Corosolic acid prevents oxidative stress, inflammation and hypertension in SHR/NDmcr-cp rats, a model of metabolic syndrome

Ziziphus jujuba (Jujube) in Metabolic Syndrome: From Traditional Medicine to Scientific Validation

PURPOSE OF REVIEW

This review evaluates the therapeutic potential of Ziziphus jujuba and its main components in managing complications of metabolic syndrome, including diabetes, dyslipidemia, obesity, and hypertension.

RECENT FINDINGS

The reviewed studies provide evidence supporting the use of Z. jujuba and its main components (lupeol and betulinic acid) as natural treatments for complications of metabolic syndrome. These substances enhance glucose uptake through the activation of signaling pathways such as phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), reduce hepatic glucose synthesis, and increase glucose uptake by adipocytes and skeletal muscle cells. They also improve insulin sensitivity by modulating AMP-activated protein kinase (AMPK) activity and regulating insulin signaling proteins and glucose transporters. In the field of dyslipidemia, they inhibit triglyceride synthesis, lipid accumulation, and adipogenic enzymes, while influencing key signaling pathways involved in adipogenesis. Z. jujuba and its constituents demonstrate anti-adipogenic effects, inhibiting lipid accumulation and modulating adipogenic enzymes and transcription factors. They also exhibit positive effects on endothelial function and vascular health by enhancing endothelial nitric oxide synthase (eNOS) expression, NO production, and antioxidant enzyme activity. Z. jujuba, lupeol, and betulinic acid hold promise as natural treatments for complications of metabolic syndrome. They improve glucose metabolism, insulin sensitivity, and lipid profiles while exerting anti-adipogenic effects and enhancing endothelial function. However, further research is needed to elucidate the mechanisms and confirm their efficacy in clinical trials. These natural compounds offer potential as alternative therapies for metabolic disorders and contribute to the growing body of evidence supporting the use of natural medicines in their management.

Corosolic acid attenuates cardiac ischemia/reperfusion injury through the PHB2/PINK1/parkin/mitophagy pathway

Despite advances in treatment, myocardial infarction remains the leading cause of heart failure and death worldwide, and the restoration of coronary blood flow can also cause heart damage. In this study, we found that corosolic acid (CA), also known as plant insulin, significantly protects the heart from ischemia-reperfusion (I/R) injury. In addition, CA can inhibit oxidative stress and improve mitochondrial structure and function in cardiomyocytes. Subsequently, our study demonstrated that CA improved the expression of the mitophagy-related proteins Prohibitin 2 (PHB2), PTEN-induced putative kinase protein-1 (PINK1), and Parkin. Meanwhile, through molecular docking, we found an excellent binding between CA and PHB2 protein. Finally, the knockdown of PHB2 eliminated the protective effect of CA on hypoxia-reoxygenation in cardiomyocytes. Taken together, our study reveals that CA increases mitophagy in cardiomyocytes via the PHB2/PINK1/Parkin signaling pathway, inhibits oxidative stress response, and maintains mitochondrial function, thereby improving cardiac function after I/R.

Recent advances in anti-inflammation via AMPK activation

Inflammation is a complex physiological phenomenon, which is the body's defensive response, but abnormal inflammation can have adverse effects, and many diseases are related to the inflammatory response. AMPK, as a key sensor of cellular energy status, plays a crucial role in regulating cellular energy homeostasis and glycolipid metabolism. In recent years, the anti-inflammation effect of AMPK and related signalling cascade has begun to enter everyone's field of vision - not least the impact on metabolic diseases. A great number of studies have shown that anti-inflammatory drugs work through AMPK and related pathways. Herein, this article summarises recent advances in compounds that show anti-inflammatory effects by activating AMPK and attempts to comment on them.

Sustainable methods for the carboxymethylation and methylation of ursolic acid with dimethyl carbonate under mild and acidic conditions

Ursolic acid is a triterpene plant extract that exhibits significant potential as an anti-cancer, anti-tumour, and anti-inflammatory agent. Its direct use in the pharmaceutical industry is hampered by poor uptake of ursolic acid in the human body coupled with rapid metabolism causing a decrease in bioactivity. Modification of ursolic acid can overcome such issues, however, use of toxic reagents, unsustainable synthetic routes and poor reaction metrics have limited its potential. Herein, we demonstrate the first reported carboxymethylation and/or methylation of ursolic acid with dimethyl carbonate (DMC) as a green solvent and sustainable reagent under acidic conditions. The reaction of DMC with ursolic acid, in the presence of PTSA, ZnCl2, or H2SO4-SiO2 yielded the carboxymethylation product 3β-[[methoxy]carbonyl]oxyurs-12-en-28-oic acid, the methylation product 3β-methoxyurs-12-en-28-oic acid and the dehydration product urs-2,12-dien-28-oic acid. PTSA demonstrated high conversion and selectivity towards the previously unreported carboxymethylation of ursolic acid, while the application of formic acid in the system led to formylation of ursolic acid (3β-formylurs-12-en-28-oic acid) in quantitative yields via esterification, with DMC acting solely as a solvent. Meanwhile, the methylation product of ursolic acid, 3β-methoxyurs-12-en-28-oic acid, was successfully synthesised with FeCl3, demonstrating exceptional conversion and selectivity, >99% and 99%, respectively. Confirmed with the use of qualitative and quantitative green metrics, this result represents a significant improvement in conversion, selectivity, safety, and sustainability over previously reported methods of ursolic acid modification. It was demonstrated that these methods could be applied to other triterpenoids, including corosolic acid. The study also explored the potential pharmaceutical applications of ursolic acid, corosolic acid, and their derivatives, particularly in anti-inflammatory, anti-cancer, and anti-tumour treatments, using molecular ADMET and docking methods. The methods developed in this work have led to the synthesis of novel molecules, thus creating opportunities for the future investigation of biological activity and the modification of a wide range of triterpenoids applying acidic DMC systems to deliver novel active pharmaceutical intermediates.

Comparative transcriptome and metabolite profiling reveal diverse pattern of CYP-TS gene expression during corosolic acid biosynthesis in Lagerstroemia speciosa (L.) Pers

KEY MESSAGE

Extensive leaf transcriptome profiling and differential gene expression analysis of field grown and elicited shoot cultures of L. speciosa suggest that differential synthesis of CRA is mediated primarily by CYP and TS genes, showing functional diversity. Lagerstroemia speciosa L. is a tree species with medicinal and horticultural attributes. The pentacyclic triterpene, Corosolic acid (CRA) obtained from this species is widely used for the management of diabetes mellitus in traditional medicine. The high mercantile value of the compound and limited availability of innate resources entail exploration of alternative sources for CRA production. Metabolic pathway engineering for enhanced bioproduction of plant secondary metabolites is an attractive proposition for which, candidate genes in the pathway need to be identified and characterized. Therefore, in the present investigation, we focused on the identification of cytochrome P450 (CYP450) and oxidosqualene cyclases (OSC) genes and their differential expression during biosynthesis of CRA. The pattern of differential expression of these genes in the shoot cultures of L. speciosa, elicited with different epigenetic modifiers (azacytidine (AzaC), sodium butyrate (NaBu) and anacardic acid (AA)), was studied in comparison with field grown plant. Further, in vitro cultures with varying (low to high) concentrations of CRA were systematically assessed for the expression of CYP-TS and associated genes involved in CRA biosynthesis by transcriptome sequencing. The sequenced samples were de novo assembled into 180,290 transcripts of which, 92,983 transcripts were further annotated by UniProt. The results are collectively given in co-occurrence heat maps to identify the differentially expressed genes. The combined transcript and metabolite profiles along with RT-qPCR analysis resulted in the identification of CYP-TS genes with high sequence variation. Further, instances of concordant/discordant relation between CRA biosynthesis and CYP-TS gene expression were observed, indicating functional diversity in genes.

Corosolic acid inhibits metastatic response of human renal cell carcinoma cells by modulating ERK/MMP2 signaling

Corosolic acid (CA), a plant-derived pentacyclic triterpenoid, has potent anti-inflammatory, anti-metabolic, and anti-neoplastic actions against a variety of human cancers. However, the specific mechanism by which CA inhibits the progression of renal cell carcinoma (RCC) is yet unclear. We found that CA (≤8 μM) had no influence on either the growth or viability of RCC cell lines (786-O, ACHN, and Caki-1) or normal HK2 cells. However, in a dose-dependent manner, CA prevented the invasion and migration of RCC cells. Human protease array analysis showed that CA reduced MMP2 expression. At increasing concentrations of CA, the expression of MMP2 was dose-dependently reduced, as shown by western blot and RT-PCR analyses as well as immunofluorescence staining. CA also stimulated ERK1/2 phosphorylation in 786-O and Caki-1 cells. Transfection of CA-treated RCC cells with siRNA-ERK restored MMP2 protein expression and the motility and invasion capabilities of RCC cells. Molecular docking study results showed that CA and MMP2 interact strongly. These findings elucidate the mechanism by which CA prevents RCC cells from migrating and invading, and these findings indicate that CA may be a potential anti-metastatic therapy for RCC.

