Pharmacological activities of natural triterpenoids and their therapeutic implications

Evaluation of cytotoxic, analgesic, antidiarrheal and phytochemical properties of Hygrophila spinosa (T. Anders) whole plant

BACKGROUND

Synthetic drugs are going to be replaced by plant-derived traditional drugs due to their cost effectiveness, relatively less harmfulness, and efficacy against multidrug resistance organisms. Hygrophila spinosa (Acanthaceae) has been used in a wide range of ailments including flatulence, diarrhea, dysentery, gonorrhea, and menorrhagia. Therefore, we investigated the cytotoxic, antinociceptive, and antidiarrheal effects of H. spinosa ethanol extract (EExHs).

METHODS

Preliminary phytochemical screening was accomplished by established methods modified in experimental protocol. EExHs was undertaken for cytotoxic assay by Brine shrimp lethality bioassay, antinociceptive action by acetic acid induced writhing test, and antidiarrheal activity by castor oil induced antidiarrheal test. Data were analyzed by GraphPad Prism 6.0 software using Dunnett's test for multiple comparisons.

RESULTS

Reducing sugar, steroid, glycoside, tannin, alkaloid, saponins, and flavonoids were found to be present in EExHs. Lethal concentration (LC50) of EExHs for brine shrimps was 50.59 µg/mL which was relatively lower than that of the standard drug vincristine sulfate. In acetic acid induced writhing test, oral administration of EExHs at three different doses (125, 250, and 500 mg/kg) decreased writhing in dose-dependent manner while the highest dose (500 mg/kg) achieved the maximum percentages of pain inhibition (58.8%). Diclofenac sodium (25 mg/kg) was used as a reference antinociceptive drug. The antidiarrheal action of EExHs was not found to be very promising for further use; however, the pure compounds from EExHs could be analyzed to justify the effects.

CONCLUSIONS

This research demonstrates that the secondary metabolites guided cytotoxic and analgesic effects could be extensively studied in multiple models to confirm the effects.

Triterpene derivatives from Euphorbia enhance resistance against Verticillium wilt of tomato

Oxidation of α-euphorbol and 31-norlanostenol, two triterpenic compounds isolated from the latex of Euphorbia resinifera and Euphorbia officinarum respectively, yielded four products named 3β-tosyloxy-4α,14α-dimethyl-5α-cholesta-7,9-diene; 4α,14α-dimethyl-5α-cholesta-7,9-dien-3β-ol; 24-methylen-elemo-lanosta-8,24-dien-3-one and elemo-lanost-8-en-3,11,24-trione. They were evaluated for protection of tomato plants against Verticillium dahliae in a greenhouse. The four semisynthesized products were phytotoxic at higher concentrations as they completely inhibited tomato germination at 100 and 500 μg/ml. However at lower concentrations (10 and 50 μg/ml) germination and root length were not affected. Disease resistance against Verticillium wilt was assessed in tomato plants derived from seeds that germinated in the presence of 10 and 50 μg/ml of the four products. All of them were able to reduce significantly disease severity, with 10 μg/ml being more effective than 50 μg/ml. Reduction of leaf alteration index and of stunting index ranged from 52 to 68% and from 43 to 67%, respectively, while vessel discoloration was reduced by at least 95%. The compounds were also able to elicit H₂O₂ accumulation before and after fungal inoculation and to significantly enhance peroxidase and polyphenol oxidase activities. These results suggest that the hemisynthetized triterpenes can be used as elicitors of disease resistance.

Two rare antioxidant and anti-inflammatory oleanenes from loop root Asiatic mangrove Rhizophora mucronata

Two oleanenes, olean-18(19)-en-3β-yl-(3,6-dimethyl-3E,6Z-dienoate) and (13α)-27-frido-olean-14(15)-en-(17α)-furanyl-3β-ol representing a class of rare natural pentacyclic triterpenoids were isolated from the chloroform extract of Asiatic mangrove, Rhizophora mucronata Lam. (Family: Rhizophoraceae). The furanyl oleanene exhibited significantly greater antioxidative activities (IC₅₀ 0.73-0.76 mg/mL), than prenylated oleanene (IC₅₀ 0.84-0.96 mg/mL) (P < 0.05). No significant differences in anti-5-lipoxygenase activities of these compounds with the synthetic drug ibuprofen was discernable (IC₅₀ 0.8-0.9 mg/mL), whilst furanyl oleanene demonstrated significantly greater anti-cyclooxygenase-2 (IC₅₀ 0.84 mg/mL) and anti-5-lipoxygenase activities (IC₅₀ 0.78 mg/mL) over prenylated oleanene (IC₅₀ > 0.90 mg/mL). These compounds exhibited lesser activity against cyclooxygenase-1 than cyclooxygenase-2 isoform, and therefore, their selectivity indices remained significantly greater (anti-cyclooxygenase-1_IC50/anti-cyclooxygenase-2_IC50 > 1) than the aspirin (0.02) and ibuprofen (0.44). The lipophilic and steric molecular descriptors were found to occupy a prominent role in determining the bioactivities of the compounds. These previously undescribed oleanenes might serve as potential antioxidative and anti-inflammatory lead molecules in medicinal formulations and food industries.

Cytotoxic conjugates of betulinic acid and substituted triazoles prepared by Huisgen Cycloaddition from 30-azidoderivatives

In this work, we describe synthesis of conjugates of betulinic acid with substituted triazoles prepared via Huisgen 1,3-cycloaddition. All compounds contain free 28-COOH group. Allylic bromination of protected betulinic acid by NBS gave corresponding 30-bromoderivatives, their substitution with sodium azides produced 30-azidoderivatives and these azides were subjected to CuI catalysed Huisgen 1,3-cycloaddition to give the final conjugates. Reactions had moderate to high yields. All new compounds were tested for their in vitro cytotoxic activities on eight cancer and two non-cancer cell lines. The most active compounds were conjugates of 3β-O-acetylbetulinic acid and among them, conjugate with triazole substituted by benzaldehyde 9b was the best with IC50 of 3.3 μM and therapeutic index of 9.1. Five compounds in this study had IC50 below 10 μM and inhibited DNA and RNA synthesis and caused block in G0/G1 cell cycle phase which is highly similar to actinomycin D. It is unusual that here prepared 3β-O-acetates were more active than compounds with the free 3-OH group and this suggests that this set may have common mechanism of action that is different from the mechanism of action of previously known 3β-O-acetoxybetulinic acid derivatives. Benzaldehyde type conjugate 9b is the best candidate for further drug development.

