Transcriptome analysis of Citrus Aurantium L. to study synephrine biosynthesis during developmental stages.

Citrus aurantium L., sometimes known as "sour orange," is an important Chinese herb with young, immature fruits, or "zhishi," that are high in synephrine. Synephrine is a commonly utilized natural chemical with promising applications in effectively increasing metabolism, heat expenditure, energy level, oxidative fat, and weight loss. However, little is known about the genes and pathways involved in synephrine production during the critical developmental stages of C. aurantium L., which limits the development of the industry. According to this study, the concentration of synephrine gradually decreased as the fruit developed. Transcriptome sequencing was used to examine the DEGs associated with synephrine connections and served as the foundation for creating synephrine-rich C. aurantium L. Comparisons conducted between different developmental stages to obtain DEGs, and the number of DEGs varied from 690 to 3,019. Tyrosine and tryptophan biosynthesis, glycolysis/gluconeogenesis, pentose phosphate pathway, phenylalanine, and tyrosine metabolism were the main KEGG pathways that were substantially enriched. The results showed that 25 genes among these KEGG pathways may be related to synephrine synthesis. The WGCNA and one-way ANOVA analysis adoption variance across the groups suggested that 11 genes might play a crucial role in synephrine synthesis and should therefore be further analyzed. We also selected six DEGs at random and analyzed their expression levels by RT-qPCR, and high repeatability and reliability were demonstrated by our finished RNA-seq study results. These results may be useful in selecting or modifying genes to increase the quantity of synephrine in sour oranges.

[Quality identification of Aurantii Fructus Immaturus from different origins and their adulterants].

Aurantii Fructus Immaturus(AFI) is a traditional Chinese herbal medicine with multiple origins from Citrus aurantium and its legally cultivated variants. With advancements in agricultural biotechnology, many new cultivated varieties have sprung up,leading to an abundance of AFI adulterants and chaos in the herbal medicine markets. This study developed a specific identification method for AFI and its closely related adulterants by examining the appearance trait, content of extract, and multiple ingredients,involving indicators such as the ratio of pulp capsule to cross section diameter(Pc/Cs ratio), the content of extract, and the profile of 11 ingredients. The research finds that:(1) Pc/Cs ratio can conveniently identify adulterants such as Poncirus trifoliata, Ju, and Babagan from the genuine AFI.(2) The extract content can be used to identify adulterants originated from C. wilsonii with C. aurantium.(3) The contents of synephrine in all the samples were in accordance with the Chinese Pharmacopoeia except for the adulterants from P. trifoliata, C. wilsonii, C. aurantium 'Changshanhuyou' and orah mandarins. The synephrine content was high as 1. 40% in some C. sinensis varieties. The mass fraction of hesperidin was over 10. 00% in C. sinensis, while it was below 2. 50% in C. aurantium. C. aurantium contained high levels of naringin(3. 96%-15. 21%) and neo-hesperidin(9. 38%-21. 93%).(4) The compositions of adulterants from P. trifoliata and C. wilsonii were more similar to that of C. aurantium 'Daidai', but with significantly lower neo-hesperidin content(0. 03%-0. 14%) than that in C. aurantium, and they lacked hesperetin and tangeretin. C. maxima(originating from C. maxima) showed closer composition to Choucheng and hybrid originated from Citrus aurantium × Poncirus trifoliata, but had higher hesperidin content(3. 13%) than that in C. aurantium. Ju was closely related to C. sinensis and neither contained naringin nor neo-hesperidin. Hesperidins in Babagan and orah mandarins were similar to that in C. sinensis, with none containing rhoifolin. These quality indicators in combination can accurately distinguish between C. sinensis, C. aurantium, and their closely related adulterants(P. trifoliata, C. wilsonii, C. maxima, orah mandarins and C. reticulata), which are expected to provide a systematic method for quality control of AFI.

Application of Synephrine to Grape Increases Anthocyanin via Production of Hydrogen Peroxide, Not Phytohormones.

Global warming has caused such problems as the poor coloration of grape skin and the decreased production of high-quality berries. We investigated the effect of synephrine (Syn) on anthocyanin accumulation. Anthocyanin accumulation in cultured grape cells treated with Syn at concentrations of 1 mM or higher showed no significant difference, indicating that the accumulation was concentration-independent. On the other hand, anthocyanin accumulation was dependent on the compound used for treatment. The sugar/acid ratio of the juice from berries treated with Syn did not differ from the control. The expression of anthocyanin-biosynthesis-related genes, but not phytohormones, was increased by the treatment with Syn at 24 h or later. The Syn treatment of cultured cells increased SOD3 expression and hydrogen peroxide (H2O2) production from 3 to 24 h after treatment. Subsequently, the expression of CAT and APX6 encoding H2O2-scavenging enzymes was also increased. Treatment of cultured cells with Syn and H2O2 increased the expression of the H2O2-responsive gene Chit4 and the anthocyanin-biosynthesis-related genes mybA1 and UFGT 4 days after the treatment and increased anthocyanin accumulation 7 days after the treatment. On the other hand, the treatment of berries with Syn and H2O2 increased anthocyanin accumulation after 9 days. These results suggest that Syn increases anthocyanin accumulation through H2O2 production without changing phytohormone biosynthesis. Syn is expected to improve grape skin coloration and contribute to high-quality berry production.

