Effects of dietary broccoli on human drug metabolising activity

Mechanism-Driven and Clinically Focused Development of Botanical Foods as Multitarget Anticancer Medicine: Collective Perspectives and Insights from Preclinical Studies, IND Applications and Early-Phase Clinical Trials

Cancer progression and mortality remain challenging because of current obstacles and limitations in cancer treatment. Continuous efforts are being made to explore complementary and alternative approaches to alleviate the suffering of cancer patients. Epidemiological and nutritional studies have indicated that consuming botanical foods is linked to a lower risk of cancer incidence and/or improved cancer prognosis after diagnosis. From these observations, a variety of preclinical and clinical studies have been carried out to evaluate the potential of botanical food products as anticancer medicines. Unfortunately, many investigations have been poorly designed, and encouraging preclinical results have not been translated into clinical success. Botanical products contain a wide variety of chemicals, making them more difficult to study than traditional drugs. In this review, with the consideration of the regulatory framework of the USFDA, we share our collective experiences and lessons learned from 20 years of defining anticancer foods, focusing on the critical aspects of preclinical studies that are required for an IND application, as well as the checkpoints needed for early-phase clinical trials. We recommend a developmental pipeline that is based on mechanisms and clinical considerations.

Resistin mediates tomato and broccoli extract effects on glucose homeostasis in high fat diet-induced obesity in rats

Background

Resistin is an adipocyte hormone that regulates glucose metabolism. Elevated levels of resistin may cause insulin resistance. This may link obesity, and increased fat mass to type II diabetes and insulin resistance. We hypothesized that treatment with tomato and broccoli extracts regulates glucose homeostasis via modulation of resistin levels in high fat diet-induced obesity rats (HFD).

Methods

Forty-eight male albino rats were divided into 8 groups as follows: control, HFD, stop fat diet (SD), Tomato 200 mg/kg (T200), Tomato 400 mg/kg (T400), Broccoli 200 mg/kg (B200), Broccoli 400 mg/kg (B400), and Chromax (CX). Treatment continued for 1 month. Serum levels of resistin, leptin, adiponectin, glucose and insulin were measured using ELISA and spectrophotometry.

Results

Serum levels of resistin were significantly reduced in the T 200, T 400, B 200, B 400 and CX groups to: 4.13 ± 0.22 ng/ml, 1.51 ± 0.04 ng/ml, 4.13 ± 0.22 ng/ml, 2.32 ± 0.15 ng/ml and 1.37 ± 0.03 ng/ml, respectively, compared to HFD group and SD group (P value < 0.0001). Non-significant differences were found between T 400, B 400 and CX groups. Serum levels of leptin were significantly reduced in the T 400 (22.7 ± 0.84 pg/ml) group compared to the B 400 (41 ± 2.45 Pg/ml) and CX groups (45.7 ± 2.91 Pg/ml), P value < 0.001. Serum levels of adiponectin were significantly increased in the T 400 group (131 ± 3.84 pg/ml) compared to the CX group (112 ± 4.77 pg/ml), P value < 0.01.

Conclusions

Our results demonstrate that tomato and broccoli extract treatment regulates glucose homeostasis via reduction of serum resistin and may be a useful non-pharmacological therapy for obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1203-0) contains supplementary material, which is available to authorized users.

Influence of environmental and genetic factors on CYP1A2 activity in individuals of South Asian and European ancestry

The drug-metabolizing enzyme CYP1A2 contributes to the metabolism of a number of commonly used medicines and displays wide interindividual variability. The aim of this study was to investigate CYP1A2 activity in a population of South Asian ancestry and compare it with a population of European ancestry. CYP1A2 activity was determined using the 4 h paraxanthine/caffeine saliva concentration ratio following a 100-mg oral dose of caffeine in healthy individuals of South Asian (n = 166) and European (n = 166) ancestry. Participants were surveyed for extrinsic ethnic factors and genotyped for polymorphisms in CYP1A2 and related genes. Significantly lower CYP1A2 activity was observed in South Asian participants (median: 0.42; range: 0.10-1.06) as compared with European participants (0.54; 0.12-1.64) (P < 0.01). Multiple linear regression indicated that 41% of the variability in CYP1A2 activity could be explained by the diet, lifestyle, and genetic factors studied.

Health benefits and possible risks of broccoli - an overview

Chemopreventive effects of broccoli, a highly valued vegetable, have been known for a long time. Several studies have demonstrated that broccoli might be beneficial by reducing the risk for the development of certain forms of cancer. These effects are generally attributed to glucosinolate-derived degradation products like isothiocyanates and indoles which are formed by the hydrolytic action of plant myrosinase and/or glucosidases deriving from the human microbial flora. However, recent in vitro and experimental animal studies indicate that broccoli, its extracts and the glucosinolate-derived degradation products might also have undesirable effects, especially genotoxic activities. However, the relevance of the genotoxic activities to human health is not known yet. This paper gives an overview on genotoxic, anti-genotoxic/chemopreventive, nutritive and antinutritive properties of broccoli, its ingredients and their degradation products. A qualitative comparison of the benefit and risk of broccoli consumption benefit-risk assessment shows that the benefit from intake in modest quantities and in processed form outweighs potential risks. For other preparations (fortified broccoli-based dietary supplements, diets with extraordinary high daily intake, consumption as a raw vegetable) further studies both for potential risks and beneficial effects are needed in order to assess the benefit and risk in the future.

