Acute oral intake of a higenamine-based dietary supplement increases circulating free fatty acids and energy expenditure in human subjects

Determination of doping higenamine in Chinese herbal medicines and their concentrated preparations by LC-MS/MS

The World Anti-Doping Agency (WADA) has included higenamine in the β2 agonist (S3) category of the Prohibited List since 2017 due to its pharmacological effects on adrenergic receptors. Although higenamine contained in Chinese herbal medicines has been identified by previous studies, comprehensive investigation on the higenamine content of Chinese herbs and their concentrated preparations is still required. This study aimed to determine the levels of higenamine in Chinese medicinal materials and their concentrated preparations used in Chinese medicine prescriptions in Taiwan. The levels of higenamine in Chinese medicinal materials, including Cortex Phellodendri, Flos Caryophylli, Fructus Euodiae, Fructus Kochiae, Plumula Nelumbinis, Radix Aconiti Preparata, Radix Aconiti Lateralis Preparata, and Radix Asari, and their concentrated preparations were determined by a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Our results showed that the amounts of higenamine were detected and quantified in studied Chinese medicinal materials and their concentrated preparations, except for Flos Caryophylli, Radix Aconiti Preparata, and Radix Aconiti Lateralis Preparata. Plumula Nelumbinis and Cortex Phellodendri have higher levels of higenamine when compared to other Chinese herbs tested in the present study. The highest level of higenamine was 2100 μg/g found in the Plumula Nelumbinis medicinal material. In contrast with Plumula Nelumbinis and Cortex Phellodendri, higenamine levels below 10 μg/g were found in other most of the studied Chinese medicinal materials and their concentrated preparations. This study confirmed that various Chinese herbs and their concentrated preparations contained higenamine, and it provided more coherent and comprehensive information for reducing the potential risk of higenamine misuse in sports.

Insights into human eNOS, nNOS and iNOS structures and medicinal indications from statistical analyses of their interactions with bound compounds

83 Structures of human nNOS, 55 structures of human eNOS, 13 structures of iNOS, and about 126 reported NOS-bound compounds are summarized and analyzed. Structural and statistical analysis show that, at least one copy of each analyzed compound binds to the active site (the substrate arginine binding site) of human NOS. And binding features of the three isoforms show differences, but the binding preference of compounds is not in the way helpful for inhibitor design targeting nNOS and iNOS, or for activator design targeting eNOS. This research shows that there is a strong structural and functional similarity between oxygenase domains of human NOS isoforms, especially the architecture, residue composition, size, shape, and distribution profile of hydrophobicity, polarity and charge of the active site. The selectivity and efficacy of inhibitors over the rest of isoforms rely a lot on chance and randomness. Further increase of selectivity via rational improvement is uncertain, unpredictable and unreliable, therefore, to achieve high selectivity through targeting this site is complicated and requires combinative investigation. After analysis on the current two targeting sites in NOS, the highly conserved arginine binding pocket and H4B binding pocket, new potential drug-targeting sites are proposed based on structure and sequence profiling. This comprehensive analysis on the structure and interaction profiles of human NOS and bound compounds provides fresh insights for drug discovery and pharmacological research, and the new discovery here is practically applied to guide protein-structure based drug discovery.

Dietary higenamine from Annonaceae family fruits as a possible source of unintentional doping

Members of the genus Aconitum have been used for millennia, both as poisons and medicines, in Eastern culture. Higenamine has non-selective beta-agonist effects, activating both β₁ and β₂ adrenoreceptors, and is present in a variety of plants. The World Anti-Doping Agency has banned Higenamine both in competition and out of competition. Due to the common uses of higenamine in Brazilian culture, both as medicine and food, we studied the urinary concentrations of higenamine after the consumption of fruits of the Annona genus. We evaluated whether the ingestion of these fruits has the potential to cause anti-doping code violations. We measured higenamine concentrations for a 72 h period in the urine of ten healthy, physically active males (age 20-30; weight 70-80 kg; not consuming supplements or medications) after eating a unique meal containing fruits. Fruit consumption ranges were: Carica papaya (control) 348 ± 98 g; A. muricata 450 ± 282 g; and A. squamosa 314 ± 60 g. (all mean± SD). Higenamine was measured using ultra-performance liquid chromatography coupled with electrospray-tandem mass spectrometry. The appearance of urinary higenamine occurred within the first 12 h after eating A. muricata (n = 3), and the maximum concentration found was 1.9 ng/mL. The ingestion of A. squamosa has also been shown to cause higenamine urinary excretion. The elimination kinetics of the subjects who ingested A. squamosa (n = 4) were different from each other. After ingestion of the control fruit, C. papaya, we detected no higenamine in the urine of any participants (n = 3). Although the kinetics varied by individuals and fruits, A. muricata ingestion produced higher higenamine excretion; however, the A. squamosa portion weighed ∼66 % of the A. muricata portion. We conclude that eating Annonaceae family fruits cause detectable higenamine excretion. Conversely, single ingestion did not reach the WADA's threshold to cause adverse analytical findings.

