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.

Rotundic acid alleviates hyperlipidemia in rats by regulating lipid metabolism and gut microbiota

Disturbances in lipid metabolism and dysbiosis of the gut microbiota play an important role in the progression of hyperlipidemia. Previous study indicated that Ilicis Rotundae Cortex possesses anti-hyperlipidemic activity, and rotundic acid (RA) identified as a key active compound to be incorporated into the body. The study aimed to evaluate the anti-hyperlipidemia effects of RA and explored its impact on gut microbiota and lipid metabolism, as well as its possible mechanisms for improving hyperlipidemia. The study methodology included a comprehensive evaluation of the effects of RA on steatosis markers of hyperlipidemia, lipid metabolism, and gut microbiota by assessing biochemical parameters and histopathology, lipidomics, 16S rRNA gene sequencing, and short-chain fatty acid (SCFA) assays. The results showed that RA effectively reduced body weight and the steatosis markers in serum and liver. Moreover, the lipidomic analysis revealed significant changes in plasmatic and hepatic lipid levels, and these were restored by RA. According to the results of 16S rRNA gene sequencing, RA supplementation raised the relative abundance of Bacteroidetes and Proteobacteria while decreasing the relative abundance of Firmicutes. RA significantly boosted the relative abundance of SCFAs by increasing SCFAs-producing bacteria such as Bacteroides, Alloprevotella, Desulfovibrio, etc. In summary, RA could regulate triglyceride metabolism and glycerophospholipid metabolism, restore gut microbiota structure, and increase the relative abundance of SCFAs-producing bacteria to exert its hypolipidemic effects. These findings suggest RA to be a promising therapeutic agent for hyperlipidemia.

Five glycosylated phenolic derivatives from the bark of Ilex rotunda Thunb. and their anti-inflammatory activities

Five new glycosylated phenolic derivatives, rotundosides A-E (1-5), and three known glycosides (6-8) were isolated from the 95% alcohol extract of the bark of Ilex rotunda. Their structures were elucidated by extensive spectroscopic analysis and comparison with the literature data. All new compounds possessed a [5-O-(E)-caffeoyl]-β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyl group. The anti-inflammatory properties of all isolated compounds were evaluated using a modified nitric oxide (NO) production in lipopolysaccharide (LPS)-induced leukemia cells in mouse macrophage (RAW264.7) method. Compound 8, dracunculifoside H, showed significant anti-inflammatory activity in vitro.

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.

A systematic review: Botany, phytochemistry, traditional uses, pharmacology, toxicology, quality control and pharmacokinetics of Ilex rotunda Thunb

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex rotunda Thunb. (I. rotunda) is an Ilex species of Aquifoliaceae, widely distributed in East Asia. Its dried bark is commonly used as a medicinal part in the field of traditional Chinese medicine (TCM), named Ilicis Rotundae Cortex. This medicinal plant is commonly used for clearing heat and removing toxin, draining dampness and relieving pain in TCM to treat tonsillitis, acute gastroenteritis, gastric and duodenal ulcer, rheumatism, traumatic injury, and so on. It also has significant development value on lipid-lowering, hepatoprotection and anti-inflammation, but the potential mechanism needs to be further explored.

AIM OF THE REVIEW

More and more medicinal substances are being discovered in I. rotunda with multiple biological activities, which help to advance the ethno-pharmacological research in I. rotunda. However, to date there is a lack of a systematic summary of research progress on I. rotunda. This review aims to provide a critical summary of the current studies on I. rotunda. The progress in research on botany, phytochemistry, traditional uses, pharmacology, toxicology, quality control and pharmacokinetics of the plant is discussed. It hopes to provide useful references and guidance for the future directions of research on I. rotunda.

MATERIALS AND METHODS

Studies of I. rotunda were collected via Google Scholar and Baidu Scholar, PubMed, ScienceDirect, SciFinder, Web of Science, China National Knowledge Infrastructure (CNKI), WANFANG DATA and libraries. Some local books, official websites, PhD or MS's dissertations were also included. The literature cited in this review covered the period from 1956 to January 2022.

RESULTS

Analysis of the literature indicates that I. rotunda is a potentially valuable herbal medicine for the therapeutic of various diseases. To date, 120 compounds were found and identified in I. rotunda, mainly including triterpenoids, phenylpropanoids, etc. Modern pharmacological studies also found that the plant has the activities of protecting the cardiovascular system, lowering lipids and protecting the liver, as well as being an anti-inflammatory, anti-tumor and antibacterial.

CONCLUSIONS

This review summarizes the results from current studies of I. rotunda. However, the current explanation seems insufficient and unsatisfactory, in terms of the relationships between the traditional uses and the modern pharmacological activities, the mechanisms and the material basis. Thus, a critical and comprehensive evaluation is necessary to explore its future research prospects and development direction.

