Triterpenoids-Enriched Extract from the Aerial Parts ofSalvia miltiorrhizaRegulates Macrophage Polarization and Ameliorates Insulin Resistance in High-Fat Fed Mice

Recent advances of traditional Chinese medicine for the prevention and treatment of atherosclerosis

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS) is a common systemic disease with increasing morbidity and mortality worldwide. Traditional Chinese medicine (TCM) with characteristics of multiple pathways and targets, presents advantages in the diagnosis and treatment of atherosclerosis.

AIM OF THE STUDY

With the modernization of TCM, the active ingredients and molecular mechanisms of TCM for AS treatment have been gradually revealed. Therefore, it is necessary to examine the existing studies on TCM therapies aimed at regulating AS over the past two decades.

MATERIALS AND METHODS

Using "atherosclerosis" and "Traditional Chinese medicine" as keywords, all relevant TCM literature published in the last 10 years was collected from electronic databases (such as Elsevier, Springer, PubMed, CNKI, and Web of Science), books and papers until March 2022, and the critical information was statistically analyzed.

RESULTS

In this review, we highlighted extracts of 8 single herbs, a total of 41 single active ingredients, 20 TCM formulae, and 25 patented drugs, which were described with chemical structure, source, model, efficacy and potential mechanism.

CONCLUSION

We summarized the cytopathological basis for the development of atherosclerosis involving vascular endothelial cells, macrophages and vascular smooth muscle cells, and categorically elaborated the medicinal TCM used for AS, all of which provide the current evidence on the better management of atherosclerosis by TCM.

Recent advancement on development of drug-induced macrophage polarization in control of human diseases

Macrophages, an important part of human immune system, possess a high plasticity and heterogeneity (macrophage polarization) as classically activated macrophages (M1) and alternatively activated macrophages (M2), which exert pro-inflammatory/anti-tumor and anti-inflammatory/pro-tumor effects, respectively. Thus, drug development in induction of macrophage polarization could be used to treat different human diseases. This review summarizes the recent advancement on modulation of macrophage polarization and its related molecular mechanisms induced by a number of agents. Research on the anti-inflammatory drugs to regulate the macrophage polarization accounts for a large proportion in the field and types of diseases investigated could include atherosclerosis, enteritis, nephritis, and the nervous system and skeletal diseases, while study of the anti-tumor agents to modify macrophage polarization is a novel area of research. Future study of the molecular mechanisms by which the different agents regulate the macrophage polarization could lead to an effective control of various human diseases, including inflammation and cancers.

The Metaflammatory and Immunometabolic Role of Macrophages and Microglia in Diabetic Retinopathy

Emergent studies reveal the roles of inflammatory cells and cytokines in the development of diabetic retinopathy (DR), which is gradually portrayed as a chronic inflammatory disease accompanied by metabolic disorder. Through the pathogenesis of DR, macrophages or microglia play a critical role in the inflammation, neovascularization, and neurodegeneration of the retina. Conventionally, macrophages are generally divided into M1 and M2 phenotypes which mainly rely on glycolysis and oxidative phosphorylation, respectively. Recently, studies have found that nutrients (including glucose and lipids) and metabolites (such as lactate), can not only provide energy for cells, but also act as signaling molecules to regulate the function and fate of cells. In this review, we discussed the intrinsic correlations among the metabolic status, polarization, and function of macrophage/microglia in DR. Hyperglycemia and hyperlipidemia could induce M1-like and M2-like macrophages polarization in different phases of DR. Targeting the regulation of microglial metabolic profile might be a promising therapeutic strategy to modulate the polarization and function of macrophages/microglia, thus attenuating the progression of DR.

Salvia miltiorrhiza in diabetes: A review of its pharmacology, phytochemistry, and safety

BACKGROUND

Salvia miltiorrhiza (SM), one of the frequently used herbs in traditional Chinese medicine (TCM), has now attracted rising interests for a possible alternative in the management of diabetes. This review is aimed to providing a comprehensive perspective of SM in phytochemical constituents, pharmacological activities against diabetes and its complications, and safety.