Pharmacological effects of higenamine based on signalling pathways and mechanism of action

Higenamine (HG) is a chemical compound found in various plants, such as aconite. Recent pharmacological studies have demonstrated its effectiveness in the management of many diseases. Several mechanisms of action of HG have been proposed; however, they have not yet been classified. This review summarises the signalling pathways and pharmacological targets of HG, focusing on its potential as a naturally extracted drug. Articles related to the pharmacological effects, signalling pathways and pharmacological targets of HG were selected by searching the keyword “Higenamine” in the PubMed, Web of Science and Google Scholar databases without limiting the search by publication years. HG possesses anti-oxidant, anti-apoptotic, anti-inflammatory, electrophysiology regulatory, anti-fibrotic and lipid-lowering activities. It is a structural analogue of catecholamines and possesses characteristics similar to those of adrenergic receptor ligands. It can modulate multiple targets, including anti-inflammation- and anti-apoptosis-related targets and some transcription factors, which directly or indirectly influence the disease course. Other naturally occurring compounds, such as cucurbitacin B (Cu B) and 6-gingerol (6-GR), can be combined with HG to enhance its anti-apoptotic activity. Although significant research progress has been made, follow-up pharmacological studies are required to determine the exact mechanism of action, new signalling pathways and targets of HG and the effects of using it in combination with other drugs.

Higenamine Attenuates Doxorubicin-Induced Cardiac Remodeling and Myocyte Apoptosis by Suppressing AMPK Activation

Background: As an effective antitumor drug, doxorubicin (DOX) is primarily used to treat solid tumors and hematologic malignancies. However, increasing evidence has emerged indicating its cardiotoxicity, and few solutions have been proposed to counter this side effect. Higenamine (HG) is a natural compound widely found in many Chinese herbs and also serves as a component in many healthcare products. Several studies have demonstrated its cardioprotective effect in different models, but little is known about the underlying influences of HG against myocardial damage from DOX-induced chronic cardiotoxicity.

Methods and Results: C57BL/6 mice and neonatal rat ventricular cardiomyocytes (NRVMs) were used to evaluate the cardioprotective effect of HG against DOX-induced myocardial damage. In mice, DOX (intraperitoneally injected 5 mg/kg every 3 days for 4 weeks) significantly increased cardiomyocyte apoptosis, cardiac atrophy, and cardiac dysfunction, which were significantly attenuated by HG (intragastrically administered with 10 mg/kg every day for 4 weeks). In NRVMs, DOX (3 μM for 24 h) significantly increased cell apoptosis and the level of reactive oxygen species while reducing the level of superoxide dismutase and mitochondrial membrane potential. Remarkably, HG can reverse these pathological changes caused by DOX. Interestingly, the protective effect of HG on DOX-induced cardiotoxicity was independent of the activation of the beta-2 adrenergic receptor (β2-AR), known for mediating the effect of HG on antagonizing ischemia/reperfusion-induced cardiac apoptosis. Furthermore, HG attenuated the abnormal activation of phosphorylated adenosine-activated protein kinase (AMPK). Consistently, AMPK agonists (AICAR) can eliminate these pharmacological actions of HG.

Conclusion: Collectively, our results suggested that HG alleviated DOX-induced chronic myocardial injury by suppressing AMPK activation and ROS production.

Dietary Supplements as Source of Unintentional Doping

Background

The substances used in sport could be divided into two major groups: those banned by the World Anti-Doping Agency and those which are not. The prohibited list is extremely detailed and includes a wide variety of both medicinal and nonmedicinal substances. Professional athletes are exposed to intense physical overload every day. They follow a relevant food regime and take specific dietary supplements, which is essential for the better recovery between trainings and competitions. However, the use of “nonprohibited” dietary supplements (DS) is not always completely safe. One of the risks associated with the use of dietary supplements is the risk of unintended doping—originating from contaminated products. The presence of undeclared compounds in the composition of DS is a serious concern. The aim of this study is to evaluate the risk of unintentional doping.

