A 60day double-blind, placebo-controlled safety study involving Citrus aurantium (bitter orange) extract

Naringin: Cardioprotective properties and safety profile in diabetes treatment

Flavonoids derived from plants offer a broad spectrum of therapeutic potential for addressing metabolic syndrome, particularly diabetes mellitus (DM), a prevalent non-communicable disease. Hyperglycemia in DM is a known risk factor for cardiovascular diseases (CVDs), which substantially impact global mortality rates. This review examines the potential effects of naringin, a citrus flavonoid, on both DM and its associated cardiovascular complications, including conditions like diabetic cardiomyopathy. The safety profile of naringin is summarized based on various pre-clinical studies. The data for this review was gathered from diverse electronic databases, including Medline, PubMed, ScienceDirect, SpringerLink, Google Scholar, and Emerald Insight. Multiple pre-clinical studies have demonstrated that naringin exerts hypoglycemic and cardioprotective effects by targeting various vascular mechanisms. Specifically, research indicates that naringin down-regulates the renin-angiotensin and oxidative stress systems while concurrently upregulating β-cell and immune system functions. Clinical trial outcomes also support the therapeutic potential of naringin in managing hyperglycemic states and associated cardiovascular issues. Moreover, toxicity studies have confirmed the safety of naringin in animal models, suggesting its potential for safe administration in humans. In conclusion, naringin emerges as a promising natural candidate for both antidiabetic and cardioprotective purposes, offering potential improvements in health outcomes. While naringin presents a new avenue for therapies targeting DM and CVDs, additional controlled and long-term clinical trials are necessary to validate its efficacy and safety for human use.

Non-invasive assessment of proarrhythmic risks associated with isoprenaline and the dietary supplement ingredient synephrine using human induced pluripotent stem cell-derived cardiomyocytes

Background

There have been conflicting reports about the proarrhythmic risk of p-synephrine (SYN). To address this, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) combined with the microelectrode array (MEA) system have been utilized to assess arrhythmia risks, particularly in the context of adrenomimetic drugs.

Aim

This study aims to determine whether MEA recordings from hiPSC-CMs could predict the proarrhythmic risk of adrenomimetic drugs and to investigate the cardiovascular effects and mechanisms of SYN.

Materials and methods

We employed MEA recordings to assess the electrophysiological properties of hiPSC-CMs and conducted concentration-response analyses to evaluate the effects of SYN and Isoprenaline (ISO) on beating rate and contractility. A risk scoring system for proarrhythmic risks was established based on hiPSC-CMs in this study. ISO, a classic beta-adrenergic drug, was also evaluated. Furthermore, the study evaluated the risk of SYN and recorded the concentration-response of beating rate, contractility and the change in the presence or absence of selective β1, β2 and β3 adrenergic blockers.

Results

Our results suggested that ISO carries a high risk of inducing arrhythmias, aligning with existing literature. SYN caused a 30% prolongation of the field potential duration (FPD) at a concentration of 206.326 μM, a change significantly different from baseline measurements and control treatments. The half maximal effective concentration (EC50) of SYN (3.31 μM) to affect hiPSC-CM beating rate is much higher than that of ISO (18.00 nM). The effect of SYN at an EC50 of 3.31 μM is about ten times more potent in hiPSC-CMs compared to neonatal rat cardiomyocytes (34.12 μM). SYN increased the contractility of cardiomyocytes by 29.97 ± 11.65%, compared to ISO's increase of 50.56 ± 24.15%. β1 receptor blockers almost eliminated the beating rate increase induced by both ISO and SYN, while neither β2 nor β3 blockers had a complete inhibitory effect.

Conclusion

The MEA and hiPSC-CM system could effectively predict the risk of adrenomimetic drugs. The study concludes that the proarrhythmia risk of SYN at conventional doses is low. SYN is more sensitive in increasing beating rate and contractility in human cardiomyocytes compared to rats, primarily activating β1 receptor.