METHODS

A comprehensive search of published literatures was conducted to locate original publications pertaining to SM and diabetes till the end of 2017 using PubMed, China National Knowledge Infrastructure, National Science and Technology Library, China Science and Technology Journal Database, and Web of Science database. The main inquiry was used for the presence of the following keywords in various combinations in the titles and abstracts: Salvia miltiorrhiza, diabetes, obesity, phytochemistry, pharmacology, and safety. About 200 research papers and reviews were consulted.

RESULTS

SM exhibited anti-diabetic activities by treating macro- and micro-vascular diseases in preclinical experiments and clinical trials through an improvement of redox homeostasis and inhibition of apoptosis and inflammation via the regulation of Wnt/β-catenin, TSP-1/TGF-β1/STAT3, JNK/PI3K/Akt, kinin B2 receptor-Akt-GSK-3β, AMPKβ/PGC-1α/Sirt3, Akt/AMPK, TXNIP/NLRP3, TGF-β1/NF-κB, mineralocorticoid receptor/Na⁺/K⁺-ATPase, AGEs/RAGE, Nrf2/Keap1, CaMKKβ/AMPK, AMPK/ACC, IRS-1/PI3K signaling pathways, and modulation of K⁺-Ca²⁺ channels, as well as influence of VEGF, NOS, AGEs, PPAR expression and hIAPP aggregation. The antidiabetic effects of this herb may be related to its TCM characters of improving blood circulation and reliving blood stasis. The main ingredients of SM included salvianolic acids and diterpenoid tanshinones, which have been well studied in the diabetic animals. Acute and subacute toxicity studies supported the notion that SM is well tolerated.

CONCLUSION

SM may offer a new strategy for prevention and treatment of diabetes and its complications that stimulates extensive research into identifying potential anti-diabetic compounds and fractions as well as exploring the underlying mechanisms of this herb. Further scientific evidences are still required from well-designed preclinical experiments and clinical trials on its anti-diabetic effects and safety.

Dioscin attenuates high‑fat diet‑induced insulin resistance of adipose tissue through the IRS‑1/PI3K/Akt signaling pathway

Insulin resistance, as a common metabolic disorder, may be caused by diet‑induced obesity. The aim of the present study is to investigate the effects of dioscin on regulating insulin resistance of adipose tissue induced by a high‑fat diet (HFD). An animal model was established successfully using C57BL/6J mice with high‑fat feeding, followed by treatment with 5, 10 and 20 mg/kg dioscin through gavage for 18 weeks, and randomly divided into a control group, a HFD model group and a dioscin group treated with 5, 10 and 20 mg/kg/day dioscin for 12 weeks. Histopathological changes in adipose tissues were examined using hematoxylin and eosin staining. Biochemical parameters of the serum were also monitored, including glucose, insulin, total triglyceride, homeostasis model assessment of insulin resistance (HOMA‑IR) and adipose insulin resistance (Adipo‑IR) levels. Expression of the mRNA and associated proteins of the insulin receptor substrate 1 (IRS‑1)/phosphoinositide 3‑kinase (PI3K)/protein kinase B (Akt) pathways were determined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, respectively. HOMA‑IR and Adipo‑IR values of mice fed with a HFD were significantly higher compared with those in the control group (P<0.01). However, dioscin administration significantly decreased HOMA‑IR and Adipo‑IR values in a dose‑dependent manner (P<0.05), suggesting the effects of dioscin on attenuating insulin resistance. RT‑qPCR results indicated that the associated genes of the IRS‑1/PI3K/Akt pathway were significantly downregulated by HFD compared with the control group (P<0.05), while dioscin significantly increased the expression of those genes compared with the control group (P<0.05). Similarly, the significant increase in phosphorylated (p‑)IRS‑1/IRS‑1 (P<0.05) and p‑Akt/Akt (P<0.05) values were substantially reversed by dioscin treatment. Dioscin pronouncedly mitigated insulin resistance in adipose tissues through the IRS‑1/PI3K/Akt pathway and has potential to be used as a novel therapeutic agent for the therapy of HFD‑induced insulin resistance in adipose tissue.