Aldo-Keto Reductase Family 1 Member B10 Inhibitors: Potential Drugs for Cancer Treatment

Cytosolic NADPH-dependent reductase AKR1B10 is a member of the aldo-keto reductase (AKR) superfamily. This enzyme is normally expressed in the gastrointestinal tract. However, it is overexpressed in many solid tumors, such as hepatocarcinoma, lung cancer and breast cancer. AKR1B10 may play a role in the formation and development of carcinomas through multiple mechanisms including detoxification of cytotoxic carbonyls, modulation of retinoic acid level, and regulation of cellular fatty acid synthesis and lipid metabolism. Studies have suggested that AKR1B10 may be a useful biomarker for cancer diagnosis and a potential target for cancer treatment. Over the last decade, a number of AKR1B10 inhibitors including aldose reductase inhibitors (ARIs), endogenous substances, natural-based derivatives and synthetic compounds have been developed, which could be novel anticancer drugs. This review provides an overview on related articles and patents about AKR1B10 inhibitors, with a focus on their inhibition selectivity and mechanism of function.

Anticancer properties of ester derivatives of betulin in human metastatic melanoma cells (Me-45)

Background

Betulinic acid and betulin are triterpenes that have anticancer properties in various types of cancer. Unfortunately, the bioavailability and the bio-distribution of betulinic acid and its metabolic precursor, betulin are very low because of poor solubility in aqueous buffers.

Methods

In this study, we examined the anticancer properties of the ester derivatives of betulin compared to their precursors in a malignant melanoma cell line. We assessed five amino acid esters of betulin. The compounds contained four basic amino acids—natural lysine (l-Lys-OH) and three of its derivatives (l-Dap-OH, l-Dab-OH, and l-Orn-OH)—and alanine (l-Ala-OH) as a negative control (amino acid without an amine group in the side chain). The derivatives were more soluble than their precursors (betulin and betulinic acid) in water. The betulin esters were tested in the malignant melanoma cell line Me-45. To evaluate the cytotoxicity, MTT test was performed after 24, 48 and 72 h of incubation with the test compounds at a concentration range of 0.75–100 μM. For analysis of the apoptotic activity, TUNEL assay was performed. Additionally, expression of caspase-3 and PARP-1 was investigated immunocytochemically.

Results

The highest biological activity was observed with the lysine ester. The results showed that the highest cytotoxicity and the highest number of positively stained nuclei in metastatic melanoma Me-45 cells were obtained after 72 h of incubation with betulin derivatives containing lysine and ornithine.

Conclusions

The betulin ester derivatives showed enhanced antitumor activity compared to their non-modified precursors. Esters of betulin can be more potent anticancer agents than their precursor as a consequence of the rapid bioavailability and increased concentration in cancer cells.

Discovery of FZU-03,010 as a self-assembling anticancer amphiphile for acute myeloid leukemia

Recently various drug candidates with excellent anticancer potency have been demonstrated, whereas their clinical application largely suffers from several limitations especially poor solubility. Ursolic acid (UA) as one of ubiquitous pentacyclic triterpenes in plantkingdom exhibited versatile antiproliferative effects in various cancer cell lines. However, the unfavorable pharmaceutical properties became the main obstacle for its clinical development. With the aim of development of novel derivatives with enhanced potency, a series of diversified UA amphiphiles have been designed, synthesized, and pharmacologically evaluated. Amphiphile 10 (FZU-03,010) with significant improved antiproliferative effect can self-assemble into stable nanoparticles in water, which may serve as a promising candidate for further development.

Dietary Phytochemicals and Cancer Chemoprevention: A Perspective on Oxidative Stress, Inflammation, and Epigenetics

Oxidative stress occurs when cellular reactive oxygen species levels exceed the self-antioxidant capacity of the body. Oxidative stress induces many pathological changes, including inflammation and cancer. Chronic inflammation is believed to be strongly associated with the major stages of carcinogenesis. The nuclear factor erythroid 2-related factor 2 (Nrf2) pathway plays a crucial role in regulating oxidative stress and inflammation by manipulating key antioxidant and detoxification enzyme genes via the antioxidant response element. Many dietary phytochemicals with cancer chemopreventive properties, such as polyphenols, isothiocyanates, and triterpenoids, exert antioxidant and anti-inflammatory functions by activating the Nrf2 pathway. Furthermore, epigenetic changes, including DNA methylation, histone post-translational modifications, and miRNA-mediated post-transcriptional alterations, also lead to various carcinogenesis processes by suppressing cancer repressor gene transcription. Using epigenetic research tools, including next-generation sequencing technologies, many dietary phytochemicals are shown to modify and reverse aberrant epigenetic/epigenome changes, potentially leading to cancer prevention/treatment. Thus, the beneficial effects of dietary phytochemicals on cancer development warrant further investigation to provide additional impetus for clinical translational studies.