Roles of citrus fruits on energy expenditure, body weight management, and metabolic biomarkers: a comprehensive review

Citrus fruits are widely consumed for their nutritional and health benefits. They belong to the Rutaceae and have many varieties, such as sweet orange (Citrus sinensis), which is the most popular. Citrus fruits are rich in water (>80%), dietary fiber, and vitamins. They also contain bioactive components, which may modulate energy metabolism and lipid oxidation through various mechanisms. These mechanisms include stimulating β3-adrenergic receptors, increasing mitochondrial biogenesis and thermogenesis, activating AMP kinase and peroxisome proliferator-activated receptor-gamma coactivator-1α pathways, inhibiting lipogenesis and lipid accumulation, and inducing browning of white adipose tissue. This review summarizes the mechanisms and outcomes of citrus fruits and their metabolites on energy metabolism and body weight in different experimental models. The literature was searched for in vitro and in vivo animal and human studies that investigated the effects of citrus consumption on energy expenditure, thermogenesis, adipogenesis, and lipid accumulation. Citrus fruits and their metabolites have shown promising effects on energy metabolism and lipid oxidation in in vitro and in vivo animal studies. However, the evidence from human studies is limited and inconsistent. Possible reasons for the discrepancy are briefly discussed, and knowledge gaps and research needs are identified for future studies. Citrus fruits may have beneficial effects on energy metabolism and body weight, but more rigorous and well-designed human trials are needed to confirm their efficacy and safety.

A review of citrus plants as functional foods and dietary supplements for human health, with an emphasis on meta-analyses, clinical trials, and their chemical composition

Fruits, flowers, leaves, essential oils, hydrosols, and juices of citrus spp. Are utilized to prepare various forms of food products. Along with their nutritional values, in the health industry, different parts of the plants of the citrus genus have been used as supplements or remedies to prevent or control diseases. This review focused on reported meta-analyses and clinical trials on the health benefits of citrus plants as functional foods. Also, chemical compounds of various citrus species were reviewed. The following information sources were used for data collection: Google Scholar, the Web of Science, Scopus, and PubMed. Various keywords, including "citrus AND chemical compounds," "citrus AND phytochemicals," "citrus species," "citrus AND meta-analysis," "nutritional and therapeutical values of citrus spp.," "clinical trials AND citrus," "clinical trials AND Rutaceae," "health benefits of citrus spp.," "citrus edible or non-edible applications," and scientific names of the citrus plants were utilized to collect data for the review. The scientific name and common name of all twenty-eight citrus species, along with any of the above keywords, were also searched in the mentioned databases. Scientific papers and data sources were sought to review and discuss the citrus plant's nutritional and therapeutic importance. Several meta-analyses and clinical trials have reported beneficial effects of citrus spices on a variety of cancer risks, cardiovascular risk factors, neurologic disorders, urinary tract conditions, and gastrointestinal tract conditions. They have shown anxiolytic, antimicrobial, and pain-alleviating effects. Some of them can be helpful in managing obesity and cardiovascular risk factors.

Mutagenic, Acute, and Subchronic Toxicity Studies of the Hesperetin-7-Glucoside-β-Cyclodextrin Inclusion Complex

Hesperetin glucosides such as hesperidin and hesperetin-7-glucoside are abundantly present in citrus fruits and have various pharmacological properties. However, the potential toxicity of hesperetin glucosides remains unclear. An initial assessment of the safety of hesperetin-7-glucoside-β-cyclodextrin inclusion complex (HPTGCD) as a functional food ingredient was undertaken to assess toxicity and mutagenic potential. A bacterial reverse mutation assay (Ames test) using Salmonella typhimurium (strains TA98, TA1535, TA100, and TA1537) and Escherichia coli (strain WP2 uvrA) with HPTGCD (up to 5000 µg/plate) in the absence and presence of metabolic activation was negative. In a single oral (gavage) toxicity study in male and female rats, HPTGCD at dose up to 2000 mg/kg did not produce mortality nor clinical signs of toxicity or change in body weight. In a subchronic oral (dietary admix) toxicity study in rats receiving 0, 1.5, 3, and 5% HPTGCD for 13 weeks, no adverse effects were noted and the no-observed-adverse-effect level (NOAEL) was 5% in the diet (equivalent to 3267.7 mg/kg/day for males and to 3652.4 mg/kg/day for females). These results provide initial evidence of the safety of HPTGCD.

Dietary supplements for obesity

Obesity and associated complications including diabetes, cardiometabolic dysfunction, disability, malignancy and premature mortality are considered epidemic. Research on obesity is therefore of worldwide importance. The development of obesity is a multifactorial phenomenon with contributions from biological, behavioral, genetic and environmental factors. Obesity and its associated issues require various lifestyle modifications and treatment options such medication, exercise, diet, surgery, pharmacological therapy and dietary supplements. Dietary supplements are considered an attractive alternative to traditional therapy due to their low toxicity profile and their accessibility to the general population. Dietary supplements may include one or more dietary ingredients. In this narrative review, we analyze the effects on obesity and obesity-related issues of various natural components. For example, there are a myriad of supplements that have been used as dietary supplements for weight loss such as minerals, vitamins, amino acids, metabolites, herbs, and plant extracts. This narrative review aims to present the benefits and side-effects of several ingredients of dietary supplements for weight loss and treatment of obesity. In particular, the mechanism of action, results of clinical trials, and possible side effects will be presented for the following ingredients: β-Glucans, bitter orange, calcium, vitamin D, chitosan, chromium, cocoa, coleus forskohlii, conjugate linoleic acid, ephedra sinica, fucoxanthin, garcinia cambogia, glucomannan, green coffee, green tea, guar gum, raspberry, hoodia gordonii, irvingia gabonensis, phenylpropylamine, pyruvate, white kidney bean.

