Anti-Diabetic Effects of Madecassic Acid and Rotundic Acid

Hydroalcoholic Extract of Centella asiatica and Madecassic Acid Reverse Depressive-Like Behaviors, Inflammation and Oxidative Stress in Adult Rats Submitted to Stress in Early Life

Major depressive disorder (MDD) is a severe disorder that causes enormous loss of quality of life, and among the factors underlying MDD is stress in maternal deprivation (MD). In addition, classic pharmacotherapy has presented severe adverse effects. Centella asiatica (C. asiatica) demonstrates a potential neuroprotective effect but has not yet been evaluated in MD models. This study aimed to evaluate the effect of C. asiatica extract and the active compound madecassic acid on possible depressive-like behavior, inflammation, and oxidative stress in the hippocampus and serum of young rats submitted to MD in the first days of life. Rats (after the first day of birth) were separated from the mother for 3 h a day for 10 days. When adults, these animals were divided into groups and submitted to treatment for 14 days. After subjecting the animals to protocols of locomotor activity in the open field and behavioral despair in the forced swimming test, researchers then euthanized the animals. The hippocampus and serum were collected and analyzed for the inflammatory cytokines and oxidative markers. The C. asiatica extract and active compound reversed or reduced depressive-like behaviors, inflammation in the hippocampus, and oxidative stress in serum and hippocampus. These results suggest that C. asiatica and madecassic acid have potential antidepressant action, at least partially, through anti-inflammatory and antioxidant profiles.

Efficacy of Rotundic Acid and Its Derivatives as Promising Natural Anticancer Triterpenoids: A Literature-Based Study

Rotundic acid (RA) is a naturally occurring pentacyclic triterpene with a multitude of pharmacological activities. The primary emphasis of this study is on summarizing the anticancer properties with the underlying mechanisms of RA and its derivatives, as well as the pharmacokinetic features. Data was collected (up to date as of November 10, 2023) from various reliable and authentic literatures by searching in different academic search engines, including PubMed, Springer Link, Scopus, Wiley Online, Web of Science, ScienceDirect, and Google Scholar. The findings imply that RA and its synthetic derivatives possess promising anti-cancer properties against breast, colorectal, liver, and cervical cancers in various preclinical pharmacological test systems. The results also indicate that RA and its derivatives demonstrated anticancer effects via a number of cellular mechanisms, including apoptotic cell death, inhibition of oxidative stress, anti-inflammatory effect, cytotoxicity, cell cycle arrest, anti-proliferative effect, anti-angiogenic effect, and inhibition of cancer cell migration and invasion. It has been proposed that RA and its derived compounds have the capability to serve as a hopeful chemotherapeutic agent, so further extensive clinical research is necessary.

EVOO supplement prevents type 1 diabetes by modulating gut microbiota and serum metabolites in NOD mice

AIMS

Extra virgin olive oil (EVOO) is the highest quality olive oil available and has been shown to regulate postprandial blood glucose in patients with type 1 diabetes (T1D). However, it remains uncertain whether EVOO can prevent the onset of T1D. In this study, we investigated the potential preventive effect of orally administered EVOO on T1D in non-obese diabetic (NOD) mice.

MAIN METHODS

We analyzed changes in fecal microbes using 16 s rDNA sequencing and serum metabolites using Ultra High-Performance Liquid Chromatography and Quadrupole Time-of-Flight Mass Spectrometry (Q-TOF-MS).

KEY FINDINGS

Our findings showed that EVOO supplementation in NOD mice slowed gastric emptying, reduced insulitis, and delayed T1D onset. Moreover, EVOO altered the composition of fecal microbes, increasing the Bacteroidetes/Firmicutes ratio, and promoting the growth of short-chain fatty acids (SCFAs)-producing bacteria, such as Lachnoclostridium and Ruminococcaceae_UCG-005. Moreover, it also increased beneficial serum metabolites, including unsaturated fatty acid and triterpenoid, which positively correlated with the increased SCFA-producing bacteria and negatively correlated with the disease indicators. Conversely, most decreased serum lipid metabolites, such as Oleamide, showed the opposite trend.

SIGNIFICANCE

Our study demonstrates that EVOO may ameliorate pancreas inflammation and prevent T1D onset in NOD mice by modulating gut microbiota and serum metabolites.

Rotundic acid improves nonalcoholic steatohepatitis in mice by regulating glycolysis and the TLR4/AP1 signaling pathway

BACKGROUND

Steatosis and inflammation are the hallmarks of nonalcoholic steatohepatitis (NASH). Rotundic acid (RA) is among the key triterpenes of Ilicis Rotundae Cortex and has exhibited multipronged effects in terms of lowering the lipid content and alleviating inflammation. The study objective is to systematically evaluate the potential mechanisms through which RA affects the development and progression of NASH.

METHODS

Transcriptomic and proteomic analyses of primary hepatocytes isolated from the control, high-fat diet-induced NASH, and RA treatment groups were performed through Gene Ontology analysis and pathway enrichment. Hub genes were identified through network analysis. Integrative analysis revealed key RA-regulated pathways, which were verified by gene and protein expression studies and cell assays.

