Zanthoxylum alkylamides activate phosphorylated AMPK and ameliorate glycolipid metabolism in the streptozotocin-induced diabetic rats

Comprehensive review of the phytochemistry, pharmacology, pharmacokinetics, and toxicology of alkamides (2016-2022)

Alkamides refer to a class of natural active small-molecule products composed of fatty acids and amine groups. These compounds are widely distributed in plants, and their unique structures and various pharmacological activities have caught the attention of scholars. This review provides a collection of literatures related to the phytochemistry, pharmacological effects, pharmacokinetics, and toxicity of alkamides published in 2016-2022 and their summary to provide references for further development of this class of ingredients. A total of 234 components (including chiral isomers) were summarized, pharmacological activities, such as anti-inflammatory, antitumor, antidiabetic, analgesic, neuroprotective, insecticidal, antioxidant, and antibacterial, and miscellaneous properties of alkamides were discussed. In addition, the pharmacokinetic characteristics and toxicity of alkamides were reviewed. However, information on the pharmacological mechanisms of the action, drug safety, and pharmacokinetics of alkamides is limited and thus requires further investigation and evaluation.

Hydroxy-α-sanshool isolated from Zanthoxylum bungeanum Maxim. has antidiabetic effects on high-fat-fed and streptozotocin-treated mice via increasing glycogen synthesis by regulation of PI3K/Akt/GSK-3β/GS signaling

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease characterized by hyperglycemia. The fruits of Zanthoxylum bungeanum Maxim. is a common spice and herbal medicine in China, and hydroxy-α-sanshool (HAS) is the most abundant amide in Z. bungeanum and reported to have significant hypoglycemic effects. The purpose of this study was to evaluate the ameliorative effects of HAS on T2DM and the potential mechanisms responsible for those effects. An acute toxicity test revealed the median lethal dose (LD50) of HAS is 73 mg/kg. C57BL/6 J mice were fed a high-fat diet and given an intraperitoneal injection of streptozotocin (STZ) to induce T2DM in mice to evaluate the hypoglycemic effects of HAS. The results showed that HAS significantly reduced fasting blood glucose, reduced pathological changes in the liver and pancreas, and increased liver glycogen content. In addition, glucosamine (GlcN)-induced HepG2 cells were used to establish an insulin resistance cell model and explore the molecular mechanisms of HAS activity. The results demonstrated that HAS significantly increases glucose uptake and glycogen synthesis in HepG2 cells and activates the PI3K/Akt pathway in GlcN-induced cells, as well as increases GSK-3β phosphorylation, suppresses phosphorylation of glycogen synthase (GS) and increases glycogen synthesis in liver cells. Furthermore, these effects of HAS were blocked by the PI3K inhibitor LY294002. The results of our study suggest that HAS reduces hepatic insulin resistance and increases hepatic glycogen synthesis by activating the PI3K/Akt/GSK-3β/GS signaling pathway.

Functional validation of ZbFAD2 and ZbFAD3 in the alkylamide biosynthesis pathway from Zanthoxylum bungeanum Maxim

The spicy taste and medicinal properties of Zanthoxylum bungeanum are imparted by several alkylamides. Although most studies have focused on their isolation and identification, few have reported their biosynthesis pathways. Among the differentially expressed genes (DEGs) reported in the numerous varieties of Z. bungeanum, some might contribute to alkylamide biosynthesis. However, they are not yet functionally validated. The present study explored the function of two genes, ZbFAD2 and ZbFAD3, in the alkylamide biosynthesis pathway, and their stable and transient expression in Arabidopsis thaliana and Nicotiana benthamiana were also analyzed. As compared with the wild-type (WT), the fatty acid content analysis indicated that ZbFAD2-A. thaliana transgenic seeds had lower oleic acid and higher linoleic acid contents, while the ZbFAD3-A. thaliana transgenic seeds showed lower linoleic acid and higher α-linolenic acid levels. Moreover, hydroxy-α-sanshool, a major alkylamide, was considerably higher in the ZbFAD2-N. benthamiana transgenic plants (0.2167 ± 0.0026 mg/g) than in the WT (0.0875 ± 0.0049 mg/g), while it was lower in the ZbFAD3-N. benthamiana transgenic plants (0.0535 ± 0.0037 mg/g). These results suggest that both ZbFAD2 and ZbFAD3 are vital alkylamide biosynthesis enzymes in Z. bungeanum. Our study not only helps to scale up the alkylamide production, but also establishes the role of the uncharacterized genes.