The Safety and Efficacy of Citrus aurantium (Bitter Orange) Extracts and p-Synephrine: A Systematic Review and Meta-Analysis

Synephrine has been used to promote weight loss; however, its safety and efficacy have not been fully established. The goals of our study were to give an overview of the safety and efficacy of p-synephrine, to systematically evaluate its efficacy regarding weight loss and to assess its safety, focusing on its cardiovascular side effects in a meta-analysis. PubMed, the Cochrane Library, Web of Science and Embase were searched for relevant studies. Only placebo-controlled, human clinical trials with synephrine intervention were included in the meta-analysis. The meta-analysis was reported according to the PRISMA guidelines using the PICOS format and taking into account the CONSORT recommendations. Altogether, 18 articles were included in the meta-analysis. Both systolic and diastolic blood pressure (DBP) increased significantly after prolonged use (6.37 mmHg, 95% CI: 1.02–11.72, p = 0.02 and 4.33 mmHg, 95% CI: 0.48–8.18, p = 0.03, respectively). The weight loss in the synephrine group was non-significant after prolonged treatment, and it did not influence body composition parameters. Based on the analyzed clinical studies, synephrine tends to raise blood pressure and heart rate, and there is no evidence that synephrine can facilitate weight loss. Further studies are needed to confirm evidence of its safety and efficacy.

Wen Dan Tang: A Potential Jing Fang Decoction for Headache Disorders?

Background: Chinese herbal medicine is considered relatively safe, inexpensive, and easily accessible. Wen Dan Tang (WDT), a Jing Fang ancient classical Chinese herbal formula with a broad indication profile has been used for several centuries in China to treat various illnesses. Question: Are there evidence-based clinical trials that show that WDT has a significant impact on the treatment of various diseases, especially in patients with migraine and tension-type headaches (TTH)? Methods: This study is based on an online database search using PubMed, Medline, Cochrane Library, AcuTrials, Embase, Semantic Scholar, Jstor, internet research, and review of ancient and modern Chinese medical textbooks regarding WDT and its compounds. Results: There were no studies on WDT in migraine and TTH; therefore, this work gathers and describes data for every single compound in the formula. Conclusion: This study suggests that the bioactive compounds found in WDT composition show potential in treating patients with neurological, psychiatric disorders, cardiovascular diseases, metabolic syndrome, and digestive disorders. Some coherence between WDT in headache reduction and improvements in the quality of life in patients with migraines and TTH could be evaluated, showing positive results of WDT in these patients.

Effects of p-Synephrine during Exercise: A Brief Narrative Review

The p-synephrine is the principal phytochemical found in bitter orange (Citrus aurantium). This substance is widely included in dietary supplements for weight loss/body fat reduction due to its potential benefits of increasing fat oxidation. For years, p-synephrine-containing dietary supplements have been marketed without proper knowledge of their true effectiveness to enhance fat utilization, especially when combined with exercise. However, the effects of p-synephrine on fat oxidation during exercise have been investigated in the last few years. The aim of the current discussion is to summarize the evidence on the effects of p-synephrine intake on fat oxidation and performance during exercise. Previous investigations have demonstrated that the acute intake of p-synephrine does not modify running sprint performance, jumping capacity, or aerobic capacity. However, the acute intake of p-synephrine, in a dose of 2-3 mg/kg of body mass, has been effective to enhance the rate of fat oxidation during incremental and continuous exercise. This effect has been observed in a range of exercise workloads between 30% and 80% of peak oxygen uptake (VO_2peak). The p-synephrine has the ability to increase the maximal rate of fat oxidation during exercise of increasing intensity without affecting the workload at which maximal fat oxidation is obtained (Fatmax). The effect of p-synephrine on fat oxidation is normally accompanied by a concomitant reduction of carbohydrate utilization during exercise, without modifying the energy expended during exercise. The shifting in substrate oxidation is obtained without any effect on heart rate during exercise and the prevalence of adverse effects is negligible. Thus, the acute use of p-synephrine, or p-synephrine-containing products, might offer some benefits for those individuals seeking higher fat utilization during exercise at low to moderate intensities. However, more research is still necessary to determine if the effect of p-synephrine on fat oxidation during exercise is maintained with chronic ingestion, in order to ascertain the utility of this substance in conjunction with exercise programs to produce an effective body fat/weight loss reduction.

