Assessment of the adverse event reports associated with Citrus aurantium (bitter orange) from April 2004 to October 2009

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.

Description of Ventricular Arrhythmia after Taking Herbal Medicines in Middle-Aged Couples

Medicinal herbs and some derivatives have been used in the treatment of heart disease which is rarely responsible for ventricular arrhythmias and cardiac arrest. Ventricular tachycardia (VT) increases the risk of sudden cardiac death (SCD). However, only a few reports are available about the cardiac ventricular arrhythmia followed by taking herbal medicines. We present two patients (a couple) without a history of heart disease who referred to the hospital with ventricular arrhythmia.

Co-Existence of Hypertensive and Anti-Hypertensive Constituents, Synephrine, and Nobiletin in Citrus unshiu Peel

A single herb can contain multiple constituents with diverse bioactivities. We found that the extract of Citrus unshiu peel (CUP), induced abnormal vasoconstriction responses on the freshly isolated rat aortic rings in vitro. CUP stimulated the vasoconstriction alone, and it suppressed the phenylephrine-stimulated vasoconstriction. We studied the reasons behind this abnormal vasoconstriction pattern. Major constituents of CUP were determined and evaluated for their vaso-activities. Notably, synephrine, a contractile agonist, and nobiletin, newly identified to have anti-contractile activity co-existed in CUP. Synephrine and nobiletin competitively blocked or activated the same contractile targets resulting in contradicting and abnormal vasoconstriction responses. Accordingly, the vasoconstriction pattern varies significantly depending on the relative contents of synephrine and nobiletin in CUP. Interestingly, this response pattern could be observed with another plant extract, Acorus gramineus Sol. Collectively, we demonstrated that active ingredients with contradicting bioactivities could co-exist in a single plant extract, interact and produce abnormal response patterns in bioassay, which would give an important insight into the interpretation of unusual activity patterns induced by plant extracts.

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.

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.

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.

Chemical composition, antifeedant, repellent, and toxicity activities of the rhizomes of galangal, Alpinia galanga against Asian subterranean termites, Coptotermes gestroi and Coptotermes curvignathus (Isoptera: Rhinotermitidae)

Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD50) of C. curvignathus was 945 mg/kg, whereas LD50 value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices.

Acute myocardial infarction associated with dietary supplements containing 1,3-dimethylamylamine and Citrus aurantium

We describe the case of a previously healthy 22-year-old man who presented with anginal chest pain and was diagnosed with a non-ST-elevation myocardial infarction. For 3 weeks, he had been ingesting the dietary supplements Jack3d® (principal ingredient, 1,3-dimethylamylamine) and Phenorex™ (principal ingredient, Citrus aurantium) daily, before undertaking physical activity. Coronary angiograms revealed a proximal left anterior descending coronary artery thrombus with distal embolization. A combined medical regimen led to resolution of the thrombus. Three months later, the patient was asymptomatic with no evidence of ischemia. The primary ingredients in the sympathomimetic supplements taken by our patient are controversial in the medical community and have been individually associated with adverse cardiac events. There are no safety data on their simultaneous use. We discuss other reports of adverse effects associated with these supplements and recommend that the relevant safety guidelines be revised.

An evidence-based systematic review of bitter orange (Citrus aurantium) by the Natural Standard Research Collaboration

An evidence-based systematic review of bitter orange (Citrus aurantium) by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

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

Bitter orange (Citrus aurantium) extract and its primary protoalkaloid p-synephrine are widely consumed in dietary supplements for weight management and sports performance. p-Synephrine is also present in foods derived from a variety of Citrus species. Bitter orange extract is commonly used in combination with multiple herbal ingredients. Most clinical studies conducted on bitter orange extract alone have involved single doses. The purpose of this study was to assess the safety of bitter orange extract (approximately 49mg p-synephrine) alone or in combination with naringin and hesperidin twice daily given to 25 healthy subjects per group for 60days in a double-blinded, placebo-controlled protocol. No significant changes occurred in systolic or diastolic blood pressures, blood chemistries or blood cell counts in control or p-synephrine treated groups. Small, clinically insignificant differences in heart rates were observed between the p-synephrine plus naringin and hesperidin group and the p-synephrine alone as well as the placebo group. No adverse effects were reported in the three groups. Bitter orange extract and p-synephrine appear to be without adverse effects at a dose of up to 98mg daily for 60days based on the parameters measured.

A review of the receptor-binding properties of p-synephrine as related to its pharmacological effects

Bitter orange (Citrus aurantium) extract and its primary protoalkaloid p-synephrine are used widely in weight loss/weight management and sports performance products. Because of structural similarities, the pharmacological effects of p-synephrine are widely assumed to be similar to those of ephedrine, m-synephrine (phenylephrine), and endogenous amine neurotransmitters as norepinephrine and epinephrine. However, small structural changes result in the receptor binding characteristics of these amines that are markedly different, providing a plausible explanation for the paucity of adverse effects associated with the wide-spread consumption of p-synephrine in the form of dietary supplements as well as in various Citrus foods and juices. This paper summarizes the adrenoreceptor binding characteristics of p-synephrine relative to m-synephrine, norepinephrine, and other amines as related to the observed pharmacological effects.

The safety of Citrus aurantium (bitter orange) and its primary protoalkaloid p-synephrine

Citrus aurantium (bitter orange) extract and its principal protoalkaloidal constituent p-synephrine are widely used in weight loss and weight management as well as in sports performance products. However, questions are raised frequently regarding the safety of these ingredients. The potential inherent dangers associated with the use of products containing C. aurantium extract are frequently touted, while conversely, millions of doses of dietary supplements have been consumed by possibly millions of individuals in recent years. Furthermore, millions of people consume on a daily basis various juices and food products from Citrus species that contain p-synephrine. This review summarizes current information regarding the safety of C. aurantium (bitter orange) extract and p-synephrine based on human, animal and in vitro assessments as well as receptor binding and mechanistic studies. The data indicate that based on current knowledge, the use of bitter orange extract and p-synephrine appears to be exceedingly safe with no serious adverse effects being directly attributable to these ingredients.