The cytotoxic principles of Prunella vulgaris, Psychotria serpens, and Hyptis capitata: ursolic acid and related derivatives

In Vitro and In Silico Analysis of PTP1B Inhibitors from Cleistocalyx operculatus Leaves and Their Effect on Glucose Uptake

As part of our ongoing research on new anti-diabetic compounds from ethnopharmacologically consumed plants, two previously undescribed lupane-type triterpenoids (1 and 2) with dicarboxylic groups, an undescribed nor-taraxastane-type triterpenoid (3), and 14 known compounds (4-17) were isolated from the leaves of Cleistocalyx operculatus. Extensive spectroscopic analysis (IR, HRESIMS, 1D, and 2D NMR) was used for structure elucidation, while the known compounds were compared to reference data reported in the scientific literature. All the isolates (1-17) were evaluated for their inhibitory effects on the protein tyrosine phosphatase 1B (PTP1B) enzyme. Compounds 6, 9, and 17 showed strong PTP1B inhibitory activities. The mechanism of PTP1B inhibition was studied through enzyme kinetic experiments. A non-competitive mechanism of inhibition was determined using Lineweaver-Burk plots for compounds 6, 9, and 17. Additionally, Dixon plots were employed to determine the inhibition constant. Further insights were gained through a structure-activity relationship study and molecular docking analysis of isolated compounds with the PTP1B crystal structure. Moreover, all isolates (1-17) were tested for their stimulatory effects on the uptake of 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl) amino]-D-glucose (2-NBDG) in differentiated 3T3-L1 adipocyte cells. Compounds 6, 13, and 17 exhibited strong glucose absorption stimulation activity in a dose-dependent manner.

Chemical Composition, Antioxidant, and Mosquito Larvicidal Activity of Essential Oils from Hyptis capitata Jacq

Background

Mortality and morbidity associated with vector-borne diseases, particularly those caused by mosquitoes, are increasing and new means of controlling them, including bio-larvicides, are needed. Malaria is a serious threat in many countries of Africa and Asia, and eco-friendly vector preventing measures are very much essential. Plant-derived larvicides are of great importance in this context. Hyptis capitata is an aromatic medicinal plant which is widely distributed in tropical countries. The aim of the present study is to examine the chemical composition, antioxidant and mosquito larvicidal effects of essential oils of this plant, extracted by hydro-distillation.

Methods

Chemical compositions of essential oils were analyzed using gas chromatography–mass spectrometry (GC-MS). Antioxidant activity was tested by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) assay and the mosquito larvicidal activity was checked against the fourth instar larvae of the malarial vector Anopheles stephensi. Fingerlings of Oreochromis mossambicus were used as a bio-model for toxicity studies.

Results

A total of 48 constituents, inclusive of 44 (94.67%) from inflorescence and 19 (97.09%) from leaf oil were identified; δ-cadinene (14.68%) and linalool (6.99%) were the major constituents of the inflorescence oil, while leaf oil contained 1-octen-3-ol (34.08%), methyl linoleate (17.2%), and germacrene D (11.16%). Antioxidant analysis showed an effective concentration (EC₅₀) value of 22.76 μg/mL for leaf oil and 26.18 μg/mL for the inflorescence oil, corresponding to 17.57 μg/mL of ascorbic acid. Both oils showed a respectable larvicidal effect and the lethal concentrations (LC₅₀) are 39.08 μg/mL and 33.19 μg/mL for the inflorescence and leaf oil, respectively. Notably, both the inflorescence and leaf oils are not very toxic to fish with respect to the concentrations tested.

Conclusion

This study showed that the essential oils extracted from the leaves and inflorescences of H. capitata are effective antioxidants and can act as inexpensive mosquito larvicidal agents.

Subtribe Hyptidinae (Lamiaceae): A promising source of bioactive metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

The subtribe Hyptidinae contains approximately 400 accepted species distributed in 19 genera (Hyptis, Eriope, Condea, Cantinoa, Mesosphaerum, Cyanocephalus, Hypenia, Hyptidendron, Oocephalus, Medusantha, Gymneia, Marsypianthes, Leptohyptis, Martianthus, Asterohyptis, Eplingiella, Physominthe, Eriopidion and Rhaphiodon). This is the Lamiaceae clade with the largest number of species in Brazil and high rates of endemism. Some species have been used in different parts of the world mainly as insecticides/pest repellents, wound healing and pain-relief agents, as well as for the treatment of respiratory and gastrointestinal disorders.

AIM OF THE REVIEW

This review aims to discuss the current status concerning the taxonomy, ethnobotanical uses, phytochemistry and biological properties of species which compose the subtribe Hyptidinae.

MATERIALS AND METHODS

The available information was collected from scientific databases (ScienceDirect, Pubmed, Web of Science, Scopus, Google Scholar, ChemSpider, SciFinder ACS Publications, Wiley Online Library), as well as other literature sources (e.g. books, theses).