Lupane-type triterpenes and their anti-cancer activities against most common malignant tumors: A review

In recent times, a great deal of interest has been motivated on plant derived compounds known as nutraceuticals. These compounds exert important beneficial activities that improve people's health status when are consumed regularly, and now they appear as a viable option to explore their possible therapeutic effects against diseases like cancer. Particularly, lupane-type triterpenes have shown great ability to modulate multiple cancer-related signaling pathways and processes, including NF-κB, Wnt/β-catenin, PI3K/Akt, apoptosis, and many other routes related to proliferation or cell death, which are uncontrolled in malignant tumors. These investigations have promoted in vitro and in vivo studies, searching their mechanisms of action; although more research is still needed to prove its potential in human clinical trials. This review focuses on the ability of betulin, betulinic acid and lupeol to show benefits against the most common types of malignant tumors, which are considered a major global threat for public health.

Synthesis of acyl oleanolic acid-uracil conjugates and their anti-tumor activity

BACKGROUND

Oleanolic acid, which can be isolated from many foods and medicinal plants, has been reported to possess diverse biological activities. It has been found that the acylation of the hydroxyl groups of the A-ring in the triterpene skeleton of oleanolic acid could be favorable for biological activities. The pyrimidinyl group has been constructed in many new compounds in various anti-tumor studies.

RESULTS

Five acyl oleanolic acid-uracil conjugates were synthesized. Most of the IC₅₀ values of these conjugates were lower than 10.0 μM, and some of them were even under 0.1 μM. Cytotoxicity selectivity detection revealed that conjugate 4c exhibited low cytotoxicity towards the normal human liver cell line HL-7702. Further studies revealed that 4c clearly possessed apoptosis inducing effects, could arrest the Hep-G2 cell line in the G1 phase, induce late-stage apoptosis, and activate effector caspase-3/9 to trigger apoptosis.

CONCLUSIONS

Conjugates of five different acyl OA derivatives with uracil were synthesized and identified as possessing high selectivity toward tumor cell lines. These conjugates could induce apoptosis in Hep-G2 cells by triggering caspase-3/9 activity.Graphical abstractFive acyl oleanolic aicd-uracil conjugates were synthesized. These conjugates exhibited selective cytotoxicity toward tumor cells achieved via inducing apoptosis by activation of caspase-3/9.

Autoxidation Products of Betulonaldehyde

Three major degradation products resulted from the exposure of betulonaldehyde (1) to air in solution at room temperature. From HRMS and NMR data, the products, which were isolated by preparative supercritical fluid chromatography (SFC), were identified as betulonic acid (2) and C-17 hydroperoxide epimers 3 (β-OOH) and 4 (α-OOH). For 3 and 4, the H-18 multiplet pattern of the isolated products established the configuration at C-17.

Natural Triterpenoids for the Treatment of Diabetes Mellitus: A Review

Triterpenoids, an important group of secondary metabolites, are widely distributed in nature. Many triterpenoids have been found with potential therapeutic effect against diabetes mellitus. However, the use of triterpenoids for the treatment of diabetes has not been systematically discussed previously. This review summarized the anti-diabetic activity of natural triterpenoids reported since the late 1980s with the emphasis on the molecular mechanisms.

Biodegradable Micellar HPMA-Based Polymer-Drug Conjugates with Betulinic Acid for Passive Tumor Targeting

Here, we present the synthesis, physicochemical, and preliminary biological characterization of micellar polymer-betulinic acid (BA) conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer carriers, enabling the controlled release of cytotoxic BA derivatives in solid tumors or tumor cells. Various HPMA copolymer conjugates differing in the structure of the spacer between the drug and the carrier were synthesized, all designed for pH-triggered drug release in tumor tissue or tumor cells. The high molecular weight of the micellar conjugates should improve the uptake of the drug in solid tumors due to the Enhanced permeability and retention (EPR) effect. Nevertheless, only the conjugate containing BA with methylated carboxyl groups enabled pH-dependent controlled release in vitro. Moreover, drug release led to the disassembly of the micellar structure, which facilitated elimination of the water-soluble HPMA copolymer carrier from the body by renal filtration. The methylated BA derivative and its polymer conjugate exhibited high cytostatic activity against DLD-1, HT-29, and HeLa carcinoma cell lines and enhanced tumor accumulation in HT-29 xenograft in mice.

Preparation of novel ring-A fused azole derivatives of betulin and evaluation of their cytotoxicity

An efficient scheme to synthesize novel ring-A fused heterocyclic derivatives of betulin was developed. The starting reaction of this synthesis was one-pot selective bacterial oxidation of betulin to betulone used as the key compound to synthesize the substituted azoles such as C(2)-C(3)-fused 1,2,3-triazoles, oxazoles and 1,2,4-triazine, as well as C(1)-C(2)-fused isoxazoles. The semi-synthetic compounds were screened for their cytotoxic activity against human cancer cell lines A549, HCT 116, HEp-2, MS and RD TE32 with use of the photometric MTT assays. Among the tested compounds, N-acetyltriazole of betulin (10) displayed impressive cytotoxic activity with IC₅₀ 2.3-7.5 μM against HCT 116, HEp-2, MS and RD TE32 cell lines as well as 3-methyl-4-oxido-1,2,4-triazine-derivative of betulonic acid (12) that was active against HCT 116 and HEp-2 cell lines with IC₅₀ 1.4 and 1.5 μM, respectively. Comparative experiments showed triazole (10) to have a lower cytotoxicity to normal epithelial cells, in comparison with compound (12). In accord with the in vivo acute toxicity test, the LD₅₀ of triazole (10) exceeded 600 mg/kg. The ability of the most potent active triazole (10) to trigger apoptotic cell death was explored in the Annexin V-FITC test and by analyzing of caspase activity and morphological alterations in mitochondria and nuclei of HCT 116 cells.