Natural compounds targeting mitochondrial dysfunction: emerging therapeutics for target organ damage in hypertension

Hypertension generally causes target organ damage (TOD) in the heart, brain, kidney, and blood vessels. This can result in atherosclerosis, plaque formation, cardiovascular and cerebrovascular events, and renal failure. Recent studies have indicated that mitochondrial dysfunction is crucial in hypertensive target organ damage. Consequently, mitochondria-targeted therapies attract increasing attention. Natural compounds are valuable resources for drug discovery and development. Many studies have demonstrated that natural compounds can ameliorate mitochondrial dysfunction in hypertensive target organ damage. This review examines the contribution of mitochondrial dysfunction to the development of target organ damage in hypertension. Moreover, it summarizes therapeutic strategies based on natural compounds that target mitochondrial dysfunction, which may be beneficial for preventing and treating hypertensive target organ damage.

In Vitro Antiglycation Potential of Erva-Baleeira (Varronia curassavica Jacq.)

BACKGROUND

Varronia curassavica Jacq. (Boraginaceae) is traditionally used in the treatment of inflammatory processes. The ethanolic extract of its leaves (EEVc) showed anti-inflammatory properties and low toxicity. Medicinal plants have aroused interest for their antiglycation activities. The formation and accumulation of advanced glycation end products (AGEs) are associated with several chronic diseases. The objective of this study was to evaluate the antiglycation potential of EEVc and two isolated compounds.

METHODS

The compounds brickellin and cordialin A were obtained by chromatographic methods and identified by spectrometric techniques. Analysis of fluorescent AGEs, biomarkers of amino acid residue oxidation, protein carbonyl groups and crosslink formation were performed in samples obtained from an in vitro model system of protein glycation with methylglyoxal.

RESULTS

EEVc, brickellin and cordialin A significantly reduced the in vitro formation of AGEs, and reduced the damage caused by oxidative damage to the protein.

CONCLUSIONS

According to the results, EEVc, brickellin and cordialin A are potential candidates against AGEs formation, which opens the way to expand the therapeutic arsenal for many pathologies resulting from glycoxidative stress.

Corosolic acid ameliorates vascular remodeling in pulmonary arterial hypertension via the downregulation of STAT3 signaling

Pulmonary arterial hypertension (PAH) is a progressive and fatal disease that is characterized by vascular remodeling of the pulmonary artery. PAH remodeling is primarily caused by the excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs). Therefore, an inhibitory mechanism is expected as a target for the treatment of PAH. Corosolic acid (CRA) is a pentacyclic triterpenoid extracted from the leaves of Banaba (Lagerstroemia speciosa) that exerts anti-diabetic, anti-inflammatory, and anti-tumor effects. In the present study, the effects of CRA on PAH remodeling were examined using PASMCs from idiopathic pulmonary arterial hypertension (IPAH) patients and monocrotaline (MCT)-induced pulmonary hypertensive (PH) rats. CRA inhibited the excessive proliferation of IPAH-PASMCs in a concentration-dependent manner (IC₅₀ = 14.1 μM). It also reduced the migration of IPAH-PASMCs. The CRA treatment downregulated the expression of signal transducer and activator of transcription 3 (STAT3) in IPAH-PASMCs. In MCT-PH rats, the administration of CRA (1 mg/kg/day) attenuated increases in right ventricular systolic pressure, pulmonary vascular remodeling, and right ventricular hypertrophy. CRA also decreased the expression of STAT3 in pulmonary arterial smooth muscles from MCT-PH rats. In conclusion, the anti-proliferative and anti-migratory effects of CRA in PASMCs ameliorated PAH remodeling by downregulating STAT3 signaling pathways.

Protective Effects of Dipterocarpus tuberculatus in Blue Light-Induced Macular Degeneration in A2E-Laden ARPE19 Cells and Retina of Balb/c Mice

Natural products with significant antioxidant activity have been receiving attention as one of the treatment strategies to prevent age-related macular degeneration (AMD). Reactive oxygen intermediates (ROI) including oxo-N-retinylidene-N-retinylethanolamine (oxo-A2E) and singlet oxygen-induced damage, are believed to be one of the major causes of the development of AMD. To investigate the therapeutic effects of methanol extracts of Dipterocarpus tuberculatus Roxb. (MED) against blue light (BL)-caused macular degeneration, alterations in the antioxidant activity, apoptosis pathway, neovascularization, inflammatory response, and retinal degeneration were analyzed in A2E-laden ARPE19 cells and Balb/c mice after exposure of BL. Seven bioactive components, including 2α-hydroxyursolic acid, ε-viniferin, asiatic acid, bergenin, ellagic acid, gallic acid and oleanolic acid, were detected in MED. MED exhibited high DPPH and ABTS free radical scavenging activity. BL-induced increases in intracellular reactive oxygen species (ROS) production and nitric oxide (NO) concentration were suppressed by MED treatment. A significant recovery of antioxidant capacity by an increase in superoxide dismutase enzyme (SOD) activity, SOD expression levels, and nuclear factor erythroid 2-related factor 2 (NRF2) expression were detected as results of MED treatment effects. The activation of the apoptosis pathway, the expression of neovascular proteins, cyclooxygenase-2 (COX-2)-induced inducible nitric oxide synthase (iNOS) mediated pathway, inflammasome activation, and expression of inflammatory cytokines was remarkably inhibited in the MED treated group compared to the Vehicle-treated group in the AMD cell model. Furthermore, MED displayed protective effects in BL-induced retinal degeneration through improvement in the thickness of the whole retina, outer nuclear layer (ONL), inner nuclear layer (INL), and photoreceptor layer (PL) in Balb/c mice. Taken together, these results indicate that MED exhibits protective effects in BL-induced retinal degeneration and has the potential in the future to be developed as a treatment option for dry AMD with atrophy of retinal pigment epithelial (RPE) cells.

Cardioprotective Effects of Vitex negundo: A Review of Bioactive Extracts and Compounds

There has been accumulating interest in the application of medicinal plants as alternative medicine to treat various diseases and/or to develop modern medicines. Vitex negundo is one of such medicinal plants that has been of interest to many researchers and has been of use in traditional medicine. V. negundo is found in Sri Lanka, Madagascar, Malaysia, India, China, The Philippines and East Africa. Therapeutic properties of V. negundo have previously been reviewed. Different parts, preparations and bioactive components of V. negundo possess potential protective and therapeutic effects against cardiovascular disease and related conditions as demonstrated in previous studies. We review the present state of scientific knowledge on the potential use of V. negundo and some of its bioactive components in protecting against cardiovascular diseases and related pathologies. Previous studies in animal and non-animal experimental models, although limited in number and vary in design, seem to support the cardioprotective effect of V. negundo and some of its active components. However, there is need for further preclinical and clinical studies to validate the use of V. negundo and its active constituents in protection and treatment of cardiovascular diseases. Additionally, since only a few V. negundo compounds have been evaluated, specific cardioprotective effects or mechanisms and possible side effects of other V. negundo compounds need to be extensively evaluated.

Corosolic Acid Inhibits Secretory Phospholipase A2IIa as an Anti-Inflammatory Function and Exhibits Anti-Tumor Activity in Ehrlich Ascites Carcinoma Bearing Mice

Background

Inflammation is generally connected to tumour progression and development. The secretory phospholipase A2IIa (sPLA2IIa) is an important inflammatory enzyme that catalyse the hydrolysis of membrane phospholipids into arachidonic and lysophosphatidic acid, which are the precursors for production of a lot of pro-inflammatory mediators like prostaglandins, prostacyclins, thromboxanes, leukotrienes and platelet activating factors, which involved in the proliferation, migration, invasion, and metastasis. Therefore, investigating safe and effective sPLA2IIa inhibitors as a therapeutic agent to treat cancer is indeed in need.