Anti-obesity effects of Diospyros lotus leaf extract in mice with high-fat diet-induced obesity

Diospyros (D.) lotus has been demonstrated to have antioxidant and anti‑inflammatory properties. The purpose of the present study was to evaluate the effect of D. lotus leaf water extract (DLE) on high‑fat diet (HFD)‑induced obesity in C57BL/6 mice. The present study first investigated the effect of DLE on the lipid accumulation and triglyceride (TG) contents in 3T3‑L1 cells, and the results revealed that treatment with DLE suppressed the lipid accumulation and TG level. Subsequently, the anti‑obesity effects of DLE were investigated in vivo. Oral administration of DLE reduced the body weight gain, food efficiency ratio, and liver and visceral fat weight in mice fed with a HFD. DLE administration in these mice also reduced TG, total cholesterol, low‑density lipoprotein cholesterol, glucose, insulin and leptin levels, as well as the atherogenic index. Furthermore, DLE administration decreased hepatic steatosis, as well as serum aspartate transaminase, alanine transaminase and alkaline phosphatase levels in mice fed with HFD. It was further observed that treatment of the HFD‑fed mice with DLE prevented lipid peroxidation, while it recovered glutathione depletion and the activities of superoxide dismutase, catalase and glutathione peroxidase. In conclusion, the current study suggests that the anti‑obesity effect of DLE may provide positive insights as a potential functional food ingredient for the prevention of obesity.

Comparison of three different extracts of Centella asiatica for anti-amnesic, antioxidant and anticholinergic activities: in vitro and in vivo study

Centella asiatica (CA) has been used by Ayurvedic medical practitioners in India for almost 3000 years. The neuropharmacological properties of CA and its constituents have been studied extensively. Anti-oxidant, free radical scavenging and cholinergic modulatory activities are the reported mechanisms of action for its efficacy in memory disorders. Its medicinal values are mainly attributed to the presence of several triterpenes, namely asiatic acid, madecassic acid, asiaticoside, and madecassoside. The present study was aimed to investigate the role of these triterpenes content in CA extract on the antioxidant, cholinesterase modulation and anti-amnesic properties. The fractions of CA extract enriched for (CAE-EF) and depleted/freed of (CAE-FF) triterpenes contents were compared with methanolic extract (CAE). Both in vitro and in vivo methods for evaluation of antioxidant and anticholinergic activities were used. In vitro, free radical scavenging assays (ABTS, DPPH, NO, NORAC, and ORAC) and cholinesterase (AChE and BuChE) inhibition assays were used. For evaluation of anti-amnesic effect, scopolamine induced amnesia in rats, as the acute model of memory loss was used. Following behavioural assessments (MWM, PA, EPM), biomarkers of oxidative stress (reduced GSH, MDA and SOD activity) and cholinesterase (AChE and BuChE) status were also estimated in cerebral cortex and hippocampus of rat brain. The methanolic extract (CAE) was found to perform best among all three fractions for in vitro free radical scavenging, cholinesterase inhibition, improvement of scopolamine-induced amnesia and also in vivo antioxidant effect and cholinesterase inhibitory activities. Interestingly triterpenes free fraction (CAE-FF) showed better antioxidant activity than triterpenes enriched fraction (CAE-EF) along with comparable anti-amnesic effect. This indicates that triterpenes are not solely responsible for antioxidant activity, cholinesterase inhibitory and anti-amnesic effect of CA.

Pedunculoside, a novel triterpene saponin extracted from Ilex rotunda, ameliorates high-fat diet induced hyperlipidemia in rats

Pedunculoside (PE) is a novel triterpene saponin extracted from the dried barks of Ilex rotunda Thunb. The present study aims to explore lipid-lowering effects of PE on hyperlipidemia rat induced by high-fat diet. The rats were fed with the high-fat diet and subjected to intragastric administration of PE at doses of 30, 15, or 5 mg/kg daily for 7 weeks. The results demonstrated that treatment with PE for 7-week dramatically decreased serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and reduced liver TC in hyperlipidemia rat induced by high-fat diet. Furthermore, the results also showed that PE modulated the expression of enzymes involved in lipid metabolism including peroxisome proliferator-activated receptor α (PPAR-α), sterol regulatory element-binding protein 1 (SREBP-1), fatty acid synthase (FAS) and stearoyl CoA desaturase-1 (SCD-1) mRNA in liver. Besides, PE-treated group decreased weights and diameters of epididymal adipose hyperlipidemia rat. Mechanism study demonstrated that PE regulated PPAR-γ, CCAAT/Enhancer-binding Protein α (C/EBPα)、and SREBP-1 expression as well as inhibited phosphorylation of AMPK in MDI (methylisobutylxanthine, dexamethasone, insulin) induced-3T3L1 cells. Molecular Docking confirmed interaction between PE with proteins involving PPAR-γ, C/EBPα and SREBP-1. In summary, these findings may support that PE is a novel lipid-lowering drug candidate.