The safety and effectiveness of commonly-marketed natural supplements for weight loss in populations with obesity: A critical review of the literature from 2006 to 2016

Objective: To evaluate the evidence published from 2006 to 2016 on the effectiveness and safety of commonly used natural supplements for weight loss in individuals with obesity.Methods: Amazon and Google were searched for names of mono-agent natural supplements marketed for weight loss and a list of the 10 supplements was created. Google Scholar, Pubmed, Science Direct, and the Cochrane Library were searched for articles that met inclusion.Results: At least one article was published on the effectiveness or safety of bitter orange, capsinoid, carnitine, chromium picolinate, Coleus forskohlii, conjugated linoleic acid, glucomannan, green tea and psyllium for weight loss in populations with obesity from 2006 to 2016. There was insufficient evidence to suggest that the natural supplements examined contribute to significant weight loss, with the exception of perhaps glucomannan in the form of PGX. In general, the majority of side-effects reported were minor to moderate, and gastrointestinal-related. However, in some cases extreme side-effects such as liver and kidney failure were observed.Conclusion: Contrary to popular belief, results of this review suggest that the use of natural supplements for weight loss are unlikely to contribute to meaningful weight loss and in some cases may contribute to harm.

Acridone alkaloids from the stem bark of Citrus aurantium display selective cytotoxicity against breast, liver, lung and prostate human carcinoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Citrus aurantium L. (Rutaceae) is used, either singly or as a part of a polyherbal preparation, in Nigerian traditional medicine for the management of cancer and inflammatory diseases. Currently, there is a dearth of knowledge demonstrating its anticancer potential.

AIM OF THE STUDY

This study was carried out to determine the in vitro cytotoxicity of the crude extract of the stem bark of C. aurantium, identify and isolate the bioactive constituents and to establish the cytotoxicity of such constituents.

MATERIALS AND METHODS

The powdered bark of C. aurantium was extracted by MeOH at room temperature (25-34 °C) and the crude extract was partitioned successively, with n-hexane, dichloromethane and methanol. Amongst the fractions, the DCM fraction was the most active and compounds were isolated from this fraction using a combination of chromatographic techniques. The structures of the isolated compounds were elucidated by spectroscopic means (MS, 1D and 2D NMR). The cytotoxicity of the extract, and the isolated compounds were evaluated by the MTT assay against four human cancer cell lines: A549 (lung), HepG2 (liver), MCF7 (breast) and PC3 (prostate). The selectivity of the isolated compounds was assessed using the normal human prostate epithelium cells (PNT2).

RESULTS AND DISCUSSION

Of the three plant fractions, the DCM fraction showed significant cytotoxicity, with its highest activity against A549 cells (IC₅₀ = 3.88 µg/mL) and the least activity on HepG2 cells (IC₅₀ = 5.73 µg/mL). Six acridone alkaloids, citrusinine-I (1), citracridone-I (2), 5-hydroxynoracronycine (3), natsucitrine-I (4), glycofolinine (5) and citracridone-III (6), were isolated from the DCM fraction of C. aurantium. The isolated compounds demonstrated potent to moderate cytotoxicity (IC₅₀ = 12.65-50.74 µM) against the cancer cells under investigation. It is noteworthy that the compounds exerted cytotoxicity at least four times more selective towards the carcinoma cells than the PNT2 cells.

CONCLUSION

The results obtained from this study have provided some evidence for the ethnomedicinal use of C. aurantium against cancer and the acridone alkaloids present in its stem bark, have appeared to be responsible for the anticancer effects.

Sympathomimetic amine compounds and hepatotoxicity: Not all are alike-Key distinctions noted in a short review

Sympathomimetic amine compounds are often pooled together and incorrectly assumed to be interchangeable with respect to potential adverse effects. A brief and specific review of sympathomimetic compounds and one instance (i.e., hepatotoxicity) where these compounds have been improperly grouped together is covered. A review of the proposed mechanisms through which known hepatotoxic sympathomimetic agents (e.g., 3,4-methylenedioxymethamphetamine or MDMA, methamphetamine and amphetamine) cause liver injury, along with a corresponding review of in vitro data, interventional data, animal model studies and observational data allow for a comparison/contrast of different agents and reveals a lack of potential toxicity for some agents (e.g., pseudoephedrine, phenylephrine, ephedrine, 1,3-dimethylamylamine, phentermine) in this broad category. Data show that compounds within the broad group of sympathomimetics display divergent pharmacological and toxicological profiles and can be clearly distinguished with respect to liver injury. These data serve as a reminder to clinicians and others, that even small structural differences between molecules can lead to drastically different pharmacological/toxicological profiles and that one should not assume that all sympathomimetic agents are hepatotoxic. Such assumptions could lead to diagnostic errors and incorrect or insufficient treatment.

