Diet-derived Compounds Research Articles

The Effects of Natural Epigenetic Therapies in 3D Ovarian Cancer and Patient-Derived Tumor Explants: New Avenues in Regulating the Cancer Secretome.

High mortality rates in ovarian cancer have been linked to recurrence, metastasis, and chemoresistant disease, which are known to involve not only genetic changes but also epigenetic aberrations. In ovarian cancer, adipose-derived stem cells from the omentum (O-ASCs) play a crucial role in supporting the tumor and its tumorigenic microenvironment, further propagating epigenetic abnormalities and dissemination of the disease. Epigallocatechin gallate (EGCG), a DNA methyltransferase inhibitor derived from green tea, and Indole-3-carbinol (I3C), a histone deacetylase inhibitor from cruciferous vegetables, carry promising effects in reprograming aberrant epigenetic modifications in cancer. Therefore, we demonstrate the action of these diet-derived compounds in suppressing the growth of 3D ovarian cancer spheroids or organoids as well as post-treatment cancer recovery through proliferation, migration, invasion, and colony formation assays when compared to the synthetic epigenetic compound Panobinostat with or without standard chemotherapy. Finally, given the regulatory role of the secretome in growth, metastasis, chemoresistance, and relapse of disease, we demonstrate that natural epigenetic compounds can regulate the secretion of protumorigenic growth factors, cytokines, extracellular matrix components, and immunoregulatory markers in human ovarian cancer specimens. While further studies are needed, our results suggest that these treatments could be considered in the future as adjuncts to standard chemotherapy, improving efficiency and patient outcomes.

Can epigenetic treatments efficiently revoke the ability of 3D ovarian cancer cells to proliferate, migrate, and invade?

e17562 Background: 3D ovarian cancer propagation and metastasis arise not only from genetic mutations, but from aberrant epigenetic modifications known to involve mechanisms of DNA methylation and histone deacetylation. Clinically, cancer induces epigenetic aberrations in adipose-derived stem cells from omentum (O-ASCs), creating a tumorigenic microenvironment that supports chemoresistance and dissemination of disease. Epigallocatechin gallate (EGCG), a DNA methyltransferase inhibitor derived from green tea, and Indole-3-carbinol (I3C), a histone deacetylase inhibitor from cruciferous vegetables, carry promising effects in reprograming aberrant epigenetic modifications in cancer. Therefore, we investigate whether these diet-derived compounds can suppress proliferation, migration and invasion of ovarian cancer in 3D-spheroids or 3D-organoids with O-ASCs when compared to synthetic Panobinostat (Pano) and cisplatin/paclitaxol (C/T). Methods: 3D ovarian cancer spheroids and organoids (30% O-ASCs) were treated with EGCG (10, 50 µm), I3C (50, 200 µm), Pano (5, 15 µm) and C/T. Percent growth was followed for 17 days and compared to an untreated control group. Post-treated cancer was then derived from 3D structures and tested for its ability to regrow (MTT assay), to form colonies (CFU), and to migrate and invade (CytoSelect Cell Migration and Invasion assay). Results: Our results show that higher doses of epigenetic regimens more efficiently suppress growth of 3D ovarian cancer when compared to the control and C/T groups (p<.05). Additionally, the synthetic epigenetic drug Pano also efficiently suppressed cancer as compared to control and C/T treated cells (p<.05). Given that experimental treatments efficiently down-regulated 3D cancer growth, follow up of post-treatment cancer recovery was analyzed through multiple biochemical and biological assays. 3D derived cells pre-treated with EGCG, I3C and Pano had significant lower proliferation capacity as compared to control or C/T as demonstrated by an MTT assay (p<.05). While all epigenetic treatments inhibited CFU in the spheroid derived group, EGCG was not able to fully inhibit CFU in the organoid group. Further, inhibition of CFU was not noted in the C/T pre-treated cells. Finally, the ability of cells to migrate and invade following treatment was more efficiently suppressed in cells derived from organoids. I3C and Pano significantly suppressed cancer migration, while EGCG and Pano suppressed invasion (p<.05). Conclusions: Diet-derived epigenetic treatments can reprogram epigenetic aberrations involved in mechanisms of proliferation, migration and invasion of 3D ovarian cancer. Our results suggest that these treatments not only suppress 3D cancer growth and post-treatment regrowth, but could be considered as adjuncts to standard chemotherapy, improving efficiency and patient outcomes.