Materials and Methods

Literature search was done through PubMed, Science Direct, Google Scholar, and Web of Science. Studies investigating the presence of undeclared compounds, in dietary supplements, banned by WADA met the inclusion criteria. The last search was conducted in June 2021. The present review is based on a total of 50 studies, which investigated the presence of undeclared compounds in DS.

Results

The total number of analyzed DS is 3132, 875 of which were found to contain undeclared substances. Most frequently found undeclared substances are sibutramine and anabolic-androgenic steroids.

Conclusion

More than 28% of the analyzed dietary supplements pose a potential risk of unintentional doping. Athletes and their teams need to be aware of the issues associated with the use of DS. They should take great care before inclusion of DS in the supplementation regime.

Higenamine in Plants as a Source of Unintentional Doping

BACKGROUND

Higenamine is a β₂ agonist of plant origin. The compound has been included in WADA's prohibited list since 2017. Higenamine may be detected in different plants and many food supplements of natural origin.

METHODS

Our literature search was conducted through PubMed, Science Direct, Google Scholar, and Web of Science studies investigating the presence of higenamine in plants that are used in traditional folk medicine or included in food supplements. Our study aimed to assess the risk of adverse analytical findings caused by higenamine-containing plants.

RESULTS

Based on our literature search, Nelumbo nucifera, Tinospora crispa, Nandina domestica, Gnetum parvifolium, Asarum siebodii,Asarum heterotropoides, Aconitum carmichaelii, and Aristolochia brasiliensis are higenamine-containing plants. Based on data from Eastern folk medicine, these plants can provide numerous health benefits. Professional athletes likely ingest these plants without knowing that they contain higenamine; these herbs are used in treatments for different conditions and various foods/food supplements in addition to folk medicine.

CONCLUSION

Athletes and their teams must be aware of the issues associated with the use of plant-based products. They should avoid consuming higenamine-containing plants during and outside of competition periods.

Influence of Higenamine on Exercise Performance of Recreational Female Athletes: A Randomized Double-Blinded Placebo-Controlled Trial

The aim of this study was to determine the ergogenic effects and the safety profile of a one-component higenamine supplement in female recreational athletes. Twelve recreational female basketball players (age 29-41 years, oxygen consumption (VO₂max) > 30 ml⋅kg^-1⋅min^-1, with training > 5 h wk^-1) were randomized either to the higenamine group, or to the placebo group for 3 weeks. In order to determine ergogenic effects and safety profile of higenamine administration, we assessed the following variables before and after 3 weeks of supplementation: anthropometric parameters, resting metabolic rate (RMR), exercise testing variables, serum free fatty acids (FFAs), blood pressure, enzyme activity, urea, lipid profile, and complete blood count. There were no differences between groups in anthropometric parameters, including basal metabolic rate (BMR), RMR and body fat [p = 0.706 (Cohen's d 0.223), p = 0.169 (Cohen's d 0.857), and p = 0.223 (Cohen's d 0.750), respectively], FFAs [0.43 ± 0.03 vs. 0.54 ± 0.23, p = 0.206 (Cohen's d 0.540)], neither significant differences in cardiopulmonary parameters after the intervention period. Furthermore, all measured outcome variables in the safety assessment were not significant, with values remaining stable during the intervention period for participants in both groups. This is the first study to document the effects and the safety profile of higenamine-based dietary supplements at a specified dose in female recreational athletes. Our data indicate that 21-day of supplementation with 75 mg higenamine would not result in improving cardiopulmonary exercise fitness and weight loss in female recreational athletes. Moreover, supplementation with 75 mg higenamine is safe and well-tolerated in younger recreational female athletes.

Higenamine attenuates cardiac fibroblast abstract and fibrosis via inhibition of TGF-β1/Smad signaling

RATIONALE

Higenamine (HG), is one of the main active components in many widely used Chinese herbs, and a common ingredient of health products in Europe and North America. Several groups, including our own, have previously shown the beneficial effects of HG against cardiomyocyte death during acute ischemic damage. However, the effect of HG on chronic cardiac remodeling, such as cardiac fibrosis, remains unknown.

