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

de Jonge M.L., Kieviet L.C., Sierts M., Egberink L.B., van der Heyden M.A.

AbstractThe 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.

Wang Y., Lin S., Wang Y., Liang T., Jiang T., Liu P., Li X., Lang D., Liu Q., Shen C.

p-Synephrine has been popularly used as a dietary supplement for weight loss. This study showed that p-synephrine treatment prevented diabetes mellitus by inhibiting oxidative stress and inflammation via suppressing the NF-kappa B and MAPK pathways.

Taheri R., Hamzkanlu N., Rezvani Y., Niroumand S., Samandar F., Amiri-Tehranizadeh Z., Saberi M.R., Chamani J.

• Multi-spectroscopies have proved that p-Synephrine can bind to HSA and increase in a-helix content in the HSA structure. • Molecular docking and molecular dynamic (MD) simulation analysis validated that p -Synephrine tends to bind in HSA's site 1. • Viscosity and ionic strength studies have confirmed that p -Synephrine tends to bind in ctDNA's groove. As a phenolic amine, p -Synephrine (SN) is known to exhibit lipolytic properties as well as enhancing energy expenditure, which can be an excellent alternative to ephedra as a dietary supplement. This study aimed to explore the subtle yet profound complex qualities and aspects of the interaction between SN, human serum albumin (HSA), and calf thymus DNA (ctDNA). To achieve a full comprehension on these fine-point distinctions, a nuanced and detail-oriented approach was implemented through a combination of different biophysical methods and molecular dynamics simulation techniques. The fluorescence spectroscopy revealed the binding of SN to HSA that led to the inducement of conformational changes. The quenching constants (K SV ) of SN-HSA complex at 298, 303, and 308 K and were evaluated to be 2.95 × 10 4 , 2.21 × 10 4 and 0.85×10 4 M -1 , respectively. The thermodynamic parameters indicated the spontaneous formation of SN-HSA complex along with its regulation through H-bonding and van der Waals forces. The distance between SN and Trp residue of HSA was estimated at 3.91 nm by the Forster’s theory of non-radiative resonance energy transfer. According to CD spectroscopy, the binding of SN to HSA results in stabilization and promotes its functionality. Various spectroscopy methods and viscosity measurements proved the propensity of SN for binding to the grooves of ctDNA. Thermodynamic parameters indicate that the SN binds to DNA via a spontaneous and entropy-driven process that is mainly regulated by hydrophobic interactions. In conformity to the molecular modeling of HSA-SN complex, SN can be located in the active site of HSA and make a firm interaction, while the outcomes of ctDNA-SN interaction also indicated its tendency towards binding in DNA groove. In comparison to normal cells, SN caused a more pronounced reduction in lung cancer cell viability by increasing the expression of Bax and p53 at the mRNA and protein levels. Moreover, the incubation of H460 cells with the IC50 concentration of SN induced a notable decease in mRNA levels of PI3K, AKT, and mTOR, as well as protein levels of PI3Kγ-P110, P-AKT, and P-m TOR. These data indicate the potential of SN in binding with HSA, which reduces the proliferation of lung cancer cells mediated by apoptosis through the down regulation of PI3K/AKT/m TOR signaling pathway.

Cacheiro-Llaguno C., Hernández-Subirá E., Díaz-Muñoz M.D., Fresno M., Serrador J.M., Íñiguez M.A.

Cyclooxygenase (COX) is the key enzyme in prostanoid synthesis from arachidonic acid (AA). Two isoforms, named COX-1 and COX-2, are expressed in mammalian tissues. The expression of COX-2 isoform is induced by several stimuli including cytokines and mitogens, and this induction is inhibited by glucocorticoids (GCs). We have previously shown that the transcriptional induction of COX-2 occurs early after T cell receptor (TCR) triggering, suggesting functional implications of this enzyme in T cell activation. Here, we show that dexamethasone (Dex) inhibits nuclear factor of activated T cells (NFAT)-mediated COX-2 transcriptional induction upon T cell activation. This effect is dependent on the presence of the GC receptor (GR), but independent of a functional DNA binding domain, as the activation-deficient GRLS7 mutant was as effective as the wild-type GR in the repression of NFAT-dependent transcription. Dex treatment did not disturb NFAT dephosphorylation, but interfered with activation mediated by the N-terminal transactivation domain (TAD) of NFAT, thus pointing to a negative cross-talk between GR and NFAT at the nuclear level. These results unveil the ability of GCs to interfere with NFAT activation and the induction of pro-inflammatory genes such as COX-2, and explain some of their immunomodulatory properties in activated human T cells.