The Role of Nutrition in Primary and Secondary Prevention of Cardiovascular Damage in Childhood Cancer Survivors.

Innovative therapeutic strategies in childhood cancer led to a significant reduction in cancer-related mortality. Cancer survivors are a growing fragile population, at risk of long-term side effects of cancer treatments, thus requiring customized clinical attention. Antineoplastic drugs have a wide toxicity profile that can limit their clinical usage and spoil patients’ life, even years after the end of treatment. The cardiovascular system is a well-known target of antineoplastic treatments, including anthracyclines, chest radiotherapy and new molecules, such as tyrosine kinase inhibitors. We investigated nutritional changes in children with cancer from the diagnosis to the end of treatment and dietary habits in cancer survivors. At diagnosis, children with cancer may present variable degrees of malnutrition, potentially affecting drug tolerability and prognosis. During cancer treatment, the usage of corticosteroids can lead to rapid weight gain, exposing children to overweight and obesity. Moreover, dietary habits and lifestyle often dramatically change in cancer survivors, who acquire sedentary behavior and weak adherence to dietary guidelines. Furthermore, we speculated on the role of nutrition in the primary prevention of cardiac damage, investigating the potential cardioprotective role of diet-derived compounds with antioxidative properties. Finally, we summarized practical advice to improve the dietary habits of cancer survivors and their families.

110 Effects of Dietary Phytoestrogens on Aneurysm Wall Inflammation and Intracranial Aneurysm Formation

INTRODUCTION: The discovery of pharmacologic treatments that can reduce the incidence of aneurysm formation or rupture is of considerable interest. Prior studies demonstrated that supplemental estrogen can protect against the formation and rupture of aneurysms in ovariectomized female mice. This is of particular clinical significance, as post-menopausal women are at an increased risk for aneurysmal rupture. However, systemic estrogen hormone replacement is associated with adverse clinical outcomes primarily due to off-target effects thus limiting its clinical applicability. Isoflavones are plant-based, diet-derived compounds that structurally resemble estrogens but exhibit tissue and receptor specificity resulting in the potential for targeted, tissue-specific activation of estrogen receptors while limiting potentially deleterious off-target effects. METHODS: Using a systemic hypertension and elastase injection murine model, we induced intracranial aneurysms in ovariectomized adult female mice. We fed the mice with an isoflavone-free diet with/without daidzein supplementation or in a combination of intraperitoneal equol; a separate group were also given oral vancomycin. Experiments were repeated using estrogen-receptor-beta knockout mice. RESULTS: Both dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen-receptor-beta. Oral vancomycin induced disruption of the intestinal microbial conversion of daidzein to equol abolished the protective effects of daidzein against aneurysm formation. mRNA expression analyses demonstrated that mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis. CONCLUSION: Our study establishes that both dietary daidzein and its metabolite - equol - are protective against aneurysm formation in ovariectomized female mice through the activation of estrogen-receptor-beta and subsequent suppression of inflammation. Dietary daidzein's protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and equol for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.

Fucoxanthin and Colorectal Cancer Prevention.

Simple SummaryColorectal cancer (CRC) is suggested to be preventable by certain food intakes. Fucoxanthin (Fx) is an anticancer agent contained abundantly in edible brown algae. However, epidemiological studies, in vivo and in vitro experiments for CRC, using Fx and Fx-rich foods, have not been fully outlined. To date, it has been reported that Fx, its metabolite of fucoxanthinol (FxOH) and Fx-rich algal extracts exerted anticancer potentials in human CRC cell lines, their cancer stem-cells-like spheroids and CRC animal models through a number of molecular mechanisms. Moreover, many in vivo experiments and interventional human trials have demonstrated that Fx, Fx-rich algal extracts and brown alga itself may improve CRC and/or certain risks, such as obesity, diabetes, metabolic syndrome, inflammation, oxidation, tumor microenvironment and/or gut microbiota. This review is the first report that summarizes the improving effects by Fx, FxOH and its rich brown algae for CRC and the risk factors.Colorectal cancer (CRC), which ranks among the top 10 most prevalent cancers, can obtain a good outcome with appropriate surgery and/or chemotherapy. However, the global numbers of both new cancer cases and death from CRC are expected to increase up to 2030. Diet-induced lifestyle modification is suggested to be effective in reducing the risk of human CRC; therefore, interventional studies using diets or diet-derived compounds have been conducted to explore the prevention of CRC. Fucoxanthin (Fx), a dietary carotenoid, is predominantly contained in edible brown algae, such as Undaria pinnatifida (wakame) and Himanthalia elongata (Sea spaghetti), which are consumed particularly frequently in Asian countries but also in some Western countries. Fx is responsible for a majority of the anticancer effects exerted by the lipophilic bioactive compounds in those algae. Interventional human trials have shown that Fx and brown algae mitigate certain risk factors for CRC; however, the direct mechanisms underlying the anti-CRC properties of Fx remain elusive. Fx and its deacetylated type “fucoxanthinol” (FxOH) have been reported to exert potential anticancer effects in preclinical cancer models through the suppression of many cancer-related signal pathways and the tumor microenvironment or alteration of the gut microbiota. We herein review the most recent studies on Fx as a potential candidate drug for CRC prevention.