Triterpenoids from the leaves of Alphitonia xerocarpus Baill and their biological activity

Ten previously undescribed triterpenoid saponins and a previously undescribed norlupane triterpenoid were isolated, with three known saponins, four known flavonoids, two known lupane derivatives, sitosterol and 6'-heptadecanoyl-3-O-β-d-glucopyranosylsitosterol from the leaves of Alphitonia xerocarpus (Rhamnaceae), an endemic tree of New Caledonia. The chemical structures of the purified compounds were identified by nuclear magnetic resonance and mass spectrometry. The isolated compounds were tested for their antioxidant, antityrosinase, antibacterial and cytotoxic activity. The aqueous methanol extract showed antioxidant activity (DPPH assay) due to the presence of rutin. Ceanothenic acid showed good cytotoxic activity against a KB cell line (IC50 = 2.6 μM) and antibacterial activity against Staphylococcus aureus and Enterococcus faecalis with MIC values of 8 and 16 μg/mL, respectively. The previously undescribed 29-hydroxyceanothenic acid exhibited moderate cytotoxic activity (IC50 = 10 μM), good antibacterial activity against S. aureus (MIC = 4 μg/mL) and moderate antibacterial activity against E. faecalis (MIC = 16 μg/mL).

Synthesis of ring-C modified oleanolic acid derivatives and their cytotoxic evaluation

Ring-C of oleanolic acid was chemically modified by treating with NBS under a variety of experimental conditions. The structures of the synthesized compounds were established by spectral analysis ((1)H &(13)C NMR and Mass). All the compounds were evaluated against a panel of five human cancer cell lines by using MTT assay. Among the tested compounds, 2 and 7 showed significant activity against breast cancer cell line, MCF-7. Most significantly, compound 7 showed several folds enhanced activity against MCF-7 cancer cell lines (IC50: 2.96μM) than that of the parent (1) and the intermediate compound (6). Flow cytometric analysis revealed that these compounds arrested the cell cycle in G0/G1 phase and induced mitochondrial mediated apoptosis.

Cytotoxic and Apoptosis-inducing Activities of Taraxastane-type Triterpenoid Derivatives in Human Cancer Cell Lines

Twenty-eight taraxastane-type triterpenoid derivatives 4 - 31 were prepared from the naturally occurring triterpenoids faradiol (1) and heliantriol C (3). The cytotoxic activities of these compounds and arnidiol (2) were evaluated in leukemia (HL60), lung (A549), duodenal (AZ521), and breast (SK-BR-3) cancer cell lines. 21-Oxoarnidiol (18) and faradiol 3,16-di-O-l-alaninate (31) exhibited potent cytotoxicity, with 50% inhibitory concentrations of 0.5 - 2.7 μm. In particular, flow cytometric analysis indicated that compound 31 induced typical apoptotic cell death in HL60 cells. These results suggested that taraxastane-type triterpenoid derivatives might provide useful antitumor agents with apoptosis-inducing activity.

Strong and Long-Lasting Antinociceptive and Anti-inflammatory Conjugate of Naturally Occurring Oleanolic Acid and Aspirin

The conjugate 8 was obtained as a result of condensation of 3-hydroxyiminooleanolic acid morfolide (7) and aspirin in dioxane. Analgesic effect of OAO-ASA (8) for the range of doses 0.3–300.0 mg/kg (p.o.) was performed in mice using a hot-plate test. Anti-inflammatory activity was assessed on carrageenan-induced paw edema in rats for the same range of doses. The conjugate OAO-ASA (8) did not significantly change locomotor activity of mice, therefore sedative properties of the compound should be excluded. The compound 8 proved a simple, proportional, dose-dependent analgesic action and expressed strong anti-inflammatory activity showing a reversed U-shaped, dose-dependent relation with its maximum at 30.0 mg/kg. After its combined administration with morphine (MF, 5.0 mg/kg, s.c.) the lowering of antinociceptive activity was found; however, the interaction with naloxone (NL, 3.0 mg/kg, s.c.) did not affect the antinociceptive effect of OAO-ASA (8), therefore its opioid mechanism of action should be rather excluded. After combined administration with acetylsalicylic acid (ASA, 300.0 mg/kg, p.o.) in hot-plate test, the examined compound 8 enhanced the antinociceptive activity in significant way. It also shows that rather the whole molecule is responsible for the antinociceptive and anti-inflammatory effect of the tested compound 8, however, it cannot be excluded that the summarizing effect is produced by ASA released from the compound 8 and the rest of triterpene derivative. The occurrence of tolerance for triterpenic derivative 8 was not observed, since the analgesic and anti-inflammatory effects after chronic administration of the conjugate OAO-ASA (8) was on the same level as after its single treatment. It seemed that the anti-inflammatory mechanism of action of OAO-ASA (8) is not simple, even its chronic administration lowered both blood concentration of IL-6 and mRNA IL-6 expression. However, the effects of the conjugate OAO-ASA (8) on TNF-α level and mRNA expression were opposite. Moreover, compound 8 did not change unequivocally mRNA TLR1, and TLR3 expression. Concluding, the obtained results regarding the antinociceptive and anti-inflammatory activity of new conjugate of oleanolic acid oxime and acetylsalicylic acid (OAO-ASA 8) are very interesting, but for explanation of its mechanism of action, more detailed studies are necessary.

Influence of sulfur fumigation on glycoside profile in Platycodonis Radix (Jiegeng)

BACKGROUND

Over recent decades, sulfur fumigation is becoming abused in processing some freshly harvested herbs used as both medicine and food, although it has been questioned whether sulfur fumigation will change the efficacy and safety of the herbs. One of the herbs commonly processed by sulfur fumigation is Platycodonis Radix (Jiegeng in Chinese). Glycosides are the main bioactive components of Jiegeng. Up to the present, no study has been carried out to evaluate the impact of sulfur fumigation on glycoside profile of Jiegeng.

METHODS

A rapid and versatile ultra-high performance liquid chromatography coupled with ultra-high resolution quadrupole time-of-flight mass spectrometry (UHPLC UHD Q-TOF MS/MS) method was developed for comprehensive analysis of the glycoside profiles of sulfur-fumigated and air-dried Jiegeng samples.

