Slowing tumorigenic progression in TRAMP mice and prostatic carcinoma cell lines using natural anti-oxidant from spinach, NAO--a comparative study of three anti-oxidants

Self-emulsifying formulation of Spinacia oleracea reduces the dose and escalates bioavailability of bioactive compounds to accelerate fracture repair in rats

Background

Spinach (Spinacia oleracea) is a rich source of flavonoids and therefore widely used therapeutically as an antioxidant agent in traditional medicine. The present study was undertaken to study the bone regenerating property of dried Spinacia oleracea extract (DSE) and self-emulsifying formulation of the extract (FDSE) on drill-hole model of fracture repair in rats.

Methods

0.8 mm hole was drilled in the diaphyseal region of femur in adult SD rats. DSE and formulated extract (FDSE) was administered orally and fractured femur was collected after treatment regimen. Micro-CT, transcriptional analysis and measurement of calcein intensity of callus formed at the injured site was performed to study the efficacy of the extract and formulation on bone regeneration. Further, compounds from extract were assessed for in-vitro osteoblast activity.

Results

Micro-architecture of the regenerated bone at injured site exhibited 26% (p < 0.001) and 35% (p < 0.01) increased BV/TV (bone volume /tissue volume) and Tb.N. (trabecular number) for DSE (500 mg.kg− 1). Further, FDSE exhibited similar augmentation in BV/TV (p < 0.01) and Tb. N (p < 0.01) parameters at dose of 250 mg.kg− 1. Analogous results were obtained from transcriptional analysis and calcein intensity at the fractured site. 3-O-Methylpatuletin, one of the compound isolated from the extract stimulated the differentiation and mineralization of primary osteoblast and depicted concentration dependent antagonizing effect of H2O2 in osteoblast apparently, minimizing ROS generation thus affectivity in fracture repair.

Conclusions

The present study showed that bone regenerating property of spinach was augmented by formulating extract to deliverable form and can be further studied to develop as therapeutic agent for fracture repair.

Graphical abstract

Green Tea Catechins for Prostate Cancer Prevention: Present Achievements and Future Challenges

Green tea catechins (GTCs) are a family of chemically related compounds usually classified as antioxidant molecules. Epidemiological evidences, supported by interventional studies, highlighted a more than promising role for GTCs in human prostate cancer (PCa) chemoprevention. In the last decades, many efforts have been made to gain new insights into the mechanism of action of GTCs. Now it is clear that GTCs' anticancer action can no longer be simplistically limited to their direct antioxidant/pro-oxidant properties. Recent contributions to the advancement of knowledge in this field have shown that GTCs specifically interact with cellular targets, including cell surface receptors, lipid rafts, and endoplasmic reticulum, modulate gene expression through direct effect on transcription factors or indirect epigenetic mechanisms, and interfere with intracellular proteostasis at various levels. Many of the effects observed in vitro are dose and cell context dependent and take place at concentrations that cannot be achieved in vivo. Poor intestinal absorption together with an extensive systemic and enteric metabolism influence GTCs' bioavailability through still poorly understood mechanisms. Recent efforts to develop delivery systems that increase GTCs' overall bioavailability, by means of biopolymeric nanoparticles, represent the main way to translate preclinical results in a real clinical scenario for PCa chemoprevention.

Chemoprevention in African American Men With Prostate Cancer

BACKGROUND

Recommendations for cancer screening are uncertain for the early detection or prevention of prostate cancer in African American men. Thus, chemoprevention strategies are needed to specifically target African American men.

METHODS

The evidence was examined on the biological etiology of disparities in African Americans related to prostate cancer. Possible chemopreventive agents and biomarkers critical to prostate cancer in African American men were also studied.

RESULTS

High-grade prostatic intraepithelial neoplasia may be more prevalent in African American men, even after controlling for age, prostate-specific antigen (PSA) level, abnormal results on digital rectal examination, and prostate volume. Prostate cancer in African American men can lead to the overexpression of signaling receptors that may mediate increased proliferation, angiogenesis, and decreased apoptosis. Use of chemopreventive agents may be useful for select populations of men.

CONCLUSIONS

Green tea catechins are able to target multiple pathways to address the underlying biology of prostate carcinogenesis in African American men, so they may be ideal as a chemoprevention agent in these men diagnosed with high-grade prostatic intraepithelial neoplasia.

Extraction of functional ingredients from spinach (Spinacia oleracea L.) using liquid solvent and supercritical CO₂ extraction

BACKGROUND

In this work three different techniques were applied to extract dry leaves of spinach (Spinacia oleracea): solid-liquid extraction (SLE), pressurised liquid extraction (PLE) and supercritical fluid extraction (SFE) to investigate the influence of extraction solvent and technique on extracts composition and antioxidant activity. Moreover, the influence of carotenoids and phenolic compounds on the antioxidant and anti-inflammatory activities of spinach extracts was also studied.

RESULTS

The higher concentrations of carotenoids and the lower content of phenolic compounds were observed in the supercritical CO₂ extracts; whereas water and/or ethanol PLE extracts presented low amounts of carotenoids and the higher concentrations of phenolic compounds. PLE extract with the highest content of phenolic compounds showed the highest antioxidant activity, although SFE carotenoid rich extract also showed a high antioxidant activity. Moreover, both extracts presented an important anti-inflammatory activity.

