The cytotoxic activity of ursolic acid derivatives

Biotransformations of diterpenoids and triterpenoids: a review

During the past few years, research has focused on the microbial transformation of a huge variety of organic compounds to obtain compounds of therapeutic and/or industrial interest. Microbial transformation is a useful tool for organic chemists looking for new compounds, as a consequence of the variety of reactions for natural products. Terpenoids are a large family of natural products exhibiting a wide range of biological activities such as antibiotics, anti-inflammatory, anti-HIV and anti-tumor effects; hypotensive agents; sweeteners; insecticides; anti-feedants; phytotoxic agents; perfumery intermediates; and plant growth hormones. This article describes the biotransformation products of diterpenoids and triterpenoids in a variety of biological media. Emphasis is placed on reporting the metabolites that may be of special interest as well as the practical aspects of this work in the field of microbial transformations. This review covers the literature from 1991 to 2012.

Targeting cancer using cholesterol conjugates

Conjugation of cholesterol moiety to active compounds for either cancer treatment or diagnosis is an attractive approach. Cholesterol derivatives are widely studied as cancer diagnostic agents and as anticancer derivatives either in vitro or in vivo using animal models. In largely growing studies, anticancer agents have been chemically conjugated to cholesterol molecules, to enhance their pharmacokinetic behavior, cellular uptake, target specificity, and safety. To efficiently deliver anticancer agents to the target cells and tissues, many different cholesterol-anticancer conjugates were synthesized and characterized, and their anticancer efficiencies were tested in vitro and in vivo.

Ursolic acid promotes apoptosis of SGC-7901 gastric cancer cells through ROCK/PTEN mediated mitochondrial translocation of cofilin-1

Ursolic acid, extracted from the traditional Chinese medicine bearberry, can induce apoptosis of gastric cancer cells. However, its pro-apoptotic mechanism still needs further investigation. More and more evidence demonstrates that mitochondrial translocation of cofilin-1 appears necessary for the regulation of apoptosis. Here, we report that ursolic acid (UA) potently induces the apoptosis of gastric cancer SGC-7901 cells. Further mechanistic studies revealed that the ROCK1/PTEN signaling pathway plays a critical role in UA-mediated mitochondrial translocation of cofilin-1 and apoptosis. These findings imply that induction of apoptosis by ursolic acid stems primarily from the activation of ROCK1 and PTEN, resulting in the translocation of cofilin-1 from cytoplasm to mitochondria, release of cytochrome c, activation of caspase-3 and caspase-9, and finally inducing apoptosis of gastric cancer SGC-7901 cells.

Synthesis and biological evaluation of ursolic acid-triazolyl derivatives as potential anti-cancer agents

A series of ursolic acid-1-phenyl-1H-[1,2,3]triazol-4-ylmethylester congeners have been designed and synthesized in an attempt to develop potent antitumor agents. A regioselective approach using Huisgen 1,3-dipolar cycloaddition reaction of ursolic acid-alkyne derivative with various aromatic azides was employed to target an array of triazolyl derivatives in an efficient manner. Their structures were confirmed by using (1)H NMR, (13)C NMR, IR and MS analysis. All the compounds were evaluated for anti-cancer activity against a panel of four human cancer cell lines including A-549 (lung), MCF-7 (breast), HCT-116 (colon), THP-1 (leukemia) and a normal human epithelial cell line (FR-2) using sulforhodamine-B assay. The pharmacological results showed that most of the compounds displayed high level of antitumor activities against the tested cancer cell lines compared with ursolic acid. Compounds 7b, 7g, 7p and 7r were found to be the most potent compounds in this study.

Cytotoxic activity of ursolic acid derivatives obtained by isolation and oxidative derivatization

Structure-activity relationships of ursane-type pentacyclic triterpenes obtained from natural sources and by chemical derivatization are reviewed. Ursolic acid, corosolic acid, and a new ursane-type pentacyclic triterpene, 7,24-dihydroxyursolic acid, were isolated from the methanolic extract of the leaves of the Bangladeshi medicinal plant, Saurauja roxburghii. Derivatization of ursolic acid by oxidation with dioxoruthenium (VI) tetraphenylporphyrins was investigated. Oxidation selectivity on the terpene structure was modulated by the auxiliaries introduced on the tetraphenylporphyrin. The natural triterpenes and oxidized derivatives were tested for cytotoxicity against the C6 rat glioma and A431 human skin carcinoma cell lines. Although they have the same ursane-type pentacyclic triterpene cores, the position and numbers of hydroxyls on the terpene structures significantly affected the activity and the selectivity towards the tested cell lines.

Ursolic acid in cancer prevention and treatment: molecular targets, pharmacokinetics and clinical studies

Discovery of bioactive molecules and elucidation of their molecular mechanisms open up an enormous opportunity for the development of improved therapy for different inflammatory diseases, including cancer. Triterpenoids isolated several decades ago from various medicinal plants now seem to have a prominent role in the prevention and therapy of a variety of ailments and some have already entered Phase I clinical trials. One such important and highly investigated pentacyclic triterpenoid, ursolic acid has attracted great attention of late for its potential as a chemopreventive and chemotherapeutic agent in various types of cancer. Ursolic acid has been shown to target multiple proinflammatory transcription factors, cell cycle proteins, growth factors, kinases, cytokines, chemokines, adhesion molecules, and inflammatory enzymes. These targets can potentially mediate the chemopreventive and therapeutic effects of ursolic acid by inhibiting the initiation, promotion and metastasis of cancer. This review not only summarizes the diverse molecular targets of ursolic acid, but also provides an insight into the various preclinical and clinical studies that have been performed in the last decade with this promising triterpenoid.