RESULTS

The phytochemical investigations of plants of this subtribe have led to the identification of almost 300 chemical constituents of different classes such as diterpenes, triterpenes, lignans, α-pyrones, flavonoids, phenolic acids and monoterpenes and sesquiterpenes, as components of essential oils. Extracts, essential oils and isolated compounds showed a series of biological activities such as insecticide/repellent, antimicrobial and antinociceptive, justifying some of the popular uses of the plants. In addition, a very relevant fact is that several species produce podophyllotoxin and related lignans.

CONCLUSION

Several species of Hyptidinae are used in folk medicine for treating many diseases but only a small fraction of the species has been explored and most of the traditional uses have not been validated by current investigations. In addition, the species of the subtribe appear to be very promising as alternative sources of podophyllotoxin-like lignans which are the lead compounds for the semi-synthesis of teniposide and etoposide, important antineoplastic agents. Thus, there is a wide-open door for future studies, both to support the popular uses of the plants and to find new biologically active compounds in this large number of species not yet explored.

Network pharmacology based virtual screening of active constituents of Prunella vulgaris L. and the molecular mechanism against breast cancer

Prunella vulgaris L, a perennial herb widely used in Asia in the treatment of various diseases including cancer. In vitro studies have demonstrated the therapeutic effect of Prunella vulgaris L. against breast cancer through multiple pathways. However, the nature of the biological mechanisms remains unclear. In this study, a Network pharmacology based approach was used to explore active constituents and potential molecular mechanisms of Prunella vulgaris L. for the treatment of breast cancer. The methods adopted included active constituents prescreening, target prediction, GO and KEGG pathway enrichment analysis. Molecular docking experiments were used to further validate network pharmacology results. The predicted results showed that there were 19 active ingredients in Prunella vulgaris L. and 31 potential gene targets including AKT1, EGFR, MYC, and VEGFA. Further, analysis of the potential biological mechanisms of Prunella vulgaris L. against breast cancer was performed by investigating the relationship between the active constituents, target genes and pathways. Network analysis showed that Prunella vulgaris L. exerted a promising preventive effect on breast cancer by acting on tumor-associated signaling pathways. This provides a basis to understand the mechanism of the anti-breast cancer activity of Prunella vulgaris L.

Evaluation of the cytotoxic potential of a new pentacyclic triterpene from Rhododendron arboreum stem bark

CONTEXT

Traditionally, Rhododendron arboreum Sm. (Ericaceae) is a very important medicinal plant having oxytocic, estrogenic, anti-inflammatory, analgesic and hepatoprotective activities; it also inhibits the prostaglandin synthetase.

OBJECTIVES

This study determines the cytotoxic potential of 15-oxoursolic acid isolated from R. arboreum against selected human cancer cell lines.

MATERIALS AND METHODS

Extraction from stem bark (5 kg) of R. arboreum was performed with methanol, which was successively partitioned into hexane, dichloromethane and ethyl acetate fractions, respectively. The new antitumor agent [15-oxoursolic acid (1)] was isolated from ethyl acetate fraction through column chromatography. Structure elucidation of new compound was performed through extensive spectroscopy i.e., IR, MS and 1D and 2D NMR. Cytotoxicity of isolated compound was determined at doses 5-100 μM for a period of 72 h on specified human cancer cell lines [renal cell carcinoma (A498), non-small cell lung (NCI-H226), squamous cell carcinoma (H157) and human ovarian carcinoma (MDR-2780AD)].

RESULTS

Structure of isolated compound was characterized as 15-oxoursolic acid on the basis of various extensive spectroscopic techniques. 15-Oxoursolic acid revealed considerable anticancer activity with IC50 values of 2.3 ± 0.1 μM, 4.9 ± 0.2 μM, 9.2 ± 0.2 μM and 10.3 ± 0.1 μM against MDR 2780AD, Hep G2, H157 and NCI-H226, respectively, while in the case of A498, the activity was good (IC50 32.8 ± 1.2 μM).

CONCLUSIONS

This study highlighted the potential of 15-oxoursolic acid to be further explored as a new lead compound for cancer chemotherapy.