RESULTS

Hub genes were identified and enriched in the Toll-like receptor 4 (TLR4)/activator protein-1 (AP1) signaling pathway and glycolysis pathway. RA reversed glycolysis and attenuated the TLR4/AP1 pathway, thereby reducing lipid accumulation and inflammation. Additionally, lactate release in L-02 cells increased with NaAsO2-treated and significantly decreased with RA treatment, thus revealing that RA had a major impact on glycolysis.

CONCLUSIONS

RA is effective in lowering the lipid content and reducing inflammation in mice with NASH by ameliorating glycolysis and TLR4/AP1 pathways, which contributes to the existing knowledge and potentially sheds light on the development of therapeutic interventions for patients with NASH.

In Silico Analysis Reveals the Inhibitory Potential of Madecassic Acid against Entry Factors of SARS-CoV-2

Coronavirus disease 19 (COVID-19) is the ongoing global health emergency caused by SARS-CoV-2 infection. The virus is highly contagious, affecting millions of people worldwide. SARS-CoV-2, with its trimeric spike glycoprotein, interacts with the angiotensin-converting enzyme 2 (ACE2) receptor and other co-receptors like basigin to invade the host cell. Moreover, certain host proteases like transmembrane serine proteases, furin, neuropilin 1 (NRP1), and endosomal cathepsins are involved in the priming of spike glycoproteins at the S1/S2 interface. This is critical for the entry of viral genome and its replication in the host cytoplasm. Vaccines and anti-SARS-CoV-2 drugs have been developed to overcome the infection. Nonetheless, the frequent emergence of mutant variants of the virus has imposed serious concerns regarding the efficacy of therapeutic agents, including vaccines that were developed for previous strains. Thus, screening and development of pharmaceutical agents with multi-target potency could be a better choice to restrain SARS-CoV-2 infection. Madecassic acid (MDCA) is a pentacyclic triterpenoid found in Centella asiatica. It has multiple medicinal properties like anti-oxidative, anti-inflammatory, and anti-diabetic potential. However, its implication as an anti- SARS-CoV-2 agent is still obscure. Hence, in the present in silico study, the binding affinities of MDCA for spike proteins, their receptors, and proteases were investigated. Results indicated that MDCA interacts with ligand-binding pockets of the spike receptor binding domain, ACE2, basigin, and host proteases, viz. transmembrane serine proteinase, furin, NRP1, and endosomal cathepsins, with greater affinities. Moreover, the MDCA-protein interface was strengthened by prominent hydrogen bonds and several hydrophobic interactions. Therefore, MDCA could be a promising multi-target therapeutic agent against SARS-CoV-2 infection.

Antibacterial Activity and Mechanism of Madecassic Acid against Staphylococcus aureus

Antibacterial resistance has become one of the most serious problems threating global health. To overcome this urgent problem, many scientists have paid great attention to developing new antibacterial drugs from natural products. Hence, for exploring new antibacterial drugs from Chinese medicine, a series of experiments were carried out for verifying and elucidating the antibacterial activity and mechanisms of madecassic acid (MA), which is an active triterpenoid compound isolated from the traditional Chinese medicine, Centella asiatica. The antibacterial activity was investigated through measuring the diameter of the inhibition zone, the minimum inhibitory concentration (MIC), the growth curve, and the effect on the bacterial biofilm, respectively. Meanwhile, the antibacterial mechanism was also discussed from the aspects of cell wall integrity variation, cell membrane permeability, and the activities of related enzymes in the respiratory metabolic pathway before and after the intervention by MA. The results showed that MA had an inhibitory effect on eight kinds of pathogenic bacteria, and the MIC values for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Bacillus megaterium were 31.25, 62.5, 250, 125, 62.5, and 62.5 µg/mL, respectively. For instance, 31.25 µg/mL MA could inhibit the growth of Staphylococcus aureus within 28 h. The antibacterial mechanism experiments confirmed that MA could destroy the integrity of the cell membrane and cell wall of Staphylococcus aureus, causing the leakage of macromolecular substances, inhibiting the synthesis of soluble proteins, reducing the activities of succinate dehydrogenase and malate dehydrogenase, and interacting with DNA, leading to the relaxation and ring opening of supercoiled DNA. Besides, the activities of DNA topoisomerase I and II were both inhibited by MA, which led to the cell growth of Staphylococcus aureus being repressed. This study provides a theoretical basis and reference for the application of MA in the control and inhibition of food-borne Staphylococcus aureus.