Methods

Anti-inflammatory function of corosolic acid was evaluated by docking it with sPLA2IIa enzyme, sPLA2IIa inhibition, calcium and substrate concentration-dependent assays; intrinsic fluorescence and UV-CD analysis; neutralisation of sPLA2IIa induced indirect hemolytic and edema. Evaluated the anticancer activity of corosolic acid by MTT assays and caspase-3 expression; the anti-tumour activity by EAC-induced cell line and interleukin 6 expression.

Results

The corosolic acid inhibits sPLA2IIa activity to 82.21±2.82%. The inhibition was evaluated by increasing calcium from 2.5 to 15 µM and substrate from 20 to 120 nM, it did not affect the level of inhibition. Corosolic acid altered the intrinsic fluorescence and UV-CD spectra of sPLA2IIa enzyme, indicating the direct interaction. It neutralised sPLA2IIa induced hemolytic activity from 97±1.23% to 15.75±1.44% and edema from 171.51±2.39% to 119.3±2.6%. Further, as antiproliferative activity, corosolic acid reduced the PC3 cell viability from 99.66±0.57% to 23±2.64% and suppressed LPS-induced IL-6 level from 94.35±2.2% to 34.36±2.4%. It increased mean survivability time from 30 to 38 days and displayed the drug-like qualities.

Conclusion

All the experimental results have proven the corosolic acid as an anti-inflammatory and anticancer molecule that may further be used to develop it as a drug.

Friedelin Attenuates Neuronal Dysfunction and Memory Impairment by Inhibition of the Activated JNK/NF-κB Signalling Pathway in Scopolamine-Induced Mice Model of Neurodegeneration

Oxidative stress (OS) and c-Jun N-terminal kinase (JNK) are both key indicators implicated in neuro-inflammatory signalling pathways and their respective neurodegenerative diseases. Drugs targeting these factors can be considered as suitable candidates for treatment of neuronal dysfunction and memory impairment. The present study encompasses beneficial effects of a naturally occurring triterpenoid, friedelin, against scopolamine-induced oxidative stress and neurodegenerative pathologies in mice models. The treated animals were subjected to behavioural tests i.e., Y-maze and Morris water maze (MWM) for memory dysfunction. The underlying mechanism was determined via western blotting, antioxidant enzymes and lipid profile analyses. Molecular docking studies were carried out to predict the binding modes of friedelin in the binding pocket of p-JNK protein. The results reveal that scopolamine caused oxidative stress by (1) inhibiting catalase (CAT), peroxidase enzyme (POD), superoxide dismutase (SOD), and reduced glutathione enzyme (GSH); (2) the up-regulation of thiobarbituric acid reactive substances (TBARS) in mice brain; and (3) affecting the neuronal synapse (both pre- and post-synapse) followed by associated memory dysfunction. In contrast, friedelin administration not only abolished scopolamine-induced oxidative stress, glial cell activation, and neuro-inflammation but also inhibited p-JNK and NF-κB and their downstream signaling molecules. Moreover, friedelin administration improved neuronal synapse and reversed scopolamine-induced memory impairment accompanied by the inhibition of β-secretase enzyme (BACE-1) to halt amyloidogenic pathways of amyloid-β production. In summary, all of the results show that friedelin is a potent naturally isolated neuro-therapeutic agent to reverse scopolamine-induced neuropathology, which is characteristic of Alzheimer’s disease.

Photosynthetic Parameters and Oxidative Stress during Acclimation of Crepe-Myrtle (Lagerstroemia speciosa (L.) Pers.) in a meta-Topolin-Based Micropropagation System and Genetic Fidelity of Regenerated Plants

An improved and stable micropropagation system using the cytokinin, meta-Topolin (N6 (3-hydroxybenzylamino purine—mT), with nodal explants in Lagerstroemia speciosa L. was established. Among the different doses of mT, the maximum number of shoots with the highest shoot length was obtained using Murashige and Skoog’s (MS) medium supplemented with 5.0 µM mT. The results were consistent throughout the proliferation period, when recorded at week 4, 8, and 12 of being cultured, with an average of 16.4 shoots per nodal explant, and having a mean length of 4.10 cm at week 8. Shoot proliferation rates could be further improved by a combination of 5.0 µM mT with 0.5 µM α-naphthalene acetic acid in MS medium; nodal explants produced an average of 24.3 shoots with a mean length of 5.74 cm after 8 weeks of being cultured. Among the five different concentrations of three auxins tested for the rooting of microshoots in MS medium, a 1.0 µM indole-3-butyric acid treatment was the best, with an average of 10.3 roots per microshoot at an average length of 3.56 cm in 93% of microshoots within 4 weeks of being transferred to this medium. A significant reduction of both chlorophyll a and b in leaves during the first week of acclimation corresponded with a high accumulation of malondialdehyde (MDH), indicating that lipid peroxidation affected chlorophyll pigments. From the second week of acclimation, photosynthetic pigment content significantly increased and MDH content decreased. The net photosynthetic rate and leaf carotenoid content showed almost linear increases throughout the acclimation period. Activity of antioxidant enzymes, namely, superoxide dismutase, catalase, and peroxidases, consistently increased throughout the acclimation period, corresponding with the accumulation of photosynthetic pigments, thus demonstrating the role of the improved antioxidant enzymatic defense system during acclimation. A comparison of parent plant DNA with that of the greenhouse acclimated plants using random amplified polymorphic DNA and inter-simple sequence repeat markers showed a monomorphic pattern indicating genetic stability and the suitability of the method for micropropagation of L. speciosa.

Bioactive compound from Lagerstroemia speciosa: activating apoptotic machinery in pancreatic cancer cells

The study was aimed at the identification of a potential anti-cancer compound from the leaf extract of Lagerstroemia speciosa, against pancreatic cancer cells (PANC-1). Out of different extracts tested, methanolic extract showed significant cytotoxicity at an IC₅₀ of 289.5 ± 0.03 µg/mL after 24 h (MTT assay). The safety of the extract was ascertained using normal pancreatic cells (hTERT-HPNE). Methanolic extract was able to induce apoptosis in 28.9 ± 0.01% of PANC-1 cells as determined by flow cytometry. RT-PCR analysis of PANC-1 cells also recorded an increase in the mRNA expression of pro-apoptotic genes i.e., Caspase-3 (12.82 folds), Rb (10 folds) and Bad (8.74 folds) after treatment. Expression of other pro-apoptotic genes such as Bax and TNF was also upregulated by 4.04 and 4.01 folds, respectively. However, the mRNA expression of anti-apoptotic genes, NF-κB, Cdk and Bcl-2 was found to be downregulated. The bioactive extract was then fractionated on preparative silica gel plates into 24 bands. Out of these, band fraction 9 exhibited significant cytotoxicity (IC₅₀ 219 ± 0.04 µg/mL) on the PANC-1 cells. The mass spectral (HPLC-MS) and FTIR analysis of the fraction indicated the bioactive compound to be a derivative of Diosgenin, which can be a possible candidate for cancer therapeutics in future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03155-w.

Effect of Banaba (Lagerstroemia speciosa) on Metabolic Syndrome, Insulin Sensitivity, and Insulin Secretion

To evaluate the effect of Banaba (Lagerstroemia speciosa) on metabolic syndrome (MetS), insulin sensitivity, and insulin secretion. A randomized, double-blind, placebo-controlled clinical trial was carried out in 24 patients with diagnosis of MetS according to the International Diabetes Federation criteria. Body weight, waist circumference, and blood pressure were evaluated. Fasting plasma glucose (FPG) and insulin concentrations were measured every 30 min during 2 h after a 75-g dextrose load. Lipid profile was determined before and after the pharmacological intervention. Twelve patients received Banaba (500 mg) twice a day, before breakfast and dinner for 12 weeks. The remaining 12 patients received placebo at the same dosage. Body mass index, area under the curve (AUC) of glucose and insulin, insulin sensitivity, total insulin secretion, and the first phase of insulin secretion were calculated. After Banaba administration, there were significant decreases in systolic blood pressure (SBP) (121.5 ± 12.9 vs. 116.3 ± 9.8 mmHg, P = .050), FPG (5.9 ± 0.4 vs. 5.7 ± 0.4 mmol/L, P = .034), triglycerides (TG) (2.3 ± 0.4 vs. 1.7 ± 0.5 mmol/L, P = .021), very low-density lipoprotein (VLDL) (0.5 ± 0.1 vs. 0.3 ± 0.1 mmol/L, P = .021), AUC of insulin (50,675 ± 14,309 vs. 37,983 ± 19,298 mmol/L, P = .017), and insulinogenic index (0.4 ± 0.2 vs. 0.3 ± 0.2, P = .047). Eight patients (67%) of the Banaba group showed remission of MetS. In the placebo group, there was a downward trend toward statistical significance in the Stumvoll index (910.3 ± 514.1 vs. 651.0 ± 405.2, P = .062). Banaba administration leads to remission of MetS and a significant decrease in SBP, FPG, TG, VLDL, AUC of insulin, and total insulin secretion. Clinical Trial Registration number: NCT02767869.