RESULTS

Twenty-three glycosides were detected in air-dried and sulfur-fumigated Jiegeng samples. After sulfur fumigation, the peak heights of eight glycosides, namely platycogenin A, platycodin D, platycodin D2, platycodin D3, polygalacin D, polygalacin D2, deapio-platycodin D and 3″-O-acetylplatycodin D2, remarkably decreased; while peak heights of five glycosides, namely syringin, lobetyolin, platycoside E, deapio-platycodin D2 and deapio-platycoside E, slightly increased; in addition, peaks of ten glycosides, platycodin A, platycodin C, platycodin V, platycoside C, 16-oxoplatycodin D, 2″-O-acetylpolygalacin D, 2″-O-acetylpolygalacin D2, 3″-O-acetylpolygalacin D, 3″-O-acetylpolygalacin D2, and platycogenic acid B, disappeared.

CONCLUSION

Sulfur fumigation caused significant changes of glycoside components of Jiegeng. Further investigations are warranted to explore how these chemical changes occurred and whether these changes would affect the efficacy and safety of Jiegeng.

THE EFFECTS OF Syzygium aromaticum-DERIVED TRITERPENES ON GASTROINTESTINAL GHRELIN EXPRESSION IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

Background:

Diabetic polyphagia has been associated with elevated plasma ghrelin levels in experimental type 1 diabetes. This increase in food consumption contributes to chronic hyperglycaemia in diabetes thus contributing to the development of micro- and macrovascular complications. We have reported that plant-derived oleanolic acid (OA) and maslinic acid (MA) reduce blood glucose levels, in part, through the inhibition of intestinal carbohydrate hydrolyzing enzymes and glucose transporters. However, their effects on food intake and plasma ghrelin concentrations are unclear. Accordingly, we investigated the effects of these triterpenes on food intake and ghrelin expression in streptozotocin-induced diabetic rats.

Material:

The effects of OA and MA on blood glucose concentration; food and water intake were monitored over five weeks after which plasma ghrelin concentrations were measured. Additionally, the expression of ghrelin in the various sections of the GIT was determined using Western blot analysis.

Results:

Ghrelin concentrations in untreated STZ-induced diabetic rats were significantly higher in comparison to the non-diabetic control. Interestingly, the administration of OA and MA reduced food intake, blood glucose levels and plasma ghrelin levels in STZ-induced diabetic rats. This was further complemented by significant reductions in the gastrointestinal expression of ghrelin suggesting that the anti-diabetic properties of these triterpenes are mediated, in part, through the reduction of food intake and the modulation of ghrelin expression.

Conclusion:

The findings of the study suggest that the control of food intake through the reduction of ghrelin expression by plant-derived OA and MA may constitute an avenue of glycaemic control in diabetes mellitus.

New ursane triterpenoids from Ficus pandurata and their binding affinity for human cannabinoid and opioid receptors

Phytochemical investigation of Ficus pandurata Hance (Moraceae) fruits has led to the isolation of two new triterpenoids, ficupanduratin A [1β-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (11) and ficupanduratin B [21α-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (17), along with 20 known compounds: α-amyrin acetate (1), α-amyrin (2), 3β-acetoxy-20-taraxasten-22-one (3), 3β-acetoxy-11α-methoxy-olean-12-ene (4), 3β-acetoxy-11α-methoxy-12-ursene (5), 11-oxo-α-amyrin acetate (6), 11-oxo-β-amyrin acetate (7), palmitic acid (8), stigmast-4,22-diene-3,6-dione (9), stigmast-4-ene-3,6-dione (10), stigmasterol (12), β-sitosterol (13), stigmast-22-ene-3,6-dione (14), stigmastane-3,6-dione (15), 3β,21β-dihydroxy-11α-methoxy-olean-12-ene (16), 3β-hydroxy-11α-methoxyurs-12-ene (18), 6-hydroxystigmast-4,22-diene-3-one (19), 6-hydroxystigmast-4-ene-3-one (20), 11α,21α-dihydroxy-3β-acetoxy-urs-12-ene (21), and β-sitosterol-3-O-β-D-glucopyranoside (22). Compound 21 is reported for the first time from a natural source. The structures of the 20 compounds were elucidated on the basis of IR, 1D ((1)H and (13)C), 2D ((1)H-(1)H COSY, HSQC, HMBC and NOESY) NMR and MS spectroscopic data, in addition to comparison with literature data. The isolated compounds were evaluated for their anti-microbial, anti-malarial, anti-leishmanial, and cytotoxic activities. In addition, their radioligand displacement affinity on opioid and cannabinoid receptors was assessed. Compounds 4, 11, and 15 exhibited good affinity towards the CB2 receptor, with displacement values of 69.7, 62.5 and 86.5 %, respectively. Furthermore, the binding mode of the active compounds in the active site of the CB2 cannabinoid receptors was investigated through molecular modelling.

A systematic review of pentacyclic triterpenes and their derivatives as chemotherapeutic agents against tropical parasitic diseases

Parasitic infections are among the leading global public health problems with very high economic and mortality burdens. Unfortunately, the available treatment drugs are beset with side effects and continuous parasite drug resistance is being reported. However, new findings reveal more promising compounds especially of plant origin. Among the promising leads are the pentacyclic triterpenes (PTs) made up of the oleanane, ursane, taraxastane, lupane and hopane types. This paper reviews the literature published from 1985 to date on the in vitro and in vivo anti-parasitic potency of this class of phytochemicals. Of the 191 natural and synthetic PT reported, 85 have shown high anti-parasitic activity against various species belonging to the genera of Plasmodium, Leishmania, Trypanosoma, as well as various genera of Nematoda. Moreover, structural modification especially at carbon 3 (C3) and C27 of the parent backbone of PT has led to improved anti-parasitic activity in some cases and loss of activity in others. The potential of this group of compounds as future alternatives in the treatment of parasitic diseases is discussed. It is hoped that the information presented herein will contribute to the full exploration of this promising group of compounds as possible drugs for parasitic diseases.