UPLC-QTOF-MS Based Comparison of Rotundic Acid Metabolic Profiles in Normal and NAFLD Rats

Rotundic acid, the principal bioactive constituent of the herbal remedy "Jiubiying", has been considered as a candidate compound for treating non-alcoholic fatty liver disease (NAFLD). However, the in vivo and in vitro metabolism of rotundic acid has remained unclear. With the aim of elucidating its metabolic profile, a reliable approach that used ultra-high performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was applied for screening and identifying rotundic acid in vivo (plasma, feces, urine, and liver tissue of normal and NAFLD model rats) and in vitro (rat liver microsomes) metabolites. Herein, 26 metabolites of rotundic acid were identified, including 22 metabolites in normal rats, 20 metabolites in NAFLD model rats, and eight metabolites in rat liver microsomes. Among them, 17 metabolites were identified for the first time. These data illustrate that the pathological status of NAFLD affects the metabolism of rotundic acid. Furthermore, the major pathways of metabolism included phase Ⅰ (demethylation, desaturation, etc.) and phase Ⅱ (sulfation and glucuronidation) reactions, as well as a combined multiple-step metabolism. This work provides important information on the metabolism of rotundic acid and lays the foundation for its future clinical application.

Madecassic Acid Ameliorates the Progression of Osteoarthritis: An in vitro and in vivo Study

PURPOSE

Osteoarthritis (OA) places a significant burden on society and finance, and there is presently no effective treatment besides late replacement surgery and symptomatic relief. The therapy of OA requires additional research. Madecassic acid (MA) is the first native triterpenoid compound extracted from Centella asiatica, which has a variety of anti-inflammatory effects. However, the role of MA in OA therapy has not been reported. This study aimed to explore whether MA could suppress the inflammatory response, preserve and restore chondrocyte functions, and ameliorate the progression of OA in vitro and in vivo.

METHODS

Rat primary chondrocytes were treated with IL-1β to simulate inflammatory environmental conditions and OA in vitro. We examined the effects of MA at concentrations ranging from 0 to 200 µM on the viability of rat chondrocytes and selected 10 µM for further study. Using qRT-PCR, immunofluorescent, immunocytochemistry, and Western blotting techniques, we identified the potential molecular mechanisms and signaling pathways that are responsible for these effects. We established an OA rat model by anterior cruciate ligament transection (ACLT). The animals were then periodically injected with MA into the knee articular cavity.

RESULTS

We found that MA could down-regulate the IL-1β-induced up-regulation of COX-2, iNOS and IL-6 and restore the cytoskeletal integrity of chondrocytes treated with IL-1β. Moreover, MA protects chondrocytes from IL-1β-induced ECM degradation by upregulating ECM synthesis related protein expression, including collagen-II and ACAN, and further down-regulating ECM catabolic related protein expression, including MMP-3 and MMP-13. Furthermore, we found that NF-κB/IκBα and PI3K/AKT signaling pathways were involved in the regulatory effects of MA on the inflammation inhibition and promotion of ECM anabolism on IL-1β-induced chondrocytes.

CONCLUSION

These findings suggest that MA appears to be a potentially small molecular drug for rat OA.

Intestinal absorption mechanism of rotundic acid: Involvement of P-gp and OATP2B1

ETHNOPHARMACOLOGICAL RELEVANCE

Ilicis Rotundae Cortex (IRC), the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), has been used for the prevention or treatment of colds, tonsillitis, dysentery, and gastrointestinal diseases in folk medicine due to its antibacterial and anti-inflammatory effects. However, there is no report about the intestinal absorption of major compounds that support traditional usage.

AIM OF STUDY

Considering the potential of rotundic acid (RA) - major biologically active pentacyclic triterpenes found in the IRC, this study was purposed to uncover the oral absorption mechanism of RA using in situ single-pass intestinal perfusion (SPIP) model, in vitro cell models (Caco-2, MDCKII-WT, MDCKII-MDR1, MDCKII-BCRP, and HEK293-OATP2B1 cells) and in vivo pharmacokinetics studies in rats.

MATERIALS AND METHODS

The molecular properties (solubility, lipophilicity, and chemical stability) and the effects of principal parameters (time, compound concentrations, pH, paracellular pathway, and the different intestinal segments) were analyzed by liquid chromatography-tandem mass spectrometry. The susceptibility of RA to various inhibitors, such as P-gp inhibitor verapamil, BCRP inhibitor Ko143, OATP 2B1 inhibitor rifampicin, and absorption enhancer EGTA were assessed.

RESULTS

RA was a compound with low water solubility (12.89 μg/mL) and strong lipophilicity (LogP = 4.1). RA was considered stable in all media during the SPIP and transport studies. The SPIP and cell experiments showed RA was moderate absorbed in the intestines and exhibited time, concentration, pH, and segment-dependent permeability. In addition, results from the cell model, in situ SPIP model as well as the in vivo pharmacokinetics studies consistently showed that verapamil, rifampicin, and EGTA might have significant effect on the intestinal absorption of RA.

CONCLUSION

The mechanisms of intestinal absorption of RA might involve multiple transport pathways, including passive diffusion, the participation of efflux (i.e., P-gp) and influx (i.e., OATP2B1) transporters, and paracellular pathways.