Production of a highly potent epoxide through the microbial metabolism of 3β-acetoxyurs-11-en-13β,28-olide by Aspergillus niger culture

Context 3β-Acetoxyurs-11-en-13β,28-olide (I), a triterpenoid, is found in most plant species. Pharmacologically triterpenes are very effective compounds with potent anticancer, anti-HIV and antimicrobial activities. Objectives Microbial transformation of 3β-acetoxyurs-11-en-13β,28-olide (I) was performed in order to obtain derivatives with improved pharmacological potential. Materials and methods Compound (I, 100 mg) was incubated with Aspergillus niger culture for 12 d. The metabolite formed was purified through column chromatography. Structure elucidation was performed through extensive spectroscopy (IR, MS and NMR). In vitro α- and β-glucosidase inhibitory, and antiglycation potentials of both substrate and metabolite were evaluated. Results Structure of metabolite II was characterized as 3β-acetoxyurs-11,12-epoxy-13β,28-olide (II). Metabolite II was found to be an oxidized product of compound I. In vitro α- and β-glucosidases revealed that metabolite II was a potent and selective inhibitor of α-glucosidase (IC50 value = 3.56 ± 0.38 μM), showing that the inhibitory effect of metabolite II was far better than compound I (IC50 value = 14.7 ± 1.3 μM) as well as acarbose (IC50 value = 545 ± 7.9 μM). Antiglycation potential of compound II was also high with 82.51 ± 1.2% inhibition. Thus, through oxidation, the biological potential of the substrate molecule can be enhanced. Conclusion Biotransformation can be used as a potential tool for the production of biologically potent molecules.

Hyaluronidase Inhibitory Activity of Pentacylic Triterpenoids from Prismatomeris tetrandra (Roxb.) K. Schum: Isolation, Synthesis and QSAR Study

The mammalian hyaluronidase degrades hyaluronic acid by the cleavage of the β-1,4-glycosidic bond furnishing a tetrasaccharide molecule as the main product which is a highly angiogenic and potent inducer of inflammatory cytokines. Ursolic acid 1, isolated from Prismatomeris tetrandra, was identified as having the potential to develop inhibitors of hyaluronidase. A series of ursolic acid analogues were either synthesized via structure modification of ursolic acid 1 or commercially obtained. The evaluation of the inhibitory activity of these compounds on the hyaluronidase enzyme was conducted. Several structural, topological and quantum chemical descriptors for these compounds were calculated using semi empirical quantum chemical methods. A quantitative structure activity relationship study (QSAR) was performed to correlate these descriptors with the hyaluronidase inhibitory activity. The statistical characteristics provided by the best multi linear model (BML) (R² = 0.9717, R²cv = 0.9506) indicated satisfactory stability and predictive ability of the developed model. The in silico molecular docking study which was used to determine the binding interactions revealed that the ursolic acid analog 22 had a strong affinity towards human hyaluronidase.

Antimicrobial activity of oleanolic and ursolic acids: an update

Triterpenoids are the most representative group of phytochemicals, as they comprise more than 20,000 recognized molecules. These compounds are biosynthesized in plants via squalene cyclization, a C30 hydrocarbon that is considered to be the precursor of all steroids. Due to their low hydrophilicity, triterpenes were considered to be inactive for a long period of time; however, evidence regarding their wide range of pharmacological activities is emerging, and elegant studies have highlighted these activities. Several triterpenic skeletons have been described, including some that have presented with pentacyclic features, such as oleanolic and ursolic acids. These compounds have displayed incontestable biological activity, such as antibacterial, antiviral, and antiprotozoal effects, which were not included in a single review until now. Thus, the present review investigates the potential use of these triterpenes against human pathogens, including their mechanisms of action, via in vivo studies, and the future perspectives about the use of compounds for human or even animal health are also discussed.

Bioactivity-guided isolation of anticancer agents from Bauhinia kockiana Korth

BACKGROUND

Flowers of Bauhinia kockiana were investigated for their anticancer properties.

METHODS

Gallic acid (1), and methyl gallate (2), were isolated via bioassay-directed isolation, and they exhibited anticancer properties towards several cancer cell lines, examined using MTT cell viability assay. Pyrogallol (3) was examined against the same cancer cell lines to deduce the bioactive functional group of the phenolic compounds.

RESULTS

The results showed that the phenolic compounds could exhibit moderate to weak cytotoxicity towards certain cell lines (GI50 30 - 86 µM), but were inactive towards DU145 prostate cancer cell (GI50 > 100 µM).

CONCLUSION

It was observed that pyrogallol moiety was one of the essential functional structures of the phenolic compounds in exhibiting anticancer activity. Also, the carboxyl group of compound 1 was also important in anticancer activity. Examination of the PC-3 cells treated with compound 1 using fluorescence microscopy showed that PC-3 cells were killed by apoptosis.