Acute hematological and mood perception effects of bitter orange extract (p-synephrine) consumed alone and in combination with caffeine: A placebo-controlled, double-blind study

The purpose of this study was to examine acute hematological and mood perception responses to supplementation with p-synephrine alone and in combination with caffeine during quiet sitting. Sixteen subjects visited the laboratory on 6 occasions and were given (in randomized double-blind manner) 103-mg p-synephrine (S), 233-mg caffeine + 104-mg p-synephrine, 240-mg caffeine, 337-mg caffeine + 46-mg p-synephrine, 325-mg caffeine, or a placebo (PL). The subjects sat quietly for 3 hr while completing mood state questionnaires every 30 min. Venous blood samples were collected at baseline (pre) and 3 hr (post) to determine immune, lipid, and chemistry panels. Compared with PL, no significant supplement differences were observed during the S trial with the exception of differential time effects seen in hematocrit (decrease in PL, no change in S), triglycerides and very low-density lipoproteins (no changes in PL, significant decreases in S), and iron (no change in PL, significant elevation in S). Supplements containing caffeine showed increased feelings of attention, excitement, energy, and vigor. These data indicate that consumption of 103-mg p-synephrine does not negatively impact acute blood parameters, does not augment the effects of caffeine, or produce stimulant-like perceptual mood effects.

Safety evaluation of p-synephrine following 15 days of oral administration to healthy subjects: A clinical study

Extracts of bitter orange (BOE, Citrus aurantium L.) and its primary protoalkaloid p-synephrine are extensively consumed as dietary supplements. p-Synephrine is also present in foods and juices prepared from various Citrus species. The safety of p-synephrine has been questioned as a result of structural similarities with ephedrine. This study assessed the cardiovascular (stimulant) and hemodynamic effects of BOE (49 mg p-synephrine) daily given to 16 healthy subjects for 15 days in a placebo-controlled, cross-over, double-blinded study. A physical evaluation by a cardiologist, as well as heart rates, blood pressures, and electrocardiograms were determined, and blood samples were drawn at baseline, and Days 5, 10, and 15. Serum levels for caffeine and p-synephrine were measured at 1 and 2 weeks. Subjects completed a 10-item health and metabolic questionnaire at baseline and on Day 15. No significant changes occurred in heart rate, electrocardiograms, systolic blood or diastolic pressures, blood cell counts, or blood chemistries in either the control or p-synephrine treated groups at any time point. No adverse effects were reported in response to the bitter orange (p-synephrine). Caffeine consumed by the participants varied markedly. Under these experimental conditions, BOE and p-synephrine were without stimulant (cardiovascular) and adverse effects.

Bitter orange (Citrus aurantium L.) extract subchronic 90-day safety study in rats

Bitter orange (Citrus aurantium L.) extracts are widely used in dietary supplements and bitter oranges are used in various juices and food products. p-Synephrine, the primary active constituent, comprises approximately 90% of total protoalkaloids. This study, performed per OECD 408 guidance, examined the 90-day subchronic safety/toxicity of an extract standardized to 50% p-synephrine at doses of 100, 300 and 1000 mg/kg/day to male and female rats. No adverse effects were observed with respect to any of the observed parameters of clinical signs, functional observations of sensory reactivity, grip strength and motor activity, ophthalmology, body weights, hematology, food consumption, urinalysis, organ weights, as well as gross and microscopic pathology at termination at any of the doses in either sex. Treatment at 1000 mg/kg body weight/day of the extract resulted in non-adverse effects including fully reversible signs of repetitive head burrowing in the bedding material and piloerection for short periods of time in both sexes immediately after administration, which gradually disappeared by treatment day-81. A slight and reversible elevation of BUN and urea levels in male rats, and slight to mild increase in the relative but not absolute heart weights of male and female rats was observed. Based on these results, the no-observed-effect-level (NOEL) for this bitter orange extract standardized to 50% p-synephrine was 300 mg/kg, while the no-observed-adverse-effect-level (NOAEL) was 1000 mg/kg. The results indicate a high degree of safety for this bitter orange extract.