Rapid analysis of bioactive compounds from citrus samples by direct analysis in real-time mass spectrometry combined with chemometrics.

Renowned for their nutritional benefits, citrus fruits are harvested at various stages in China for functional food production. This study introduces an innovative analytical method, DART-MS, enabling direct qualitative analysis of citrus samples without the need for preprocessing. Simultaneously, the combination of chemometrics can be applied to distinguish between three different citrus samples: Citri Reticulatae Pericarpium, Citri Reticulatae Pericarpium Viride, and Citri Reticulatae "Chachi". Notably, given the international regulatory concerns surrounding synephrine, a precise quantitative analysis method for synephrine was developed. The limit of detection (LOD) and the limit of quantification (LOQ) were 39 ng mL-1 and 156 ng mL-1, respectively. The recovery rates obtained varied from 98.46% to 100.71%. Furthermore, the intra-day and inter-day precision demonstrated robust consistency, with values spanning 5.0-6.1% and 5.03-6.08%, respectively, offering quicker results compared to those from HPLC-MS, promising a safer assessment of herbal and food products.

Establishing an Artificial Pathway for the Biosynthesis of Octopamine and Synephrine.

In this study, we designed an artificial pathway composed of tyramine ß-hydroxylase (TBH) and phenylethanolamine N-methyltransferase (PNMT) for the biosynthesis of both octopamine and synephrine. As most TBH and PNMT originate from eukaryotic animals and plants, the heterologous expression and identification of functional TBH and PNMT are critical for establishing the pathway in mode microorganisms like Escherichia coli. Here, three TBHs were evaluated, and only TBH from Drosophila melanogaster was successfully expressed in the soluble form in E. coli. Its expression was promoted by evaluating the effects of different expression strategies. The specific enzyme activity of TBH was optimized up to 229.50 U·g-1, and the first step in the biosynthetic pathway was successfully established and converted tyramine to synthesize 0.10 g/L of octopamine. Furthermore, the second step to produce synephrine from octopamine was developed by screening PNMT, enhancing enzyme activity, and optimizing reaction conditions, with a maximum synephrine production of 2.02 g/L. Finally, based on the optimization of the reaction conditions for each individual reaction, the one-pot cascade reaction for synthesizing synephrine from tyramine was constructed by combining the TBH and PNMT. The synthetic synephrine reached 30.05 mg/L with tyramine as substrate in the two-step enzyme cascade system. With further optimization and amplification, the titers of octopamine and synephrine were increased to 0.45 and 0.20 g/L, respectively, with tyramine as substrate. This work was the first achievement of the biosynthesis of octopamine and synephrine to date.

Scavenging Glyoxal and Methylglyoxal by Synephrine and Neohesperidin from Flowers of Citrus aurantium L. var. amara Engl. in Mice and Humans.

There is considerable research evidence that α-dicarbonyl compounds, including glyoxal (GO) and methylglyoxal (MGO), are closely related to many chronic diseases. In this work, after comparison of the capture capacity, reaction pathway, and reaction rate of synephrine (SYN) and neohesperidin (NEO) on GO/MGO in vitro, experimental mice were administrated with SYN and NEO alone and in combination. Quantitative data from UHPLC-QQQ-MS/MS revealed that SYN/NEO/HES (hesperetin, the metabolite of NEO) could form the GO/MGO-adducts in mice (except SYN-MGO), and the levels of GO/MGO-adducts in mouse urine and fecal samples were dose-dependent. Moreover, SYN and NEO had a synergistic scavenging effect on GO in vivo by promoting each other to form more GO adducts, while SYN could promote NEO to form more MGO-adducts, although it could not form MGO-adducts. Additionally, human experiments showed that the GO/MGO-adducts of SYN/NEO/HES found in mice were also detected in human urine and fecal samples after drinking flowers of Citrus aurantium L. var. amara Engl. (FCAVA) tea using UHPLC-QTOF-MS/MS. These findings provide a novel strategy to reduce endogenous GO/MGO via the consumption of dietary FCAVA rich in SYN and NEO.

Scavenging Glyoxal and Methylglyoxal by Synephrine Alone or in Combination with Neohesperidin at High Temperatures.