Protein tyrosine phosphatase 1B (PTP1B) inhibitors from Morinda citrifolia (Noni) and their insulin mimetic activity

As part of our ongoing search for new antidiabetic agents from medicinal plants, we found that a methanol extract of Morinda citrifolia showed potential stimulatory effects on glucose uptake in 3T3-L1 adipocyte cells. Bioassay-guided fractionation of this active extract yielded two new lignans (1 and 2) and three new neolignans (9, 10, and 14), as well as 10 known compounds (3-8, 11-13, and 15). The absolute configurations of compounds 9, 10, and 14 were determined by ECD spectra analysis. Compounds 3, 6, 7, and 15 showed inhibitory effects on PTP1B enzyme with IC50 values of 21.86 ± 0.48, 15.01 ± 0.20, 16.82 ± 0.42, and 4.12 ± 0.09 μM, respectively. Furthermore, compounds 3, 6, 7, and 15 showed strong stimulatory effects on 2-NBDG uptake in 3T3-L1 adipocyte cells. This study indicated the potential of compounds 3, 6, 7, and 15 as lead molecules for antidiabetic agents.

In vitro antioxidant and anticancer effects of solvent fractions from Prunella vulgaris var. lilacina

BACKGROUND

Recently, considerable attention has been focused on exploring the potential antioxidant properties of plant extracts or isolated products of plant origin. Prunella vulgaris var. lilacina is widely distributed in Korea, Japan, China, and Europe, and it continues to be used to treat inflammation, eye pain, headache, and dizziness. However, reports on the antioxidant activities of P. vulgaris var. lilacina are limited, particularly concerning the relationship between its phenolic content and antioxidant capacity. In this study, we investigated the antioxidant and anticancer activities of an ethanol extract from P. vulgaris var. lilacina and its fractions.

METHODS

Dried powder of P. vulgaris var. lilacina was extracted with ethanol, and the extract was fractionated to produce the hexane fraction, butanol fraction, chloroform fraction and residual water fraction. The phenolic content was assayed using the Folin-Ciocalteu colorimetric method. Subsequently, the antioxidant activities of the ethanol extract and its fractions were analyzed employing various antioxidant assay methods including DPPH, FRAP, ABTS, SOD activity and production of reactive oxygen species. Additionally, the extract and fractions were assayed for their ability to exert cytotoxic activities on various cancer cells using the MTT assay. We also investigated the expression of genes associated with apoptotic cell death by RT-PCR.

RESULTS

The total phenolic contents of the ethanol extract and water fraction of P. vulgaris var. lilacina were 303.66 and 322.80 mg GAE/g dry weight (or fractions), respectively. The results showed that the ethanol extract and the water fraction of P. vulgaris var. lilacina had higher antioxidant content than other solvent fractions, similar to their total phenolic content. Anticancer activity was also tested using the HepG2, HT29, A549, MKN45 and HeLa cancer cell lines. The results clearly demonstrated that the P. vulgaris var. lilacina ethanol extract induced significant cytotoxic effects on the various cancer cell lines, and these effects were stronger than those induced by the P. vulgaris var. lilacina solvent fractions. We also investigated the expression of genes associated with apoptotic cell death. We confirmed that the P. vulgaris var. lilacina ethanol extract and water fraction significantly increased the expression of p53, Bax and Fas.

CONCLUSIONS

These results suggest that the ethanol extract from P. vulgaris var. lilacina and its fractions could be applied as natural sources of antioxidants and anticancer activities in food and in the pharmaceutical industry.

Antibacterial and anti-inflammatory effects of Syzygium jambos L. (Alston) and isolated compounds on acne vulgaris

BACKGROUND

Acne vulgaris is a chronic skin disorder leading to inflammation as a result of the production of reactive oxygen species due to the active involvement of Propionibacterium acnes (P. acnes) in the infection site of the skin. The current study was designed to assess the potential of the leaf extract of Syzygium jambos L. (Alston) and its compounds for antibacterial and anti-inflammatory activity against the pathogenic P. acnes.

METHODS

The broth dilution method was used to assess the antibacterial activity. The cytotoxicity investigation on mouse melanocyte (B16-F10) and human leukemic monocyte lymphoma (U937) cells was done using sodium 3'-[1-(phenyl amino-carbonyl)-3,4-tetrazolium]-bis-[4-methoxy-6-nitrobenzene sulfonic acid hydrate (XTT) reagent. The non-toxic concentrations of the samples was investigated for the suppression of cytokines interleukin 8 (IL 8) and tumour necrosis factor (TNF α) by testing the supernatants in the co-culture of the human U937 cells and heat killed P. acnes using enzyme immunoassay kits (ELISA). The statistical analysis was done using the Graph Pad Prism 4 program.

RESULTS

Bioassay guided isolation of ethanol extract of the leaves of S. jambos led to the isolation of three known compounds namely; squalene, an anacardic acid analogue and ursolic acid which are reported for the first time from this plant. The ethanol extract of S. jambos and one of the isolated compound namely, anacardic acid analogue were able to inhibit the growth of P. acnes with a noteworthy minimum inhibitory concentration (MIC) value of 31.3 and 7.9 μg/ml, respectively. The ethanol extract and three commercially acquired compounds namely; myricetin, myricitrin, gallic acid exhibited significant antioxidant activity with fifty percent inhibitory concentration (IC50) ranging between 0.8-1.9 μg/ml which was comparable to that of vitamin C, the reference antioxidant agent. The plant extract, compounds ursolic acid and myricitrin (commercially acquired) significantly inhibited the release of inflammatory cytokines IL 8 and TNF α by suppressing them by 74 - 99%. TEM micrographs showed the lethal effects of selected samples against P. acnes.