Corosolic Acid Attenuates the Invasiveness of Glioblastoma Cells by Promoting CHIP-Mediated AXL Degradation and Inhibiting GAS6/AXL/JAK Axis

Corosolic acid (CA), a bioactive compound obtained from Actinidia chinensis, has potential anti-cancer activities. Glioblastoma (GBM) is a malignant brain tumor and whether CA exerts anti-cancer activity on GBM remains unclear. This study was aimed to explore the anticancer activity and its underlying mechanism of CA in GBM cells. Our findings showed that CA ≤ 20 μM did not affect cell viability and cell proliferative rate of normal astrocyte and four GBM cells. Notably, 10 or 20 μM CA significantly inhibited cell migration and invasion of three GBM cells, decreased the protein level of F-actin and disrupted F-actin polymerization in these GBM cells. Further investigation revealed that CA decreased AXL level by promoting ubiquitin-mediated proteasome degradation and upregulating the carboxyl terminus of Hsc70-interacting protein (CHIP), an inducer of AXL polyubiquitination. CHIP knock-down restored the CA-reduced AXL and invasiveness of GBM cells. Additionally, we observed that CA-reduced Growth arrest-specific protein 6 (GAS6) and inhibited JAK2/MEK/ERK activation, and GAS6 pre-treatment restored attenuated JAK2/MEK/ERK activation and invasiveness of GBM cells. Furthermore, molecular docking analysis revealed that CA might bind to GAS6 and AXL. These findings collectively indicate that CA attenuates the invasiveness of GBM cells, attributing to CHIP upregulation and binding to GAS6 and AXL and subsequently promoting AXL degradation and downregulating GAS6-mediated JAK2/MEK/ERK cascade. Conclusively, this suggests that CA has potential anti-metastatic activity on GBM cells by targeting the CHIP/GAS6/AXL axis.

Corosolic acid and its structural analogs: A systematic review of their biological activities and underlying mechanism of action

BACKGROUND

The corosolic acid (CA), also known as plant insulin, is a pentacyclic triterpenoid extracted from plants such as Lagerstroemia speciosa. It has been shown to have anti-diabetic, anti-inflammatory and anti-tumor effects. Its structural analogs ursolic acid (UA), oleanolic acid (OA), maslinic acid (MA), asiatic acid (AA) and betulinic acid (BA) display similar individual pharmacological activities to those of CA. However, there is no systematic review documenting pharmacological activities of CA and its structural analogues. This study aims to fill this gap in literature.

PURPOSE

This systematic review aims to summarize the medical applications of CA and its analogues.

METHODS

A systematic review summarizes and compares the extraction techniques, pharmacokinetic parameters, and pharmacological effects of CA and its structural analogs. Hypoglycemic effect is one of the key inclusion criteria for searching Web of Science, PubMed, Embase and Cochrane databases up to October 2020 without language restrictions. 'corosolic acid', 'ursolic acid', 'oleanolic acid', 'maslinic acid', 'asiatic acid', 'betulinic acid', 'extraction', 'pharmacokinetic', 'pharmacological' were used to extract relevant literature. The PRISMA guidelines were followed.

RESULTS

At the end of the searching process, 140 articles were selected for the systematic review. Information of CA and five of its structural analogs including UA, OA, MA, AA and BA were included in this review. CA and its structural analogs are pentacyclic triterpenes extracted from plants and they have low solubilities in water due to their rigid scaffold and hydrophobic properties. The introduction of water-soluble groups such as sugar or amino groups could increase the solubility of CA and its structural analogs. Their biological activities and underlying mechanism of action are reviewed and compared.

CONCLUSION

CA and its structural analogs UA, OA, MA, AA and BA are demonstrated to show activities in lowering blood sugar, anti-inflammation and anti-tumor. Their oral absorption and bioavailability can be improved through structural modification and formulation design. CA and its structural analogs are promising natural product-based lead compounds for further development and mechanistic studies.

Molecular mechanism of DLBS3733, a bioactive fraction of Lagerstroemia speciosa (L.) Pers., on ameliorating hepatic lipid accumulation in HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lagerstroemia speciosa (L.) Pers., commonly known as banaba and locally known as bungur, is widely used in Indonesia and other countries as a folk remedy for various chronic diseases such as diabetes mellitus and hypertension. L. speciosa (L.) Pers. has been used and evaluated on conditions associated to liver diseases by altering cholesterol absorption, lipid metabolism, as well as the related gene expressions.

AIM OF THE STUDY

The aim of this study is to evaluate the effect of DLBS3733, a standardized bioactive fraction of Lagerstroemia speciosa (L.) Pers. leaves, on ameliorating hepatic steatosis induced by oleic acid, and elucidate its mechanism of action to ameliorate lipid accumulation in HepG2 cells.

MATERIALS AND METHODS

Effects of DLBS3733 on expression of genes and proteins associated with lipid metabolism were evaluated in HepG2 cells in this study. Genes associated with lipid metabolism were evaluated using PCR, while the protein levels were revealed using western blot and ELISA. Cellular lipid accumulations and triglyceride (TG) synthesis were measured using ELISA, and antioxidant assay was conducted using DPPH assay.

RESULTS

DLBS3733 significantly reduced lipid accumulation and TG synthesis by 51% and 32% (p < 0.01), respectively, through the significant increment of adiponectin expression by 58% (p < 0.01). Subsequently, adiponectin enhanced PPARα expression and AMPK phosphorylation which further regulate the downstream signaling pathway of lipogenesis and lipolysis. Moreover, 2.5 µg/mL DLBS3733 was found to significantly downregulate the expression of HMGCR, ACC and SREBP by 66%, 61% and 36%, respectively (p < 0.01), as well as significantly upregulate CPT-1 by 300% at the protein level (P < 0.05). DLBS3733 was also found to possess high antioxidant activity, where the highest concentration exhibited DPPH inhibition activity by up to 93% (P < 0.01).

CONCLUSIONS

We propose that DLBS3733 may provide a prevention on hepatic steatosis through its activity as anti-lipogenesis, anti-cholesterologenesis and pro-lipolysis in HepG2 cells. This is the first report that revealed the molecular mechanism of L. speciosa (L.) Pers. as a potential treatment of hepatic steatosis-related diseases.

Ursolic Acid and Related Analogues: Triterpenoids with Broad Health Benefits

Ursolic acid (UA) is a well-studied natural pentacyclic triterpenoid found in herbs, fruit and a number of traditional Chinese medicinal plants. UA has a broad range of biological activities and numerous potential health benefits. In this review, we summarize the current data on the bioavailability and pharmacokinetics of UA and review the literature on the biological activities of UA and its closest analogues in the context of inflammation, metabolic diseases, including liver and kidney diseases, obesity and diabetes, cardiovascular diseases, cancer, and neurological disorders. We end with a brief overview of UA’s main analogues with a special focus on a newly discovered naturally occurring analogue with intriguing biological properties and potential health benefits, 23-hydroxy ursolic acid.

Lipophilic extracts from leaves, inflorescences and fruits of Prunus padus L. as potential sources of corosolic, ursolic and oleanolic acids with anti-inflammatory activity

Chloroform extracts from leaves, inflorescences and fruits of Prunus padus were analysed for anti-inflammatory activity and accumulation of corosolic (CA), ursolic (UA) and oleanolic (OA) acids. The analytes were identified and quantified by GC-MS and UHPLC-PDA. Their total levels depend on plant material type and harvesting time, and varied from 0.25 mg/g DW in fruits, through 0.76-1.09 mg/g DW in flowers, to 1.41-4.54 mg/g DW in leaves. Significant variation in the leaf analytes contents was observed during vegetation with the peak amounts in autumn, which indicated the optimal harvesting season. The plant extracts inhibited pro-inflammatory enzymes (lipoxygenase and hyaluronidase) in a concentration-dependent manner, and their activity parameters correlated with the levels and activity of pure triterpene acids, especially CA and UA. The results of the comparison with the positive controls (heparin, indomethacin, dexamethasone) might partly support the application of P. padus in anti-inflammatory therapies, reported by traditional medicine.