Hyptis verticillata Jacq: a review of its traditional uses, phytochemistry, pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis verticillata Jacq. (Lamiaceae) (John Charles) is an important medicinal plant with a long history of traditional use, originating in Central America and now extending from Florida to Colombia and across the Caribbean. Records of its earliest use date back to the ancient Mayan and Aztec cultures of Mesoamerica. There is no indication that this plant is being used outside of the Americas.

AIM OF THE REVIEW

This review aims to provide a comprehensive overview of the traditional use, phytochemistry, pharmacological activity and toxicology of Hyptis verticillata and to highlight the opportunities for greater development of the plant's medicinal properties at a local and international level.

MATERIALS AND METHODS

An extensive and systematic review of the literature was undertaken and all relevant abstracts and full-text articles analysed and included in the review.

KEY FINDINGS

A wide range of traditional uses are cited in the literature, from internal uses for conditions affecting the respiratory system, digestive tract and gynaecological system to external uses for conditions affecting the skin and musculoskeletal system. Pharmacological studies to date have demonstrated significant activity which support the traditional use of the plant as an antiinflammatory, antimicrobial, antisecretory agent and hormone modulator. In addition studies have identified anti-cancer, acaricidal, insecticidal and molluscicidal activity. No clinical trials had been completed at the time of this review. A number of key phytochemicals have been isolated, identified and published to date including: 17 lignans; 4 triterpenes; 11 diterpenes, 3 sesquiterpenes, 3 monoterpenes, 2 flavonoids, 1 polyphenol and 1 alkaloid. Nine of these phytochemicals are novel to Hyptis verticillata. Plant extracts and isolated phytochemicals exhibit a broad range of activities that include: antimitotic; antiproliferative; cytotoxic; antioxidant; antiinflammatory; antibacterial; antifungal; antiviral; anti-HIV; antisecretory; hepatoprotective; insecticidal and acaricidal.

CONCLUSIONS

Hyptis verticillata is a medicinal plant with current widespread traditional use in the Americas that warrants further research, clinical trials and product development to fully exploit its medicinal value.

Chemical and preclinical studies on Hedyotis diffusa with anticancer potential

This paper presents the chemical and preclinical anticancer research on Hedyotis diffusa Willd. in detail, one of the most renowned herbs often prescribed in the polyherbal formulas for cancer treatment in traditional Chinese medicine. Anthraquinones, flavonoids, and terpenoids constitute the majority of the 69 compounds that have been isolated and identified from H. diffusa. The anticancer effects of the methanolic, ethanolic, and aqueous extracts in various preclinical cancer models have been described. This review also summarized the anticancer activity of constituents of the herb and the mechanisms of action. All the studies suggest that H. diffusa has enormous potential in the therapy of cancer and warrants further chemical and pharmacological investigation.

Antiproliferative activity and apoptosis-inducing mechanism of constituents from Toona sinensis on human cancer cells

Background

Natural products, including plants, microorganisms and marines, have been considered as valuable sources for anticancer drug discovery. Many Chinese herbs have been discovered to be potential sources of antitumor drugs.

Methods

In the present study, we investigated the antitumor efficacy of the compounds isolated from Toona sinensis, an important herbal medicine. The inhibitory activities of these compounds were investigated on MGC-803, PC3, A549, MCF-7, and NIH3T3 cells in vitro by MTT assay. The mechanism of the antitumor action of active compounds was investigated through AO/EB staining, Hoechst 33258 staining, TUNEL assay, flow cytometry analysis, and western blotting analysis.

Results

Fifteen compounds were isolated from the roots of Toona sinensis. Betulonic acid (BTA) and 3-oxours-12-en-28-oic acid (OEA) isolated from the plant inhibited the proliferation of MGC-803 and PC3 cells, with IC₅₀ values of 17.7 μM and 13.6 μM, 26.5 μM and 21.9 μM, respectively. Both could lead to cell apoptosis, and apoptosis ratios reached 27.3% and 24.5% in MGC-803 cells at 72 h after treatment at 20 μM, respectively. Moreover, the study of cancer cell apoptotic signaling pathway indicated that both of them could induce cancer cell apoptosis through the mitochondrial pathway, involving the expressions of p53, Bax, caspase 9 and caspase 3.

Conclusions

The study shows that most of the compounds obtained from Toona sinensis could inhibit the growth of human cancer cells. Furthermore, BTA and OEA exhibited potent antitumor activities via induction of cancer cell apoptosis.