The Role of Cyclodextrins in the Design and Development of Triterpene-Based Therapeutic Agents

Triterpenic compounds stand as a widely investigated class of natural compounds due to their remarkable therapeutic potential. However, their use is currently being hampered by their low solubility and, subsequently, bioavailability. In order to overcome this drawback and increase the therapeutic use of triterpenes, cyclodextrins have been introduced as water solubility enhancers; cyclodextrins are starch derivatives that possess hydrophobic internal cavities that can incorporate lipophilic molecules and exterior surfaces that can be subjected to various derivatizations in order to improve their biological behavior. This review aims to summarize the most recent achievements in terms of triterpene:cyclodextrin inclusion complexes and bioconjugates, emphasizing their practical applications including the development of new isolation and bioproduction protocols, the elucidation of their underlying mechanism of action, the optimization of triterpenes’ therapeutic effects and the development of new topical formulations.

Influence of verapamil on the pharmacokinetics of rotundic acid in rats and its potential mechanism

CONTEXT

Rotundic acid (RA), a plant-derived pentacyclic triterpene acid, has been reported to possess extensive pharmacological activities. The poor bioavailability limits its further development and potential clinic application.

OBJECTIVE

To clarify the potential mechanism for poor oral bioavailability.

MATERIALS AND METHODS

The single-dose pharmacokinetics of orally administered RA (10 mg/kg) in Sprague-Dawley rats without or with verapamil (25 or 50 mg/kg) were investigated. Additionally, MDCKII-MDR1 and Caco-2 cell monolayers, five recombinant human cytochrome P450 (rhCYP) enzymes (1A2, 2C8, 2C9, 2D6 and 3A4), and rat liver microsomes were also conducted to investigate its potential mechanism.

RESULTS

Verapamil could significantly affect the plasma concentration of RA. Co-administered verapamil at 25 and 50 mg/kg, the AUC_0-∞ increased from 432 ± 64.2 to 539 ± 53.6 and 836 ± 116 ng × h/mL, respectively, and the oral clearance decreased from 23.6 ± 3.50 to 18.7 ± 1.85 and 12.2 ± 1.85 L/h/kg, respectively. The MDCKII-MDR1 cell assay showed that RA might be a P-gp substrate. The rhCYPs experiments indicated that RA was mainly metabolized by CYP3A4. Additionally, verapamil could increase the absorption of RA by inhibiting the activity of P-gp, and slow down the intrinsic clearance of RA from 48.5 ± 3.18 to 12.0 ± 1.06 µL/min/mg protein.

DISCUSSION AND CONCLUSIONS

These findings indicated that verapamil could significantly affect the pharmacokinetic profiles of RA in rats. It was demonstrated that P-gp and CYP3A were involved in the transport and metabolism of RA, which might contribute to the low oral bioavailability of RA.

Rotundic acid ameliorates non-alcoholic steatohepatitis via SREBP-1c/ SCD1 signaling pathway and modulating gut microbiota

Non-alcoholic steatohepatitis (NASH) is a devastating form of non-alcoholic fatty liver disease (NAFLD) with distinguished hallmarks of steatosis and inflammation. Rotundic acid (RA) is a natural pentacyclic triterpene compound extracted from the bank of Ilex rotunda Thunb with a wide range of biological activities. The aim of the study is to evaluate the pharmacological effect and action mechanism of RA on NASH in vitro and in vivo. RA has weak lipid lowering ability in rat primary hepatocytes, significantly decreases serum LDL level, hepatic TG and TC levels and lipid droplets, reduces NAS compared with the NASH group, and alleviates hepatic inflammation. RA also enhances the recovery of intestinal bacterial community and intestinal-derived short-chain fatty acid caused by high food diet (HFD). Further investigation shows that RA protects against HFD-induced NASH via downregulating the expression of SREBP-1c/SCD1 signaling pathway and improving gut microbiota. These findings imply that RA might be helpful for the alleviation of NASH.

Actions and Therapeutic Potential of Madecassoside and Other Major Constituents of Centella asiatica: A Review

Centella asiatica is a popular herb well-known for its wide range of therapeutic effects and its use as a folk medicine for many years. Its therapeutic properties have been well correlated with the presence of asiaticoside, madecassoside, asiatic and madecassic acids, the pentacyclic triterpenes. The herb has been extensively known to treat skin conditions; nevertheless, several pre-clinical and clinical studies have scientifically demonstrated its effectiveness in other disorders. Among the active constituents that have been identified in Centella asiatica, madecassoside has been the subject of only a relatively small number of scientific reports. Therefore, this review, while including other major constituents of this plant, focuses on the therapeutic potential, pharmacokinetics and toxicity of madecassoside.

Ethanolic Extract of Centella asiatica Treatment in the Early Stage of Hyperglycemia Condition Inhibits Glomerular Injury and Vascular Remodeling in Diabetic Rat Model

Background

Diabetes mellitus (DM) is marked by oxidative stress, inflammation, and vascular dysfunction that caused diabetic nephropathy that resulted in end-stage renal disease (ESRD). Vascular dysfunction is characterized by an imbalance in vasoconstrictor and vasodilator agents which underlies the mechanism of vascular injury in DM. Additionally, diminished podocytes correlate with the severity of kidney injury. Podocyturia often precedes proteinuria in several kidney diseases, including diabetic kidney disease. Centella asiatica (CeA) is known as an anti-inflammatory and antioxidant and has neuroprotective effects. This research aimed to investigate the potential effect of CeA to inhibit glomerular injury and vascular remodeling in DM.