Acute cardiovascular effects of bitter orange extract (p-synephrine) consumed alone and in combination with caffeine in human subjects: A placebo-controlled, double-blind study

The purpose was to examine cardiovascular responses to supplementation with p-synephrine alone and in combination with caffeine during quiet sitting. Sixteen subjects were given (in double-blind manner) either 103 mg of p-synephrine (S), 233 mg of caffeine +104 mg of p-synephrine (LC + S), 240 mg of caffeine (LC), 337 mg of caffeine +46 mg of p-synephrine (HC + S), 325 mg of caffeine (HC), or a placebo. The subjects sat quietly for 3 hr while heart rate (HR) and blood pressure were measured. Only HC + S and HC significantly increased mean systolic blood pressure (SBP) during the second hour and tended to increase mean SBP during the third hour. Mean diastolic blood pressure in S was significantly lower than the other trials during the first and second hours, and mean arterial pressure was significantly lower in S compared to the LC, LC + S, HC, and HC + S trials. No differences were observed in HR. Consumption of p-synephrine may acutely reduce diastolic blood pressure and mean arterial pressure and not affect SBP or HR during quiet sitting. The addition of p-synephrine to caffeine did not augment SBP or HR indicating that consumption of up to 104 mg of p-synephrine does not induce cardiovascular stress during quiet sitting.

Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p-Synephrine

Citrus aurantium L. (bitter orange) extracts that contain p-synephrine as the primary protoalkaloid are widely used for weight loss/weight management, sports performance, appetite control, energy, and mental focus and cognition. Questions have been raised about the safety of p-synephrine because it has some structural similarity to ephedrine. This review focuses on current human, animal, in vitro, and mechanistic studies that address the safety, efficacy, and mechanisms of action of bitter orange extracts and p-synephrine. Numerous studies have been conducted with respect to p-synephrine and bitter orange extract because ephedra and ephedrine were banned from use in dietary supplements in 2004. Approximately 30 human studies indicate that p-synephrine and bitter orange extracts do not result in cardiovascular effects and do not act as stimulants at commonly used doses. Mechanistic studies suggest that p-synephrine exerts its effects through multiple actions, which are discussed. Because p-synephrine exhibits greater adrenergic receptor binding in rodents than humans, data from animals cannot be directly extrapolated to humans. This review, as well as several other assessments published in recent years, has concluded that bitter orange extract and p-synephrine are safe for use in dietary supplements and foods at the commonly used doses. Copyright © 2017 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd.

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males

BACKGROUND

The purpose of this study was to examine whether ingesting a pre-workout dietary supplement (PWS) with and without synephrine (S) during training affects training responses in resistance-trained males.

METHODS

Resistance-trained males (N = 80) were randomly assigned to supplement their diet in a double-blind manner with either a flavored placebo (PLA); a PWS containing beta-alanine (3 g), creatine nitrate as a salt (2 g), arginine alpha-ketoglutarate (2 g), N-Acetyl-L-Tyrosine (300 mg), caffeine (284 mg), Mucuna pruiriens extract standardized for 15% L-Dopa (15 mg), Vitamin C as Ascorbic Acid (500 mg), niacin (60 mg), folate as folic acid (50 mg), and Vitamin B12 as Methylcobalamin (70 mg); or, the PWS supplement with Citrus aurantium extract containing 20 mg of synephrine (PWS + S) once per day for 8-weeks during training. Participants donated a fasting blood sample and had body composition (DXA), resting heart rate and blood pressure, cognitive function (Stroop Test), readiness to perform, bench and leg press 1 RM, and Wingate anaerobic capacity assessments determined a 0, 4, and 8-weeks of standardized training. Data were analyzed by MANOVA with repeated measures. Performance and cognitive function data were analyzed using baseline values as covariates as well as mean changes from baseline with 95% confidence intervals (CI). Blood chemistry data were also analyzed using Chi-square analysis.

RESULTS

Although significant time effects were seen, no statistically significant overall MANOVA Wilks' Lambda interactions were observed among groups for body composition, resting heart and blood pressure, readiness to perform questions, 1RM strength, anaerobic sprint capacity, or blood chemistry panels. MANOVA univariate analysis and analysis of changes from baseline with 95% CI revealed some evidence that cognitive function and 1RM strength were increased to a greater degree in the PWS and/or PWS + S groups after 4- and/or 8-weeks compared to PLA responses. However, there was no evidence that PWS + S promoted greater overall training adaptations compared to the PWS group. Dietary supplementation of PWS and PWS + S did not increase the incidence of reported side effects or significantly affect the number of blood values above clinical norms compared to PLA.