Synthesis and cytotoxicity of novel ursolic acid derivatives containing an acyl piperazine moiety

This study designed and synthesized a series of novel ursolic acid derivatives in an attempt to develop potent antitumor agents. Their structures were confirmed using MS, IR, (1)H NMR and (13)C NMR. The inhibitory activities of the title compounds against the MGC-803 (gastric cancer cell) and Bcap-37 (breast cancer cell) human cancer cell lines were evaluated using standard MTT assay in vitro. The pharmacological results showed that some of the compounds displayed moderate to high levels of antitumor activities against the tested cancer cell lines and that most exhibited more potent inhibitory activities compared with ursolic acid. The mechanism of compound 4b was preliminarily investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, TUNEL assay and flow cytometry, which revealed that the compound can induce cell apoptosis in MGC-803 cells.

Bioactive constituents in Prunus africana: geographical variation throughout Africa and associations with environmental and genetic parameters

Prunus africana--an evergreen tree found in Afromontane forests--is used in traditional medicine to cure benign prostate hyperplasia. Different bioactive constituents derived from bark extracts from 20 tree populations sampled throughout the species' natural range in Africa were studied by means of GC-MSD. The average concentration [mg/kgw/w] in increasing order was: lauric acid (18), myristic acid (22), n-docosanol (25), ferulic acid (49), β-sitostenone (198), β-sitosterol (490), and ursolic acid (743). The concentrations of many bark constituents were significantly correlated and concentration of n-docosanol was highly significantly correlated with all other analytes. Estimates of variance components revealed the highest variation among populations for ursolic acid (66%) and the lowest for β-sitosterol (20%). In general, environmental parameters recorded (temperature, precipitation, altitude) for the samples sites were not correlated with the concentration of most constituents; however, concentration of ferulic acid was significantly correlated with annual precipitation. Because the concentration of compounds in bark extracts may be affected by tree size, the diameter of sampled plants at 1.3m tree height (as proxy of age) was recorded. The only relationship with tree diameter was a negative correlation with ursolic acid. Under the assumption that genetically less variable populations have less variable concentrations of bark compounds, correlations between variation parameters of the concentration and the respective genetic composition based on chloroplast and nuclear DNA markers were assessed. Only variation of β-sitosterol concentration was significantly correlated with haplotypic diversity. The fixation index (F(IS)) was positively correlated with the variation in concentration of ferulic acid. Principal Components Analysis (PCA) indicated a weak geographic pattern. Mantel tests, however, revealed associations between the geographic patterns of bioactive constituents and the phylogenetic relationship among the populations sampled. This suggests an independent evolution of bark metabolism within different phylogeographical lineages, and the molecular phylogeographic pattern is partly reflected in the variation in concentration of bark constituents. The results have important implications for the design of strategies for the sustainable use and conservation of this important African tree species.

Fast separation of triterpenoids by supercritical fluid chromatography/evaporative light scattering detector

The screening of plant material, the chemical composition, the abundance and the biological activity of triterpenoids are of a major economical importance. The classical analytical methods, such as TLC, GC, and HPLC are either little resolutive, or require derivatization steps, or fail in sensitivity. The supercritical fluid chromatography/evaporative light scattering detector (SFC/ELSD) coupling provides high resolution, fast analysis and higher responses for the analysis of triterpenoids. After the initial screening of seven stationary phases to select the well suited one, analytical conditions (modifier percentage, from 10 to 3%; backpressure (from 12 to 18 MPa) and temperature (from 15 to 25 °C) were studied to improve the separation, and ELSD detection of a standard mixture composed of 8 triterpenoids (oleanolic acid, erythrodiol, β-amyrin, ursolic acid, uvaol, betulinic acid, betulin, lupeol). Applied to apple pomace extracts, this method allows the separation of about 15 triterpenoid compounds, in less than 20 min, with isocratic conditions. Moreover, the ELSD response is dramatically higher than the one provided by UV detection, and avoids derivatization steps. An attempt to identify some compounds was done by collecting chromatographic peaks and further analyzing them with mass spectrometry. Complete identification or molecular formula could be proposed for 11 compounds. However, due to the presence of position and orientation isomers the absolute identification remains difficult, despite some retention rules deduced from the standard analysis.

Ursane-type pentacyclic triterpenoids as useful platforms to discover anticancer drugs

This review highlights the potential of natural and semisynthetic ursane-type triterpenoids as candidates for the design of multi-target bioactive compounds, with focus on their anticancer effects. A brief illustration of the biosynthesis, sources, and general biological effects of the main classes of naturally occurring pentacyclic triterpenoids (PTs) are provided.

Microbial transformation of ursolic acid by Syncephalastrum racemosum (Cohn) Schroter AS 3.264

Biotransformation of ursolic acid by the filamentous fungus Syncephalastrum racemosum (Cohn) Schroter AS 3.264 yielded five metabolites. Their structures were identified as 3β,21β-dihydroxy-urs-11-en-28-oic acid-13-lactone, 3β,7β,21β-trihydroxy-urs-11-en-28-oic acid-13-lactone, 1β,3β-dihydroxy-urs-12-en-21-one-28-oic acid, 1β,3β,21β-trihydroxy-urs-12-en-28-oic acid and 11,26-epoxy-3β,21β-dihydroxy-urs-12-en-28-oic acid based on NMR and MS spectroscopic analyses. The condensation reactions to form 28-oic acid-13-lactone ring and 11,26-epoxy ring are not frequently seen for the biotransformation of triterpenoids. One compound showed moderate inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).