Bigelovii A Protects against Lipopolysaccharide-Induced Acute Lung Injury by Blocking NF-κB and CCAAT/Enhancer-Binding Protein δ Pathways

Optimal methods are applied to acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS), but the mortality rate is still high. Accordingly, further studies dedicated to identify novel therapeutic approaches to ALI are urgently needed. Bigelovii A is a new natural product and may exhibit anti-inflammatory activity. Therefore, we sought to investigate its effect on lipopolysaccharide- (LPS-) induced ALI and the underlying mechanisms. We found that LPS-induced ALI was significantly alleviated by Bigelovii A treatment, characterized by reduction of proinflammatory mediator production, neutrophil infiltration, and lung permeability. Furthermore, Bigelovii A also downregulated LPS-stimulated inflammatory mediator expressions in vitro. Moreover, both NF-κB and CCAAT/enhancer-binding protein δ (C/EBPδ) activation were obviously attenuated by Bigelovii A treatment. Additionally, phosphorylation of both p38 MAPK and ERK1/2 (upstream signals of C/EBPδ activation) in response to LPS challenge was also inhibited by Bigelovii A. Therefore, Bigelovii A could attenuate LPS-induced inflammation by suppression of NF-κB, inflammatory mediators, and p38 MAPK/ERK1/2-C/EBPδ, inflammatory mediators signaling pathways, which provide a novel theoretical basis for the possible application of Bigelovii A in clinic.

Bryonolic Acid, a Triterpenoid, Protect Against N-methyl-d-Aspartate-Induced Neurotoxicity in PC12 Cells

Calcium overload is considered to be one of the mechanisms of cerebral ischemia. Ca(2+) influx and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and cAMP response element-binding protein (CREB) phosphorylation are considered to be involved in N-Methyl-d-aspartate (NMDA)-induced apoptosis process. This study investigated the neuroprotective effects of bryonolic acid (BA) in an NMDA-induced rat adrenal pheochromocytoma cell line (PC12) cells and the potential mechanism. PC12 was treated by NMDA to establish an excitotoxicity model. BA (110,100 and 1000 μM final concentration) was added to the medium 24 h prior to the addition of NMDA. Subsequently, a methyl thiazolyl tetrazolium (MTT) assay and a lactate dehydrogenase (LDH) release were performed. Ca(2+) concentration was demonstrated using a scanning-dual wavelength fluorimetric method. In addition, protein and mRNA levels were determined via Western blot and real-time PCR. In the presence of BA, MTT assay and LDH assay showed that more cells were viable in comparison with the NMDA group. Moreover, the concentration of Ca(2+) decreased with the addition of BA in culture. Furthermore, BA could upregulate protein expressions of Bcl-2, p-CREB, and p-CaMKII and downregulate protein expression of Bax. The mRNA results showed that the pattern of mRNA expression were similar to their respective protein levels. All these results indicate that BA protected PC12 cells against NMDA-induced apoptosis by inhibiting Ca(2+) influx and regulating gene expression in the Ca(2+)-CaMKII-CREB signal pathway. Therefore, the present study supports the notion that BA may be a promising neuroprotective agent for the treatment of cerebral ischemia disease.

Synthesis and anticancer activity of novel fluorinated asiatic acid derivatives

A series of novel fluorinated Asiatic Acid (AA) derivatives were successfully synthesized, tested for their antiproliferative activity against HeLa and HT-29 cell lines, and their structure activity relationships were evaluated. The great majority of fluorinated derivatives showed stronger antiproliferative activity than AA in a concentration dependent manner. The most active compounds have a pentameric A-ring containing an α,β-unsaturated carbonyl group. The compounds with better cytotoxic activity were then evaluated against MCF-7, Jurkat, PC-3, A375, MIA PaCa-2 and BJ cell lines. Derivative 14 proved to be the most active compound among all tested derivatives and its mechanism of action was further investigated in HeLa cell line. The results showed that compound 14 induced cell cycle arrest in G0/G1 stage as a consequence of up-regulation of p21(cip1/waf1) and p27(kip1) and down-regulation of cyclin D3 and Cyclin E. Furthermore, compound 14 was found to induce caspase driven-apoptosis with activation of caspases-8 and caspase-3 and the cleavage of PARP. The cleavage of Bid into t-Bid, the up-regulation of Bax and the down-regulation of Bcl-2 were also observed after treatment of HeLa cells with compound 14. Taken together, these mechanistic studies revealed the involvement of extrinsic and intrinsic pathways in the apoptotic process induced by compound 14. Importantly, the antiproliferative activity of this compound on the non-tumor BJ human fibroblast cell line is weaker than in the tested cancer cell lines. The enhanced potency (between 45 and 90-fold more active than AA in a panel of cancer cell lines) and selectivity of this new AA derivative warrant further preclinical evaluation.

Efficacy of a Standardized Extract of Prunus mume in Liver Protection and Redox Homeostasis: A Randomized, Double-Blind, Placebo-Controlled Study

The antioxidant, anti-inflammatory and hepatoprotective effects of Prunus mume (PM) have previously been demonstrated. This double-blind, placebo-controlled study was designed to evaluate the influence of two doses of a food supplement, made of 150 mg of a standardized PM extract on liver transaminases, lipid profile, glycemia, neopterin and reduced and oxidized thiols in plasma and erythrocytes, during a 3-month treatment period, in healthy subjects with transaminases levels between 20 and 40 UI/L. Forty-five subjects (56.0 ± 11.6 years) were enrolled. The results showed a beneficial and statistically significant effect versus placebo of PM extract on liver function, with a decrease versus baseline in alanine aminotransferase (47%), aspartate aminotransferase (7%), gamma-glutamyl transpeptidase (15%) and glycemia (11%). The lipid profile modification was also positive with an increase versus baseline in HDL cholesterol (13%), and a decrease in LDL/HDL ratio (12%) and triglycerides (8%). The antioxidant action of PM translated into a decrease in oxidized glutathione, reduced/oxidized cysteine-glycine, oxidized cysteine (intracellular pro-oxidant) and neopterin (inflammation biomarker), was associated with an increase in reduced glutathione. These results are in favor of the use of a standardized extract of P. mume for the support of liver health and prevention of common metabolic and inflammation-based diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents

Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities.

