versatile biomedical therapeutic agent against abnormal macrophage polarization and its associated pathologies.

Using Science and Technology to Unveil The Hidden Delicacy Terfezia arenaria, a Desert Truffle

Terfezia arenaria is a desert truffle native to the Mediterranean Basin region, highly appreciated for its nutritional and aromatic properties. Despite the increasing interest in this desert truffle, T. arenaria is not listed as an edible truffle authorized for trade in the European Union. Therefore, our objective was to showcase T. arenaria's nutritional and chemical composition and volatile profile. The nutritional analysis showed that T. arenaria is a good source of carbohydrates (67%), proteins (14%), and dietary fibre (10%), resulting in a Nutri-Score A. The truffle's volatile profile was dominated by eight-carbon volatile compounds, with 1-octen-3-ol being the most abundant (64%), and 29 compounds were reported for the first time for T. arenaria. T. arenaria's nutritional and chemical compositions were similar to those of four commercial mushroom and truffle species, while the aromatic profile was not. An electronic nose corroborated that T. arenaria's aromatic profile differs from that of the other four tested mushroom and truffle species. Our data showed that T. arenaria is a valuable food resource with a unique aroma and an analogous composition to meat, which makes it an ideal source for plant-based meat products. Our findings could help promote a sustainable future exploitation of T. arenaria and ensure the quality and authenticity of this delicacy.

Macrofungal Diversity and Distribution Patterns in the Primary Forests of the Shaluli Mountains

The Shaluli Mountains are located in the southeastern part of the Tibetan Plateau at an elevation of 2500-5000 m. They are characterized by a typical vertical distribution of climate and vegetation and are considered a global biodiversity hotspot. We selected ten vegetation types at different elevation gradients representing distinct forests in the Shaluli Mountains to assess the macrofungal diversity, including subalpine shrub, Pinus spp., Populus spp., Pinus spp. and Quercus spp., Quercus spp., Abies spp., Picea spp. and Abies spp., Picea spp., Juniperus spp., and alpine meadow. In total, 1654 macrofungal specimens were collected. All specimens were distinguished by morphology and DNA barcoding, resulting in the identification of 766 species belonging to 177 genera in two phyla, eight classes, 22 orders, and 72 families. Macrofungal species composition varied widely among vegetation types, but ectomycorrhizal fungi were predominant. In this study, the analysis of observed species richness, the Chao1 diversity index, the invsimpson diversity index, and the Shannon diversity index revealed that the vegetation types with higher macrofungal alpha diversity in the Shaluli Mountains were composed of Abies, Picea, and Quercus. The vegetation types with lower macrofungal alpha diversity were subalpine shrub, Pinus spp., Juniperus spp., and alpine meadow. The results of curve-fitting regression analysis showed that macrofungal diversity in the Shaluli Mountains was closely related to elevation, with a trend of increasing and then decreasing with rising elevation. This distribution of diversity is consistent with the hump-shaped pattern. Constrained principal coordinate analysis based on Bray-Curtis distances indicated that macrofungal community composition was similar among vegetation types at similar elevations, while vegetation types with large differences in elevation differed significantly in macrofungal community composition. This suggests that large changes in elevation increase macrofungal community turnover. This study is the first investigation of the distribution pattern of macrofungal diversity under different vegetation types in high-altitude areas, providing a scientific basis for the conservation of macrofungal resources.

Proapoptotic and Antiproliferative Effects of the Desert Truffle Terfezia boudieri on Colon Cancer Cell Lines

Background

Colon cancer is the second leading cause of cancer-related mortality, and ranks third among cancers in terms of prevalence. Despite advances in early detection and treatment with chemotherapy and surgery, colon cancer continues to be associated with high recurrence rates, thereby resulting in a heavy disease burden. Moreover, the effectiveness of currently available treatment modalities is limited by the occurrence of toxic side effects. Hence, there is an urgent need to develop alternative treatments. Extracts from the black desert truffle Terfezia boudieri (T. boudieri) have shown promising anticancer properties. However, the cellular mechanisms underlying this activity remain poorly understood.