Methods

The DM rat model was induced through intraperitoneal injection of streptozotocin 60 mg/kg body weight (BW), and then rats were divided into 1-month DM (DM1, n = 5), 2-month DM (DM2, n = 5), early DM concurrent with CeA treatment for 2 months (DMC2, n = 5), and 1-month DM treated with CeA for 1-month (DM1C1, n = 5). The CeA (400 mg/kg BW) was given daily via oral gavage. The control group (Control, n = 5) was maintained for 2 months. Finally, rats were euthanized and kidneys were harvested to assess vascular remodeling using Sirius Red staining and the mRNA expression of superoxide dismutase, podocytes marker, ACE2, eNOS, and ppET-1 using RT-PCR.

Results

The DM groups demonstrated significant elevation of glucose level, glomerulosclerosis, and proteinuria. A significant reduction of SOD1 and SOD3 promotes the downregulation of nephrin and upregulation of TRPC6 mRNA expressions in rat glomerular kidney. Besides, this condition enhanced ppET-1 and inhibited eNOS and ACE2 mRNA expressions that lead to the development of vascular remodeling marked by an increase of wall thickness, and lumen wall area ratio (LWAR). Treatment of CeA, especially the DMC2 group, attenuated glomerular injury and showed the reversal of induced conditions.

Conclusions

Centella asiatica treatment at the early stage of diabetes mellitus ameliorates glomerulosclerosis and vascular injury via increasing antioxidant enzymes.

Rotundic acid reduces LPS-induced acute lung injury in vitro and in vivo through regulating TLR4 dimer

Acute lung injury (ALI) is a serious clinical disease. Rotundic acid (RA), a natural ingredient isolated from Ilex rotunda Thunb, exhibits multiple pharmacological activities. However, RA's therapeutic effect and mechanism on ALI remain to be elucidated. The present study aimed to further clarify its regulating effects on inflammation in vitro and in vivo. Our results indicated that RA significantly inhibited the overproduction of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). RA decreased ROS production and calcium influx. In addition, RA inhibited the activation of PI3K, MAPK, and NF-κB pathways and enhanced the activity of nuclear factor E2-related factor 2 (Nrf2) signaling. The cellular thermal shift assay and docking results indicated that RA bind to TLR4 to block TLR4 dimerization. Furthermore, RA pretreatment effectively inhibited ear edema induced by xylene and LPS-induced endotoxin death and had a protective effect on LPS-induced ALI. Our findings collectively indicated that RA has anti-inflammatory effects, which may serve as a potential therapeutic option for pulmonary inflammation.

Rotundic Acid Regulates the Effects of Let-7f-5p on Caco2 Cell Proliferation

BACKGROUND & OBJECTIVE

Nowadays, the interaction between natural products and microRNAs provides a promising field for exploring the chemopreventive agents for various cancers. As a member of microRNAs, the expression of let-7f-5p is universally downregulated in Colorectal Cancer (CRC). The present study aimed to uncover the function of let-7f-5p in the proliferation of human colon cancer cell line Caco2 and explored chemopreventive agents from natural resources that can prevent the development of CRC.

METHODS

Herein, Caco2 cells were transfected with let-7f-5p mimic and inhibitor to manipulate let-7f-5p levels, and the expression of let-7f-5p was performed by RT-qPCR. Next, we determined how let-7f-5p regulates Caco2 cell proliferation by using MTT, wound-healing, cell cycle, and colony formation assays. Besides, to further understand the effect of let-7f-5p, we evaluated the protein level of AMER3 and SLC9A9 by using western blotting assays.

RESULTS

The results showed a suppressive function of let-7f-5p on Caco2 cell proliferation and then put forward a triterpenoid (Rotundic Acid, RA) which significant antagonized the effect of cell proliferation, restitution after wounding, and colony formation caused by let-7f-5p. Moreover, the western blot results further indicated that the inhibitory effect of RA might be due to its suppressive role in let-7f-5p-targeted AMER3 and SLC9A9 regulation.

CONCLUSION

Our validation study results confirmed that let-7f-5p was a potent tumor suppressor gene of Caco2 cell proliferation, and RA showed as a regulator of the effect of let-7f-5p on cell proliferation and then could be a potential chemopreventive agent for CRC treatment.

Absolute bioavailability, dose proportionality, and tissue distribution of rotundic acid in rats based on validated LC-QqQ-MS/MS method

Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column (4.6 mm × 50 mm, 5 μm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2–500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10–40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

•

A simple, rapid, and sensitive LC-QqQ-MS/MS method was developed and validated for RA quantification in rat plasma and tissue.

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Absolute bioavailability of RA was calculated to range from 16.1% to 19.4%.

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Dose proportionality and tissue distribution of RA were assessed for in rats.