CONCLUSIONS

The interesting antibacterial, antioxidant and anti-inflammatory effects of S. jambos shown in the present study warrant its further investigation in clinical studies for a possible alternative anti-acne agent.

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.

Microwave-assisted extraction and rapid isolation of ursolic acid from the leaves of Eucalyptus × hybrida Maiden and its quantification using HPLC-diode array technique

Ursolic acid (UA) is the most important bioactive phytoconstituent of Eucalyptus × hybrida Maiden leaves and exhibits anticancer, antimutagenic, anti-inflammatory, antioxidative, and antiprotozoal activities. In this study, microwave-assisted extraction technique was employed for rapid isolation of UA from the leaves of Eucalyptus × hybrida and simultaneously HPLC-diode array method was developed for the quantification of UA. Effects of several experimental parameters on the extraction efficiencies of UA, such as type and volume of extraction solvents, microwave power and extraction time, were evaluated. The optimal extraction conditions were found to be 20 mL of a mixture of chloroform/methanol, 60:40; liquid-to-material ratio, 4:1; preleaching time, 10 min; microwave power, 600 W; temperature, 50°C; and microwave irradiation time, 5 min. Under the optimum conditions, the yield of UA was found to be 1.95 ± 0.08% in the dry leaves of Eucalyptus × hybrida. The results showed that microwave-assisted extraction is a more rapid extraction method with higher yield and lower solvent consumptions than the conventional method. It is a faster, convenient, and appropriate method and it may be used for rapid isolation and quantification of UA and other important phytoconstituents present in the leaves of Eucalyptus × hybrida.

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.

Antiulcerogenic activity of the essential oil of Hyptis martiusii Benth. (Lamiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis martiusii (Lamiaceae), popularly known as "cidreira-do-mato" or "cidreira-brava", grows in abundance in the Northeast region of Brazil, where its leaves are traditionally used in folk medicine in the treatment of intestinal and stomach diseases. The aim of this study was to characterize the chemical constituents and to evaluate the anti-ulcerogenic activity of the essential oil of the leaves of Hyptis martiusii (EOHM) in in vivo models of experimental ulcers in rodents.

MATERIALS AND METHODS

EOHM was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Acute gastric ulcer was induced using absolute ethanol, HCl/ethanol and indomethacin. The volume, pH and total acidity of gastric secretion were determined by the pyloric ligature method and gastrointestinal motility using gastric emptying and intestinal transit.

RESULTS

Chemical analysis revealed the presence of 24 components that account for 92.13% of the essential oil of dried leaves, indicating the occurrence of mono and sesquiterpenes. Oral administration of EOHM (100, 200 and 400mg/kg) inhibited ethanol-, HCl/ethanol- and indomethacin-induced ulcers. In the case of pylorus ligature, the oil reduced the volume of gastric juices and total acidity, and increased gastric pH. The EOHM reduced the rate of gastric emptying with only the highest doses, but did not show any effect on intestinal transit at any of the three doses.

CONCLUSIONS

The results indicate that the essential oil of leaves of Hyptis martiusii has an antiulcerogenic activity, as evidenced by its significant inhibition of the formation of ulcers in various models. This effect could be related to an increase of gastric mucosal defensive factors. Further pharmacological studies are being undertaken in order to provide more precise elucidation of the action mechanism involved in this activity.

Ursolic acid inhibits proliferation and induces apoptosis of cancer cells in vitro and in vivo

The aims of the study are to explore the effect of ursolic acid (UA) on the growth of gastric cancer cell line BGC-803 and hepatocellular cancer cell H22 xenograft and to understand the mechanism. UA inhibits growth of BGC-803 cells in vitro in dose-dependent and time-dependent manner. Treated with UA in vivo, tumor cells can be arrested to G0/G1 stage. The apoptotic rate was significantly increased in tumor cells treated with UA both in vitro and in vivo. DNA fragmentation was found in BGC-803 cells exposed to UA. UA activated caspase-3, -8, and -9 and down regulated expression of Bcl-2 in BGC-803 cells. The expression of caspase-3 and -8 was elevated in tumor cells from xenograft treated with UA. ¹⁸F-FLT PET-CT imaging confirmed tumor model and UA effectiveness. Our results indicated that UA inhibits growth of tumor cells both in vitro and in vivo by decreasing proliferation of cells and inducing apoptosis.