Protective effects of the key compounds isolated from Corni fructus against β-amyloid-induced neurotoxicity in PC12 cells

β-Amyloid (Aβ) peptide is the major component of senile plaques and is considered to have a causal role in the development and progression of Alzheimer’s disease (AD). There is compelling evidence supporting the notion that Aβ-induced cytotoxicity is mediated though the generation of ROS. In the present study, we investigated the neuroprotective effects of ursolic acid (UA), p-coumaric acid (p-CA), and gallic acid (GA) isolated from Corni fructus (CF) against Aβ(25-35)-induced toxicity in PC12 cell. Exposure of PC12 cells to 50 μM Aβ(25-35) increased cellular oxidative stress, the number of apoptotic cells and caspase-3 activity and finally caused significant cell death. However, UA, p-CA, and GA not only suppressed the generation of ROS but also attenuated DNA fragmentation and eventually attenuated Aβ-induced apoptosis in a dose-dependent manner. In protecting cells against Aβ neurotoxicity, UA and GA possessed stronger ability against ROS generation than p-CA, while p-CA showed the strongest anti-apoptotic activity. Particularly, p-CA protected cells at the concentration range from 0.5 up to 125 μM without any adverse effect. Taken together, these effects of UA, p-CA, and GA may be partly associated with the neuroprotective effect of CF. Furthermore, our findings might raise a possibility of therapeutic applications of CF for preventing and/or treating neurodegenerative diseases.

Semisynthetic ursolic acid fluorolactone derivatives inhibit growth with induction of p21(waf1) and induce apoptosis with upregulation of NOXA and downregulation of c-FLIP in cancer cells

A series of ursolic acid ((1S,2R,4aS,6aR,6aS,6bR,8aR,10S,12aR,14bS)-10-hydroxy-1,2,6a,6b,9,9,12a-heptamethyl-2,3,4,5,6,6a,7,8,8a,10,11,12,13,14b-tetradecahydro-1H-picene-4a-carboxylic acid) derivatives with a 12-fluoro-13,28β-lactone moiety were synthesized using the electrophilic fluorination reagent Selectfluor. The antiproliferative effects of these novel compounds were evaluated in AsPC-1 pancreatic cancer cells, and the structure-activity relationships (SARs) were evaluated. Of the compounds synthesized, ursolic acid derivatives carrying a heterocyclic ring, such as imidazole or methylimidazole, and cyanoenones were among the more potent inhibitors of AsPC-1 pancreatic cancer cell growth. 2-Cyano-3-oxo-12α-fluoro-urs-1-en-13,28β-olide, compound 20, was the most effective inhibitor with IC(50) values of 0.7, 0.9 and 1.8 μM in pancreatic cancer cell lines AsPC-1, MIA PaCa-2 and PANC-1, respectively. This compound also exhibited better antiproliferative activities against breast (MCF7), prostate (PC-3), hepatocellular (Hep G2) and lung (A549) cancer cell lines, with IC(50) values lower than 1 μM. The mechanism of action by which these compounds exert their biological effect was evaluated in AsPC-1 cells using the most potent inhibitor synthesized, compound 20. At 1 μM, the cell cycle arrested at the G1 phase with upregulation of p21(waf1). Apoptosis was induced at an inhibitor concentration of 8 μM with upregulation of NOXA and downregulation of c-FLIP. These data indicate that fluorolactone derivatives of ursolic acid have improved antiproliferative activity, acting through arrest of the cell cycle and induction of apoptosis.

Synthesis and antitumor activity evaluation of new asiatic acid derivatives

Twelve novel asiatic acid (AA) derivatives were designed and synthesized. Their structures were confirmed using NMR, MS, and IR spectra. Their in vitro cytotoxicities on various cancer cell lines (HeLa, HepG2, BGC-823, and SKOV3) were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Most of the derivatives were found to have stronger cell growth inhibitory activity than AA. Among them, compounds 5-8 and 11 with substituted amide group at C-28 exhibited more potent cytotoxicity than AA, Gefitinib, and etoposide (positive control).

Pharmacophore, QSAR, and ADME based semisynthesis and in vitro evaluation of ursolic acid analogs for anticancer activity

In the present work, QSAR models for predicting the activities of ursolic acid analogs against human lung (A-549) and CNS (SF-295) cancer cell lines were developed by a forward stepwise multiple linear regression method using a leave-one-out approach. The regression coefficient (r(2)) and the cross-validation regression coefficient (rCV(2)) of the QSAR model for cytotoxic activity against the human lung cancer cell line (A-549) were 0.85 and 0.80, respectively. The QSAR study indicated that the LUMO energy, ring count, and solvent-accessible surface area were strongly correlated with anticancer activity. Similarly, the QSAR model for cytotoxic activity against the human CNS cancer cell line (SF-295) also showed a high correlation (r(2) = 0.99 and rCV(2) = 0.96), and indicated that dipole vector and solvent-accessible surface area were strongly correlated with activity. Ursolic acid analogs that were predicted to be active against these cancer cell lines by the QSAR models were semisynthesized and characterized on the basis of their (1)H and (13)C NMR spectroscopic data, and were then tested in vitro against the human lung (A-549) and CNS (SF-295) cancer cell lines. The experimental results obtained agreed well with the predicted values.