Abstract 18: The CXCR4/CXCL12 axis is a target of a polyphenol extract from olive oil processing with potential cancer prevention and interception activities

Abstract The olive mill wastewater polyphenol extracts exhibit chemopreventive properties in lung cancer cell lines, acting on the CXCR4/CXCL12 axis. Lung cancer still is a leading cause of cancer death worldwide. Although avoidance of tobacco use and smoking cessation will have the greatest impact on lung cancer development, (chemo)prevention could prove to be very effective, particularly in high risk individuals. Diverse diet-derived compounds have been reported to exert antioxidant, anti-proliferative and anti-angiogenic effects. Olive oil production involves the generation of an aqueous phase, defined as olive mill wastewater (OMWW), a polluting effluent rich in soluble polyphenols. We established a polyphenol rich, purified extract, from OMWW, that we termed A009. The effect of A009 on cell proliferation was determined by the crystal violet assay, while induction of apoptosis was measured by flow cytometry. The ability of the A009 to regulate the cell migration/invasion axis CXCR4/CXL12 and the production of pro angiogenic factors (VEGF, CXCL8, CCL2), was investigated by flow cytometry. The sprouting assay on Matrigel was used to functional verify the ability of A009 to limit invasive properties. Hydroxytyrosol, the most abundant polyphenols present in our A009, was used as reference molecules in all the assays performed. We found that the A009 limit A549 and H1560 cell proliferation, in a dose and time dependent manner. These effects were associated with induction of apoptosis at 24 and 48 hours of treatment, that was higher in H1650, as compared to A549 cells. The A009 extracts were effective in inhibiting the production of CXCR4 and CXCL12 in both the A549 and H1650 cells, accompanied with reduction in H1650 cell capability to generate invasive sprouts. in a Matrigel layer. Finally, A009 interfere with the production of VEGF, CXCL8 and CCL2 in both the A549 and H1650 cells. Our preliminary results suggest that A009 exhibit promising preventing and interceptive properties on lung cancer cell lines in vitro. Citation Format: Matteo Gallazzi, Marco Festa, Clementina Sansone, Paola Corradino, Douglas Noonan, Adriana Albini. The CXCR4/CXCL12 axis is a target of a polyphenol extract from olive oil processing with potential cancer prevention and interception activities [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 18.

Quantifying the human diet in the crosstalk between nutrition and health by multi-targeted metabolomics of food and microbiota-derived metabolites.

Metabolomics is a powerful tool for investigating the association between nutrition and health status. Although urine is commonly employed for studying the metabolism and transformation of food components, the use of blood samples could be preferable to gain new insights into the bioavailability of diet-derived compounds and their involvement in health. However, the chemical complexity of blood samples hinders the analysis of this biological fluid considerably, which makes the development of novel and comprehensive analytical methods mandatory. In this work, we optimized a multi-targeted metabolomics platform for the quantitative and simultaneous analysis of 450 food-derived metabolites by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. To handle the chemical complexity of blood samples, three complementary extraction methods were assayed and compared in terms of recovery, sensitivity, precision and matrix effects with the aim of maximizing metabolomics coverage: protein precipitation, reversed solid-phase extraction, and hybrid protein precipitation with solid-phase extraction-mediated phospholipid removal. After careful optimization of the extraction conditions, protein precipitation enabled the most efficient and high-throughput extraction of the food metabolome in plasma, although solid-phase extraction-based protocols provided complementary performance for the analysis of specific polyphenol classes. The developed method yielded accurate recovery rates with negligible matrix effects, and good linearity, as well as high sensitivity and precision for most of the analyzed metabolites. The multi-targeted metabolomics platform optimized in this work enables the simultaneous detection and quantitation of 450 dietary metabolites in short-run times using small volumes of biological sample, which facilitates its application to epidemiological studies.