Zare F., Solhjoo A., Sadeghpour H., Sakhteman A., Dehshahri A.

Glucocorticoids have been used in the treatment of many diseases including inflammatory and autoimmune diseases. Despite the wide therapeutic effects of synthetic glucocorticoids, the use of these compounds has been limited due to side effects such as osteoporosis, immunodeficiency, and hyperglycaemia. To this end, extensive studies have been performed to discover new glucocorticoid modulators with the aim of increasing affinity for the receptor and thus less side effects. In the present work, structure-based virtual screening was used for the identification of novel potent compounds with glucocorticoid effects. The molecules derived from ZINC database were screened on account of structural similarity with some glucocorticoid agonists as the template. Subsequently, molecular docking was performed on 200 selected compounds to obtain the best steroidal and non-steroidal conformations. Three compounds, namely ZINC_000002083318, ZINC_000253697499 and ZINC_000003845653, were selected with the binding energies of -11.5, -10.5, and -9.5 kcal/mol, respectively. Molecular dynamic simulations on superior structures were accomplished with the glucocorticoid receptor. Additionally, root mean square deviations, root mean square fluctuation, radius of gyration, hydrogen bonds, and binding-free energy analysis showed the binding stability of the proposed compounds compared to budesonide as an approved drug. The results demonstrated that all the compounds had suitable binding stability compared to budesonide, while ZINC_000002083318 showed a tighter binding energy compared to the other compounds.Communicated by Ramaswamy H. Sarma.

Zhidkova E.M., Lylova E.S., Grigoreva D.D., Kirsanov K.I., Osipova A.V., Kulikov E.P., Mertsalov S.A., Belitsky G.A., Budunova I., Yakubovskaya M.G., Lesovaya E.A.

Regulated in Development and DNA Damage Response 1 (REDD1)/DNA Damage-Induced Transcript 4 (DDIT4) is an immediate early response gene activated by different stress conditions, including growth factor depletion, hypoxia, DNA damage, and stress hormones, i.e., glucocorticoids. The most known functions of REDD1 are the inhibition of proliferative signaling and the regulation of metabolism via the repression of the central regulator of these processes, the mammalian target of rapamycin (mTOR). The involvement of REDD1 in cell growth, apoptosis, metabolism, and oxidative stress implies its role in various pathological conditions, including cancer and inflammatory diseases. Recently, REDD1 was identified as one of the central genes mechanistically involved in undesirable atrophic effects induced by chronic topical and systemic glucocorticoids widely used for the treatment of blood cancer and inflammatory diseases. In this review, we discuss the role of REDD1 in the regulation of cell signaling and processes in normal and cancer cells, its involvement in the pathogenesis of different diseases, and the approach to safer glucocorticoid receptor (GR)-targeted therapies via a combination of glucocorticoids and REDD1 inhibitors to decrease the adverse atrophogenic effects of these steroids.

