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1.  Unifying Mechanisms of Action of the Anticancer Activities of Triterpenoids and Synthetic Analogs 
Triterpenoids such as betulinic acid (BA) and synthetic analogs of oleanolic acid [2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO)] and glycyrrhetinic acid [2-cyano-3,11-dioxo-18β-oleana-1,12-dien-30-oc acid (CDODA)] are potent anticancer agents that exhibit antiproliferative, antiangiogenic, anti-inflammatory and pro-apoptotic activities. Although their effects on multiple pathways have been reported, unifying mechanisms of action have not been reported. Studies in this laboratory have now demonstrated that several triterpenoids including BA and some derivatives, celastrol, methyl ursolatee, β-boswellic acid derivatives, and the synthetic analogs CDDO, CDODA and their esters decreased expression of specificity protein (Sp) transcription factors and several pro-oncogenic Sp-regulated genes in multiple cancer cell lines. The mechanisms of this response are both compound- and cell context-dependent and include activation of both proteasome-dependent and -independent pathways. Triterpenoid-mediated induction of reactive oxygen species (ROS) has now been characterized as an important proteasome-independent pathway for downregulation of Sp transcription factors. ROS decreases expression of microRNA-27a (miR-27a) and miR-20a/miR-17-5p and this results in the induction of the transcriptional “Sp-repressors” ZBTB10 and ZBTB4, respectively, which in turn downregulate Sp and Sp-regulated genes. Triterpenoids also activate or deactive nuclear receptors and G-protein coupled receptors, and these pathways contribute to their antitumorigenic activity and may also play a role in targeting Sp1, Sp3 and Sp4 which are highly overexpressed in multiple cancers and appear to be important for maintaining the cancer phenotype.
PMCID: PMC3532564  PMID: 22583404
Sp transcription factors; downregulation; reactive oxygen species
2.  Synthesis and Pro-Apoptotic Activity of Novel Glycyrrhetinic Acid Derivatives 
Chembiochem  2011;12(5):784-794.
Triterpenoids are used for medicinal purposes in many countries. Some, such as oleanolic and glycyrrhetinic acids, are known to be anti-inflammatory and anticarcinogenic. However, the biological activities of these naturally occurring molecules against their particular targets are weak, so the synthesis of new synthetic analogues with enhanced potency is needed. By combining modifications to both the A and C rings of 18βH-glycyrrhetinic acid, the novel synthetic derivative methyl 2-cyano-3,12-dioxo-18βH-olean-9(11),1(2)-dien-30-oate was obtained. This derivative displays high antiproliferative activity in cancer cells, including a cell line with a multidrug-resistance phenotype. It causes cell death by inducing the intrinsic caspase-dependent apoptotic pathway.
doi:10.1002/cbic.201000618
PMCID: PMC3085123  PMID: 21328513
antitumor agents; apoptosis; biological activity; glycyrrhetinic acid derivatives; medicinal chemistry
3.  Boswellic acid inhibits expression of acid sphingomyelinase in intestinal cells 
Background
Boswellic acid is a type of triterpenoids with antiinflammatory and antiproliferative properties. Sphingomyelin metabolism generates multiple lipid signals affecting cell proliferation, inflammation, and apoptosis. Upregulation of acid sphingomyelinase (SMase) has been found in several inflammation-related diseases such as inflammatory bowel diseases, atherosclerosis, and diabetes.
Methods
The present study is to examine the effect of 3-acetyl-11-keto-β-boswellic acids (AKBA), a potent boswellic acid, on acid SMase activity and expression in intestinal cells. Both transformed Caco-2 cells and non-transformed Int407 cells were incubated with AKBA. After incubation, the change of acid SMase activity was assayed biochemically, the enzyme protein was examined by Western blot, and acid SMase mRNA was quantified by qPCR.