Translating knowledge generated by epidemiological and in vitro studies into dietary cancer prevention

Epidemiological studies have identified an inverse relationship between ingestion of plant foods and cancer risk. However, only approximately 2/3 of such studies show this association. Clinical trials based on epidemiological findings require preclinical studies to provide insight into reproducibility. The beta carotene story is an example of clinical trials based on epidemiological data, before mechanism, dose or the bioactive component had been clearly identified. Results showed rather than prevention, an increase in lung cancer in smokers. Epidemiological studies are used successfully to generate hypotheses for in vitro mechanistic studies of isolated components from plant foods, such as sulforaphane from broccoli. Yet even these studies are insufficient to plan clinical trials of whole foods, since bioavailability, disposition, dose, and effects of the food matrix remain unknown. Evidence-based information, from animal and small clinical studies carried out prior to clinical trials can assure an optimal design. Research into effects of broccoli and sulforaphane make an excellent example of how data gaps have closed between epidemiology and clinical trials. Data on efficacy of broccoli in animal cancer prevention studies are strong, and small clinical studies are emerging. The time is right for clinical trials of purified and semipurified sulforaphane, as well as whole broccoli.

Selected diet and lifestyle factors are associated with estrogen metabolites in a multiracial/ethnic population of women

Diet and lifestyle factors, body size, and smoking behavior may influence estrogen metabolism, but the nature of these relations may vary according to race/ethnic groups. We evaluated the association of lifestyle factors with estrogen metabolites 2-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1) in a racially diverse population. With a cross-sectional study design, urine samples from 1881 African-American, Caucasian, Chinese, Japanese, and Hispanic women, aged 42-52 y, from the Study of Women's Health Across the Nation (SWAN) were assayed by EIA for 2-OHE1 and 16alpha-OHE1. Dietary factors and beverages were measured using a modified Block FFQ. Dietary fiber, vegetable and fruit servings, Brassica vegetables, polyphenols, coffee, caffeine, green and black tea, and total alcohol and wine were related to metabolite values using multiple variable regression analyses. In adjusted analyses, 2-OHE1 concentrations were significantly associated with race/ethnicity, weight, smoking, and consumption of hydroxybenzoic acid, anthocyanidins, wine, and caffeine (P < 0.05). Regression models incorporating these variables explained 19-20% of the variation in 2-OHE1 concentrations. Regression models for 16alpha-OHE1, which explained 16-17% of the variability, included race/ethnicity, smoking, caffeine, total dietary fiber, and fiber from fruits and vegetables as variables. These associations may reflect why increased consumption of polyphenol-containing foods and fruit as well as decreased smoking, caffeine intake, and body size would be consistent with hypothesized benefits and risks for selected health outcomes.

Role of Cytochrome P450 Activity in the Fate of Anticancer Agents and in Drug Resistance

Although activity of cytochrome P450 isoenzymes (CYPs) plays a major role in the fate of anticancer agents in patients, there are relatively few clinical studies that evaluate drug metabolism with therapeutic outcome. Nevertheless, many clinical reports in various non-oncology fields have shown the dramatic importance of CYP activity in therapeutic efficacy, safety and interindividual variability of drug pharmacokinetics. Moreover, variability of drug metabolism in the liver as well as in cancer cells must also be considered as a potential factor mediating cancer resistance. This review underlines the role of drug metabolism mediated by CYPs in pharmacokinetic variability, drug resistance and safety. As examples, biotransformation pathways of tamoxifen, paclitaxel and imatinib are reviewed. This review emphasises the key role of therapeutic drug monitoring as a complementary tool of investigation to in vitro data. For instance, pharmacokinetic data of anticancer agents have not often been published within subpopulations of patients who show ultra-rapid, extensive or poor metabolism (e.g. due to CYP2D6 and CYP2C19 genotypes). Besides kinetic variability in the systemic circulation, induction of CYP activity may participate in creating drug resistance by speeding up the cancer agent degradation specifically in the target cells. For one cancer agent, various mechanisms of resistance are usually identified within different cell clones. This review also tries to emphasise that drug resistance mediated by CYP activity in cancer cells should be taken into consideration to a greater degree. The unequivocal identification of the metabolising enzymes involved in clinical conditions will eventually allow improvement and individualisation of anticancer agent therapy, i.e. drug dosage and selection. In addition, a more complete understanding of the metabolism of anticancer agents will assist in the prediction of drug-drug interactions, as anticancer agent combinations are becoming more prevalent.

Differential pharmacokinetics of theophylline in elderly patients

The clinical use of theophylline as a first-line bronchodilator has declined during the last two decades. However, in many clinical settings, such as an emergency bronchial asthma attack, theophylline may have a first-line role, in combination with beta(2)-adrenoreceptor agonists and corticosteroids, for improving the asthmatic status. Furthermore, many therapeutic mechanisms of theophylline for bronchial asthma have been reported, and recent studies have suggested that theophylline therapy may have a beneficial role in the management of chronic stable asthma as well as exacerbated disease. However, theophylline has a low therapeutic index because the bronchodilation it produces has a linear relationship with logarithmic increases in serum concentration for the therapeutic range of 5-20 mg/L. Thus, the knowledge of its basic pharmacokinetics and the factors that can alter its clearance is clinically relevant for physicians. Especially when used in elderly asthmatic patients, dosage adjustment of theophylline is a requisite since the elderly have several risk factors that may increase the plasma theophylline level, such as reduced clearance, various underlying diseases and multiple coadministered drugs. After theophylline treatment has been initiated, therapeutic drug monitoring is required.