Methods

In this study, the colon cancer cell lines HCT-116 and Caco-2 were treated with either water or ethanolic extract of T. boudieri. Cell viability and the half-maximal inhibitory concentration were determined using MTT assays. Then, the activity of the more potent water extract was further verified using crystal violet assays, and its role in inhibiting colony formation and wound healing was investigated. Protein levels of p53, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X (Bax), cyclin D1 (CCND1), and c-Myc were measured in cells treated with different doses of the water extract.

Results

Treatment with the water extract of T. boudieri reduced the capacity of cells for wound healing and colony formation in a dose-dependent manner. The Bax/Bcl-2 ratio and p53 expression were elevated in both cell lines. In contrast, the levels of cyclin D1 and c-Myc were suppressed.

Conclusion

T. boudieri water extract exerted a cytotoxic effect on colon cancer cells, and blocked colony formation and wound healing potentially through inhibition of proliferation. Mechanistically, these effects are attributed to influence the mitochondrial pathway of apoptosis, proteins involved in cellular proliferation, and the cell cycle.

The Microbiome Structure of the Symbiosis between the Desert Truffle Terfezia boudieri and Its Host Plant Helianthemum sessiliflorum

The desert truffle Terfezia boudieri is an ascomycete fungus that forms ect-endomycorrhiza in the roots of plants belonging to Cistaceae. The fungus forms hypogeous edible fruit bodies, appreciated as gourmet food. Truffles and host plants are colonized by various microbes, which may contribute to their development. However, the diversity and composition of the bacterial community under field conditions in the Negev desert are still unknown. The overall goal of this research was to identify the rhizosphere microbial community supporting the establishment of a symbiotic association between T. boudieri and Helianthemum sessiliflorum. The bacterial community was characterized by fruiting bodies, mycorrhized roots, and rhizosphere soil. Based on next-generation sequencing meta-analyses of the 16S rRNA gene, we discovered diverse bacterial communities of fruit bodies that differed from those found in the roots and rhizosphere. Families of Proteobacteria, Planctomycetes, and Actinobacteria were present in all four samples. Alpha diversity analysis revealed that the rhizosphere and roots contain significantly higher bacterial species numbers compared to the fruit. Additionally, ANOSIM and PCoA provided a comparative analysis of the bacterial taxa associated with fruiting bodies, roots, and rhizosphere. The core microbiome described consists of groups whose biological role triggers important traits supporting plant growth and fruit body development.

Gaz Alafi: A Traditional Dessert in the Middle East With Anticancer, Immunomodulatory, and Antimicrobial Activities

Background

From the earliest times, manna has been widely used as a tasty local sweet or folk medicine. The type of manna being investigated in the present study is called Gaz-alafi, a mixture of insect and Quercus brantii leaves secretions from oak forests in the north of Iraq and west of Iran.

Methods

Aqueous and ethanol extracts were prepared as decoction. Various phytochemical tests were conducted to analyze manna composition, including total phenolic contents using the Folin-Ciocalteu method and LC-MS. Gallic acid and catechin were detected in both extracts, in addition to tiliroside presence in ethanol extract, which added more value to the phenolic content of ethanol extract. Cytotoxic activities of Gaz alafi were evaluated against breast cancer cell lines and compared to normal cell lines and doxorubicin using the MTT assay. Antimicrobial properties were assessed against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Candida albicans using the dilution method of the micro-titer plate. Serum levels of IFN-γ, interleukin-2 (IL-2), interleukin-4 (IL-4), and interleukin-10 (IL-10) were measured using ELISA. The effect of extracts on splenocyte proliferation was evaluated using the lymphocytes proliferation assay. Macrophage function was evaluated using the nitro blue tetrazolium assay, whereas pinocytosis was evaluated using the neutral red uptake assay. Ten days after tumor inoculation, changes in tumor size, survival rates, levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine were measured.