Bovine α-Lactalbumin Hydrolysates (α-LAH) Ameliorate Adipose Insulin Resistance and Inflammation in High-Fat Diet-Fed C57BL/6J Mice

Obesity-induced adipose inflammation has been demonstrated to be a key cause of insulin resistance. Peptides derived from bovine α-lactalbumin have been shown to inhibit the activities of dipeptidyl peptidase IV (DPP-IV) and angiotensin converting enzyme (ACE), scavenge 2,2'-azinobis [3-ethylbenzothiazoline-6-sulfonate] (ABTS⁺) radical and stimulate glucagon-like peptide-2 secretion. In the present study, the effects of bovine α-lactalbumin hydrolysates (α-LAH) on adipose insulin resistance and inflammation induced by high-fat diet (HFD) were investigated. The insulin resistance model was established by feeding C57BL/6J mice with HFD (60% kcal from fat) for eight weeks. Then, the mice were fed with HFD and bovine α-LAH of different doses (100 mg/kg b.w., 200 mg/kg b.w. and 400 mg/kg b.w.) for another 12 weeks to evaluate its protective effects against HFD-induced insulin resistance. The oral glucose tolerance test (OGTT) and intraperitoneal insulin tolerance test (ipITT) were conducted after intervention with α-LAH for 10 weeks and 11 weeks, respectively. Results showed that bovine α-LAH significantly reduced body weight, blood glucose, serum insulin, and HOMA-IR (homeostatic model assessment of insulin resistance) levels, lowered the area-under-the-curve (AUC) during OGTT and ipITT, and downregulated inflammation-related gene [tumor necrosis factor (TNF)-α, interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1] expression in adipose tissues of HFD-fed C57BL/6J mice. Furthermore, bovine α-LAH also suppressed insulin receptor substrate 1 (IRS-1) serine phosphorylation (Ser307, Ser612), enhanced protein kinase B (known as Akt) phosphorylation, and inhibited the activation of inhibitor of kappaB kinase (IKK) and mitogen activated protein kinase (MAPK) signaling pathways in adipose tissues of HFD-fed C57BL/6J mice. These results suggested that bovine α-LAH could ameliorate adipose insulin resistance and inflammation through IKK and MAPK signaling pathways in HFD-fed C57BL/6J mice.

Comparative Analysis of the Major Chemical Constituents in Salvia miltiorrhiza Roots, Stems, Leaves and Flowers during Different Growth Periods by UPLC-TQ-MS/MS and HPLC-ELSD Methods

Salvia miltiorrhiza is a traditional Chinese herbal medicine containing multiple components that contribute to its notable bioactivities. This article investigated the distribution and dynamic changes of chemical constituents in various parts of S. miltiorrhiza from different growth periods. An ultra-high performance liquid chromatography-triple quadrupole mass spectrometer (UPLC-TQ-MS/MS) and high-performance liquid chromatography coupled with evaporative light scattering detector (HPLC-ELSD) methods were developed for accurate determination of 24 compounds (including phenolic acids, flavonoids, triterpenes, and saccharides) in S. miltiorrhiza. The established methods were validated with good linearity, precision, repeatability, stability, and recovery. Results indicated that there were category and quantity discrepancies in different parts of the plant, for the roots mainly contained salvianolic acids and tanshinones, and most of the saccharides are stachyose. In the aerial parts, salvianolic acids, flavonoids, and triterpenes, except the tanshinones, were detected, and the saccharides were mainly monosaccharides. Dynamic accumulation analysis suggested the proper harvest time for S. miltiorrhiza Bunge was the seedling stage in spring, and for the aerial parts was July to August. This study provided valuable information for the development and utilization value of the aerial parts of S. miltiorrhiza and was useful for determining the optimal harvest time of the plant.