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RA showed good dose proportionality over a dose range of 10–40 mg/kg.

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RA was rapidly and extensively distributed and exhibited the highest concentration in the liver after oral administration.

Ethnobotany, Phytochemistry and Pharmacological Features of Centella asiatica: A Comprehensive Review

Centella asiatica (CA) or Gotu cola is an herbal plant from the Apiaceae family with a long history of usage in different traditional medicines. It has long been used for the treatment of various ailments such as central nervous system (CNS), skin and gastrointestinal disorders especially in the Southeast Asia. This chapter focused on the phytochemical constituent and pharmacological activities of CA based on preclinical and clinical studies. Additionally, botanical description and distribution, traditional uses, interactions, and safety issues are reviewed. Electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies on the pharmacological activities of CA. Approximately, 124 chemical compounds including triterpenoids, polyphenolic compounds, and essential oils have been isolated and identified from CA. Ethnomedicinal applications of CA mostly include treatment of gastrointestinal diseases, wounds, nervous system disorders, circulatory diseases, skin problems, respiratory ailments, diabetes and sleep disorders in various ethnobotanical practices. Pharmacological studies revealed a wide range of beneficial effects of CA on CNS, cardiovascular, lung, liver, kidney, gastrointestinal, skin, and endocrine system. Among them, neuroprotective activity, wound healing and treatment of venous insufficiency, as well as antidiabetic activity seem to be more frequently reported. At the moment, considering various health benefits of CA, it is marketed as an oral supplement as well as a topical ingredient in some cosmetic products. Additional preclinical studies and particularly randomized controlled trials are needed to clarify the therapeutic roles of CA.

Inhibition of the activation of γδT17 cells through PPARγ-PTEN/Akt/GSK3β/NFAT pathway contributes to the anti-colitis effect of madecassic acid

Type-17 immune response, mediated mainly by IL-17, plays a critical role in ulcerative colitis. Previously, we showed that madecassic acid (MA), the main active ingredient of Centella asiatica herbs for anti-colitis effect, ameliorated dextran sulfate sodium (DSS)-induced mouse colitis through reducing the level of IL-17. Here, we explore the effect of MA on the activation of γδT17 cells, an alternative source of IL-17 in colitis. In DSS-induced colitis mice, oral administration of MA decreased the number of γδT17 cells and attenuated the inflammation in the colon, and the anti-colitis effect of MA was significantly counteracted by redundant γδT17 cells, suggesting that the decrease in γδT17 cells is important for the anti-colitis effect of MA. In vitro, MA could inhibit the activation but not the proliferation of γδT17 cells at concentrations without evident cytotoxicity. Antibody microarray profiling showed that the inhibition of MA on the activation of γδT17 cells involved PPARγ–PTEN/Akt/GSK3β/NFAT signals. In γδT17 cells, MA could reduce the nuclear localization of NFATc1 through inhibiting Akt phosphorylation to promote GSK3β activation. Moreover, it was confirmed that MA inhibited the Akt/GSK3β/NFATc1 pathway and the activation of γδT17 cells through activating PPARγ to increase PTEN expression and phosphorylation. The correlation between activation of PPARγ, decrease in γδT17 cell number, and amelioration of colitis by MA was validated in mice with DSS-induced colitis. In summary, these findings reveal that MA inhibits the activation of γδT17 cells through PPARγ–PTEN/Akt/GSK3β/NFAT pathway, which contributes to the amelioration of colitis.

UPLC/Q-TOF-MS/MS-based metabolomics revealed the lipid-lowering effect of Ilicis Rotundae Cortex on high-fat diet induced hyperlipidemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ilicis Rotundae Cortex (IRC), a Chinese crude drug, has been widely utilized in Guangdong and Guangxi provinces of China to treat or prevent cardiovascular diseases.

AIM OF STUDY

This investigation aims to study the lipid-lowering effect of IRC, as well as the regulating effect on the endogenous metabolites in hyperlipidemia rats.

MATERIALS AND METHODS

High-fat diet induced hyperlipidemia rats were administrated with different doses of IRC extract (0.5, 1.0 and 2.0 g/kg/day) for 5 weeks. Simvastatin was used as the positive control. Body weight, serum lipid levels and histopathology of liver were evaluated. The metabolic profiles of plasma, urine and cecum content were analyzed using UPLC/Q-TOF-MS/MS-based metabolomics approach coupled with multivariate data analysis.

RESULTS

The levels of serum TC, TG, LDL-C, AST and ALT were significantly decreased and HDL-C level was increased in IRC treatment groups. The hepatic histomorphology was partially restored. 23, 26 and 15 metabolites in plasma, urine and cecum content were determined as the biological biomarkers, respectively. IRC extract could partially recover the disturbed metabolic pathways of bile acid metabolism, linoleic acid metabolism, arachidonic acid metabolism, taurine and hypotaurine metabolism, glyoxylate and dicarboxylate metabolism, glycerophospholipid metabolism, synthesis and degradation of ketone bodies, sphingolipid metabolism and riboflavin metabolism.