Natural pentacyclic triterpenoid acids potentially useful as biocompatible nanocarriers

The importance of natural raw materials has grown recently because of their ready availability, renewable nature, biocompatibility and controllable degradability. One such group of plant-derived substances includes the triterpenoid acids, terpenic compounds consisting of six isoprene units, a carboxyl group and other functional groups producing various isomers. Most can be easily extracted from different parts of the plant and modified successfully. By themselves or as aglycones (genins) of triterpene saponins, they have potentially useful pharmaceutical activity. This review focuses on the supramolecular properties of triterpenoid acids with regard to their subsequent use as biocompatible nanocarriers. The review also considers the current list of pentacyclic triterpene acids for which molecular self-assembly has been confirmed without the need for structural modification.

Biological effects of corosolic acid as an anti-inflammatory, anti-metabolic syndrome and anti-neoplasic natural compound

Accumulating evidence has indicated that corosolic acid exerts anti-diabetic, anti-obesity, anti-inflammatory, anti-hyperlipidemic and anti-viral effects. More importantly, corosolic acid has recently attracted much attention due to its anticancer properties and innocuous effects on normal cells. Furthermore, the increasing proportion of obese and/or diabetic populations has led to an epidemic of non-alcoholic fatty liver disease (NAFLD), which frequently progresses to hepatocellular carcinoma (HCC). Evidence has indicated that NAFLD is closely associated with the development of HCC and comprises a high risk factor. The present review summarizes the anticancer effects of corosolic acid in vitro and in vivo, and its related molecular mechanisms. It also describes the inhibitory effects of corosolic acid on the progression of NAFLD and its associated molecular mechanisms, providing guidance for future research on corosolic acid in NAFLD-related HCC prevention and treatment. To the best of our knowledge, a review of corosolic acid as an anticancer agent has not yet been reported. Due to its multitargeted activity in cancer cells, corosolic acid exerts anticancer effects when administered alone, and acts synergistically when administered with chemotherapeutic drugs, even in drug-resistant cells. In addition, as a novel tool to treat metabolic syndromes, corosolic acid uses the same mechanism in its action against cancer as that used in the progression of NAFLD-related HCC. Therefore, corosolic acid has been suggested as an agent for the prevention and treatment of NAFLD-related HCC.

Eriobotrya japonica leaf triterpenoid acids ameliorate metabolic syndrome in C57BL/6J mice fed with high-fat diet

BACKGROUND

It has been demonstrated in some studies that triterpenoid acid extract fromEriobotrya japonica leaf is beneficial to prevent hyperlipidemia or insulin resistance. However, the effect of triterpenoid acids in Eriobotrya japonica leaf on a series of typical symptoms of metabolic syndrome (MetS) has been rarely studied systematically. Therefore, the present study aims to systematically evaluate the effect of Eriobotrya japonica leaf triterpenoid acids (ELTA) on MetS and explore its potential mechanism.

METHODS

ELTA (HPLC purity 95.2 %) was prepared and administered orally (200 mg/kg) to C57BL/6 J mice fed with a high-fat diet (HFD) for 12 weeks. Pioglitazone (30 mg/kg) was used as a positive control drug. Food intake, body weight, total lipid in feces, lipid profiles, inflammatory factors in serum, hepatic glutathione, and lipid peroxide were measured. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed to evaluate insulin sensitivity. RT-qPCR and molecular docking were performed to explore the potential mechanism.

RESULTS

ELTA administration reduced body weight gain, relative liver weight, and relative visceral adipose weight. The levels of serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, hepatic total cholesterol, and hepatic triglycerides were also reduced. ELTA reduced the area under curve (AUC) of blood glucose curves in OGTT and ITT. Relative mRNA level analysis of genes related to MetS showed that ELTA can effectively increase the transcriptional levels of Nrf2, HO-1, PPAR-γ, GluT2, GK, FXR, while effectively decrease those of PTP1B, p65, TNF-α, IL-6, SREBP, 11βHSD-1. Molecular docking showed that the ligands in ELTA can bind to 11βHSD-1, GK, PPAR-γ, and JNK, the important targets involved in MetS.

CONCLUSIONS

ELTA can effectively alleviate visceral central obesity, insulin resistance, dyslipidemia, oxidative stress, and inflammation of HFD-induced MetS in C57BL/6 J mice. This is possibly achieved by acting on 11βHSD-1, GK, PPAR-γ, and JNK.

Corosolic acid attenuates cardiac fibrosis following myocardial infarction in mice

Corosolic acid (CRA) is a pentacyclic triterpenoid isolated from Lagerstroemia speciosa. The aim of the present study was to determine whether CRA reduces cardiac remodelling following myocardial infarction (MI) and to elucidate the underlying mechanisms. C57BL/6J mice were randomly divided into control (PBS-treated) or CRA-treated groups. After 14 days of pre-treatment, the mice were subjected to either sham surgery or permanent ligation of the left anterior descending artery. Following surgery, all animals were treated with PBS or CRA (10 or 20 mg/kg/day) for 4 weeks. After 4 weeks, echocardiographic, haemodynamic, gravimetric, histological and biochemical analyses were conducted. The results revealed that, upon MI, mice with CRA treatment exhibited decreased mortality rates, improved ventricular function and attenuated cardiac fibrosis compared with those in control mice. Furthermore, CRA treatment resulted in reduced oxidative stress, inflammation and apoptosis, as well as inhibited the transforming growth factor β1/Smad signalling pathway activation in cardiac tissue. In vitro studies further indicated that inhibition of AMP-activated protein kinase α (AMPKα) reversed the protective effect of CRA. In conclusion, the study revealed that CRA attenuated MI-induced cardiac fibrosis and dysfunction through modulation of inflammation and oxidative stress associated with AMPKα.

The Potential of Chinese Herbal Medicines in the Treatment of Cervical Cancer

Cervical cancer is a global health issue and places a considerable economic and medical burden on society. Thus, a concerted effort to improve the treatment of cervical cancer is warranted. Although several treatment options are currently available for treating patients with cervical cancer, such as chemoradiation and neoadjuvant or adjuvant chemotherapy, more aggressive systemic therapies and newer therapeutic agents are under investigation. Medicinal herbs have long been used to treat diseases. In this review, we summarize studies analyzing the antitumor effects and underlying mechanisms of Chinese herbal medicines, including the effects of crude extracts and compounds in vitro or in animal models for inducing apoptosis and inhibiting invasion or metastasis. Chinese herbal medicines with therapeutic targeting, such as those that interfere with tumor growth and progression in cervical cancer, have been widely investigated. To apply Chinese herbal medicine in the treatment of cervical cancer, adequate clinical studies are required to confirm its clinical safety and efficiency. Further investigations focused on the purification, pharmacokinetics, and identification of compounds from Chinese herbal medicines in cervical cancer treatment are necessary to achieve the aforementioned treatment goals.

Alpha-Amylase and Alpha-Glucosidase Enzyme Inhibition and Antioxidant Potential of 3-Oxolupenal and Katononic Acid Isolated from Nuxia oppositifolia

Nuxia oppositifolia is traditionally used in diabetes treatment in many Arabian countries; however, scientific evidence is lacking. Hence, the present study explored the antidiabetic and antioxidant activities of the plant extracts and their purified compounds. The methanolic crude extract of N. oppositifolia was partitioned using a two-solvent system. The n-hexane fraction was purified by silica gel column chromatography to yield several compounds including katononic acid and 3-oxolupenal. Antidiabetic activities were assessed by α-amylase and α-glucosidase enzyme inhibition. Antioxidant capacities were examined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) scavenging assays. Further, the interaction between enzymes (α-amylase and α-glucosidase) and ligands (3-oxolupenal and katononic acid) was followed by fluorescence quenching and molecular docking studies. 3-oxolupenal and katononic acid showed IC₅₀ values of 46.2 μg/mL (101.6 µM) and 52.4 μg/mL (119.3 µM), respectively against the amylase inhibition. 3-oxolupenal (62.3 µg/mL or 141.9 μM) exhibited more potent inhibition against α-glucosidases compared to katononic acid (88.6 µg/mL or 194.8 μM). In terms of antioxidant activity, the relatively polar crude extract and n-butanol fraction showed the greatest DPPH and ABTS scavenging activity. However, the antioxidant activities of the purified compounds were in the low to moderate range. Molecular docking studies confirmed that 3-oxolupenal and katononic acid interacted strongly with the active site residues of both α-amylase and α-glucosidase. Fluorescence quenching results also suggest that 3-oxolupenal and katononic acid have a good affinity towards both α-amylase and α-glucosidase enzymes. This study provides preliminary data for the plant's use in the treatment of type 2 diabetes mellitus.

