Analysis of the cytotoxic, genotoxic, mutagenic, and pro-oxidant effect of synephrine, a component of thermogenic supplements, in human hepatic cells in vitro

Phytochemistry, pharmacological properties and pharmacokinetics of Citri Reticulatae Pericarpium: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Citri Reticulatae Pericarpium (CRP), known as Chen Pi in China, is the most commonly used medicine for regulating qi. As a traditional medicine, CRP has been extensively used in the clinical treatment of nausea, vomiting, cough and phlegm for thousands of years. It is mainly distributed in Guangdong, Sichuan, Fujian and Zhejiang in China. Due to its high frequency of use, many scholars have conducted a lot of research on it and the related chemical constituents it contains. In this review, the research progress on phytochemistry, pharmacology, pharmacokinetics and toxicology of CRP are summarized.

AIM OF THE REVIEW

The review aims to sort out the methods of extraction and purification, pharmacological activities and mechanisms of action, pharmacokinetics and toxicology of the chemical constituents in CRP, in order to elaborate the future research directions and challenges for the study of CRP and related chemical constituents.

MATERIALS AND METHODS

Valid and comprehensive relevant information was collected from China National Knowledge Infrastructure, Web of Science, PubMed and so on.

RESULTS

CRP contains a variety of compounds, of which terpenes, flavonoids and alkaloids are the main components, and they are also the primary bioactive components that play a pharmacological role. Flavonoids and terpenes are extracted and purified by aqueous and alcoholic extraction methods, assisted by ultrasonic and microwave extraction, in order to achieve higher yields with less resources. Pharmacological studies have shown that CRP possesses a variety of highly active chemical components and a wide range of pharmacological activities, including anti-tumor, anti-inflammatory, immunomodulatory, hepatoprotective, therapeutic for cardiovascular-related disorders, antioxidant, antibacterial, and neuroprotective effects.

CONCLUSIONS

There is a diversity in the chemical compositions of CRP, which have multiple biological activities and promising applications. However, the pharmacological activities of CRP are mainly dependent on the action of its chemical components, but the relationship between the structure of chemical components and the biological effects has not been thoroughly investigated, and therefore, the structure-activity relationship is an issue that needs to be elucidated urgently. In addition, the pharmacokinetic studies of the relevant components can be further deepened and the correlation studies between pharmacological effects and syndromes of TCM can be expanded to ensure the effectiveness and rationality of CRP for human use.

Marketable 1,3-dimethylamylamine and caffeine-based thermogenic supplements: Regulatory genotoxicity assessment through in vitro and in silico approaches

The consumption of dietary supplements to enhance physical performance has increased significantly in the last century, especially thermogenic pre-workout supplements. Nevertheless, this industry has faced criticism for inadequate safety measures surveillance in regulatory issues regarding their products. The aims of our study were to investigate two pre-workout supplements with respect to (1) mutagenicity utilizing Salmonella/microsome assay; (2) genotoxicity employing cytokinesis-block micronucleus (CBMN) assay protocols; and (3) hepatocytoxicity using WST cell proliferation, activities of lactate dehydrogenase (LDH) and alkaline phosphatase using human liver carcinoma (HepG2) and mouse fibroblast (F C3H) cells. Oxidative stress was determined through glutathione (GSH) measurement and in silico for predictions of pharmacokinetics and toxicity for the most abundant isolated substances present in these supplements. Both supplements induced mutagenicity in all examined bacterial strains, especially in the presence of exogenous metabolism. Further, tested supplements significantly elevated the formation of micronuclei (MN) as well as other cellular phenomena. Concentration- and time-dependent curves were observed for hepatotoxicity in both studied cell lines. In addition, both supplements decreased levels of intracellular and extracellular GSH. In silico predictions showed that the isolated individual compounds failed to induce the observed outcomes. Our findings provide contributions to the molecular mechanisms underlying two pre-workout supplement-induced toxicity and the need for surveillance.