Apoptotic action of ursolic acid isolated from Corni fructus in RC-58T/h/SA#4 primary human prostate cancer cells

Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) is a major biological active component of Corni fructus that is known to induce apoptosis. However, the apoptotic mechanism of ursolic acid using primary malignant tumor (RC-58T/h/SA#4)-derived human prostate cells is not known. In the present study, ursolic acid significantly inhibited the growth of RC-58T/h/SA#4 cells in dose- and time-dependent manners. Ursolic acid induced cell death as evidenced by an increased proportion of cells in sub-G1 phase, the formation of apoptotic bodies, nuclear condensation, and DNA fragmentation. After ursolic acid treatment at concentrations above 40 μM, the activities of caspase-3, -8, and -9 were significantly increased compared that of control. Ursolic acid modulated the upregulation of Bax (pro-apoptotic) as well as the downregulation of Bcl-2 (anti-apoptotic). Ursolic acid also stimulated Bid cleavage, which indicates that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. Thus, the apoptotic effect of ursolic acid was involved in extrinsic and intrinsic signaling pathways. In addition, ursolic acid increased the expression of the caspase-independent mitochondrial apoptosis factor (AIF) in RC-58T/h/SA#4 cells. The present results suggest that ursolic acid from Corni fructus activated apoptosis in RC-58T/h/SA#4 cells via both caspase-dependent and -independent pathways.

Prunella vulgaris L. Upregulates eNOS expression in human endothelial cells

The purported effects of "circulation-improving" herbs used in traditional Chinese medicine (TCM) show striking similarities with the vascular actions of nitric oxide (NO) produced by the endothelial NO synthase (eNOS). We have previously reported that Salviae miltiorrhizae radix and Zizyphi spinosae semen upregulate eNOS expression. In the present study, we studied the effect on eNOS gene expression of 15 Chinese herbs with potential effects on the vasculature, and identified Prunella vulgaris L. (PVL) (flowering spike) as a potent eNOS-upregulating agent. In EA.hy 926 cells, a cell line derived from human umbilical vein endothelial cells (HUVEC), an aqueous extract of PVL increased eNOS promoter activity, eNOS mRNA and protein expressions, as well as NO production in concentration- and time-dependent manners. We have previously shown that ursolic acid (a constituent of Salviae miltiorrhizae radix), betulinic acid (a compound present in Zizyphi spinosae semen), luteolin and cynaroside (ingredients of artichoke, Cynara scolymus L.) are capable of enhancing eNOS gene expression. These compounds are also present in significant quantities in PVL. Thus, PVL contains active principles that stimulate human eNOS gene expression, and such compounds may have therapeutic potential against cardiovascular diseases.

Chemopreventive effects of 13alpha,14alpha-epoxy-3beta-methoxyserratan-21beta-ol (PJJ-34), a serratane-type triterpenoid, in a rat multi-organ carcinogenesis bioassay

A novel serratane-type triterpenoid, 13alpha,14alpha-epoxy-3beta-methoxyserratan-21beta-ol (PJJ-34) derived from cuticles of Picea jezoensis Carr. var. jezoensis, has proved to be highly effective at suppressing carcinogenesis both in vitro and in vivo. To investigate possible anti-carcinogenic efficacy at the whole-body level, male Fischer 344 rats were subjected to an established rat multi-organ carcinogenesis bioassay (DMBDD model). After initiation with five carcinogens, groups 1-3 (20 in each) were intragastrically (i.g.) administered PJJ-34 dissolved in 1 ml of 0.5% CMC (5 times/week) at doses of 0, 5 and 10mg/kg body weight (b.w.), respectively, until the end of week 30. PJJ-34 did not show apparent toxicity. Incidences of adenomas (100-->75%) and carcinomas (63-->30%) in the lung were significantly decreased in the 5mg/kg b.w. group, and multiplicity of alveolar hyperplasias and total lung tumors (adenomas+carcinomas) were significantly reduced by both 5 and 10mg/kg. The incidence of colorectal tumors was also significantly decreased in the 10mg/kg group (63-->28%) along with the multiplicity. Rat liver pre-neoplastic lesions, glutathione S-transferase placental form (GST-P) foci, and tumor development in the other organs were not affected. Immunohistochemical indices for proliferating cell nuclear antigen (PCNA) and cyclin D1 in normal alveolar epithelium of the lung were significantly suppressed at both doses. In conclusion, PJJ-34 is chemopreventive against lung and colon carcinogenesis without exerting apparent toxicity, and suppression of cell proliferation could play a key role in the underlying mechanisms.

A New Hyptadienic Acid Derivative from Hyptis Verticillata (Jacq.) with Insecticidal Activity

A new triterpene, A(1)-1-benzoate-19α-hydroxy-urs-2(3),12(13)-dien-28-oic acid (1), was isolated from Hyptis verticillata, in addition to the known triterpenes tormentic acid, isolated as the diacetate (2), betulinic acid (3), α- and β-amyrin, oleanolic acid and ursolic acid. The structure of 1 was elucidated by spectroscopic analysis. Compounds 1–3 exhibited insecticidal activity against the sweet potato weevil Cylas formicarius elegantulus (Summers).