Lagerstroemia speciosa (L.) Pers Leaf Extract Attenuates Lung Tumorigenesis via Alleviating Oxidative Stress, Inflammation and Apoptosis

One of the major etiological factors that account for lung cancer is tobacco use. Benzo(a)pyrene [B(a)P], one of the main constituents of tobacco smoke, has a key role in lung carcinogenesis. The present study was conducted to investigate the cytotoxicity of an aqueous ethanolic extract of Lagerstroemia speciosa (L.) Pers leaves (LLE) on human lung adenocarcinoma cells (A549), as well as its in vivo antitumor effect on a lung tumorigenesis mice model. Our results revealed that LLE possesses cytotoxic activity against the A549 cell line. Mice orally administered B(a)P (50 mg/kg body weight) showed an increase in relative lung weight with subsequent decrease in final body weight. Serum levels of tumor marker enzymes AHH, ADA and LDH and the inflammatory mediator NF-κB increased, while total antioxidant capacity (TAC) decreased. In addition, we observed the increased activity of metalloproteinases (MMP-2 and MMP-12) and levels of the tumor angiogenesis marker VEFG and the lipid peroxidation marker MDA, as well as decreased levels of the non-enzymatic antioxidant GSH and enzymatic antioxidants CAT and GSH-Px in lung tissues. Moreover, B(a)P administration up-regulated the expression of the COX-2 gene, pro-inflammatory cytokines TNF-α and IL-6, and an anti-apoptotic gene Bcl-2, and at the same time down-regulated expression of pro-apoptotic genes BAX and caspase-3 and the p53 gene. Pre- and post-treatment with LLE (250 mg/kg body weight) attenuated all these abnormalities. Histopathological observations verified the protective effect of LLE. Overall, the present data positively confirm the potent antitumor effect of L. speciosa leaves against lung tumorigenesis.

Antileishmanial Compounds Isolated from Psidium Guajava L. Using a Metabolomic Approach

With an estimated annual incidence of one million cases, leishmaniasis is one of the top five vector-borne diseases. Currently available medical treatments involve side effects, including toxicity, non-specific targeting, and resistance development. Thus, new antileishmanial chemical entities are of the utmost interest to fight against this disease. The aim of this study was to obtain potential antileishmanial natural products from Psidium guajava leaves using a metabolomic workflow. Several crude extracts from P. guajava leaves harvested from different locations in the Lao People's Democratic Republic (Lao PDR) were profiled by liquid chromatography coupled to high-resolution mass spectrometry, and subsequently evaluated for their antileishmanial activities. The putative active compounds were highlighted by multivariate correlation analysis between the antileishmanial response and chromatographic profiles of P. guajava mixtures. The results showed that the pooled apolar fractions from P. guajava were the most active (IC₅₀ = 1.96 ± 0.47 µg/mL). Multivariate data analysis of the apolar fractions highlighted a family of triterpenoid compounds, including jacoumaric acid (IC₅₀ = 1.318 ± 0.59 µg/mL) and corosolic acid (IC₅₀ = 1.01 ± 0.06 µg/mL). Our approach allowed the identification of antileishmanial compounds from the crude extracts in only a small number of steps and can be easily adapted for use in the discovery workflows of several other natural products.

Methanolic extract of Potentilla fulgens root and its ethyl-acetate fraction delays the process of carcinogenesis in mice

People of north-eastern states of India consume raw areca-nut (RAN) and lime which could lead to oral, esophageal and gastric cancers. However, the incidence of these cancers are significantly lesser in those who consume pieces of Potentilla fulgens root along with RAN. Since evaluation of anticancer role, if any, of P. fulgens on RAN-mediated genetic alterations in human is difficult because of other compounding factors, this study was undertaken in mice to focus on gastric carcinogenesis since ad libitum administration of RAN extract with lime in drinking water induced stomach cancer due to greater exposure of its lining. A total of 160 mice were used at different time points and either methanol extract of P. fulgens roots (PRE) or mixture of four compounds of ethyl-acetate fraction (EA-mixture) was mixed with mice feed. Histological studies revealed that RAN + lime induced cancer in all the mice and interestingly only 20% developed cancer when PRE/EA-mixture was provided along with RAN + lime. Higher frequency of precocious anaphase and over expression of p53 and Securin genes were significantly reduced by PRE/EA-mixture. Thus PRE/EA-mixture mitigates the RAN-induced tumor-initiating process in stomach by maintaining expression of tumor suppressor and check-point genes under control.

Investigation of biological activities of the flowers of Lagerstroemia speciosa, the Jarul flower of Bangladesh

BACKGROUND

Lagerstroemia speciosa (L.) Pers. (Family: Lythraceae) is used in traditional medicine in the treatment of diarrhea, diabetes and other diseases. The study was performed to conduct antioxidant, cytotoxic, thrombolytic, membrane stabilizing, antimicrobial, peripheral and central analgesic and hypoglycemic activity assays and phenobarbitone sodium-induced sleeping time test using crude methanol extract of flowers of L. speciosa and its different partitionates.

METHOD

The antioxidant potential was evaluated by determining the ability of the samples to scavenge 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The cytotoxic potential was examined following the procedures of brine shrimp lethality bioassay. Thrombolytic potential was assayed using streptokinase as standard. The samples were subjected to membrane stabilizing activity assay under heat induced condition. Antimicrobial potential was observed by disc diffusion method. The ability of the extract to inhibit writhing induced by acetic acid was determined in peripheral analgesic activity assay. The extract was also tested for central analgesic and hypoglycemic activities by tail flicking and tail tipping methods in Swiss albino mice model, respectively. CNS depressant activity was evaluated by an assay in which sleep was induced in mice using phenobarbitone sodium.

RESULTS

The chloroform soluble fraction of L. speciosa extract demonstrated the highest antioxidant activity (IC50 = 4.20 ± 0.41 μg/ml) while the most prominent cytotoxic potency was showed by hexane soluble fraction (LC50 = 2.00 ± 0.31 μg/ml). Among the test samples, the carbon tetrachloride soluble fraction induced clot lysis (64.80 ± 0.27%) and prevented heat induced haemolysis (41.90 ± 0.10%) to the maximum extent. The largest zone of inhibition (19.0 mm) against Staphylococcus aureus, was also observed for the same fraction. In peripheral analgesic activity assay, 16.68% inhibition of writhing was documented for the L. speciosa extract (400 mg/kg body weight dose). The extract (400 mg/kg dose) also reduced blood sugar level by 56.12% after three hours of administration of glucose solution. In CNS depressant activity assay, mice of the sample group slept for shorter period of time compared to control group.

CONCLUSIONS

From our investigation, it can be suggested that, the extract should be further studied for possible phytochemicals responsible for the observed biological activities.

Vasodilator Activity of Compounds Isolated from Plants Used in Mexican Traditional Medicine

Arterial hypertension is one of the main risk factors in the development of cardiovascular diseases. Therefore, it is important to look for new drugs to treat hypertension. In this study, we carried out the screening of 19 compounds (triterpenes, diterpenes, sesquiterpenes, lignans, and flavonoids) isolated from 10 plants used in Mexican traditional medicine to determine whether they elicited vascular smooth muscle relaxation and, therefore, could represent novel anti-hypertension drug candidates. The vasorelaxant activity of these compounds was evaluated on the isolated rat aorta assay and the results obtained from this evaluation showed that three compounds induced a significant vasodilatory effect: meso-dihydroguaiaretic acid [half maximal effective concentration (EC₅₀), 49.9 ± 11.2 µM; maximum effect (Emax), 99.8 ± 2.7%]; corosolic acid (EC₅₀, 108.9 ± 6.7 µM; Emax, 96.4 ± 4.2%); and 5,8,4′-trihydroxy-3,7-dimethoxyflavone (EC₅₀, 122.3 ± 7.6 µM; Emax, 99.5 ± 5.4%). Subsequently, involvement of the NO/cyclic guanosine monophosphate (cGMP) and H₂S/ATP-sensitive potassium channel (K_ATP) pathways on the vasodilator activity of these compounds was assessed. The results derived from this analysis showed that the activation of both pathways contributes to the vasorelaxant effect of corosolic acid. On the other hand, the vasodilator effect of meso-dihydroguaiaretic acid and 5,8,4′-trihydroxy-3,7-dimethoxyflavone, partly involves stimulation of the NO/cGMP pathway. However, these compounds also showed an important endothelium-independent vasorelaxant effect, whose mechanism of action remains to be clarified. This study indicates that meso-dihydroguaiaretic acid, corosolic acid, and 5,8,4′-trihydroxy-3,7-dimethoxyflavone could be used as lead compounds for the synthesis of new derivatives with a higher potency to be developed as drugs for the prevention and treatment of cardiovascular diseases.