Ishida M., Takekuni C., Nishi K., Sugahara T.

p-Synephrine is the primary protoalkaloid found in Citrus species such as Citrus aurantium (bitter orange) and is widely used as a dietary supplement. Although studies have shown the anti-inflammatory effect of p-synephrine, the cells targeted and detailed mechanism(s) of action are not established. Therefore, we investigated the anti-inflammatory effects of p-synephrine and elucidated its underlying mechanisms in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, peritoneal macrophages, and an LPS-induced systemic inflammatory response syndrome (SIRS) mouse model. We found that p-synephrine inhibits the production of proinflammatory cytokines and nitric oxide in LPS-stimulated RAW264.7 cells, and proinflammatory cytokines in primary peritoneal macrophages. This effect of p-synephrine is due to downregulation of the p38 MAPK and NF-κB signaling pathway and is mediated by β-adrenergic receptors. Oral administration of p-synephrine to SIRS mice inhibited the serum levels of proinflammatory cytokines and improved their survival rate. Thus, our findings show that p-synephrine alleviates the hyperinflammatory response in macrophages and a SIRS mouse model.

Kalfeist L., Galland L., Ledys F., Ghiringhelli F., Limagne E., Ladoire S.

Thanks to their anti-inflammatory, anti-oedema, and anti-allergy properties, glucocorticoids are among the most widely prescribed drugs in patients with cancer. The indications for glucocorticoid use are very wide and varied in the context of cancer and include the symptomatic management of cancer-related symptoms (compression, pain, oedema, altered general state) but also prevention or treatment of common side effects of anti-cancer therapies (nausea, allergies, etc.) or immune-related adverse events (irAE). In this review, we first give an overview of the different clinical situations where glucocorticoids are used in oncology. Next, we describe the current state of knowledge regarding the effects of these molecules on immune response, in particular anti-tumour response, and we summarize available data evaluating how these effects may interfere with the efficacy of immunotherapy using immune checkpoint inhibitors.

Lesovaya E.A., Chudakova D., Baida G., Zhidkova E.M., Kirsanov K.I., Yakubovskaya M.G., Budunova I.V.

Glucocorticoids (Gcs) are widely used to treat inflammatory diseases and hematological malignancies, and despite the introduction of novel anti-inflammatory and anti-cancer biologics, the use of inexpensive and effective Gcs is expected to grow. Unfortunately, chronic treatment with Gcs results in multiple atrophic and metabolic side effects. Thus, the search for safer glucocorticoid receptor (GR)-targeted therapies that preserve therapeutic potential of Gcs but result in fewer adverse effects remains highly relevant. Development of selective GR agonists/modulators (SEGRAM) with reduced side effects, based on the concept of dissociation of GR transactivation and transrepression functions, resulted in limited success, and currently focus has shifted towards partial GR agonists. Additional approach is the identification and inhibition of genes associated with Gcs specific side effects. Others and we recently identified GR target genes REDD1 and FKBP51 as key mediators of Gcs-induced atrophy, and selected and validated candidate molecules for REDD1 blockage including PI3K/Akt/mTOR inhibitors. In this review, we summarized classic and contemporary approaches to safer GR-mediated therapies including unique concept of Gcs combination with REDD1 inhibitors. We discussed protective effects of REDD1 inhibitors against Gcs–induced atrophy in skin and bone and underlined the translational potential of this combination for further development of safer and effective Gcs-based therapies.

Ziemichod W., Gibula-Tarlowska E., Kotlinska J.H., Grochecki P., Kedzierska E.

Abstract There is a number of diseases for which, scientists are constantly looking for a promising new treatments. Isolation of novel substances with biological activity from plants gives hope for its use in treatment. In this review, we focused on the biological activity of p-synephrine (4-(2-aminoethyl)phenol) which was previously confirmed during both in vitro and in vivo tests. The main part of the review is dedicated to the anti-obesity activity of p-synephrine, as obesity is a disease of contemporary civilization. However, synephrine also possesses anti-diabetic, anti-inflammatory and antidepressant activity and it is confirmed to be a hypotensive agent in portal hypertension. The review also emphasize that, based on current knowledge, the use of p-synephrine appears to be exceedingly safe with only limited range of side effects. Therefore, it seems that this substance may be of great importance in the pharmacotherapy of many disease states and further research is necessary.

Lanshakov D.A., Sukhareva E.V., Bulygina V.V., Lagunov T.A., Kalinina T.S.

Koh A.H., Chess‐Williams R., Lohning A.E.