Results

The growth of cancer cells was inhibited by Gaz alafi ethanol extract. An alteration in IFN- γ, IL-2, and IL-4 levels toward antiproliferation immune response were reported for both extracts. The aqueous extract efficiently stimulated lymphocyte proliferation, phagocytosis, and pinocytosis, followed by the ethanol extracts with moderate activity. After treating the mice with ethanol extracts, a significant reduction in tumor size and several undetected tumors were recorded.

Conclusions

Gaz alafi extracts (aqueous and ethanol) are promising sources for anticancer and immunostimulatory agents. Further studies are needed to fully identify the chemical composition of Gaz alafi extracts.

Daily Consumption of Lemon and Ginger Herbal Infusion Caused Tumor Regression and Activation of the Immune System in a Mouse Model of Breast Cancer

The Mediterranean diet includes the consumption of various fruits and vegetables. Lemon and ginger are highly popular in Mediterranean cuisine. The current study aims to evaluate both anticancer and immunomodulatory activities of lemon and ginger combination. The antiproliferative activities of the combination were tested against different cancer cell lines using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The degree of apoptosis induction and vascular endothelial growth factor expression were detected using ELISA. Balb/C mice were inoculated with the EMT6/P breast cancer cells and received combination water extract orally for 14 days. The effect of the water extract on splenocytes proliferation was measured using the mitogen proliferation assay. Macrophage function was evaluated using the nitro blue tetrazolium assay and pinocytosis was assessed using the neutral red method. Gas chromatography coupled to the tandem mass spectrometry was used to determine the composition of the combination. The lemon and ginger combination showed significant apoptosis induction and angiogenesis suppression effects. Fifty percent of the mice taking this combination did not develop tumors with a percentage of tumor reduction of 32.8%. This combination showed a potent effect in stimulating pinocytosis. Alpha-pinene and α-terpineol were detected in high percentages in the combination water extract. The lemon and ginger combination represents promising options to develop anticancer infusions for augmenting conventional anticancer therapies. Further testing is required to understand the exact molecular mechanisms of this combination.

Immunomodulatory and Anticancer Activities of Hyacinthus orientalis L.: An In Vitro and In Vivo Study

Hyacinthus orientalis L. (family Hyacinthaceae) is traditionally used to treat different diseases including cancer. In this study, the anticancer and immunomodulatory effects of this plant were evaluated. Hydroalcoholic extract was prepared, and different solvent fractions were obtained using solvent-solvent extraction. In the anticancer part, MTT assay and caspase-3 ELISA kits were used to measure the antiproliferative and apoptosis induction ability for each extract, respectively. In the immunomodulatory part, lymphocyte proliferation assay and cytokines detection kit were used to measure the effect of extracts of acquired immunity. Phagocytosis and pinocytosis induction were used to evaluate the effect of extracts on the innate immunity. GC-MS, LC-MS, and Foline-Ciocalteu assays were used to identify the chemical composition of the plant. Balb/C mice were inoculated with breast cancer and treated with hydroalcoholic extract of H. orientalis L. Results showed that hydroalcoholic extract and n-hexane fraction were highly effective in apoptosis induction. Both extract and fraction were also effective in stimulating lymphocytes proliferation and phagocytosis. Significant reduction in tumor size was achieved after treating tumor-bearing mice with hydroalcoholic extract. Additionally, high cure percentages (50%) were obtained in treated mice. Results of this study showed that H. orientalis L. has promising anticancer and immunomodulatory activities. However, further studies are needed to explore more details of apoptosis induction ability and other mechanisms of action and to measure different signaling pathways responsible for the anticancer and immunomodulatory response.