An Extract of Olive Mill Wastewater Downregulates Growth, Adhesion and Invasion Pathways in Lung Cancer Cells: Involvement of CXCR4.

Several diet-derived compounds have been reported to exert antioxidant, anti-proliferative and anti-angiogenic effects in numerous cancers and could be beneficial in cancer prevention. Olive oil production involves the generation of an aqueous phase defined as olive mill wastewater (OMWW), a polluting effluent rich in soluble polyphenols. Here, we assessed the cancer preventive properties exerted by a purified extract of OMWW (A009) for its activity on lung cancer cell lines. Hydroxytyrosol, the most abundant polyphenol present in our A009 extracts, was used as reference molecule in the assays performed. Extracts from OMWW from two different olive oil cultivars were used. We found that the A009 extracts limit lung cancer cell proliferation in a dose and time dependent manner. These effects were associated with the induction of apoptosis. A009 extracts were effective in inhibiting adhesion capabilities on a fibronectin layer accompanied with a reduction in their ability to generate invasive sprouts in a Matrigel layer. The production of chemokine CXCL12 and CXCR4 receptor were reduced by treatment with the extracts. Also, A009 interfered with the production of proangiogenic and pro-inflammatory VEGF, CXCL8, and CCL2 (as detected by FACS analysis) in the lung cell lines. A009 extracts were able to decrease STAT3 phosphorylation in lung cancer cells. Our results show that A009 extracts reduced activities related to tumor cell behavior in lung cancer cell lines, suggesting that they could have a potential cancer preventive role.

Application of Metabolomics to Assess Effects of Controlled Dietary Interventions

The utilization of metabolomics technologies as part of nutritional investigations has rapidly increased during the last few years. The application of both nuclear magnetic resonance (NMR) and mass spectrometry (MS) based technologies is providing wide information on both the diet-derived compounds and their metabolites related to specific foods or diets, as well as aiding the in-depth exploration of the endogenous metabolic phenomena related to different diets. The analytical accuracy nowadays enables examination of metabolite composition of both urine and plasma to very high molecular detail even at low concentrations, and will be focal in gaining wider metabolic understanding of the relationship between eating habits and maintenance of good health.

Approaches that ascertain the role of dietary compounds in colonic cancer cells.

Preventive approaches against cancer have not been fully developed and applied. For example, the incidence of some types of cancer, including colon cancer, is highly dependent upon lifestyle, and therefore, amenable to prevention. Among the lifestyle factors, diet strongly affects the incidence of colon cancer; however, there are no definitive dietary recommendations that protect against this malignancy. The association between diet-derived bioactives and development of colonic neoplasms will remain ill defined if we do not take into account: (1) the identity of the metabolites present in the colonic lumen; (2) their concentrations in the colon; and (3) the effect of the colonic contents on the function of individual bioactives. We review two approaches that address these questions: the use of fecal water and in vitro models of the human colon. Compared to treatment with individual diet-derived compounds, the exposure of colon cancer cells to samples from fecal water or human colon simulators mimics closer the in vitro conditions and allows for more reliable studies on the effects of diet on colon cancer development. The rationale and the advantages of these strategies are discussed from the perspective of a specific question on how to analyze the combined effect of two types of bioactives, butyrate and polyphenol metabolites, on colon cancer cells.

Propolis Augments Apoptosis Induced by Butyrate via Targeting Cell Survival Pathways