Multi-ingredient pre-workout supplements (MIPS) contain Citrus aurantium as a source of bioactive amines such as p-synephrine, but concerns regarding the authenticity of ingredients in some supplements as well as adverse effects from consumption have been raised. R-(-)-Synephrine is the predominant enantiomer in Citrus aurantium extracts while synthetic preparations are often racemic. The aims of this study were to develop a screening method to determine the ratio of synephrine enantiomers in pre-workout supplements listing Citrus aurantium and to assess the ingredient authenticity by directly comparing their ratios to that found in Citrus aurantium standardised reference materials (SRMs). Quantification of enantiomers in the supplements and SRMs was achieved using a validated, high-performance liquid chromatography-single quadrupole mass spectrometry (HPLC-UV-QDa) direct enantioseparation method with a cellobiohydrolase (CBH) column (100 × 4.0 mm, 5 μM) and UV detection at 225 nm. Citrus aurantium SRMs were found to have an average enantiomeric ratio of 94:6 (R:S) with total synephrine ranging from 5.7 to 90.2 mg/g. Within the pilot sample of pre-workout supplements tested, only 42% (5/12) had enantiomeric ratios consistent with the SRMs with total synephrine ranging from 0.03 to 91.2 mg/g. For the remaining supplements, four had racemic ratios of synephrine (0.14 to 5.4 mg/g), two lacked any detectable levels of synephrine, and one had solely the S-(+)-enantiomer (0.15 mg/g). These results bring the authenticity of labelling of some pre-workout supplements into question and highlight the need for more stringent labelling regulations and testing for dietary supplements.

Ippolito M., Benovic J.L.

The β-adrenergic receptors (βARs) include three subtypes, β 1 , β 2 and β 3 . These receptors are widely expressed and regulate numerous physiological processes including cardiovascular and metabolic functions and airway tone. The βARs are also important targets in the treatment of many diseases including hypertension, heart failure and asthma. In some cases, the use of current βAR ligands to treat a disease is suboptimal and can lead to severe side effects. One strategy to potentially improve such treatments is the development of biased agonists that selectively regulate a subset of βAR signaling pathways and responses. Here we discuss the compounds identified to date that preferentially activate a G s - or β-arrestin-mediated signaling pathway through βARs. Mechanistic insight on how these compounds bias signaling sheds light on the potential development of even more selective compounds that should have increased utility in treating disease. • G protein and β-arrestin biased agonists have been characterized for the βARs. • Biased β-agonists may improve clinical outcomes compared to balanced β-agonists. • TM VII / ECL movements and GRK interaction are implicated in bias mechanism. • Biased drug discovery efforts and experimental design require careful consideration.

Ramirez-Virella J., Leinninger G.M.

Abstract The small peptide neurotensin (Nts) is implicated in myriad processes including analgesia, thermoregulation, reward, arousal, blood pressure, and modulation of feeding and body weight. Alterations in Nts have recently been described in individuals with obesity or eating disorders, suggesting that disrupted Nts signaling may contribute to body weight disturbance. Curiously, Nts mediates seemingly opposing regulation of body weight via different tissues. Peripherally acting Nts promotes fat absorption and weight gain, whereas central Nts signaling suppresses feeding and weight gain. Thus, because Nts is pleiotropic, a location-based approach must be used to understand its contributions to disordered body weight and whether the Nts system might be leveraged to improve metabolic health. Here we review the role of Nts signaling in the brain to understand the sites, receptors, and mechanisms by which Nts can promote behaviors that modify body weight. New techniques permitting site-specific modulation of Nts and Nts receptor–expressing cells suggest that, even in the brain, not all Nts circuitry exerts the same function. Intriguingly, there may be dedicated brain regions and circuits via which Nts specifically suppresses feeding behavior and weight gain vs other Nts-attributed physiology. Defining the central mechanisms by which Nts signaling modifies body weight may suggest strategies to correct disrupted energy balance, as needed to address overweight, obesity, and eating disorders.