CONCLUSION

This study demonstrated that IRC could effectively improve the serum lipids and partially restore the hepatic histomorphology. The underlying metabolic mechanism mainly included improving the metabolism of bile acids, glycerophospholipid, sphingolipid, fatty acid and amino acid. This is the first study on the lipid-lowering effect of IRC from the perspective of metabolomics.

Pentacyclic triterpenoid-rich fraction of the Hardy kiwi (Actinidia arguta) improves brain dysfunction in high fat diet-induced obese mice

This study was performed to investigate the effect of the chloroform fraction from Actinidia arguta (CFAA) on cognitive dysfunction in a C57BL/6 mouse model fed a high-fat diet (HFD) for 12 weeks. The CFAA has the protective effect on high glucose-induced neurotoxicity in MC-IXC cell (neuroblastoma cell line). In a C57BL/6 mouse model fed a HFD for 12 weeks, the improved glucose tolerance and cognitive dysfunction were observed in a group ingesting CFAA. In the brain tissue analysis, the impaired cholinergic, antioxidant system and mitochondria functions were improved in the CFAA group. In addition, in a molecular biology study, it was observed that CFAA improves HFD-induced abnormal insulin signaling such as increase of IRS phosphorylation at serine residues and reduction of Akt phosphorylation caused by the increase of JNK phosphorylation and then inhibited apoptosis. In the UPLC Q-TOF/MS analysis, pentacyclic triterpenoids such as asiatic acid (AA), madecassic acid (MA) were identified in CFAA as main compounds. Therefore, these results propose that Actinidia arguta rich in pentacyclic triterpenoids may be effective as preventive matter a therapeutic strategy to improve neurodegenerative disease caused by HFD.

Rotundic Acid Protects against Metabolic Disturbance and Improves Gut Microbiota in Type 2 Diabetes Rats

Rotundic acid (RA) is a major triterpene constituent in the barks of Ilex rotunda Thunb, which have been widely used to make herbal tea for health care in southern China. RA has a variety of bioactivities such as anti-inflammation and lipid-lowering effect. However, little is known about the effects and mechanisms of RA on metabolic disturbance in type 2 diabetes (T2D) and its effect on gut microbiota. A T2D rat model induced by high fat diet (HFD) feeding and low-dose streptozotocin (STZ) injection was employed and RA showed multipronged effects on T2D and its complications, including improving glucolipid metabolism, lowering blood pressure, protecting against cardiovascular and hepatorenal injuries, and alleviating oxidative stress and inflammation. Furthermore, 16s rRNA gene sequencing was carried out on an Illumina HiSeq 2500 platform and RA treatment could restore the gut microbial dysbiosis in T2D rats to a certain extent. RA treatment significantly enhanced the richness and diversity of gut microbiota. At the genus level, beneficial or commensal bacteria Prevotella, Ruminococcus, Leuconostoc and Streptococcus were significantly increased by RA treatment, while RA-treated rats had a lower abundance of opportunistic pathogen Klebsiella and Proteus. Spearman’s correlation analysis showed that the abundances of these bacteria were strongly correlated with various biochemical parameters, suggesting that the improvement of gut microbiota might help to prevent or attenuate T2D and its complication. In conclusion, our findings support RA as a nutraceutical agent or plant foods rich in this compound might be helpful for the alleviation of T2D and its complications through improving gut microbiota.

Madecassic Acid Derivatives as Potential Anticancer Agents: Synthesis and Cytotoxic Evaluation

A series of novel madecassic acid (1) derivatives was synthesized, and their cytotoxicity was evaluated against the NCI-60 panel of cancer cell lines. Several analogues exhibited broad-spectrum cytotoxic activities over all nine tumor types represented in the panel, with more potent antiproliferative activities observed against selected cancer cell lines, including multidrug-resistant phenotypes. Among them, compound 29 showed GI50 (50% growth inhibition) values ranging from 0.3 to 0.9 μM against 26 different tumor cell lines and selectivity for one colon (COLO 205) and two melanoma (SK-MEL-5 and UACC-257) cell lines at the TGI (total growth inhibition) level. The mode of action of 29 was predicted by CellMiner bioinformatic analysis and confirmed by biochemical and cell-based experiments to involve inhibition of the DNA replication process, particularly the initiation of replication, and disruption of mitochondrial membrane potential. The present findings suggest this novel madecassic acid derivative may have potential as an anticancer therapeutic lead for both solid and hematological tumors.