Effects of Hydroxy-Alpha-Sanshool on Intestinal Metabolism in Insulin-Resistant Mice

To explore the hydroxy-alpha-sanshool (HAS) effects on the intestinal metabolites of insulin-resistant mice, the blank group (BG), model group (MG), and HAS dose group (DG) were designed. The insulin resistance (IR) model was induced through streptozotocin (STZ) combined with a high-fat and high-sugar diet. Based on the availability of the model, the HAS dose was given by gavage for 28 days. The determination of cecum and key serum indexes was made, including the contents of insulin (INS), triglycerides (TG), total cholesterol (TC), glycosylated serum protein (GSP), and glycosylated hemoglobin (GHb). The changes in gut microbiota and metabolites in cecal contents were detected by 16S rRNA gene amplicon sequencing and UPLC/HRMS technology, respectively. The results that the levels of GSP, GHb, TG, and TC were significantly increased; this was not the case for INS; or for the changes in the gut microbiota and metabolites in MG. However, the intervention of HAS effectively reversed these changes, for instance, it decreased levels of GSP, GHb, TG, TC, and alterations of metabolite composition for linoleic acid and tyrosine metabolism and recovered trends of declining species diversity and richness of the gut microbiota in MG. It was indicated that HAS alleviated IR by regulating the gut microbiota and metabolites and affecting lipid and amino acid metabolism pathways.

Rubusoside Reduces Blood Glucose and Inhibits Oxidative Stress by Activating the AMPK Signaling Pathway in Type 2 Diabetes Mellitus Mice

The current study aimed at investigating the therapeutic effects of rubusoside on type 2 diabetes mellitus (T2DM) mice models as an alternative hypoglycemic candidate drug. T2DM mice models were established with a combination of streptozotocin (STZ) intraperitoneal injection and high-fat diet. After 10 weeks of rubusoside intragastric administration (100, 200 mg/kg/day) to the mice, the body weight, fasting blood glucose, glucose tolerance, and blood lipids were measured. The liver protein expression levels of p-AMPK, GLUT2, GLUT4 and total antioxidant capacity were also investigated.

After 10 weeks of rubusoside administration, the levels of blood glucose and lipids were decreased in T2DM mice. Compared with the model group, rubusoside administration significantly decreased the liver mass-to-body weight ratio, upregulated p-AMPK and GLUT4, and downregulated GLUT2 expression levels in the liver. Activities of superoxide dismutase (SOD), catalase (CAT), and gluathione peroxidase (GSH-Px) were increased, and the concentration of malondialdehyde (MDA) was decreased to reduce oxidative stress in the liver. Liver hematoxylin and eosin (H&E) pathological analysis also showed that rubusoside had a protective effect on T2DM mice liver.

These results demonstrate that rubusoside could be used as an anti-diabetic candidate drug, and that its hypoglycemic mechanism might be related to the activation of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) to modulate the expression of GLUT2 and GLUT4. Finally, rubusoside could also increase total antioxidant capacity to protect the liver from oxidative stress.

Physicochemical Characterization of a Polysaccharide from Green Microalga Chlorella pyrenoidosa and Its Hypolipidemic Activity via Gut Microbiota Regulation in Rats