Diet is one of the major lifestyle factors affecting incidence of colorectal cancer (CC), and despite accumulating evidence that numerous diet-derived compounds modulate CC incidence, definitive dietary recommendations are not available. We propose a strategy that could facilitate the design of dietary supplements with CC-preventive properties. Thus, nutrient combinations that are a source of apoptosis-inducers and inhibitors of compensatory cell proliferation pathways (e.g., AKT signaling) may produce high levels of programmed death in CC cells. Here we report the combined effect of butyrate, an apoptosis inducer that is produced through fermentation of fiber in the colon, and propolis, a honeybee product, on CC cells. We established that propolis increases the apoptosis of CC cells exposed to butyrate through suppression of cell survival pathways such as the AKT signaling. The programmed death of CC cells by combined exposure to butyrate and propolis is further augmented by inhibition of the JNK signaling pathway. Analyses on the contribution of the downstream targets of JNK signaling, c-JUN and JAK/STAT, to the apoptosis of butyrate/propolis-treated CC cells ascertained that JAK/STAT signaling has an anti-apoptotic role; whereas, the role of cJUN might be dependent upon regulatory cell factors. Thus, our studies ascertained that propolis augments apoptosis of butyrate-sensitive CC cells and re-sensitizes butyrate-resistant CC cells to apoptosis by suppressing AKT signaling and downregulating the JAK/STAT pathway. Future in vivo studies should evaluate the CC-preventive potential of a dietary supplement that produces high levels of colonic butyrate, propolis, and diet-derived JAK/STAT inhibitors.

A new reason to eat your veggies

Earlier this year, a study by researchers at the Linus Pauling Institute at Oregon State University in Corvallis found a new way in which broccoli, cauliflower, cabbage, and other cruciferous vegetables may help ward off cancer.1 Researchers at Temple University in Philadelphia, Pennsylvania, by contrast, linked a high-fat diet to a heightened risk of colon cancer.2 More than a decade ago, European researchers delving into historical records from northern Sweden came to a more startling conclusion. Dietary overindulgence among boys aged 8 to 12 years, which was due to the remote region's feast and famine cycles of the 1800s, led to significantly shorter life spans among their grandchildren.3 In all 3 cases, the science has highlighted how nutrition and diet may exert powerful effects on health and disease, sometimes over successive generations, through mechanisms that are firmly rooted in epigenetics. The combined efforts are fueling the rise of nutrigenomics, which examines how diet and nutritional components might help regulate genetic on-off switches. Emily Ho, PhD, associate professor of public health and human sciences at Oregon State University, says the findings to date have barely scratched the surface, especially with regard to anticancer mechanisms. “I think there's a lot of diet-derived compounds that still have potential, but just haven't been looked at yet,” she says. Dr. Ho and her colleagues found that one of those compounds, broccoli's sulforaphane, may help regulate DNA methylation and thereby dictate which genes are active. Her group had already gathered evidence that the same compound may inhibit harmful enzymes that interfere with normal interactions between histone proteins and DNA, meaning the cancer-fighting compound may influence 2 distinct epigenetic pathways. Among the follow-up studies, Dr. Ho's group is examining the potential benefit of giving a broccoli extract to male patients at high risk of prostate cancer and to female patients at risk of developing recurrent breast cancer. “I've always been a good broccoli eater,” Dr. Ho says. Her research offers yet another reason why others might want to follow her lead.

The naringenin‐induced proapoptotic effect in breast cancer cell lines holds out against a high bisphenol a background

Fruit and vegetable consumption has generally been associated with the prevention or suppression of cancer. However, food could contain a multitude of chemicals (e.g., bisphenol A; BPA) that could synergize or antagonize the effects of diet-derived compounds. Remarkably, food containers (e.g., water and infant bottles) are the largest source of exposure to BPA for human beings. Here, the effects of the coexposure of naringenin (Nar, 1.0 × 10(-9) M to 1.0 × 10(-4) M) and BPA (1.0 × 10(-5) M) in estrogen-dependent breast cancer cell lines expressing (i.e., MCF-7 and T47D) or not expressing (i.e., MDA-MB-231) estrogen receptor α (ERα) are reported. Although both Nar and BPA bind to ERα, they induce opposite effects on breast cancer cell growth. BPA induces cell proliferation, whereas Nar only decreases the number of ERα-positive cells (i.e., MCF-7 and T47D). Notably, even in the presence of BPA, Nar impairs breast cancer cell proliferation by activating caspase-3. The molecular pathways involved require p38 activation, whereas, the BPA-induced AKT activation is completely prevented by the Nar treatment. As a whole, Nar maintains its proapoptotic effects even in the presence of the food contaminant BPA, thus, enlarging the chemopreventive potential of this flavanone.