The Vasodilatory Effects of Anti-Inflammatory Herb Medications: A Comparison Study of Four Botanical Extracts

Inflammation plays a pivotal role in the development and progression of cardiovascular diseases, in which, the endothelium dysfunction has been a key element. The current study was designed to explore the vasodilatory effect of anti-inflammatory herbs which have been traditionally used in different clinical applications. The total saponins from Actinidia arguta radix (SAA), total flavonoids from Glycyrrhizae radix et rhizoma (FGR), total coumarins from Peucedani radix (CPR), and total flavonoids from Spatholobi caulis (FSC) were extracted. The isometric measurement of vasoactivity was used to observe the effects of herbal elements on the isolated aortic rings with or without endothelium. To understand endothelium-independent vasodilation, the effects of herb elements on agonists-induced vasocontractility and on the contraction of endothelium-free aortic rings exposed to a Ca²⁺-free medium were examined. Furthermore, the role of nitric oxide signaling in endothelium-dependent vasodilation was also evaluated. In summary, FGR and FSC exhibit potent anti-inflammatory effects compared to CPR and SAA. FGR exerts the strongest vasodilatory effect, while CPR shows the least. The relaxation induced by SAA and FSC required intact endothelia. The mechanism of this vasodilation might involve eNOS. CPR-mediated vasorelaxation appears to involve interference with intracellular calcium homeostasis, blocking Ca²⁺ influx or releasing intracellular Ca²⁺.

The aetiology of cardiovascular disease: a role for mitochondrial DNA?

Cardiovascular disease (CVD) is a world-wide cause of mortality in humans and its incidence is on the rise in Africa. In this review, we discuss the putative role of mitochondrial dysfunction in the aetiology of CVD and consequently identify mitochondrial DNA (mtDNA) variation as a viable genetic risk factor to be considered. We then describe the contribution and pitfalls of several current approaches used when investigating mtDNA in relation to complex disease. We also propose an alternative approach, the adjusted mutational load hypothesis, which would have greater statistical power with cohorts of moderate size, and is less likely to be affected by population stratification. We therefore address some of the shortcomings of the current haplogroup association approach. Finally, we discuss the unique challenges faced by studies done on African populations, and recommend the most viable methods to use when investigating mtDNA variation in CVD and other common complex disease.

Allspice and Clove As Source of Triterpene Acids Activating the G Protein-Coupled Bile Acid Receptor TGR5

Worldwide, metabolic diseases such as obesity and type 2 diabetes have reached epidemic proportions. A major regulator of metabolic processes that gained interest in recent years is the bile acid receptor TGR5 (Takeda G protein-coupled receptor 5). This G protein-coupled membrane receptor can be found predominantly in the intestine, where it is mainly responsible for the secretion of the incretins glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). The aim of this study was (i) to identify plant extracts with TGR5-activating potential, (ii) to narrow down their activity to the responsible constituents, and (iii) to assess whether the intestinal microbiota produces transformed metabolites with a different activity profile. Chenodeoxycholic acid (CDCA) served as positive control for both, the applied cell-based luciferase reporter gene assay for TGR5 activity and the biotransformation assay using mouse fecal slurry. The suitability of the workflow was demonstrated by the biotransformation of CDCA to lithocholic acid resulting in a distinct increase in TGR5 activity. Based on a traditional Tibetan formula, 19 plant extracts were selected and investigated for TGR5 activation. Extracts from the commonly used spices Syzygium aromaticum (SaroE, clove), Pimenta dioica (PdioE, allspice), and Kaempferia galanga (KgalE, aromatic ginger) significantly increased TGR5 activity. After biotransformation, only KgalE showed significant differences in its metabolite profile, which, however, did not alter its TGR5 activity compared to non-transformed KgalE. UHPLC-HRMS (high-resolution mass spectrometry) analysis revealed triterpene acids (TTAs) as the main constituents of the extracts SaroE and PdioE. Identification and quantification of TTAs in these two extracts as well as comparison of their TGR5 activity with reconstituted TTA mixtures allowed the attribution of the TGR5 activity to TTAs. EC50s were determined for the main TTAs, i.e., oleanolic acid (2.2 ± 1.6 μM), ursolic acid (1.1 ± 0.2 μM), as well as for the hitherto unknown TGR5 activators corosolic acid (0.5 ± 1.0 μM) and maslinic acid (3.7 ± 0.7 μM). In conclusion, extracts of clove, allspice, and aromatic ginger activate TGR5, which might play a pivotal role in their therapeutic use for the treatment of metabolic diseases. Moreover, the TGR5 activation of SaroE and PdioE could be pinpointed solely to TTAs.

Acute and Subacute Oral Toxicity Evaluation of Eriobotrya japonica Leaf Triterpene Acids in ICR Mice

The interest focusing on Eriobotrya japonica leaf triterpene acid (ELTA) has increased recently because of its beneficial effects on health. However, there has been a lack of experimental data on its toxicity. The present study therefore was conducted to evaluate its toxicity in ICR mice. The results showed that ELTA produced neither mortality nor toxicity of the main organs in ICR male and female mice in both acute (0.30, 0.65, 1.39, and 3.00 g·kg⁻¹ body weight) and subacute (150, 300, and 600 mg·kg⁻¹ BW) 28-day toxicity studies. Because of lacking apparently adverse effects found in the hematology, clinical biochemistry, and histopathology evaluation, results of the present study together with the beneficial effects make ELTA as a promising dietary supplement and indicated that ELTA administered orally might have a large safety margin for human.

Inhibition of Mitochondrial Fission and NOX2 Expression Prevent NLRP3 Inflammasome Activation in the Endothelium: The Role of Corosolic Acid Action in the Amelioration of Endothelial Dysfunction

AIMS

Corosolic acid (CRA) is a natural triterpenoid with antioxidative activity. This study was designed to elucidate the mechanism through which CRA protected vessel endothelial homeostasis by combating oxidative stress.

RESULTS

In endothelial cells, CRA induced dynamin-related protein 1 (Drp1) phosphorylation at Ser637 and thus inhibited mitochondrial fission in response to oxidative stress. It promoted AMP-activated protein kinase (AMPK) activity in an LKB1-dependent manner, and silencing AMPK abrogated its inhibitory effect on Drp1 activation and mitochondrial fission. CRA inhibited the translocation of p47(phox) and p67(phox) and the overexpression of gp91(phox) induced by palmitate (PA), demonstrating its action in suppression of NOX2 activation. Drp1 knockdown reduced PA-induced gp91(phox) expression, while Drp1 induction was also diminished by gp91(phox) knockdown, suggesting the reciprocal relationship between NOX2 and Drp1. Knockdown Drp1 or gp91(phox) attenuated PA-induced NLRP3 induction and enhanced inhibitory effects of CRA. Oral administration of CRA in high-fat diet mice reproduced similar regulation in the aorta endothelium, further confirming its protection on endothelial homeostasis in vivo.

INNOVATION

This study demonstrated that the defect in mitochondrial morphology is associated with the oxidative stress and NLRP3 inflammasome activation in the endothelium. Drp1 and NOX2 regulated each other and worked together to induce NLRP3 inflammasome activation, suggesting that modulation of Drp1 phosphorylation (Ser637) might be a potential therapeutic target for combating oxidative stress in vessel diseases.

CONCLUSION

CRA prevented mitochondrial fission by regulation of Drp1 phosphorylation (Ser637) in an AMPK-dependent manner, and this action contributed to blocking NOX2 oxidase signaling and suppressing NLRP3 inflammasome activation in the endothelium. Antioxid. Redox Signal. 24, 893-908.

2α-Hydroxyursolic Acid Inhibited Cell Proliferation and Induced Apoptosis in MDA-MB-231 Human Breast Cancer Cells through the p38/MAPK Signal Transduction Pathway

The mechanisms of action of 2α-hydroxyursolic acid in inhibiting cell proliferation and inducing apoptosis in MDA-MB-231 human breast cancer cells were investigated. The antiproliferative activity and cytotoxicity were determined by the methylene blue assay. The expression of proteins was determined using Western blot. 2α-Hydroxyursolic acid significantly inhibited MDA-MB-231 cell proliferation, and no cytotoxicity was observed at concentrations below 30 μM. 2α-Hydroxyursolic acid significantly down-regulated expressions of TRAF2, PCNA, cyclin D1, and CDK4 and up-regulated the expressions of p-ASK1, p-p38, p-p53, and p-21. 2α-Hydroxyursolic acid induced apoptosis in MDA-MB-231 cells by significantly increasing the Bax/Bcl-2 ratio and inducing the cleaved caspase-3. Additionally, treatment of SB203580, a p38 MAPK specific inhibitor, reversed the inhibition of PCNA, cyclin D1, and Bcl-2 expression induced by 2α-hydroxyursolic acid in MDA-MB-231 cells. These results suggested that 2α-hydroxyursolic acid exhibited anticancer activity through the inhibition of cell proliferation and the induction of apoptosis by regulating the p38/MAPK signal transduction pathway.