Fruit cuticular waxes as a source of biologically active triterpenoids

The health benefits associated with a diet rich in fruit and vegetables include reduction of the risk of chronic diseases such as cardiovascular disease, diabetes and cancer, that are becoming prevalent in the aging human population. Triterpenoids, polycyclic compounds derived from the linear hydrocarbon squalene, are widely distributed in edible and medicinal plants and are an integral part of the human diet. As an important group of phytochemicals that exert numerous biological effects and display various pharmacological activities, triterpenoids are being evaluated for use in new functional foods, drugs, cosmetics and healthcare products. Screening plant material in the search for triterpenoid-rich plant tissues has identified fruit peel and especially fruit cuticular waxes as promising and highly available sources. The chemical composition, abundance and biological activities of triterpenoids occurring in cuticular waxes of some economically important fruits, like apple, grape berry, olive, tomato and others, are described in this review. The need for environmentally valuable and potentially profitable technologies for the recovery, recycling and upgrading of residues from fruit processing is also discussed.

Synthesis and evaluation of ursolic acid derivatives as potent cytotoxic agents

Structural modification was performed at the C-3 and C-28 positions of ursolic acid (UA). Ten UA derivatives with distinct electrical property were synthesized. They could be divided into two groups according to their charge under physiological conditions: (1) Group I negatively charged and (2) Group II positively charged. The anti-proliferative capability of the derivatives was evaluated against HepG2, AGS, HT-29 and PC-3 cells by the MTT assay. Flow cytometry and Annexin V/PI dual staining assay were carried out to explore the antitumor mechanism. The results showed the cytotoxic capacity of the compounds was: Group I Collapse

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MESH Headings

• Antineoplastic Agents/chemical synthesis
• Antineoplastic Agents/pharmacology
• Apoptosis/drug effects
• Carcinoma
• Cell Cycle Checkpoints/drug effects
• Cell Line, Tumor
• Cell Survival/drug effects
• Cytotoxins/chemical synthesis
• Cytotoxins/pharmacology
• Drug Screening Assays, Antitumor
• Flow Cytometry
• Humans
• Hydrophobic and Hydrophilic Interactions
• Static Electricity
• Stomach Neoplasms
• Triterpenes/chemical synthesis
• Triterpenes/pharmacology
• Ursolic Acid

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Affiliation(s)

Kai-Kai Bai College of Chemistry & Chemical Engineering, Fuzhou University, Fuzhou 350002, PR China
Zhou Yu
Fen-Ling Chen
Feng Li
Wei-Yun Li
Yang-Hao Guo

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[Synthesis of A-secomethylenamino- and substituted amidoximotriterpenoids]

Development of the functionalization of triterpenoids to A-secoamidoximes, A-secomethylenamines and branched 3-(3-aminopropylamino)-3-(3-aminopropoxy)amidoximes is illustrated by the betulonic acid ketoxime. An effective way to get of the derivatives of 20,29-dihydrolupanes using diborane is suggested. The antiviral and anti-tuberculosis activity data of some compounds are presented.

Apple peels, from seven cultivars, have lipase-inhibitory activity and contain numerous ursenoic acids as identified by LC-ESI-QTOF-HRMS

Apple peel contains numerous phytochemicals, many of which show bioactivity. This study investigated the identity of triterpenoid compounds contained in ethanolic extracts of peel from seven apple cultivars. Using HPLC-ESI-QTOF-HRMS, accurate mass information was obtained for 43 compounds, and chemical identity was inferred from the calculated elemental composition, fragment masses, ms/ms, and a limited set of authentic standards. Compounds were identified as triterpene acids and tentatively identified as ursenoic (or oleanoic) acid derivatives containing hydroxyl, oxo, and coumaroyloxy groups. These apple skin extracts exhibited lipase-inhibitory activity, which may be linked to the ursenoic acid content. Furthermore, both triterpene content and lipase-inhibitory activity varied by cultivar.

Ursolic acid, a pentacyclic triterpene from Sambucus australis, prevents abdominal adiposity in mice fed a high-fat diet

Currently, there is renewed interest in plant-based medicines and functional foods for the prevention and cure of obesity and its associated risk of cardiovascular disease and metabolic syndrome. In the search for potential anti-obesity compounds from natural sources, the effects of ursolic acid (UA), a pentacyclic triterpenoid widely found in medicinal herbs and fruits, was evaluated for its effects on blood glucose, lipids, and abdominal fat deposition in mice fed a high-fat diet (HFD). Adult male Swiss mice treated or not with UA (0.05%, 50 mg/L, in drinking water) were fed HFD for 15 weeks. A sibutramine (SIB)-treated group (0.05% in drinking water) was included as the positive control. Weekly body weights and food and water consumption were measured, and at the end of the study period, the levels of blood glucose and lipids, the plasma hormones insulin, ghrelin, and leptin, and the abdominal fat accumulation were analyzed. Mice treated with UA and fed HFD showed significantly (P<.05) decreased body weights, visceral adiposity, and levels of blood glucose and plasma lipids relative to their respective controls not fed UA. Also, a significant increase was observed in plasma leptin with a decrease in ghrelin, as well as of amylase and lipase activities. The SIB-treated group also manifested effects similar to those of UA except for the blood glucose level, which was not different from the HFD control. These findings suggest that UA ameliorates abdominal adiposity and decreases the levels of blood glucose and plasma lipids in mice and thus manifests an anti-obesity potential through absorptive and metabolic targets.