OBJECTIVE

Herein, we aim to investigate the role of HG in cardiac fibrosis in vivo as well as its cellular and molecular mechanisms.

METHODS AND RESULTS

Chronic pressure overload with transverse aortic constriction (TAC) significantly increased cardiac hypertrophy, fibrosis, and cardiac dysfunction in mice, which were significantly attenuated by HG. Consistently, cardiac fibrosis induced by the chronic infusion of isoproterenol (ISO), was also significantly reduced by HG. Interestingly, our results showed that HG had no effect on adult mouse CM hypertrophy in vitro. However, HG suppressed the activation of cardiac fibroblasts (CFs) in vitro. Furthermore, TGF-β1-induced expression of ACTA2, a marker of fibroblast activation, was significantly suppressed by HG. Concomitantly, HG inhibited TGF-β1-induced phosphorylation of Smad2/3 in CFs. HG also reduced the expression of extracellular matrix molecules such as collagen I and collagen III. To our surprise, the inhibitory effect of HG on CFs activation was independent of the activation of the beta2 adrenergic receptor (β2-AR) that is known to mediate the effect of HG on antagonizing CMs apoptosis.

CONCLUSION

Our findings suggest that HG ameliorates pathological cardiac fibrosis and dysfunction at least partially by suppressing TGF-β1/Smad signaling and CFs activation.

Risk Associated with the Use of Selected Ingredients in Food Supplements

This review focuses on four new product categories of food supplements: pre-workout, fat burner/thermogenic, brain/cognitive booster, and hormone/testosterone booster. Many food supplements have been shown to be contaminated with unauthorized substances. In some cases, the ingredients in the new categories of dietary supplements were medicinal products or new synthetic compounds added without performing clinical trials. Some of the new ingredients in dietary supplements are plant materials that are registered in the pharmacopoeia as herbal medicines. In other cases, dietary supplements may contain plant materials that have no history of human use and are often used as materials to 'camouflage' stimulants. In the European Union, new ingredients of dietary supplements, according to European Food Safety Authority or unauthorized novel food. Furthermore, selected ingredients in dietary supplements may be prohibited in sports and are recognized as doping agents by World Anti-Doping Agency.

Impact of obesity on the toxicity of a multi-ingredient dietary supplement, OxyELITE Pro™ (New Formula), using the novel NZO/HILtJ obese mouse model: Physiological and mechanistic assessments

Herbal dietary supplement (HDS)-induced hepato- and cardiotoxicity is an emerging clinical problem. In this study, we investigated the liver and heart toxicity of HDS OxyELITE-PRO™ New Formula (OEP-NF), a dietary supplement marketed for weight loss and performance enhancement that was recently withdrawn from the market. Using a novel NZO/HlLtJ obese mouse model, we demonstrated that administration of clinically relevant mouse equivalent doses (MED) of OEP-NF produced cardio- and hepatotoxic risks following both short- and long-term administration schedules. Specifically, gavaging female NZO/HlLtJ with up to 2X MED of OEP-NF resulted in 40% mortality within two weeks. Feeding mice with either 1X or 3X MED of OEP-NF for eight weeks, while not exhibiting significant effects on body weights, significantly altered hepatic gene expression, increased the number of apoptotic and mast cells in the heart and affected cardiac function. The degree of toxicity in NZO/HlLtJ mice was higher than that observed previously in non-obese CD-1 and B6C3F1 strains, suggesting that an overweight/obese condition can sensitize mice to OEP-NF. Adverse health effects linked to OEP-NF, together with a number of other hepato- and cardiotoxicity cases associated with HDS ingestion, argue strongly for introduction of quality standards and pre-marketing safety assessments for multi-ingredient HDS.

Involvement of UDP-glucuronosyltransferases in higenamine glucuronidation and the gender and species differences in liver

OBJECTIVES

Higenamine (HG), an active ingredient of Aconite root in Chinese herbal medicine, is mainly metabolized by UDP-glucuronosyltransferases (UGT). However, the systematic glucuronidation of HG in humans remains unclear. The purpose of this study was to investigate the glucuronidation of HG.

METHODS

12 recombinant human UGT (rUGT) isozymes were used to characterize the HG glucuronidation. Liver microsomes from male and female mice, rats, guinea pigs, dogs, and humans were used to determine the species and gender differences using liquid chromatography-mass spectrometry.