Purity-activity relationships of natural products: the case of anti-TB active ursolic acid

The present study explores the variability of biological responses from the perspective of sample purity and introduces the concept of purity-activity relationships (PARs) in natural product research. The abundant plant triterpene ursolic acid (1) was selected as an exemplary natural product due to the overwhelming number yet inconsistent nature of its approximate 120 reported biological activities, which include anti-TB potential. Nine different samples of ursolic acid with purity certifications were obtained, and their purity was independently assessed by means of quantitative 1H NMR (qHNMR). Biological evaluation consisted of determining MICs against two strains of virulent Mycobacterium tuberculosis and IC50 values in Vero cells. Ab initio structure elucidation provided unequivocal structural confirmation and included an extensive 1H NMR spin system analysis, determination of nearly all J couplings and the complete NOE pattern, and led to the revision of earlier reports. As a net result, a sigmoid PAR profile of 1 was obtained, demonstrating the inverse correlation of purity and anti-TB bioactivity. The results imply that synergistic effects of 1 and its varying impurities are the likely cause of previously reported antimycobacterial potential. Generating PARs is a powerful extension of the routinely performed quantitative correlation of structure and activity ([Q]SAR). Advanced by the use of primary analytical methods such as qHNMR, PARs enable the elucidation of cases like 1 when increasing purity voids biological activity. This underlines the potential of PARs as a tool in drug discovery and synergy research and accentuates the need to routinely combine biological testing with purity assessment.

Cytotoxic activity of Origanum dictamnus

Several extracts of Origanum dictamnus, an endemic plant of Greece growing only in the island of Crete and the bioassay-directed isolated ursolic acid, were tested in vitro against the P388 (murine leukemia) and the human bronchial epidermoid cancer NSCLC-N6 (non small cell lung cancer) cell lines. Both the initial dichloromethane extract and the isolated from it ursolic acid exhibited cytotoxic activity. Ursolic acid was also tested in vivo, on murine ascite leukemia P388, where it exhibited at a dose of 50 mg/kg a marginal antileukemic activity.

Antihyperlipidemic and antihypertensive effect of a triterpenoid-rich extract from bamboo shavings and vasodilator effect of friedelin on phenylephrine-induced vasoconstriction in thoracic aortas of rats

Triterpenoids, which are widely distributed throughout the plant kingdom, were applied to the development of functional foods as physiological and pharmacological active agents. Some physiological activities of a triterpenoid-rich extract from bamboo shavings (EBS), i.e. antihyperlipidemic and antihypertensive effects, were systematically evaluated in the present study. The results demonstrated that EBS could reduce the serum total cholesterol (TC) and total triglyceride (TG) levels, which are the main factors directly leading to pathological changes in cardiovascular diseases, in hyperlipidemic rats (p < 0.05). Furthermore, EBS could significantly reduce the systolic pressure of spontaneously hypertensive rats (SHR) but its maximum effect time was less than 24 h. Meanwhile, EBS did not influence the heart rate of SHR. On the other hand, the vasodilator effects of friedelin, a main triterpenoid compound separated from EBS, on phenylephrine-induced vasoconstriction in the thoracic aortas of rats were also discussed. The results showed that friedelin probably served a function of vasodilator responses in the thoracic aortas of rats in accordance with the antihypertensive effect of EBS. The results also suggested that EBS might prevent some cardiovascular diseases by its impact on lipid metabolism.

Trypanocidal activity of triterpenes from Arrabidaea triplinervia and derivatives

Ethanol extract from Arrabidaea triplinervia leaves showed in vitro activity (ED100 5.0 mg/ml) against trypomastigotes of Trypanosoma cruzi, the etiologic agent of Chagas; disease. Bioactivity-directed fractionation of this extract led to the isolation of ursolic and oleanolic acids as trypanocidal compounds besides pomolic acid (not tested) and alpinetine (inactive). A series of natural and synthetic derivatives of ursolic and oleanolic acids was simultaneously assayed for structure activity relationships (SAR) studies. Ursolic acid (ED100 0.4 mg/ml) was four times more active than oleanolic acid (ED100 1.6 mg/ml). The presence of free hydroxy and/or carboxy groups is necessary for the trypanocidal activity as could be deduced from the effect of the acetates, methyl ester, and aldehyde derivatives.