Clinically useful anticancer, antitumor, and antiwrinkle agent, ursolic acid and related derivatives as medicinally important natural product

Medicinal plants are becoming an important research area for novel and bioactive molecules for drug discovery. Novel therapeutic strategies and agents are urgently needed to treat different incurable diseases. Many plant derived active compounds are in human clinical trials. Currently ursolic acid is in human clinical trial for treating cancer, tumor, and skin wrinkles. This review includes the clinical use of ursolic acid in various diseases including anticancer, antitumor, and antiwrinkle chemotherapies, and the isolation and purification of this tritepernoid from various plants to update current knowledge on the rapid analysis of ursolic acid by using analytical methods. In addition, the chemical modifications of ursolic acid to make more effective and water soluble derivatives, previous and current information regarding, its natural and semisynthetic analogs, focusing on its anticancer, cytotoxic, antitumor, antioxidant, anti-inflammatory, anti-HIV, acetyl cholinesterase, α-glucosidase, antimicrobial, and hepatoprotective activities, briefly discussion is attempted here for its research perspectives. This review article contains fourteen medicinally important ursolic acid derivatives and 351 references.

Rapid access to ketones related to oleanolic and ursolic acids

We describe in this article a process with which to obtain different ketones related to oleanolic and ursolic acids from a natural source, Salvia canariensis L., with minimal use of chromatography columns. Amongst the isolated compounds was 12α-bromo-3-oxo-olean-13, 28-olide (3), which was fully characterised, including a characterisation of its molecular configuration by X-ray crystallographic analysis by 1 and 2-dimensional NMR techniques.

Quantitative Structure Inter-Activity Relationship (QSInAR). Cytotoxicity Study of Some Hemisynthetic and Isolated Natural Steroids and Precursors on Human Fibrosarcoma Cells HT1080

Combined experimental and quantitative structure inter-activity relationship (QSIAR) computation methods were advanced in order to establish the structural and mechanistic influences that steroids and triterpenes, either as newly synthesized or naturally isolated products, have on human HT1080 mammalian cancer cells. The main Hansch structural indicators such as hydrophobicity (LogP), polarizability (POL) and total energy (Etot) were considered and both the structure-projected as well as globally computed correlations were reported; while the inter-activity correlation of the global activity with those projected on structural information was revealed as equal to the direct structural-activity one for the trial sets of compounds, the prediction for the testing set of molecules reported even superior performances respecting those characteristic for the calibration set, validating therefore the present QSInAR models; accordingly, it follows that the LogP carries the most part of the cytotoxic signal, while POL has little influence on inhibiting tumor growth—A complementary behavior with their earlier known influence on genotoxic carcinogenesis. Regarding the newly hemisynthetic compounds it was found that stigmasta-4,22-dien-3-one is not adapted for cell membrane diffusion; it is recommended that aminocinnamyl chlorohydrate be further modified in order to acquire better steric influence, while aminocinnamyl-2,3,4,6-O-tétraacétyl-α-D-glucopyranoside was identified as being inhibited in the tumor cell by other molecular mechanisms–here not revealed–although it has a moderate-high anti-cancer structurally predicted activity.

In vitro and in vivo anticancer activity evaluation of ursolic acid derivatives

Twenty-three ursolic acid (1) derivatives 2-24 (ten novel compounds 8-10, 14-17 and 22-24) modified at the C-3 and the C-28 positions were synthesized, and their structures were confirmed by IR, (1)H NMR, MS, and elemental analysis. The single crystals of compounds 15 and 17 were obtained. The cytotoxic activity of the derivatives was evaluated against HepG2, BGC-823, SH-SY5Y, HeLa and HELF cells by the MTT assay. The induction of apoptosis and affects on the cell cycle distribution with compound 14 were assessed by fluorescence microscopy, flow cytometry and the activity of caspase-3 in HepG2 cells. Compounds 14-17 had more significant antiproliferative ability against the four cancer cell lines and low cytotoxicity to human embryonic lung fibroblast cells (HELF). Compounds 11, 14-16, 21 and 23 were particularly active against HepG2 cell growth. Compound 14 was selected to investigate cell apoptosis and cell cycle distribution. Flow cytometric analysis and morphologic changes of the cell exhibited that treatment of HepG2 cells with compound 14 led to cell apoptosis accompanied by cell cycle arrest at the S phase in a dose-dependent manner. Furthermore, the activity of the caspase-3 enzyme was increased in the treated cells. In vivo studies using H22 xenografts in Kunming mice were conducted with compound 14 at doses of 50, 100 and 150 mg/kg body weight. The results revealed that the medium dosage group (100 mg/kg) showed significant anticancer activity (45.6 ± 4.3%) compared to the control group.