A bioactive polysaccharide from microalga Chlorella pyrenoidosa (CPP) was successively prepared via DEAE-52 and G-100 columns. Nuclear magnetic resonance analysis showed that the main glycosidic bonds were composed of 1,2-linked-α-l-Fucp, 1,4-linked-α-l-Rhap, 1,4-linked-β-l-Araf, 1-linked-α-d-Glcp, 1,3-linked-β-d-GlcpA, 1,4-linked-β-d-Xylp, and 1,3,6-linked-β-d-Manp. Its molecular weight was 5.63 × 10⁶ Da. The hypolipidemic effect and intestinal flora regulation of CPP on diet-induced rats were evaluated through histopathology and biochemistry analyses. CPP could improve plasma and liver lipid metabolism and accelerate the metabolism of the cecal total bile acids and short-chain fatty acids. CPP has also upregulated the adenosine-monophosphate-activated protein kinase α and downregulated the acetyl-CoA carboxylase, sterol regulatory element-binding protein 1c, and β-hydroxy β-methylglutaryl-CoA expressions. Moreover, with the 16S rRNA gene sequencing, it was revealed that the composition of intestinal flora changed drastically after treatment, such as the bloom of Coprococcus_1, Lactobacillus, and Turicibacter, whereas there was a strong reduction of the [Ruminococcus]_gauvreauii_group. The above results illustrated that CPP might be served as an effective ingredient to ameliorate lipid metabolism disorders and intestinal flora in hyperlipidemia rats.

Activation of AMPK by Medicinal Plants and Natural Products: Its Role in Type 2 Diabetes Mellitus

Type-2 Diabetes (T2D) is a metabolic disease characterized by permanent hyperglycemia, whose development can be prevented or delayed by using therapeutic agents and implementing lifestyle changes. Some therapeutic alternatives include regulation of glycemia through modulation of different mediators and enzymes, such as AMP-activated protein kinase (AMPK), a highly relevant cellular energy sensor for metabolic homeostasis regulation, with particular relevance in the modulation of liver and muscle insulin sensitivity. This makes it a potential therapeutic target for antidiabetic drugs. In fact, some of them are standard drugs used for treatment of T2D, such as biguanides and thiazolidindiones. In this review, we compile the principal natural products that are activators of AMPK and their effect on glucose metabolism, which could make them candidates as future antidiabetic agents. Phenolics such as flavonoids and resveratrol, alkaloids such as berberine, and some saponins are potential natural activators of AMPK with a potential future as antidiabetic drugs.

Genetic polymorphisms of melatonin receptors 1A and 1B may result in disordered lipid metabolism in obese patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a condition in which a woman's levels of the sex hormones (estrogen and progesterone) are out of balance, leading to the growth of ovarian cysts. PCOS can affect the menstrual cycle, fertility, cardiac function and even appearance of women. Therefore, we aimed to explore the genetic polymorphism of the melatonin receptors 1A and 1B in obese patients with PCOS to identify a new theoretical basis for its treatment. Patients presenting with PCOS (n=359) were enrolled and classified into an obese OB-PCOS group [body mass index (BMI) of PCOS patients ≥25 kg/m²] or a nonobese NOB-PCOS group, and 215 oviduct infertile patients who experienced normal ovulation were used as the control group. All baseline characteristics, endocrine hormone levels, lipid and glucose metabolism, and insulin indices were measured. The genotypes of rs2119882 within the MTNR1A gene and of rs10830963 within the MTNR1B gene were determined by PCR-RFLP; the genotype frequency and the difference in the distribution of allele frequency were compared. For rs2119882, C allele carriers who were not diagnosed with PCOS had an increased risk of developing PCOS, and C allele carriers with PCOS had an increased risk of developing OB-PCOS. For rs10830963, G allele carriers who were not diagnosed with PCOS had an increased risk of developing PCOS. The TT genotype in rs2119882 and the CC genotype in rs10830963 were protective factors for OB-PCOS, and increased levels of LH, testosterone, and estradiol and abnormal menstruation were key risk factors for PCOS. Furthermore, the TT genotype at the rs2119882 site was the key protective factor for OB-PCOS patients. Our study found that MTNR1A rs2119882 and MTNR1B rs10830963 could increase the risk for PCOS and cause glycolipid metabolism disorder in PCOS patients.

Polyunsaturated fatty acid amides from the Zanthoxylum genus – from culinary curiosities to probes for chemical biology

A critical and comprehensive review of the discovery, synthesis, and biological activities of alkamides isolated from Zanthoxylum plants and synthetic derivatives thereof.