CONCLUSION

Results provide some evidence that 4-weeks of PWS and/or PWS + S supplementation can improve some indices of cognitive function and exercise performance during resistance-training without significant side effects in apparently health males. However, these effects were similar to PLA responses after 8-weeks of supplementation and inclusion of synephrine did not promote additive benefits.

TRIAL REGISTRATION

This trial (NCT02999581) was retrospectively registered on December 16th 2016.

New Dietary Supplements for Obesity: What We Currently Know

Obesity and its associated cardiometabolic alterations currently are considered an epidemic; thus, their treatment is of major importance. The cornerstone for such treatment involves therapeutic lifestyle changes; however, the vast majority of cases fail and/or significant weight loss is maintained only in the short term because of lack of compliance. The popularity of dietary supplements for weight management has increased, and a wide variety of these products are available over the counter. However, the existing scientific evidence is insufficient to recommend their safe use. Hence, the purpose of this article is to review the clinical effects, proposed mechanism of action, and safety profile of some of the new dietary supplements, including white bean extract, Garcinia cambogia, bitter orange, Hoodia gordonii, forskolin, green coffee, glucomannan, β-glucans, chitosan, guar gum, and raspberry ketones.

A Review of Natural Stimulant and Non-stimulant Thermogenic Agents

Obesity and overweight are major health issues. Exercise and calorie intake control are recognized as the primary mechanisms for addressing excess body weight. Naturally occurring thermogenic plant constituents offer adjunct means for assisting in weight management. The controlling mechanisms for thermogenesis offer many intervention points. Thermogenic agents can act through stimulation of the central nervous system with associated adverse cardiovascular effects and through metabolic mechanisms that are non-stimulatory or a combination thereof. Examples of stimulatory thermogenic agents that will be discussed include ephedrine and caffeine. Examples of non-stimulatory thermogenic agents include p-synephrine (bitter orange extract), capsaicin, forskolin (Coleus root extract), and chlorogenic acid (green coffee bean extract). Green tea is an example of a thermogenic with the potential to produce mild but clinically insignificant undesirable stimulatory effects. The use of the aforementioned thermogenic agents in combination with other extracts such as those derived from Salacia reticulata, Sesamum indicum, Lagerstroemia speciosa, Cissus quadrangularis, and Moringa olifera, as well as the use of the carotenoids as lutein and fucoxanthin, and flavonoids as naringin and hesperidin can further facilitate energy metabolism and weight management as well as sports performance without adverse side effects. © 2016 The Authors Phytotherapy Research published by John Wiley & Sons Ltd.

Acute consumption of p-synephrine does not enhance performance in sprint athletes

P-Synephrine is a protoalkaloid widely used as an ergogenic aid in sports. This substance has been included in the World Anti-Doping Agency monitoring program, although scientific information about its effects on performance and athletes’ well-being is scarce. The purpose of this investigation was to determine the effectiveness of p-synephrine to increase performance in sprint athletes. In a randomized and counterbalanced order, 13 experienced sprinters performed 2 acute experimental trials after the ingestion of p-synephrine (3 mg·kg−1) or after the ingestion of a placebo (control trial). Forty-five minutes after the ingestion of the substances, the sprinters performed a squat jump, a countermovement jump, a 15-s repeated jump test, and subsequently performed 60-m and 100-m simulated sprint competitions. Self-reported questionnaires were used to assess side-effect prevalence. In comparison with the control trial, the ingestion of p-synephrine did not change countermovement jump height (37.4 ± 4.2 vs 36.7 ± 3.3 cm, respectively; P = 0.52), squat jump height (34.4 ± 3.6 vs 33.9 ± 3.7 cm; P = 0.34), or average 15-s repeated jumps height (31.8 ± 4.1 vs 32.2 ± 3.6 cm; P = 0.18). P-Synephrine did not modify maximal running speed during the 60-m (9.0 ± 0.5 vs 9.0 ± 0.4 m·s−1, respectively; P = 0.55) and 100-m sprint competitions (8.8 ± 0.5 vs 8.8 ± 0.5 m·s−1, respectively; P = 0.92). The ingestion of p-synephrine did not alter the prevalence of headache, gastrointestinal discomforts, muscle pain, or insomnia during the hours following the tests. Acute consumption of 3 mg·kg−1 of p-synephrine was ineffective to increase performance in competitive sprint athletes. Moreover, p-synephrine did not increase the occurrence of side effects after the competition.