Rotundic Acid Induces DNA Damage and Cell Death in Hepatocellular Carcinoma Through AKT/mTOR and MAPK Pathways

Hepatocellular carcinoma (HCC) is the fourth largest cause of cancer-related deaths worldwide with limited therapeutic interventions. Renewed interest in natural products as drug leads has resulted in a paradigm shift toward the rapid screening of medicinal plants for the discovery of new chemical entities. Rotundic acid (RA), a plant-derived triterpenoid, has been anecdotally reported to possess anti-inflammatory and cardio-protective abilities. The present study highlights the anti-cancer efficacy of RA on HCC in vitro and in vivo. The inhibitory effects of RA on HCC cell viability was determined by MTT. Soft agar colony formation and clonogenic assays also showed that RA inhibited HCC cell proliferation. Flow cytometry, confocal, and western blot results further indicated that RA induced cell cycle arrest, DNA damage, and apoptosis by modulating the AKT/mTOR and MAPK pathways. Besides the suppression of migration and invasion, tube formation and VEGF-ELISA revealed the anti-angiogenic abilities of RA on HCC. Moreover, RA also inhibited tumor growth in a HepG2 xenograft mouse model. To our best knowledge, this is the first extensive study of the anticancer activity of RA on HCC. The results demonstrate that RA could be a potential drug candidate for HCC treatment.

Beneficial effects of murtilla extract and madecassic acid on insulin sensitivity and endothelial function in a model of diet-induced obesity

Infusions of murtilla leaves exhibit antioxidant, analgesic, and anti-inflammatory properties. Several compounds that are structurally similar to madecassic acid (MA), a component of murtilla leaf extract (ethyl acetate extract, EAE), have been shown to inhibit protein tyrosine phosphatase 1B (PTP1P). The aim of this study was to evaluate if EAE and two compounds identified in EAE (MA and myricetin [MYR]) could have a beneficial effect on systemic and vascular insulin sensitivity and endothelial function in a model of diet-induced obesity. Experiments were performed in 5-week-old male C57BL6J mice fed with a standard (LF) or a very high-fat diet (HF) for 4 weeks and treated with EAE, MA, MYR, or the vehicle as control (C). EAE significantly inhibited PTP1B. EAE and MA, but not MYR, significantly improved systemic insulin sensitivity in HF mice and vascular relaxation to Ach in aorta segments, due to a significant increase of eNOS phosphorylation and enhanced nitric oxide availability. EAE, MA, and MYR also accounted for increased relaxant responses to insulin in HF mice, thus evidencing that the treatments significantly improved aortic insulin sensitivity. This study shows for the first time that EAE and MA could constitute interesting candidates for treating insulin resistance and endothelial dysfunction associated with obesity.

Synthesis and Biological Evaluation of New Madecassic Acid Derivatives Targeting ERK Cascade Signaling

In the present study, a series of novel madecassic acid derivatives was synthesized and screened against the National Cancer Institute's 60 human cancer cell line panel. Among them, compounds 5, 12, and 17 displayed potent and highly differential antiproliferative activity against 80% of the tumor cells harboring the B-Raf^V600E mutation within the nanomolar range. Structure-activity analysis revealed that a 5-membered A ring containing an α,β-unsaturated aldehyde substituted at C-23 with a 2-furoyl group seems to be crucial to produce this particular growth inhibition signature. In silico analysis of the cytotoxicity pattern of these compounds identified two highly correlated clinically approved drugs with known B-Raf^V600E inhibitory activity. Follow-up analysis revealed inhibition of the ERK signaling pathway through the reduction of cellular Raf protein levels is a key mechanism of action of these compounds. In particular, 17 was the most potent compound in suppressing tumor growth of B-Raf^V600E-mutant cell lines and displayed the highest reduction of Raf protein levels among the tested compounds. Taken together, this study revealed that modifications of madecassic acid structure can provide molecules with potent anticancer activity against cell lines harboring the clinically relevant B-Raf^V600E mutation, with compound 17 identified as a promising lead for the development of new anticancer drugs.

Synthesis of madecassic acid derivatives and their cytotoxic activity

Fifteen new 28-amide derivatives of madecassic acid, isolated from the tropical medicinal herb Centella asiatica (Apiaceae), have been synthesised, and their cytotoxicity on three cancer cell lines, KB (carcinoma cancer), HepG2 (liver cancer) and Lu-1 (lung cancer), was evaluated. The results showed that acetylation of the 2,3,23-hydroxyl group and/or amidation of the 28-COOH group strongly increased the cytotoxicity of the synthesised compounds.

Identification of rotundic acid metabolites after oral administration to rats and comparison with the biotransformation by Syncephalastrum racemosum AS 3.264

The objective of this study was to identify the metabolites of rotundic acid after oral administration to rats and compare the similarities with its biotransformation by Syncephalastrum racemosum AS 3.264 using ultra-high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry. A total of fourteen metabolites were determined based on the mass spectrometry and chromatographic behaviors, among which eleven (M1-M3, M7-M14) and six (M2, M4-M8) metabolites were identified in rats and S. racemosum, respectively. Three identical metabolites (M2, M7 and M8) were found in rats and S. racemosum, indicating that there were metabolic similarities. Moreover, to confirm the results of mass spectrometry, three (M2, M4 and M7) metabolites were obtained by the means of amplifying incubation and their structures were determined by various spectroscopic analyses, and M4 was proved to be a previously undescribed compound. This results showed that in vitro assisted preparation by microbial transformation is a feasible and effective method of obtaining metabolites which are in low amounts and difficult to be prepared in vivo.