Corosolic acid inhibits adipose tissue inflammation and ameliorates insulin resistance via AMPK activation in high-fat fed mice

BACKGROUND

Adipose tissue inflammation is tightly associated with the development of insulin resistance. Corosolic acid (CRA), a natural triterpenoid, is well known as "phyto-insulin" due to its insulin-like activities. However, its underlying mechanism remains unknown.

PURPOSE

In this study, we investigated the mechanisms of CRA on improving insulin resistance both in vivo and in vitro.

METHODS

C57BL/6 mice were fed with normal diet, high-fat diet (HFD) or HFD with CRA, respectively. General biochemical parameters in blood and glucose intolerance in mice were assayed. Meanwhile, proinflammatory cytokines and macrophage infiltrations in adipose tissues were analyzed by real-time PCR and immunohistochemical staining. The effects of CRA on insulin signaling transduction and AMPK activity in adipose tissues were investigated by western blot. Furthermore, the effects of CRA on AMPK were confirmed on 3T3-L1 cells by using both AMPK inhibitor and AMPKα1/2-specific siRNA RESULTS: CRA attenuated hyperlipidemia, improved insulin sensitivity and glucose intolerance in mice. Meanwhile, it alleviated inflammation in adipose tissues, demonstrated by the suppression of IKKβ phosphorylation and down-regulation of gene expressions of proinflammatory cytokines. Histological analysis revealed that CRA attenuated macrophage infiltrations into adipose tissue. It also improved insulin signaling transduction by modification of Ser/Thr phosphorylation of IRS-1 and downstream Akt, thereby improved insulin sensitivity in HFD-fed mice. Furthermore, CRA regulated AMPK activation in a LKB1-dependent manner. AMPKα knockdown in adipocytes abolished the inhibitory effects of CRA on IKKβ and IRS-1 serine phosphorylation, indicating that CRA inhibited inflammation and ameliorated insulin resistance via AMPK activation.

CONCLUSIONS

CRA inhibited inflammation with improvement in adipose tissue dysfunction and ameliorated insulin resistance in an AMPK-dependent manner.

Inhibitory effects and actions of pentacyclic triterpenes upon glycation

Pentacyclic triterpenic compounds including asiatic, betulinic, maslinic, oleanolic and ursolic acid occur naturally in many herbs and plant foods. It is well known that these triterpenoids possess anti-oxidative and anti-inflammatory activities. Furthermore, recent in vitro and in vivo researches indicated that these compounds could inhibit the production of advanced glycation end-products (AGEs). The impact of these triterpenes upon the activity and protein expression of enzymes involved in polyol pathway including aldose reductase and sorbitol dehydrogenase has been examined, and positive results are reported. These studies suggest that certain triterpenes are potent anti-glycative agents, and may benefit the prevention and/or therapy of glycation-related diseases such as diabetes mellitus and Alzheimer’s disease. In this review article, the anti-glycative activity and action mode of certain triterpenes are highlighted. These information may promote the anti-glycative application of these natural compounds.

Corosolic Acid Exhibits Anti-angiogenic and Anti-lymphangiogenic Effects on In Vitro Endothelial Cells and on an In Vivo CT-26 Colon Carcinoma Animal Model

We describe the anti-angiogenic and anti-lymphangiogenic effects of corosolic acid, a pentacyclic triterpenoid isolated from Cornus kousa Burg. A mouse colon carcinoma CT-26 animal model was employed to determine the in vivo anti-angiogenic and anti-lymphangiogenic effects of corosolic acid. Corosolic acid induced apoptosis in CT-26 cells, mediated by the activation of caspase-3. In addition, it reduced the final tumor volume and the blood and lymphatic vessel densities of tumors, indicating that it suppresses in vivo angiogenesis and lymphangiogenesis. Corosolic acid inhibited the proliferation and tube formation of human umbilical vein endothelial cells and human dermal lymphatic microvascular endothelial cells. In addition, corosolic acid decreased the proliferation and migration of human umbilical vein endothelial cells stimulated by angiopoietin-1. Pretreatment with corosolic acid decreased the phosphorylation of focal adhesion kinase (FAK) and ERK1/2, suggesting that corosolic acid contains anti-angiogenic activity that can suppress FAK signaling induced by angiopoietin-1.

Aortic relaxant activity of Crataegus gracilior Phipps and identification of some of its chemical constituents

This study focused on the assessment of the vasorelaxant activity of the organic and aqueous extracts obtained from leaves and fruits of a Mexican hawthorn (Crataegus gracilior) on isolated rat aorta, and on the purification and identification of some of their secondary metabolites by the use of chromatographic and spectroscopic techniques. The results obtained showed that the methanol extract has a significantly more potent and effective vasorelaxant effect than the other tested extracts, with an EC₅₀ = 8.69 ± 4.34 µg/mL and an E_max = 94.6% ± 11.30%, values that are close to that of acetylcholine, the positive control. From the same extract, two major triterpenes were isolated and identified as ursolic and corosolic acids by comparison of their experimental NMR spectroscopic data with those reported in the literature. Chlorogenic acid, rutin, quercetin, kaempferol and (+)-catechin were also identified using HPLC coupled with PDAD. All these compounds have already been proven to possess on their own antihypertensive effect and other benefits on cardiovascular diseases and they can support, at least in part, the traditional use of this plant species.

Corosolic acid content and SSR markers in Lagerstroemia speciosa (L.) Pers.: a comparative analysis among populations across the Southern Western Ghats of India

Lagerstroemia speciosa commonly known as 'Banaba' is native of south-east Asia which exhibits both horticultural and therapeutic value. The anti-diabetic and anti-obese property of the tree is attributed to corosolic acid (CRA)-a pentacyclic triterpene seen predominantly in the mature leaves. Although there are studies on either chemical or genetic variation in L. speciosa from different regions, none have dealt with their association to discuss the formation of chemical diversity. For the first time, we have analyzed CRA content in 12 natural populations corresponding to 42 samples seen in the Southern Western Ghats (SWG) using chromatography techniques and genetic variation estimated using SSR markers. Significant variation in percentage distribution of CRA ranging from 0.005% to 0.868% dr.wt. was recorded wherein populations from the north SWG contain relatively more active principle (mean=0.321%) than their counterparts in the south (mean=0.064%). Similarly, SSR data showing relatively high rate of gene flow (Nm=2.72) and low genetic differentiation (FST=0.14) is indicative that populations from north are genetically more diverse than those in the south (Nm=0.48; FST=0.38). The scatter plot derived by Principle Component Analysis (PCA) of chemical and genetic data shows similar pattern of clustering that reveals strong association between the two sets of data. It is concluded that the observed variation in CRA content in natural populations of the species depends more on the genetic background and less on edaphic factors.

The role of triterpenes in the management of diabetes mellitus and its complications

Diabetes mellitus is a chronic metabolic disease which is a serious global problem. In 2010 an estimated 285 million people had diabetes and within the next 20 years this value is expected to almost double. Many antidiabetic therapies focus on improving insulin sensitivity, increasing insulin production, and/or decreasing the level of blood glucose. Although a number of synthetic medicines are available, drugs of natural origin have aroused great interest. Triterpenes seem to demonstrate adequate properties. Many experiments have shown that these compounds have several antidiabetic mechanisms. They can inhibit enzymes involved in glucose metabolism, prevent the development of insulin resistance and normalize plasma glucose and insulin levels. These natural compounds, in contrast to synthetic drugs, apart from producing a hypoglycemic effect have also been found to manifest hypolipidemic and anti-obesity activity. Triterpenes are also promising agents in the prevention of diabetic complications. They have strong antioxidant activity and inhibit the formation of advanced glycation end products, implicated in the pathogenesis of diabetic nephropathy, embryopathy, neuropathy or impaired wound healing. Until now very few clinical studies have been concerned with the application of triterpenes in treating diabetes. However, due to their great therapeutic potential, these compounds deserve special attention.