Combinatorial Antitumor Effect of Naringenin and Curcumin Elicit Angioinhibitory Activities In Vivo

Curcumin has long been used as an antioxidative, antiinflammatory, and modulator of pathological angiogenesis, whereas naringenin is a well-known immunomodulator. In this report, we investigated the effect of curcumin and naringenin on the growth of Ehrlich ascites carcinoma tumor model. To achieve this, Swiss albino mice were implanted intraperitoneally with 1 × 106 Ehrlich ascites carcinoma cells followed by the administration of oral doses of naringenin and curcumin either individually (50 mg/kg body weight) or in combination (20 mg/kg body weight each). A marked reduction has been seen in the total number of cells (80%) and accumulation of ascetic fluid (55%) when these drugs were administered together. These drugs proved to be an effective angio-inhibitory compound and confirmed by different in vivo assay systems, viz. peritoneal/skin angiogenesis and chorioallantoic membrane assay. Antiangiogenic and antiproliferative effect of these compounds alone or in combination was further corroborated with immunoblot results where we confirmed the downregulation of vascular endothelial growth factor, Hif1α, heat shock protein 90, and p-Akt. Furthermore, treatment with naringenin and curcumin alone or in combination substantially improved hepatocellular architecture and no noticeable neoplastic lesions or cellular alteration were reported. These outcomes put forward a plausible clinical application of these diet-derived compounds, as both angioinhibitory and antitumor in association with conventional therapy.

Diet-Derived Phytochemicals: From Cancer Chemoprevention to Cardio-Oncological Prevention

Cardiovascular diseases and cancer are the leading causes of death in most countries. These diseases share many common risk factors as well as pathogenetic determinants, and their incidence is related to age in an exponential manner. Furthermore, it has become apparent that several treatments used in therapy or even in prevention of cancer can impair the structural and functional integrity of the cardiovascular system, giving rise to an interdisciplinary field: cardio-oncology. However, tumors and cardiovascular diseases also share common protective factors: they can be prevented either by avoiding exposure to recognized risk factors, and/or by favoring the intake of protective compounds and by modulating the host defense machinery. These latter approaches are generally known as chemoprevention. A great variety of dietary and pharmacological agents have been shown to be potentially capable of preventing cancer in preclinical models, most of which are of plant origin. Phytochemicals, in particular diet-derived compounds, have therefore been proposed and applied in clinical trials as cancer chemopreventive agents. There is now increasing evidence that some phytochemicals can be also protective for the heart, having the potential to reduce cancer, cardiovascular disease and even anticancer drug-induced cardiotoxicity. We introduce the concept that these compounds induce pre-conditioning, a low level cellular stress that induces strong protective mechanisms conferring resistance to toxins such as cancer chemotherapeutics. Cancer cells and cardiomyocytes have fundamental differences in their metabolism and sensitivity to preconditioning, autophagy and apoptosis, so that dosage of the prevention compounds is important. Here we discuss the mechanisms responsible for the cardiotoxicity of anticancer drugs, the possibility to prevent them and provide examples of diet-derived phytochemicals and other biological substances that could be exploited for protecting the cardiovascular system according to a joint cardio-oncological preventative approach.

Dietary nitrogen availability in macroalgae enhances growth of the sea hare Aplysia californica (Opisthobranchia: Anaspidea)

Evidence suggests that marine herbivores select for prey items with elevated nitrogen content. We tested this hypothesis with experimental growth studies of the herbivorous gastropod Aplysia californica offered diets of the rhodophyte Gracilaria ferox with varying nitrogen content. A. californica had a sevenfold feeding preference by weight for G. ferox with higher tissue % N and % protein, and lower % C, % carbohydrate and carbon-to-nitrogen ratio (C/N) as compared to treatments with lower nitrogen and protein content. A. californica provided treatment diets of varying nitrogen availability (high, medium and low) also had significantly different growth rates within 30 days. The high N diet supported a two-fold higher growth rate than that of the medium N diet and four-fold higher than the low N treatment, with mean weights over the experiment reaching 20.4, 9.8, and 5.6 g, respectively. The evolutionary value of this dietary preference may facilitate faster growth to reproductive size, outgrowth of predators and sequestration of organic compounds from nitrogen-enriched macroalgae to deter predators. Despite recent attention, the importance of diet-derived compounds as anti-predatory chemical defenses in Aplysiids remains equivocal. Nitrogen-enriched macroalgal diets, however, may provide “primary metabolites” that serve as alternative defenses for Aplysiids.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function.

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.