KEY FINDINGS

One monoglucuronide was detected in reactions catalyzed by rUGT1A6, rUGT1A8, rUGT1A9, also human and dog liver microsomes. UGT1A9 is the most important glucuronosyltransferase that metabolizes HG. Because carvacrol, a specific inhibitor of UGT1A9, can significantly decrease the glucuronidation of HG in Human liver microsomes and UGT1A9. HG metabolism by UGT1A9 described in Michaelis-Menten kinetics (K_m=15.4 mM,V_max=2.2 nmol/mg/min) and glucuronidation in liver microsomes were species dependent. Gender did not affect the kinetic parameters among species except in rats.

CONCLUSIONS

UGT1A9 is a major isoenzyme responsible for the glucuronidation of HG in Human liver microsomes (HLMs). Dog may be an appropriate animal model to evaluate HG metabolism.

Ability of higenamine and related compounds to enhance glucose uptake in L6 cells

β2-Adrenergic receptor (β2AR) agonists are employed as bronchodilators to treat pulmonary disorders, but are attracting attention for their modulation of glucose handling and energy expenditure. Higenamine is a tetrahydroisoquinoline present in several plant species and has β2AR agonist activity, but the involvement of each functional groups in β2AR agonist activity and its effectiveness compared with endogenous catecholamines (dopamine, epinephrine, and norepinephrine) has rarely been studied. Glucose uptake of muscle cells are known to be induced through β2AR activation. Here, the ability to enhance glucose uptake of higenamine was compared with that of several methylated derivatives of higenamine or endogenous catecholamines. We found that: (i) the functional groups of higenamine except for the 4'-hydroxy group are required to enhance glucose uptake; (ii) higenamine shows a comparable ability to enhance glucose uptake with that of epinephrine and norepinephrine; (iii) the S-isomer shows a greater ability to enhance glucose uptake compared with that of the R-isomer.

Synthesis and Detailed Examination of Spectral Properties of (S) and (R)-Higenamine 4'-O-β-d-Glucoside and HPLC Analytical Conditions to Distinguish the Diastereomers

Higenamine is a tetrahydroisoquinoline present in several plants that has β-adrenergic receptor agonist activity. Study of the biosynthesis of higenamine has shown the participation of norcoclaurine synthase, which controls the stereochemistry to construct the (S)-isomer. However, when isolated from nature, higenamine is found as the racemate, or even the (R)-isomer. We recently reported the isolation of higenamine 4'-O-β-d-glucoside. Herein, its (R)- and (S)-isomers were synthesized and compared to precisely determine the stereochemistry of the isolate. Owing to their similar spectral properties, determination of the stereochemistry based on NMR data was considered inappropriate. Therefore, a high-performance liquid chromatography method was established to separate the isomers, and natural higenamine 4'-O-β-d-glucoside was determined to be a mixture of isomers.

Safety assessment of the dietary supplement OxyELITE™ Pro (New Formula) in inbred and outbred mouse strains

Herbal dietary supplements have gained wide acceptance as alternatives to conventional therapeutic agents despite concerns regarding their efficacy and safety. In 2013, a spate of severe liver injuries across the United States was linked to the dietary supplement OxyELITE Pro-New Formula (OEP-NF), a multi-ingredient product marketed for weight loss and exercise performance enhancement. The principal goal of this study was to assess the hepatotoxic potential of OEP-NF in outbred and inbred mouse models. In an acute toxicity study, significant mortality was observed after administering 10X and 3X mouse-equivalent doses (MED) of OEP-NF, respectively. Increases in liver/body weight ratio, ALT and AST were observed in female B6C3F₁ mice after gavaging 2X and 1.5X MED of OEP-NF. Similar findings were observed in a 90-day feeding study. These alterations were paralleled by altered expression of gene- and microRNA-signatures of hepatotoxicity, including Cd36, Nqo1, Aldoa, Txnrd1, Scd1 and Ccng1, as well as miR-192, miR-193a and miR-125b and were most pronounced in female B6C3F₁ mice. Body weight loss, observed at week 1, was followed by weight gain throughout the feeding studies. These findings bolster safety and efficacy concerns for OEP-NF, and argue strongly for implementation of pre-market toxicity studies within the dietary supplement industry.