α-Dicarbonyl compounds, such as glyoxal (GO) and methylglyoxal (MGO), are a series of chemical hazards that exist in vivo and in vitro, posing a threat to human health. We aimed to explore the scavenging effects on GO/MGO by synephrine (SYN) alone or in combination with neohesperidin (NEO). First, through LC-MS/MS, we confirmed that both SYN and NEO could effectively remove GO and form GO adducts, while NEO could also clear MGO by forming MGO adducts, and its ability to clear MGO was stronger than that of GO. Second, a synergistic inhibitory effect on GO was found when SYN and NEO were used in combination by using the Chou-Talalay method; on the other hand, SYN could promote NEO to clear more MGO, although SYN could not capture MGO. Third, after synthesizing four GO/MGO-adducts (SYN-GO-1, SYN-GO-3, NEO-GO-7, and NEO-MGO-2) and identifying their structure through NMR, strict correlations between the GO/MGO-adducts and the GO/MGO-clearance rate were found when using SYN and NEO alone or in combination. Furthermore, it was inferred that the synergistic effect between SYN and NEO stems from their mutual promotion in capturing more GO by the quantitative analysis of the adducts in the combined model. Finally, a study was conducted on flowers of Citrus aurantium L. var. amara Engl. (FCAVA, an edible tea) rich in SYN and NEO, which could serve as an effective GO and MGO scavenger in the presence of both GO and MGO. Therefore, our study provided well-defined evidence that SYN and NEO, alone or in combination, could efficiently scavenge GO/MGO at high temperatures, whether in the pure form or located in FCAVA.

Metabolites of intestinal fora can be used as diagnostic and progressive markers for mild cognitive impairment.

Purpose: The aim of the work was to analyze the metabolites of the intestinal microbiota from the patients with mild cognitive impairment (MCI) and progressive MCI due to Alzheimer's disease (AD). Method: Two cohorts were established. The first one included 87 subjects with 30 healthy controls (NC), 22 patients with MCI due to AD, and 35 patients with AD. The second cohort included 87 patients with MCI due to AD, who were followed up for 2 years and finally were divided into progressive MCI due to AD group (P-G) and unprogressive MCI due to AD group (U-G) according their cognitive levels. Fecal samples were collected to all patients at the baseline time point. Differential metabolites were subjected to pathway analysis by MetaboAnalyst. Results: In the first cohort, we found 21 different metabolites among the three groups (AD, MCI, and NC). In the second cohort, we identified 19 differential metabolites between the P-G and U-G groups. By machine learning analysis, we found that seven characteristic metabolites [Erythrodiol, alpha-Curcumene, Synephrine, o-Hydroxylaminobenzoate, 3-Amino-4-hydroxybenzoic acid, 2-Deoxystreptamine, and 9(S] were of characteristic significance for the diagnosis of MCI due to AD, and six metabolites (Indolelactate, Indole-3-acetaldehyde, L-Proline, Perillyl, Mesaconate, and Sphingosine) were the characteristic metabolites of early warning for the progression of MCI due to AD. D-Glucuronic acid was negatively correlated with Apolipoprotein E4 (APOE4). Perillyl alcohol was negatively correlated with all of the five biomarkers [P-tau181, Neurofilament light chain (NF-light), Aß1-42, Aß1-40, and glial fibrillary acidic protein (GFAP)], but Indoleacetaldehyde was positively correlated with three biomarkers (P-tau181, Aß1-42, and GFAP). Three characteristic metabolites (3-Amino-4-hydroxybenzoate, 2-Deoxystreptamine, and p-Synephrine) were positively correlated with Aß1-42. 2-Deoxystreptamine, 9(S)-HPOT, and Indoleacetaldehyde were positively correlated with GFAP. L-Proline and Indoleacetaldehyde were positively correlated with NF-light. Conclusion: Specific metabolites of intestinal fora can be used as diagnostic and progressive markers for MCI.

Citrus p-Synephrine Improves Energy Homeostasis by Regulating Amino Acid Metabolism in HFD-Induced Mice.

p-Synephrine is a common alkaloid widely distributed in citrus fruits. However, the effects of p-synephrine on the metabolic profiles of individuals with energy abnormalities are still unclear. In the study, we investigated the effect of p-synephrine on energy homeostasis and metabolic profiles using a high fat diet (HFD)-induced mouse model. We found that p-synephrine inhibited the gain in body weight, liver weight and white adipose tissues weight induced by HFD. p-Synephrine supplementation also reduced levels of serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) but not to a statistically significant degree. Histological analysis showed that HFD induced excessive lipid accumulation and glycogen loss in the liver and adipocyte enlargement in perirenal fat tissue, while p-synephrine supplementation reversed the changes induced by HFD. Moreover, HFD feeding significantly increased mRNA expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) and reduced the mRNA expression level of interleukin-10 (IL-10) compared to the control group, while p-synephrine supplementation significantly reversed these HFD-induced changes. Liver and serum metabolomic analysis showed that p-synephrine supplementation significantly altered small molecule metabolites in liver and serum in HFD mice and that the changes were closely associated with improvement of energy homeostasis. Notably, amino acid metabolism pathways, both in liver and serum samples, were significantly enriched. Our study suggests that p-synephrine improves energy homeostasis probably by regulating amino acid metabolism in HFD mice, which provides a novel insight into the action mechanism of p-synephrine modulating energy homeostasis.

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.