Mycochemical composition and insecticidal bioactivity of Algerian desert truffles extract against two stored-product insects: Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae)

The present study aimed to highlight the insecticidal activity of the Algerian desert truffle Terfezia claveryi Chatin against two post-harvest pests of rice and other cereal products, the rice weevil Sitophilus oryzae (L.), and the lesser grain borer Rhyzopertha dominica (F.), using direct contact application method with the filter paper impregnation technique. Soxhlet apparatus was used for extraction with chloroform as solvent. The major compounds in chloroform extract of T. claveryi were identified using gas chromatography-mass spectrometry (GC-MS). The two-way ANOVA was used for statistical analysis to determine the exposure time and doses with the greatest insecticidal activity. Findings of this study revealed that the major compounds were fatty acids: linoleic acid, methyl ester (14.84%), 11,14-eicosadienoic acid, methyl ester (11.55%), oleic acid, methyl ester (7.1%), and palmitic acid (6.96%). However, chamazulene (0.88%) was found to be minor compound. Our results describe for the first time the presence of chamazulene in desert truffle. The result showed also that the most potent insecticidal activity of chloroform extract of T. claveryi was found towards S. oryzea with LD₅₀ value of 162.11 µg/mL. For concentrations of 250 and 300 µg/mL, this extract was able to eradicate 96.65 ± 1.15% and 100.0 ± 0.0% of S. oryzea after 24 h of exposure. However, it caused only 47.24 ± 1.15% and 50.66 ± 1.15% of mortality of R. dominica, respectively, after 6 days. This work offers promising prospects for the use of desert truffles extracts as a potential insecticidal agent for improving quality and safety of stored foods against damage caused by stored-product pests.

Agrobacterium tumefaciens-Mediated Genetic Transformation of the Ect-endomycorrhizal Fungus Terfezia boudieri

Mycorrhizal desert truffles such as Terfezia boudieri, Tirmania nivea, and Terfezia claveryi, form mycorrhizal associations with plants of the Cistaceae family. These valued truffles are still collected from the wild and not cultivated under intensive farming due to the lack of basic knowledge about their biology at all levels. Recently, several genomes of desert truffles have been decoded, enabling researchers to attempt genetic manipulations to enable cultivation. To execute such manipulations, the development of molecular tools for genes transformation into truffles is needed. We developed an Agrobacterium tumefaciens-mediated genetic transformation system in T. boudieri. This system was optimized for the developmental stage of the mycelia explants, bacterial optical density, infection and co-cultivation durations, and concentrations of the selection antibiotics. The pFPL-Rh plasmid harboring hph gene conferring hygromycin resistance as a selection marker and the red fluorescent protein gene were used as visual reporters. The optimal conditions were incubation with 200 μM of acetosyringone, attaining a bacterial optical density of 0.3 OD₆₀₀; transfer time of 45 min; and co-cultivation for 3 days. This is the first report on a transformation system for T. boudieri, and the proposed protocol can be adapted for the transformation of other important desert truffles as well as ectomycorrhizal species.

The Impact of Herbal Infusion Consumption on Oxidative Stress and Cancer: The Good, the Bad, the Misunderstood

The release of reactive oxygen species (ROS) and oxidative stress is associated with the development of many ailments, including cardiovascular diseases, diabetes and cancer. The causal link between oxidative stress and cancer is well established and antioxidants are suggested as a protective mechanism against cancer development. Recently, an increase in the consumption of antioxidant supplements was observed globally. The main sources of these antioxidants include fruits, vegetables, and beverage. Herbal infusions are highly popular beverages consumed daily for different reasons. Studies showed the potent antioxidant effects of plants used in the preparation of some herbal infusions. Such herbal infusions represent an important source of antioxidants and can be used as a dietary protection against cancer. However, uncontrolled consumption of herbal infusions may cause toxicity and reduced antioxidant activity. In this review, eleven widely consumed herbal infusions were evaluated for their antioxidant capacities, anticancer potential and possible toxicity. These herbal infusions are highly popular and consumed as daily drinks in different countries. Studies discussed in this review will provide a solid ground for researchers to have better understanding of the use of herbal infusions to reduce oxidative stress and as protective supplements against cancer development.