Beneficial effect of medicinal plants on the contractility of post-hypoxic isolated guinea pig atria - Potential implications for the treatment of ischemic-reperfusion injury

Context Ischemic-reperfusion injury is accompanied by a decreased contractility of the myocardium. Positive-inotropic agents have proven useful for treating this condition but may exert serious side-effects. Objective In this study, aqueous preparations from Abelmoschus esculentus L. Moench (Malvaceae), Annona muricata L. (Annonaceae), Bixa orellana L. (Bixaceae), Cecropia peltata L. (Moraceae), Erythrina fusca Lour. (Fabaceae), Psidium guajava L. (Myrtaceae) and Terminalia catappa L. (Combretaceae) were evaluated for their ability to improve the decreased contractility of isolated guinea pig atria after hypoxic stress. Materials and methods Guinea pig atria isolated in Ringer-Locke buffer gassed with 100% O2 at 30 °C were exposed for 5 min to hypoxia, then allowed to recover in oxygenated buffer alone or containing a single plant extract (0.001-1 mg/mL). The contractility (g/s) and beating frequency (beats/min), as well as troponin C contents of the bathing solution (ng/mL), were determined and expressed as means ± SDs. Results The extracts of A. muricata, B. orellana, C. peltata and T. catappa caused an increase in the contractility compared to untreated atria of 340 ± 102%, 151 ± 13%, 141 ± 14% and 238 ± 44%, respectively. However, the latter two preparations increased the troponin C contents of the bathing solution to 36 ± 11 and 69 ± 33, compared to the value of 11 ± 3 ng/mL found with untreated atria. Conclusions Preparations from A. muricata and B. orellana may possess positive-inotropic properties which may improve the contractility of the post-hypoxic myocardium. Studies to assess their usefulness in ischemic-reperfusion injury are warranted.

Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements

A number of dietary supplements used for weight loss and athletic performance enhancement have been recently shown to contain a variety of stimulants, for which there is a lack of pharmacological and toxicological information. One concern for these emerging compounds is their potential to inhibit metabolic enzymes in the liver such as cytochromes P450 (CYP), which can lead to unexpected interactions among dietary supplements, drugs, and other xenobiotics. In this study, inhibition of human recombinant CYP2D6 and CYP3A4 by 27 amine stimulants associated with dietary supplements and their analogs was evaluated by luminescence assays. The strongest CYP2D6 inhibitors were coclaurine (IC50  = 0.14 ± 0.01 μM) and N-benzylphenethylamine (IC50  = 0.7 ± 0.2 μM), followed by several other relatively strong inhibitors (IC50 , 2-12 μM) including β-methylphenethylamine, N,β-dimethylphenethylamine (phenpromethamine), 1,3-dimethylamylamine (DMAA), N,α-diethylphenethylamine, higenamine (norcoclaurine) and N,N-diethylphenethylamine. Only nine compounds inhibited CYP3A4 by 20-55% at 100 μM. Results of this study illustrate that several amine stimulants associated with dietary supplements inhibit CYP2D6 and CYP3A4 in vitro, and these compounds may participate in adverse drug-dietary supplement interactions in vivo. Copyright © 2015 John Wiley & Sons, Ltd.

Clinical safety assessment of oral higenamine supplementation in healthy, young men

OBJECTIVE

Higenamine, an herbal agent also known as norcoclaurine, is thought to stimulate β-androgenic receptors and possess lipolytic activity. It is currently making its way into the dietary supplement market. To our knowledge, no studies have been conducted to determine the safety profile of oral higenamine when used alone and in conjunction with other commonly used lipolytic agents.

METHODS

Forty-eight men were assigned to ingest either a placebo, higenamine, caffeine, or higenamine + caffeine + yohimbe bark extract daily for a period of 8 weeks. Before and after 4 and 8 weeks of supplementation, the following variables were measured: resting respiratory rate, heart rate, blood pressure, urinalysis, complete blood count, metabolic panel, liver enzyme activity, and lipid panel.

RESULTS

No interaction effects were noted for any variable (p > 0.05), with no changes of statistical significance occurring across time for any of the four conditions (p > 0.05).

CONCLUSION

This is the first study to determine the safety profile of oral higenamine intake in human subjects. Our data indicate that 8 weeks of daily higenamine supplementation, either alone or in conjunction with caffeine and yohimbe bark extract, does not result in a statistically significant change in any of the measured outcome variables. Additional studies, inclusive of a larger sample size, are needed to extend these initial findings.