Ruiz-Moreno C., Del Coso J., Giráldez-Costas V., González-García J., Gutiérrez-Hellín J.

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 (VO2peak). 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.

Hu H., Pradhan N., Xiao J., Xia R., Liao P.

Abstract Fleshy fruits are popular among consumers due to their significant nutritional value, which includes essential bioactive compounds such as pigments, vitamins, and minerals. Notably, plant-derived pigments are generally considered safe and reliable, helping to protect humans against various inflammatory diseases. Although the phytochemical diversity and their biological activities have been extensively reviewed and summarized, the status of bioactive nutrients in fleshy fruits, particularly with a focusing on different colors, has received less attention. Therefore, this review introduces five common types of fleshy fruits based on coloration and summarizes their major bioactive compounds. It also provides the latest advancements on the function, biosynthesis, and metabolic engineering of plant-derived pigments. In this review, we emphasize that promoting the consumption of a diverse array of colorful fruits can contribute to a balanced diet; however, optimal intake levels still require further clinical validation. This review may serve as a useful guide for decisions that enhance the understanding of natural pigments and accelerate their application in agriculture and medicine.

Abe H., Indo H.P., Ito H., Majima H.J., Tanaka T.

Abstract Synephrine, a protoalkaloid found in Citrus aurantium (CA) peels, exerts lipolytic, anti-inflammatory, and vasoconstrictive effects; however, its antioxidant activity remains unclear. In this study, electron spin resonance spectroscopy revealed that synephrine scavenged both hydroxyl and superoxide anion radicals. Several external stimuli, such as H2O2, X-rays, and ultraviolet (UV) radiation, cause stress-induced premature senescence (SIPS). As oxidative stress induces SIPS, we hypothesized that synephrine, an antioxidant, would suppress H2O2-induced premature senescence in WI-38 cells. Synephrine significantly decreased the reactive oxygen species levels induced by H2O2, thereby reducing lipid peroxidation, and oxidative DNA damage and preventing SIPS. Additionally, synephrine inhibited mitochondrial dysfunction in H2O2-treated WI-38 cells. The expression levels of p53, p21, and p16-INK4A, which are involved in the induction of cell cycle arrest in SIPS, were significantly lower in synephrine-treated cells than in untreated cells. Our results indicate that synephrine inhibits H2O2-induced oxidative stress and mitochondrial dysfunction, suppressing premature senescence by inhibiting activation of the p53–p21 and p16-INK4A–pRB pathways.

Song Z., Xu J., Tian J., Deng J., Deng X., Peng M., Luo W., Wei M., Li Y., Zheng G.

Wang X.X., Ji X., Lin J., Wong I.N., Lo H.H., Wang J., Qu L., Wong V.K., Chung S.K., Law B.Y.

G protein-coupled receptors (GPCRs), widely expressed in the human central nervous system (CNS), perform numerous physiological functions and play a significant role in the pathogenesis of diseases. Consequently, identifying key therapeutic GPCRs targets for CNS-related diseases is garnering immense interest in research labs and pharmaceutical companies. However, using GPCRs drugs for treating neurodegenerative diseases has limitations, including side effects and uncertain effective time frame. Recognizing the rich history of herbal treatments for neurological disorders like stroke, Alzheimer's disease (AD), and Parkinson's disease (PD), modern pharmacological research is now focusing on the understanding of the efficacy of traditional Chinese medicinal herbs and compounds in modulating GPCRs and treatment of neurodegenerative conditions. This paper will offer a comprehensive, critical review of how certain natural products and compounds target GPCRs to treat neurological diseases. Conducting an in-depth study of herbal remedies and their efficacies against CNS-related disorders through GPCRs targeting will augment our strategies for treating neurological disorders. This will not only broaden our understanding of effective therapeutic methodologies but also identify the root causes of altered GPCRs signaling in the context of pathophysiological mechanisms in neurological diseases. Moreover, it would be informative for the creation of safer and more effective GPCR-mediated drugs, thereby establishing a foundation for future treatment of various neurological diseases.