Ferruginenes A-C from Rhododendron ferrugineum and their cytotoxic evaluation

Three new compounds, ferruginenes A (1) and B (2) and a mixture of C-5'(R) and C-5'(S) ferruginene C (3) diastereomers, have been isolated from a cytotoxic chloroform-soluble fraction of the leaves of Rhododendron ferrugineum together with 12 known compounds. The structures of these new compounds were elucidated by analyses of NMR spectroscopic and mass spectrometric data. Compounds 1-3 were tested for their cytotoxicity against three human cancer cell lines, namely, HL-60, HeLa-S3, and MCF-7.

Cytotoxicity and bioavailability studies on a decoction of Oldenlandia diffusa and its fractions separated by HPLC

AIM OF THE STUDY

Oldenlandia diffusa is a traditional Chinese herbal remedy with known cytotoxic activity in vitro and in vivo. The aim of the study was to identify the most cytotoxic constituents of a water extract (a decoction is traditionally used as a treatment) by HPLC and activity-guided fractionation. The bioavailability of the decoction and certain fractions, and the mode of cell death induced by these mixtures, were also investigated.

MATERIALS AND METHODS

A decoction of O. diffusa was prepared and separated by HPLC into eleven fractions (F1-11) for testing on the growth of HL60 leukaemia cells; two of the most active fractions were also tested on Caco-2 colon cancer cells. Cell viability was measured by trypan blue exclusion, DNA content (Cyquant NF assay) and neutral red uptake. Evidence of apoptosis was gained from cells stained with the nuclear dye DAPI, and detection of cleaved poly (ADP-ribose) polymerase (PARP) by Western blot.

RESULTS

Fraction 9 was found to be the most active fraction, and, along with the decoction, induced apoptosis. Cells stained with DAPI showed a decrease in cell size and nuclear fragmentation characteristic of apoptosis. Detection of cleaved PARP further confirmed induction of apoptosis by O. diffusa decoction and fraction 9. The bioavailability of O. diffusa was investigated by production of post-absorption samples using Caco-2 intestinal epithelial monolayers. Addition of post-absorption samples (taken from the basolateral side after 3h incubation with the decoction on the apical side) inhibited the growth of HL60 cells, and suggested a degree of bioavailability. The constituents in fraction 9 were further separated by HPLC and eight major compounds were identified by LC-MS: two of these were ursolic acid (UA) and its enantiomer oleanolic acid (OA). Concentrations of UA and OA in the decoction were then calculated by reference to the area of the peaks of UA and OA found in F9. The post-absorption sample of F9 contained six of the eight constituents in the original pre-absorption fraction 9.

CONCLUSIONS

Taken together, the results suggest that certain constituents, possibly including ursolic/oleanolic acid, may be bioavailable and at sufficient concentration to induce apoptosis in cancer cells in vitro through a mechanism including the cleavage of PARP.

Synthesis and in vitro cytotoxicity of novel ursolic acid derivatives

In an effort to improve potential hepatoprotective and anti-tumor activities, eight novel ursolic acid (UA) derivatives were designed and synthesized with substitution at positions of C-3, C-11 and C-28 of UA. Their structures were confirmed using IR, MS and (1)H-NMR and elemental analysis. Their in vitro cytotoxicity against various cancer cell lines (HeLa, SKOV3 and BGC-823) was evaluated by the standard MTT assay. Among them, compound 13 exhibited more potent cytotoxicity than ursolic acid.

Cytotoxic and NF-kappaB inhibitory constituents of Artocarpus rigida

Four new prenylated flavonoids (1-4), a new stilbenoid (5), and nine known compounds were isolated from the twigs of Artocarpus rigida, collected in Indonesia. The structures of the new compounds were determined by analysis of their spectroscopic data, and the absolute configuration at C-12 of 1 and 2 and the known compounds artonin O (6), artobiloxanthone (7), and cycloartobiloxanthone (8) was determined from their CD and NMR spectroscopic data. Several of the compounds obtained were cytotoxic toward HT-29 human colon cancer cells, with the most potent being compound 2 and the known compounds 6 and 8. Of the substances obtained, compounds 1 and 7 were the most active in the NF-kappaB p50 and p65 assay, respectively.

Cytotoxic and cell cycle effects induced by two herbal extracts on human cervix carcinoma and human breast cancer cell lines

In recent times interest has increased in the complementary medicine of cancer patients. Two herbal mixtures were prepared from 17 and 12 plants, respectively. The goal of this study was to examine the in vitro cytotoxic and cell cycle effects of the aqueous-ethanol extracts (Extract 1 and Extract 2) obtained by maceration of the mixtures. The two extracts investigated exhibited significant antiproliferative activity toward two human breast cancer cell lines (MDA-MB-361 and MDA-MB-453) and a human cervix carcinoma cell line (HeLa) with 50% inhibitory concentration (IC(50)) values ranging from 9.92 to 17.38 microL/mL. The extracts did not exert any significant cytotoxicity toward healthy human peripheral blood mononuclear cells. In vitro antitumor activities were accompanied by an important apoptotic fraction of all cell lines after treatment with the extracts. The amount of total phenols was similar in both extracts, whereas the concentration of total tannins was significantly higher in Extract 1. Extract 1 was also found to be a stronger free radical scavenger, with an IC(50) value of 13.4 microg/mL. Both extracts contained rosmarinic acid, while ursolic acid was identified in Extract 2.