Tetra- and Penta-Cyclic Triterpenes Interaction with Lipid Bilayer Membrane: A Structural Comparative Study

The effect of tetracyclic (cortisol, prednisolone, and 9-fluorocortisol acetate) and pentacyclic (uvaol and erythrodiol) triterpenes (TTPs) on the fluidity of dipalmitoyl phosphatidyl choline (DPPC) liposome membrane was investigated by differential scanning calorimetry, Raman spectroscopy, and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH). Liposomes were prepared in the absence and presence of TTPs at molar ratios DPPC:TTP 100:1, 100:2.5, and 100:10. All the studied TTPs abolished the pre-transition and modified the intensity of the Raman peak at 715 cm(-1) proving the interaction of TTP molecules with the choline head group of phospholipids. An increase in the Raman height intensity ratios of the peaks I 2935/2880, I 2844/2880, and I 1090/1130, giving information about the ratio disorder/order of the alkyl chains, and a decrease of the main transition temperature demonstrated the interaction of TTPs with the alkyl chains. The tetracyclic TTPs produced broadening of the phase transition profile. Besides, a scarcely splitting of the main transition peak was obtained with prednisolone and 9-fluorocortisol acetate. The results of fluorescence depolarization of DPH showed that the studied molecules fluidized the liposomal membrane at 25, 41, and 50 °C. Pentacyclic TTPs, being more hydrophobic than tetracyclic ones, demonstrated higher fluidizing effect than tetracyclic TTPs in the liquid crystalline phase suggesting a deeper incorporation in the lipid bilayer. The presence of a free polar head group at the ring D seems to control the TTP incorporation in the bilayer and consequently its effect on the membrane fluidity.

Maslinic Acid, a Natural Triterpene, Induces a Death Receptor-Mediated Apoptotic Mechanism in Caco-2 p53-Deficient Colon Adenocarcinoma Cells

Maslinic acid (MA) is a natural triterpene present in high concentrations in the waxy skin of olives. We have previously reported that MA induces apoptotic cell death via the mitochondrial apoptotic pathway in HT29 colon cancer cells. Here, we show that MA induces apoptosis in Caco-2 colon cancer cells via the extrinsic apoptotic pathway in a dose-dependent manner. MA triggered a series of effects associated with apoptosis, including the cleavage of caspases -8 and -3, and increased the levels of t-Bid within a few hours of its addition to the culture medium. MA had no effect on the expression of the Bax protein, release of cytochrome-c or on the mitochondrial membrane potential. This suggests that MA triggered the extrinsic apoptotic pathway in this cell type, as opposed to the intrinsic pathway found in the HT29 colon-cancer cell line. Our results suggest that the apoptotic mechanism induced in Caco-2 may be different from that found in HT29 colon-cancer cells, and that in Caco-2 cells MA seems to work independently of p53. Natural antitumoral agents capable of activating both the extrinsic and intrinsic apoptotic pathways could be of great use in treating colon-cancer of whatever origin.

Synthesis and biological evaluation of novel asiatic acid derivatives with anticancer activity

Structural modification of asiatic acid afforded derivatives with improved anticancer activity.

Natural compound-derived epigenetic regulators targeting epigenetic readers, writers and erasers

Post-translational modifications can affect gene expression in a long-term manner without changes in the primary nucleotide sequence of the DNA. These epigenetic alterations involve dynamic processes that occur in histones, chromatin-associated proteins and DNA. In response to environmental stimuli, abnormal epigenetic alterations cause disorders in the cell cycle, apoptosis and other cellular processes and thus contribute to the incidence of diverse diseases, including cancers. In this review, we will summarize recent studies focusing on certain epigenetic readers, writers, and erasers associated with cancer development and how newly discovered natural compounds and their derivatives could interact with these targets. These advances provide insights into epigenetic alterations in cancers and the potential utility of these alterations as therapeutic targets for the future development of chemopreventive and chemotherapeutic drugs.

Phytochemical and Biological Investigations of Conradina Canescens

Conradina canescens (Lamiaceae) is an endemic evergreen shrub native to Florida, Mississippi and Alabama, with no phytochemical or biological studies registered in the literature. Thus, a phytochemical study and a toxicity analysis of the chloroform extract obtained from the leaves of C. canescens were performed for the first time. In our preliminary screening, the crude extract and its fractions were subjected to cytotoxicity, antimicrobial and antileishmanial bioassays. The crude extract showed substantial cytotoxic, antimicrobial and antileishmanial activities. A total of six compounds, namely ursolic acid (62.4%), betulin (8.4%), β-amyrin (4.6%), myrtenic acid (2.9%), n-tetracosane (1.4%), and oleanolic acid (1.1%), were isolated. The structures of the isolated compounds were established by spectroscopic studies using NMR and IR spectroscopy.

The oleanolic acid derivative, 3-O-succinyl-28-O-benzyl oleanolate, induces apoptosis in B16–F10 melanoma cells via the mitochondrial apoptotic pathway

Antiproliferative and proapoptotic effects of 3-O-succinyl-28-O-benzyl oleanolate on B16–F10 skin-melanoma cells.