Synephrine and Its Derivative Compound A: Common and Specific Biological Effects

This review is focused on synephrine, the principal phytochemical found in bitter orange and other medicinal plants and widely used as a dietary supplement for weight loss/body fat reduction. We examine different aspects of synephrine biology, delving into its established and potential molecular targets, as well as its mechanisms of action. We present an overview of the origin, chemical composition, receptors, and pharmacological properties of synephrine, including its anti-inflammatory and anti-cancer activity in various in vitro and animal models. Additionally, we conduct a comparative analysis of the molecular targets and effects of synephrine with those of its metabolite, selective glucocorticoid receptor agonist (SEGRA) Compound A (CpdA), which shares a similar chemical structure with synephrine. SEGRAs, including CpdA, have been extensively studied as glucocorticoid receptor activators that have a better benefit/risk profile than glucocorticoids due to their reduced adverse effects. We discuss the potential of synephrine usage as a template for the synthesis of new generation of non-steroidal SEGRAs. The review also provides insights into the safe pharmacological profile of synephrine.

Review of Case Reports on Adverse Events Related to Pre-workout Supplements Containing Synephrine

The use of pre-workout supplements has become increasingly popular, including the use of supplements containing synephrine. Synephrine might stimulate weight loss and improve sports performance by its proposed adrenergic properties. However, with its increasing popularity, numerous cases of adverse events related to synephrine use have been reported. This study provides a comprehensive overview and analysis of current case reports related to the supplemental use of synephrine. The scientific literature on cases of adverse events related to synephrine intake was collected through August 2021 using Pubmed and Google Scholar and subsequently reviewed and analysed. We obtained 30 case reports describing a total of 35 patients who suffered from medical complaints following use of synephrine-containing supplements. The patients most often presented with chest pain, palpitations, syncope and dizziness. Commonly raised diagnoses were ischaemic heart disease, cardiac arrhythmias and cerebrovascular disease. Five patients were left disabled or remained on medication at last follow-up. We here show an association between the use of pre-workout supplements containing synephrine and adverse events, mainly related to the cardiovascular system. However, we cannot exclude a role of possible confounding factors such as caffeine. Thus, the use of pre-workout supplements containing synephrine may lead to serious adverse health events, and therefore, caution is needed.

Natural Sympathomimetic Drugs: From Pharmacology to Toxicology

Sympathomimetic agents are a group of chemical compounds that are able to activate the sympathetic nervous system either directly via adrenergic receptors or indirectly by increasing endogenous catecholamine levels or mimicking their intracellular signaling pathways. Compounds from this group, both used therapeutically or abused, comprise endogenous catecholamines (such as adrenaline and noradrenaline), synthetic amines (e.g., isoproterenol and dobutamine), trace amines (e.g., tyramine, tryptamine, histamine and octopamine), illicit drugs (e.g., ephedrine, cathinone, and cocaine), or even caffeine and synephrine. In addition to the effects triggered by stimulation of the sympathetic system, the discovery of trace amine associated receptors (TAARs) in humans brought new insights about their sympathomimetic pharmacology and toxicology. Although synthetic sympathomimetic agents are mostly seen as toxic, natural sympathomimetic agents are considered more complacently in the terms of safety in the vision of the lay public. Here, we aim to discuss the pharmacological and mainly toxicological aspects related to sympathomimetic natural agents, in particular of trace amines, compounds derived from plants like ephedra and khat, and finally cocaine. The main purpose of this review is to give a scientific and updated view of those agents and serve as a reminder on the safety issues of natural sympathomimetic agents most used in the community.

Toxicogenetic assessment of a pre-workout supplement: In vitro mutagenicity, cytotoxicity, genotoxicity and glutathione determination in liver cell lines and in silico ADMET approaches