Inhibitory effects of amines from Citrus reticulata on bleomycin-induced pulmonary fibrosis in rats

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease for which, thus far, there are no effective treatments. The pericarp of Citrus reticulata, as a traditional herbal drug, has been used for the clinical treatment of lung-related diseases in China for many years. In the present study, the amines from the pericarp of Citrus reticulata were isolated, and their hydrochlorides were prepared. The results of screening using cultured human embryonic lung fibroblasts (hELFs) revealed that, of the amines, 4-methoxyphenethylamine hydrochloride (designated as amine hydrochloride 1) possessed the most potent inhibitory effect. Further in vivo experiments using a rat model of bleomycin-induced pulmonary fibrosis demonstrated that the oral administration of amine hydrochloride 1 significantly lowered the hydroxyproline content in both serum and lung tissue, and alleviated pulmonary alveolitis and fibrosis. Immunohistochemical analysis revealed that amine hydrochloride 1 exerted its inhibitory effect against IPF through the downregulation of lung transforming growth factor (TGF)-β1 protein expression. Our results demonstrated that amine hydrochloride 1 prevented the development of bleomycin‑induced lung fibrosis in rats. Thus, our data suggest that the amines from the pericarp of Citrus reticulata have therapeutic potential for use in the treatment of IPF.

The effects of supplementation with P-Synephrine alone and in combination with caffeine on resistance exercise performance

BACKGROUND

Little is known concerning the potential ergogenic effects of p-synephrine supplementation. Therefore, the purpose of the present study was to examine the effects of supplementation with p-synephrine alone and in combination with caffeine on free-weight resistance exercise performance.

METHODS

Twelve healthy, college-aged men performed a control (CT) resistance exercise protocol consisting of 6 sets of squats for up to 10 repetitions per set using 80% of their one repetition-maximum (1RM) with 2 min of rest in between sets. Each subject was randomly assigned (in double-blind, balanced manner) to a treatment sequence consisting of use of 3 supplements: p-synephrine (S; 100 mg), p-synephrine + caffeine (SCF; 100 mg of p-synephrine plus 100 mg of caffeine), or a placebo (P). For each supplement treatment (separated by 1 week), subjects consumed the supplement for 3 days prior to each protocol and the morning of each protocol, and subsequently did not consume any supplements for 3 days following (i.e. wash-out period). On each protocol day, subjects reported to the lab at a standard time, consumed a supplement, sat quietly for 45 min, performed the resistance exercise protocol, and sat quietly for 30 min post exercise. Performance (repetition number, force, velocity and power), blood lactate, and ratings of perceived exertion (RPE) data were collected during each protocol.

RESULTS

Supplements SCF and S produced a significantly (P < 0.05) greater number of repetitions performed than CT (by 11.0 ± 8.0%) and P (by 6.0 ± 7.0%) and a 10.6 ± 12.0% greater increase in volume load per protocol than CT and P. Most of the differences were seen during the last 3 sets. Mean power and velocity for all 6 sets were significantly higher in SCF compared to CT and P by ~6.2 ± 8.0%. No supplement effects were observed in RPE or blood lactate, and no adverse side effects were observed or reported.

CONCLUSIONS

S and SCF augmented resistance exercise performance (total repetitions, volume load) without increasing blood lactate or RPE. The addition of caffeine in SCF increased mean power and velocity of squat performance. These results indicate supplementation with S and SCF can enhance local muscle endurance during resistance exercise.

Effect of citrus flavonoids, naringin and naringenin, on metabolic syndrome and their mechanisms of action

Flavonoids are important natural compounds with diverse biologic activities. Citrus flavonoids constitute an important series of flavonoids. Naringin and its aglycone naringenin belong to this series of flavonoids and were found to display strong anti-inflammatory and antioxidant activities. Several lines of investigation suggest that naringin supplementation is beneficial for the treatment of obesity, diabetes, hypertension, and metabolic syndrome. A number of molecular mechanisms underlying its beneficial activities have been elucidated. However, their effect on obesity and metabolic disorder remains to be fully established. Moreover, the therapeutic uses of these flavonoids are significantly limited by the lack of adequate clinical evidence. This review aims to explore the biologic activities of these compounds, particularly on lipid metabolism in obesity, oxidative stress, and inflammation in context of metabolic syndrome.

Problems with Citrus aurantium information in "A review on botanical species and chemical compounds with appetite suppressing properties for body weight control"

Various botanical extracts are used as adjuncts in treating obesity. A recent review concerning botanical products used to suppress appetite has included a discussion of Citrus aurantium and p-synephrine. The authors have incorrectly equated the actions of C. aurantium with ephedra in terms of adrenergic receptor binding, pharmacological effects and safety. Current research literature is reviewed which clarifies these issues.