Betulinic Acid: Recent Advances in Chemical Modifications, Effective Delivery, and Molecular Mechanisms of a Promising Anticancer Therapy

An important method of drug discovery is examination of diverse life forms, including medicinal plants and natural products or bioactive compounds isolated from these sources. In cancer research, lead structures of compounds from natural sources can be used to design novel chemotherapies with enhanced biological properties. Betulinic acid (3β-hydroxy-lup-20(29)-en-28-oic acid or BetA) is a naturally occurring pentacyclic triterpene with a wide variety of biological activities, including potent antitumor properties. Non-malignant cells and normal tissues are not affected by BetA. Because BetA exerts its effects directly on the mitochondrion and triggers death of cancerous cells, it is an important alternative when certain chemotherapy drugs fail. Mitochondrion-targeted agents such as BetA hold great promise to circumvent drug resistance in human cancers. BetA is being developed by a large network of clinical trial groups with the support of the U.S. National Cancer Institute. This article discusses recent advances in research into anticancer activity of BetA, relevant modes of delivery, and the agent's therapeutic efficacy, mechanism of action, and future perspective as a pipeline anticancer drug. BetA is a potentially important agent in cancer therapeutics.

Oleanolic acid inhibits cell survival and proliferation of prostate cancer cells in vitro and in vivo through the PI3K/Akt pathway

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid and possesses diverse pharmacological activities, including anti-cancer effects that have been confirmed in multiple types of human cancers. However, the potential effect of natural OA on human prostate cancer is still unclear. The present study aimed to explore whether and how OA exerted anti-cancer effects in prostate cancer. Our data showed that OA inhibited cell viability and proliferation, and promoted cell apoptosis and G0/G1 phase cell cycle arrest in prostate cancer PC-3, DU145, and LNCaP cells, in a dose-dependent manner. In addition, OA was found to regulate the expression levels of apoptosis-related and cell cycle-related proteins, as well as the activity of PI3K/Akt pathway, in a dose-dependent manner. Mechanistically, our data revealed that OA exerted anti-cancer effects in vitro in PC-3 and DU145 cells by repressing the PI3K/Akt pathway. In agreement, OA also suppressed the tumor growth of PC-3 cells in vivo via inhibition of the PI3K/Akt pathway. In conclusion, our findings demonstrate the anti-cancer properties of OA in prostate cancer cells, both in vitro and in vivo, and provide the experimental evidence for the use of OA as an adjuvant agent for prostate cancer patients.

Ursolic Acid--A Pentacyclic Triterpenoid with a Wide Spectrum of Pharmacological Activities

Ursolic acid (UA) is a natural terpene compound exhibiting many pharmaceutical properties. In this review the current state of knowledge about the health-promoting properties of this widespread, biologically active compound, as well as information about its occurrence and biosynthesis are presented. Particular attention has been paid to the application of ursolic acid as an anti-cancer agent; it is worth noticing that clinical tests suggesting the possibility of practical use of UA have already been conducted. Amongst other pharmacological properties of UA one can mention protective effect on lungs, kidneys, liver and brain, anti-inflammatory properties, anabolic effects on skeletal muscles and the ability to suppress bone density loss leading to osteoporosis. Ursolic acid also exhibits anti-microbial features against numerous strains of bacteria, HIV and HCV viruses and Plasmodium protozoa causing malaria.

Bioassay-guided Isolation of Antiproliferative Triterpenoids from Euonymus alatus Twigs

Euonymus alatus (Celastraceae) has been used as an anticancer agent in Korean traditional medicine. However, the potential bioactive contributors to the anticancer effects have not been thoroughly studied. Our screening test revealed that the MeOH extract of E. alatus twigs exhibited significant cytotoxicity against A549, SK-OV-3, and SK-MEL-2 cell lines. A bioassay-guided separation of the MeOH extract of E. alatus twigs resulted in the isolation and identification of 14 triterpenes as main phytochemicals. The structures of the compounds were elucidated on the basis of spectroscopic evidence as lupeol (1), betulin (2), 3β,28,30-lup-20(29)-ene triol (3), lupenone (4), betulone (5), 28,30-dihydroxy-3-oxolup-20(29)-ene (6), messagenin (7), glut-5-en-3β-ol (8), maslinic acid (9), hederagenin (10), 3-oxo-11α-methoxyolean-12-ene (11), 3β-hydroxy-1-oxo-olean-12-en-28-oic acid (12), ursolic acid (13), and 2α-hydroxy-ursolic acid (14). Of these compounds, 3, 6–8, and 10–14 were isolated for the first time from this plant. All isolated triterpenoids had consistent antiproliferative activities against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines. Compounds 2, 5, and 7 showed significant cytotoxicity against all four cell lines tested, with IC50 values of 3.26–8.61 μM.

CDDO-Me inhibits tumor growth and prevents recurrence of pancreatic ductal adenocarcinoma

Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) has shown potent antitumorigenic activity against a wide range of cancer cell lines in vitro and inhibited the growth of liver, lung and prostate cancer in vivo. In the present study, we examined the antitumor activity of CDDO-Me for pancreatic ductal adenocarcinoma (PDAC) cells with and without activating K-ras mutations. Treatment of K-ras mutant MiaPaCa-2 and K-ras normal BxPC-3 cells with CDDO-Me elicited strong antiproliferative and proapop-topic responses in both cell lines in culture. The inhibition of cell proliferation and induction of apoptosis was accompanied by the inhibition of antiapoptotic/prosurvival p-Akt, NF-κB and p-mTOR signaling proteins. For testing efficacy of CDDO-Me in vivo heterotopic and orthotopic xenografts were generated by implanting BxPC-3 and MiaPaCa-2 cells subcutaneously and in the pancreatic tail, respectively. Treatment with CDDO-Me significantly inhibited the growth of BxPC-3 xenografts and reduced the levels of p-Akt and p-mTOR in tumor tissue. In mice with orthotopic MiaPaCa-2 xenografts, treatment with CDDO-Me prolonged the survival of mice when administered following the surgical resection of tumors. The latter was attributed to the eradication of residual PDAC remaining after resection of tumors. These preclinical data demonstrate the potential of CDDO-Me for treating primary PDAC tumors and for preventing relapse/recurrence through the destruction of residual disease.