Oleanolic acid, a natural triterpenoid improves blood glucose tolerance in normal mice and ameliorates visceral obesity in mice fed a high-fat diet

Excess visceral adiposity may predispose to chronic diseases like hypertension and type 2 diabetes with a high risk for coronary artery disease. Adipose tissue secreted cytokines and oxidative stress play an important role in chronic disease progression. To combat adiposity, plant-derived triterpenes are currently receiving much attention as they possess antioxidant and anti-inflammatory properties and the ability to regulate glucose and lipid metabolism. In the search for potential antiobese compounds from natural sources, this study evaluated the effects of oleanolic acid (OA), a pentacyclic triterpene commonly present in fruits and vegetables, in glucose tolerance test and on high-fat diet (HFD)-induced obesity in mice. Adult male Swiss mice treated or not with OA (10 mg/kg) were fed a HFD during 15 weeks. Sibutramine (SIB) treated group (10 mg/kg) was included for comparison. Weekly body weights, food and water consumption were measured, and at the end of study period, the levels of blood glucose and lipids, plasma hormone levels of insulin, ghrelin and leptin, and the visceral abdominal fat content were analysed. Mice treated with OA and fed a HFD showed significantly (p<0.05) improved glucose tolerance, decreased body weights, visceral adiposity, blood glucose, plasma lipids relative to their respective controls fed no OA. Additionally, OA treatment, while significantly elevating the plasma hormone level of leptin, decreased the level of ghrelin. However, it caused a greater decrease in plasma amylase activity than lipase. Sibutramine-treated group also manifested similar effects like OA except for blood glucose level that was not different from HFD control. These findings suggest that OA ameliorates visceral adiposity and improves glucose tolerance in mice and thus has an antiobese potential through modulation of carbohydrate and fat metabolism.

In vitro cytotoxic and antioxidative activity of Cornus mas and Cotinus coggygria

Cytotoxicity and antioxidant properties of the methanol extracts of leaves and flowers of Cornus mas and Cotinus coggygria were studied, together with their chemical composition. Extracts of C. coggygria flowers and leaves showed better antioxidant activity in reaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as in inhibition of lipid peroxidation (LP) than C. mas extracts. Preliminary results showed that all extracts possessed potential cytotoxic activity towards HeLa and LS174 human cancer cell lines in vitro, with stronger inhibition against growth of HeLa cell growth than against LS174 cell growth. Cytotoxic activity of C. coggygria extracts showed good correlation with their antioxidative activity in vitro. In the brine shrimp lethality test, there were no significant changes in toxicity.

[Synthesis and modification of triterpenoids with two lupan backbones]

The first derivatives containing two lupan backbones were synthesized by the interaction of betulonic acid chloride with diols (ethylene glycol and diethylene glycol) and monoethanolamine. A modification of ring A of ethylene-l,2-bis(betulonnate) led to its bis(3beta-aminopropyloxy) and bis(3,4-seco-2-cyano) derivatives.

Ursolic acid derivatives induce cell cycle arrest and apoptosis in NTUB1 cells associated with reactive oxygen species

Twenty-three ursolic acid (1) derivatives 2-24 including nine new 1 derivatives 5, 7-11, 20-22 were synthesized and evaluated for cytotoxicities against NTUB1 cells (human bladder cancer cell line). Compounds 5 and 17 with an isopropyl ester moiety at C-17-COOH and a succinyl moiety at C-3-OH showed potent inhibitory effect on growth of NTUB1 cells. Compounds 23 and 24 with seco-structures prepared from 1 also showed the increase of the cytotoxicity against NTUB1 cells. Exposure of NTUB1 to 5 (40 microM) and 23 (20 and 50 microM) for 24h significantly increased the production of reactive oxygen species (ROS) while exposure of NTUB1 to 5 (20 and 40 microM) and 23 (20 and 50 microM) for 48 h also significantly increased the production of ROS while exposure of cells to 17 did not increase the amount of ROS. Flow cytometric analysis exhibited that treatment of NTUB1 with 5 or 17 or 23 led to the cell cycle arrest accompanied by an increase in apoptotic cell death after 24 or 48 h. These data suggest that the presentation of G1 phase arrest and apoptosis in 5- and 23-treated NTUB1 for 24 h mediated through increased amount of ROS in cells exposed with 5 and 23, respectively, while the presence of G2/M arrest before accumulation of cells in sub-G1 phase in 5-treated cells for 48 h also due to increased amount of ROS in cells exposed with 5. The inhibition of tubulin polymerization and cell cycle arrest at G2/M following by apoptosis presented in the cell cycle of 23 also mediates through the increase amount of ROS induced by treating NTUB1 with 23 for 48 h.

Methyl 3-acet-oxy-3-dehydroxy-ursolate

Four of the five six-membered rings of the title penta­cyclic triterpene, C₃₃H₅₂O₄, adopt chair conformations; the fifth, which has a C=C double bond, adopts an approximate envelope conformation.

Methyl 3-dehydr-oxy-3-oxoursolate

Four of the five six-membered rings of the title penta­cylic triterpene, C₃₁H₄₈O₃, adopt chair conformations; the fifth, which has a C=C double bond, adopts an approximate envelope conformation.