The benefits of practicing physical activity, such as weight loss and control, are commonly associated with caloric restriction diets and may be improved by the ingestion of thermogenic and ergogenic supplements. However, there is a lack of safety data on commonly marketed nutritional supplements. Therefore, this investigation aims to evaluate a pre-workout supplement for mutagenicity using the Ames test, hepatocytoxicity in HepG2 and F C3H cells after 24 h, 48 h and 72 h, genotoxicity using the CBMN assay, determination of gluthatione activity and computational prediction of the three major isolated compounds present in the supplement. The mutagenicity test showed a mutagenic response in TA98 His⁺ revertants of 5 mg/plate in the presence of metabolic activation, cytotoxicity in TA98 of 5 mg/plate in the absence of metabolic conditions, and in TA102 of 0.5 mg/plate both in the presence and absence of metabolic activation. In our in vitro eukaryotic cell viability, WST-1, LDH and alkaline phosphatase assays, the supplement showed hepatocytotoxicity both dose-dependently and time-dependently. In the cytokinesis blocking micronuclei assay, the supplement induced micronuclei, nuclear buds, nucleoplasmatic, bridge formation, and a decreased in nuclear division. In addition, the supplement decreased intra and extracellular GSH. Computational analysis showed that the three isolated compounds most present in the supplement have the potential to cause hepatotoxicity. In the present investigation, the pre-workout supplement induced mutagenic, genotoxic, and cytotoxic responses and GSH decrease. Thus, considering food safety and public health sanitary vigilance, the consumption of this pre-workout supplement may harm the health of its consumers.

Regulation of reactive oxygen species by phytochemicals for the management of cancer and diabetes

Cancer and diabetes mellitus are served as typical life-threatening diseases with common risk factors. Developing therapeutic measures in cancers and diabetes have aroused attention for a long time. However, the problems with conventional treatments are in challenge, including side effects, economic burdens, and patient compliance. It is essential to secure safe and efficient therapeutic methods to overcome these issues. As an alternative method, antioxidant and pro-oxidant properties of phytochemicals from edible plants have come to the fore. Phytochemicals are naturally occurring compounds, considered promising agent applicable in treatment of various diseases with beneficial effects. Either antioxidative or pro-oxidative activity of various phytochemicals were found to contribute to regulation of cell proliferation, differentiation, cell cycle arrest, and apoptosis, which can exert preventive and therapeutic effects against cancer and diabetes. In this article, the antioxidant or pro-oxidant effects and underlying mechanisms of flavonoids, alkaloids, and saponins in cancer or diabetic models demonstrated by the recent studies are summarized.

Over a century since ephedrine discovery: an updated revisit to its pharmacological aspects, functionality and toxicity in comparison to its herbal extracts

Ephedrine, a sympathomimetic amine that exhibits several adrenaline actions, is a plant alkaloid that is a common ingredient in several cold, asthma and narcolepsy treatment preparations, and in obesity management and sport medicine. Its principal action mechanism relies on its direct adrenergic actions as well as indirect role that involves the release of epinephrine and norepinephrine, thus increasing the activity of epinephrine and norepinephrine at the postsynaptic α and β receptors. Nevertheless, its serious side effects, including stroke, heart attack, drug abuse and interactions, have never been comprehensively reviewed. We conducted a systematic review of data on ephedrine, including its occurrence in functional foods, pharmacological aspects, metabolism, pharmaco/toxicokinetics and clinical features. Furthermore, a review of ephedrine natural structural analogues with regards to their differential adrenergic receptor binding affinities, food interaction, and their impact on the pharmacokinetics and effects relative to ephedrine are presented for the first time, and in comparison to its action when present in herbs.

Synephrine and caffeine combination promotes cytotoxicity, DNA damage and transcriptional modulation of apoptosis-related genes in human HepG2 cells