Bioactive principles in the bark of Pilidiostigma tropicum

The crude dichloromethane bark extract of Pilidiostigma tropicum (Myrtaceae) from north Queensland, Australia, shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of rhodomyrtoxin B and ursolic acid-3-p-coumarate as the biologically active materials. The structures of these compounds were elucidated on the basis of spectral analysis. The intercalation interaction of rhodomyrtoxin B with DNA was investigated using molecular mechanics and ab initio molecular-orbital techniques. A favorable pi-pi interaction between rhodomyrtoxin B and the cytosine-guanine base pair is predicted, but the orientation of the interaction cannot be predicted based on frontier molecular orbitals.

Antioxidants from Rabdosia japonica

The antioxidant activities of phenolic compounds: pedalitin, quercetin, rutin, isoquercitrin, and rosmarinic acid, isolated from the dried leaves of Rabdosia japonica Hara (Labiatae) were elucidated. All the phenolics tested exhibited superoxide scavenging activity and an inhibitory effect on xanthine oxidase (EC 1.1.3.22), and pedalitin showed the most potent antioxidant activity. Pedalitin prevents the generation of superoxide radicals in part by inhibiting xanthine oxidase competitively. Both pedalitin and quercetin inhibited uric acid formation by xanthine oxidase, and the inhibition kinetics analysed by Lineweaver-Burk plots found both flavonoids to be competitive inhibitors. On the other hand, isoquercitrin, rutin and rosmarinic acid were effective in scavenging superoxide radicals generated by the xanthine-xanthine oxidase system without inhibiting the enzyme.

In vitro and in vivo immunosuppressive activity of Spica Prunellae ethanol extract on the immune responses in mice

The immunosuppressive activity of the ethanol extract of Spica Prunellae (Prunella vulgaris fruiting spikes) (EESP) consisting of a mixture of triterpenoids, flavonoids, tannins and polysaccharide was studied on the immune responses in mice. The effects of EESP on mice splenocyte proliferation in vitro were measured. EESP significantly suppressed concanavalin A (Con A)- and lipopolysaccharide (LPS)-stimulated splenocyte proliferation in vitro in a concentration-dependent manner. Furthermore, the effects of EESP at three dose levels (a single dose of 0.25, 0.5, and 1.0 mg) on the humoral and cellular immune responses of mice subcutaneously immunized with ovalbumin (OVA) were examined. ICR mice were immunized subcutaneously with OVA on day 0 and 14. Starting on the day of immunization, the mice were administered subcutaneously with EESP at 0.25, 0.5, and 1.0 mg at intervals of 7 days for a total of five doses. On day 28, antigen-specific antibodies in serum, mitogen- and OVA-induced splenocyte proliferation were investigated. EESP significantly suppressed Con A-, LPS- and OVA-induced splenocyte proliferation in the immunized mice in a dose-dependent manner. Total IgG, IgG1 and IgG2b levels in the immunized mice were significantly reduced by EESP. Moreover, the suppressing effects on the antibody responses to OVA in the immunized mice were dose-dependently enhanced according to the increase of EESP. The results suggest that EESP could suppress the cellular and humoral response in mice.

The cytotoxic activity of ursolic acid derivatives

Ursolic acid and 2alpha-hydroxyursolic acid isolated from apple peels were found to show growth inhibitory activity against four tumor cell lines, HL-60, BGC, Bel-7402 and Hela. Structural modifications were performed on the C-3, C-28 and C-11 positions of ursolic acid and the cytotoxicity of the derivatives was evaluated. The SAR revealed that the triterpenes possessing two hydrogen-bond forming groups (an H-donor and a carbonyl group) at positions 3 and 28 exhibit cytotoxic activity. The configuration at C-3 was found to be important for the activity. Introduction of an amino group increased the cytotoxicity greatly. A 3beta-amino derivative was 20 times more potent than the parent ursolic acid. The 28-aminoalkyl dimer compounds showed selective cytotoxicity.

Proliferative inhibition, cell-cycle dysregulation, and induction of apoptosis by ursolic acid in human non-small cell lung cancer A549 cells

Ursolic acid (UA) is a pentacyclic triterpene compound isolated from many types of medicinal plants and is present in human diet. It has been reported to possess a wide range of pharmacological properties, and is one of the most promising chemopreventive agents for cancer. Here, we report that UA inhibits the cell proliferation of human lung cancer cell line A549 and provide a molecular understanding of this effect. The results showed that UA blocked cell cycle progression in the G1 phase that was associated with a marked decrease in the protein expression of cyclin D1, D2, and E and their activating partner cdk2, 4, and 6 with concomitant induction of p21/WAF1. This accumulation of p21/WAF1 might be through a p53-dependent manner. Further, UA treatment also resulted in the triggering of apoptosis as determined by DNA fragmentation assay. This effect was found to correlate with the up-regulation of Fas/APO-1, Fas ligand, and Bax, and down-regulation of NF-kappaB, Bcl-2, and Bcl-XL. Taken together, our study indicated that UA might be a potential chemopreventive agent for lung cancer.