Rapid Identification of the Chemical Components of Ilex rotunda Thunb Using UPLC-Q-TOF-MS/MS

Ilicis Rotundae Cortex (IRC) consists of the bark of Ilex rotunda Thunb, and its chemical constituents mainly include flavonoid glycosides, phenols, and triterpenoid saponins. In this study, a preliminary analysis was performed to identify and obtain the chemical components from IRC to better control the quality of the medicinal materials and provide a chemical basis for the study of the efficacy of the active components. Simple and efficient sample pretreatment and ultrasonic-assisted extraction methods were used to analyze the mass spectrum fragments and fracture modes in the anion mode by UPLC-Q-TOF-MS/MS. Using a two-step strategy, the neutral loss, diagnostic ions, and characteristic fragments were studied to screen diverse skeletons and substitutions, and the possible compounds were identified by comparison with databases. The representative compounds were compared with the standard, and the mass spectrogram was found to match perfectly. Thus, our findings reveal that this method is feasible and reliable and can be used to analyze the chemical components of IRC. We identified 105 compounds, including 22 triterpenoid saponins, 15 chlorogenic acids, 33 phenylpropanoids and phenylpropanosides, 3 iridoids, 1 flavonoid, 10 lignans, 12 glycosides, and 9 other compounds. This method lays the foundation for further elucidating the pharmacodynamics of IRC and provides a practical method for the identification of IRC.

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.

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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.

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.

Natural CAC chemopreventive agents from Ilex rotunda Thunb

Colitis-associated cancer (CAC) is one of the most serious complications of inflammatory bowel disease. The pathogenesis of CAC is complicated and so far elusive, and the anti-inflammatory effect does not assure CAC preventive activity, making it difficult to discover CAC preventive drugs. In this study, we report the CAC preventive effect of the ethyl acetate (EIR) of Ilex rotunda Thunb., a traditional Chinese herbal medicine being clinically used to treat intestinal disease. We also report the results of screening for CAC preventive agents from EIR via a nuclear factor-kappa B (NF-κB) translocation model in Caco2 cells, since activated NF-κB can be used by tumor cells at the early stage of tumorigenesis. Twenty-four components were isolated from EIR and identified by multiple chromatography and spectral analysis. MTT experiments in IEC-6 and RAW264.7 cells showed that all 24 compounds were toxic-free to normal cell lines. Furthermore, compound rotundic acid (RA) (19) exhibited an inhibitory effect on LPS-induced NF-κB translocation in Caco2 cells. Moreover, RA did not induce apoptosis in Caco2 tumor cells while possessing an anti-inflammatory effect both in immune and intestinal epithelium cells (RAW264.7 and IEC-6 cells, respectively). Removing RA (19) and its 28-O-glucopyranoside (17) from EIR definitely undermined the in vivo CAC preventive activity of EIR. Therefore, the current study suggested that RA (19) could be a potential therapeutic agent against CAC.

Rapid profiling and pharmacokinetic studies of multiple potential bioactive triterpenoids in rat plasma using UPLC/Q-TOF-MS/MS after oral administration of Ilicis Rotundae Cortex extract

Triterpenoids, the major bioactive ingredients of Ilicis Rotundae Cortex, contributes a significant cardiovascular protection activity. Although many studies about the total saponins have been reported, the absorption triterpenoids and pharmacokinetic behaviors were unclear. Thus, the present study aims to comprehensive elucidate the absorption triterpenoids and their pharmacokinetics in rats after oral administration the crude extract using UPLC/Q-TOF-MS/MS. A total of forty-two triterpenoids were successfully characterized from the rat plasma, and thirty-two of them were validated by the reference substances, while the others were tentatively identified based on the mass spectral fragmental patterns. Furthermore, the plasma concentrations of six absorption bioactive triterpenoids (rotundinoside C, ilexoside O, pedunculoside, rotundic acid, rotundanonic acid and ilexgenin A) were simultaneously quantified by selected reaction monitoring in negative ionization mode. All analytes exhibited good linearity with correlation coefficients values greater than 0.99 and the LLOQ ranged from 1.2 to 3.2 ng/mL, and method validation for selectivity, precision, accuracy, recovery, matrix effect and stability were reckoned acceptable. The results were successfully applied for the multiple-component pharmacokinetic study of the six bioactive triterpenoids.

A facile and selective approach to the qualitative and quantitative analysis of triterpenoids and phenylpropanoids by UPLC/Q-TOF-MS/MS for the quality control of Ilex rotunda

Ilex rotunda, in which triterpenoids and phenylpropanoids are major bioactive constituents, has been widely used in traditional Chinese medicines. In this study, a validated UPLC/Q-TOF-MS/MS method was developed to simultaneously identify and quantify the triterpenoids and phenylpropanoids in the stem bark, fruit, leaves, roots and stem xylem of this herbal medicine. A total of seventy triterpenoids and twelve phenylpropanoids were identified with the assistance of the modified mass defect filter and key product ion filter data processing strategies, and forty-eight of them were confirmed by reference substances. Meanwhile, the contents of twelve triterpenoids and three phenylpropanoids in the five plant parts were determined with good linearity (R² ≥ 0.9993), precision (RSD ≤ 2.04%), repeatability (RSD ≤ 1.99%), stability (RSD ≤ 1.88%) and recovery (96.65-103.17% and RSD ≤ 3.54%). Furthermore, PCA and OPLS-DA methods were employed to visualize the relationships and discrimination of the forty-two stem bark samples from two origins based on the contents of fifteen analytes. Our findings may provide early scientific evidence for quality control and for elucidating the therapeutic principle of Ilex rotunda.

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.