The abusive consumption of thermogenic supplements occurs worldwide and deserves special attention due to their use to stimulate weight loss and prevent obesity. Thermogenic formulations usually contain Synephrine (SN) and Caffeine (CAF), stimulating compounds extracted from natural sources, but no genetic toxicology studies have predicted this hazardous combination potential. This study examined the toxicogenomic responses induced by SN and CAF, either alone or in combination, in the human hepatic cell line HepG2 in vitro. SN (0.03-30 μM) and CAF (0.6-600 μM) alone did neither decrease cell viability nor induce DNA damage, as assessed using the MTT and comet assays, respectively. SN (3 μM) and CAF (30-600 μM) were combined at concentrations similar to those found in commercial dietary supplements. SN/CAF at 3:90 and 3:600 μM ratios significantly decreased cell viability and increased DNA damage levels in HepG2 cells. CAF (600 μM) and the SN/CAF association at 3:60, 3:90, and 3:600 μM ratios promoted cell death by apoptosis, as demonstrated by flow cytometry. Similar results were observed in gene expression (RT-qPCR): SN/CAF up-regulated the expression of apoptosis- (BCL-2 and CASP9) and DNA repair-related (XPC) genes. SN/CAF at 3:90 μM also downregulated the expression of cell cycle control (CDKN1A) genes. In conclusion, the SN/CAF combination reduces cell viability by inducing apoptosis, damages DNA, and modulates the transcriptional expression of apoptosis-, cell cycle-, and DNA repair-related genes in human hepatic (HepG2) cells in vitro. These effects can be worrisome to consumers of thermogenic supplements.

The levels of bioactive ingredients in Citrus aurantium L. at different harvest periods and antioxidant effects on H2 O2 -induced RIN-m5F cells

BACKGROUND

Citrus aurantium L. (Aurantii fructus) is a multi-purpose citrus fruit with high medicinal and nutritional value, but currently there are no data that can be used to investigate the appropriate harvest time to obtain high-quality citrus bioactive ingredients from it.

RESULTS

Phytochemicals and the levels of the main bioactive ingredients were investigated by ultra high performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF/MS). The flavanone, polymethoxyflavone, coumarin, synephrine, and limonin content in the citrus fruit was analyzed at different harvest periods, and significant differences, ranging from 0.03 ± 0.01 to 116.26 ± 40.20 g kg^-1 (DW), were shown. These compounds were present in higher amounts in June and then decreased gradually, while the biomass accumulation of most of them showed an increasing tendency around harvest time. The H₂ O₂ -induced RIN-m5F cells model was employed to evaluate their antioxidant capacity. Citrus fruit harvested from June 11 to July 7 possessed an excellent antioxidant capacity by inhibiting the intensity of intracellular reactive oxygen species (ROS) (P < 0.01) and improving superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH) activity (P < 0.01). The chemical composition and antioxidant capacity of citrus leaves, stems, and roots were also evaluated, and these showed great variation compared with other citrus fruits. Multivariate statistical analysis indicated that harvesting time was related closely to the phytochemical contents and antioxidant capacity.

CONCLUSION

Citrus fruit can be appropriately harvested from June to early July when the levels of bioactive ingredients and antioxidant activity reach higher values. This research provides practical information for producing high-quality citrus products. © 2020 Society of Chemical Industry.

p-synephrine induces transcriptional changes via the cAMP/PKA pathway but not cytotoxicity or mutagenicity in human gastrointestinal cells

p-Synephrine (SN) is an alkaloid added to thermogenic formulations for weight loss that is predominantly absorbed in the human gastrointestinal tract (GI). As the adverse effects of SN on GI cells remain unclear, the aim of present study was to examine whether SN affected cell viability, cell cycle kinetics, genomic stability, redox status, and expression of cAMP/PKA pathway genes related to metabolism/energy homeostasis in stomach mucosa (MNP01) and colon adenocarcinoma (Caco-2) human cells. p-Synephrine at 25-5000 μM was not cytotoxic to both cell lines. At 2-200 μM, SN increased the formation of reactive oxygen species (ROS) but also enhanced levels of antioxidant defense molecules glutathione (GSH) and catalase (CAT) activity, which may account for the absence of cytotoxicity/mutagenicity in both cell lines. SN induced expression of the cAMP/PKA pathway genes ADCY3 and MAPK1 in MNP01 cells and MAPK1, GNAS, PRKACA, and PRKAR2A in Caco-2 cells, as well as modulated the transcription of genes related to cell proliferation (JUN; AKT1) and inflammation (RELA; TNF) in both cell lines. Therefore, the improved antioxidant state mitigated pro-oxidative effects attributed to SN. Evidence indicates that SN does not appear to exhibit adverse potential but modulated the cAMP/PKA pathway in human GI cell lines.