CONCLUSION

PLE seems to be a good technique for the extraction of antioxidant and anti-inflammatory compounds from spinach leaves. Moreover, spinach phenolic compounds and carotenoids present a high antioxidant activity, whereas spinach carotenoids seem to show a higher anti-inflammatory activity than phenolic compounds. It is worth noting that of our knowledge this is the first time the anti-inflammatory activity of lipophilic extracts from spinach leaves is reported.

Assessment of antioxidant and antiproliferative properties of spinach plants grown under low oxygen availability

BACKGROUND

In the human diet, the consumption of fresh fruits and vegetables is important in maintaining good health and in preventing chronic diseases. It is known that plant-derived food is a powerful source of chemopreventive molecules, i.e. antioxidants, and spinach (Spinacia oleracea L., Chenopodiaceae) possesses a wide range of metabolites with such biological activity. Plant stress response could lead to the production of metabolites with high value for human health and this could be a tool to enhance the production of molecules with antioxidant activity in plants.

RESULTS

Data reported in this paper confirm the antioxidant properties of spinach plants, and show a strong antiproliferative activity of leaf extract on HT-29 human cell line. Besides, the hypoxic stress seems to affect the pool of antioxidant molecules present in spinach leaves, as verified by means of HPLC-MS/MS analysis and the aluminium chloride and ABTS assays.

CONCLUSION

Our findings represent a basis for improving the biological and pharmacological properties of spinach plants, including the use of different growth conditions to modulate the phytocomplex profile of spinach.

Antioxidant treatment promotes prostate epithelial proliferation in Nkx3.1 mutant mice

Discordant results in preclinical and clinical trials have raised questions over the effectiveness of antioxidants in prostate cancer chemoprevention. Results from the large-scale Selenium and Vitamin E Cancer Prevention Trial (SELECT) showed that antioxidants failed to prevent, and in some cases promoted, prostate cancer formation in men without a history of the disease. One possible explanation for these alarming results is the notion that the effects of antioxidant treatment on the prostate are modified by specific, intrinsic genetic risk factors, causing some men to respond negatively to antioxidant treatment. Loss of expression of the homeobox transcription factor NKX3.1 in the prostate is frequently associated with human prostate cancer. Nkx3.1 mutant mice display prostatic hyperplasia and dysplasia and are used as a model of the early stages of prostate cancer initiation. While the mechanisms by which Nkx3.1 loss promotes prostate tumorigenicity are not completely understood, published data have suggested that elevated reactive oxygen species (ROS) associated with Nkx3.1 loss may be a causative factor. Here we have tested this hypothesis by treating Nkx3.1 mutant mice with the antioxidant N-acetylcysteine (NAC) for 13 weeks post-weaning. Surprisingly, while NAC treatment decreased ROS levels in Nkx3.1 mutant mouse prostates, it failed to reduce prostatic epithelial hyperplasia/dysplasia. Rather, NAC treatment increased epithelial cell proliferation and promoted the expression of a pro-proliferative gene signature. These results show that ROS do not promote proliferation in the Nkx3.1-null prostate, but instead inhibit proliferation, suggesting that antioxidant treatment may encourage prostate epithelial cell proliferation early in prostate tumorigenesis. Our findings provide new insight that may help explain the increased prostate cancer risk observed with vitamin E treatment in the SELECT trial and emphasize the need for preclinical studies using accurate models of cancer.

New insights into the mechanisms of green tea catechins in the chemoprevention of prostate cancer

Prostate cancer is the most commonly diagnosed cancer and second most common cause of cancer deaths in American men. Its long latency, slow progression, and high incidence rate make prostate cancer ideal for targeted chemopreventative therapies. Therefore, chemoprevention studies and clinical trials are essential for reducing the burden of prostate cancer on society. Epidemiological studies suggest that tea consumption has protective effects against a variety of human cancers, including that of the prostate. Laboratory and clinical studies have demonstrated that green tea components, specifically the green tea catechin (GTC) epigallocatechin gallate, can induce apoptosis, suppress progression, and inhibit invasion and metastasis of prostate cancer. Multiple mechanisms are involved in the chemoprevention of prostate cancer with GTCs; understanding and refining models of fundamental molecular pathways by which GTCs modulate prostate carcinogenesis is essential to apply the utilization of green tea for the chemoprevention of prostate cancer in clinical settings. The objective of this article is to review and summarize the most current literature focusing on the major mechanisms of GTC chemopreventative action on prostate cancer from laboratory, in vitro, and in vivo studies, and clinical chemoprevention trials.

Intermittent calorie restriction delays prostate tumor detection and increases survival time in TRAMP mice

Prostate cancer is the most frequently diagnosed cancer in men. Whereas chronic calorie restriction (CCR) delays prostate tumorigenesis in some rodent models, the impact of intermittent caloric restriction (ICR) has not been determined. Here, transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were used to compare how ICR and CCR affected prostate cancer development. TRAMP mice were assigned to ad libitum (AL), ICR (2 wk 50% AL consumption followed by 2 wk pair feeding to AL consumption), and CCR (25% AL consumption) groups at 7 wk of age and followed until disease burden necessitated euthanasia or mice reached terminal endpoints (48 or 50 wk of age). Body weights fluctuated in response to calorie intake (P < 0.0001). ICR mice were older at tumor detection than AL (P = 0.0066) and CCR (P = 0.0416) mice. There was no difference for age of tumor detection between AL and CCR mice (P = 0.3960). Similar results were found for survival. Serum leptin, adiponectin, insulin, and IGF-I were all significantly different among the groups. These results indicate that the way in which calories are restricted impacts both time to tumor detection and survival in TRAMP mice, with ICR providing greater protective effect compared to CCR.