Results
We found that AKBA decreased acid SMase activity in both intestinal cell lines in dose and time dependent manners without affecting the secretion of the enzyme to the cell culture medium. The effect of AKBA was more effective in the fetal bovine serum-free culture medium. Among different types of boswellic acid, AKBA was the most potent one. The inhibitory effect on acid SMase activity occurred only in the intact cells but not in cell-free extract in the test tubes. At low concentration, AKBA only decreased the acid SMase activity but not the quantity of the enzyme protein. However, at high concentration, AKBA decreased both the mass of acid SMase protein and the mRNA levels of acid SMase in the cells, as demonstrated by Western blot and qPCR, respectively. Under the concentrations decreasing acid SMase activity, AKBA significantly inhibited cell proliferation.
Conclusion
We identified a novel inhibitory effect of boswellic acids on acid SMase expression, which may have implications in human diseases and health.
doi:10.1186/1476-511X-8-51
PMCID: PMC2789714  PMID: 19951413
4.  Boswellic acid induces epigenetic alterations by modulating DNA methylation in colorectal cancer cells 
Cancer Biology & Therapy  2012;13(7):542-552.
Accumulating evidence suggests that chemopreventive effects of some dietary polyphenols may in part be mediated by their ability to influence epigenetic mechanisms in cancer cells. Boswellic acids, derived from the plant Boswellia serrata, have long been used for the treatment of various inflammatory diseases due to their potent anti-inflammatory activities. Recent preclinical studies have also suggested that this compound has anti-cancer potential against various malignancies. However, the precise molecular mechanisms underlying their anti-cancer effects remain elusive. Herein, we report that boswellic acids modulate DNA methylation status of several tumor suppressor genes in colorectal cancer (CRC) cells. We treated RKO, SW48 and SW480 CRC cell lines with the active principle present in boswellic acids, acetyl-keto-β-boswellic acid (AKBA). Using genome-wide DNA methylation and gene expression microarray analyses, we discovered that AKBA induced a modest genome-wide demethylation that permitted simultaneous re-activation of the corresponding tumor suppressor genes. The quantitative methylation-specific PCR and RT-PCR validated the gene demethylation and re-expression in several putative tumor suppressor genes including SAMD14 and SMPD3. Furthermore, AKBA inhibited DNMT activity in CRC cells. Taken together, these results lend further support to the growing notion that anti-cancer effect of boswellic acids may in part be due to its ability to demethylate and reactivate methylation-silenced tumor suppressor genes. These results suggest that not only boswellic acid might be a promising epigenetic modulator in the chemoprevention and treatment of CRC, but also provide a rationale for future investigations on the usefulness of such botanicals for epigenetic therapy in other human malignancies.
doi:10.4161/cbt.19604
PMCID: PMC3364790  PMID: 22415137
acetyl-keto-beta-boswellic acid (AKBA); boswellic acid; chemoprevention; colorectal cancer; DNA Methylation; epigenetics
5.  Oral and topical boswellic acid attenuates mouse osteoarthritis 
Objective
Boswellic acid is a plant-derived molecule with putative anti-inflammatory effects. This study was performed to determine whether oral or topical administration of boswellic acid can attenuate joint damage in a mouse model of osteoarthritis (OA).
Methods
Levels of boswellic acid were measured in the blood and synovium of mice treated with oral or topical boswellic acid. OA was generated by surgical destabilization of the medial meniscus (DMM). Therapy with oral or topical boswellic acid was initiated one day after surgery and continued for 12 weeks, when knees were harvested and scored histologically for degree of cartilage loss, osteophyte formation, and synovitis. Microdissected OA synovium was stimulated with IL-1β or lipopolysaccharide (LPS) in the presence or absence of boswellic acid and cytokine production by quantitative polymerase chain reaction (PCR) or multiplex enzyme linked immunoabsorbant assay (ELISA).
Results
Topical treatment resulted in synovial concentrations of boswellic acid 2–6-fold higher than that measured in plasma. Cartilage loss was significantly reduced in mice treated with oral or topical boswellic acid compared with vehicle control (P < 0.01 for both oral and topical therapies). Likewise, treatment with either oral boswellic acid or boswellic acid ointment reduced of synovitis (P = 0.006 and 0.025, respectively) and osteophyte formation (P = 0.009 and 0.030, respectively). In vitro, boswellic acid was able to inhibit IL-1β and TLR4 mediated induction of several inflammatory mediators from OA synovial explant tissue.
Conclusions
Significant synovial concentration and therapeutic efficacy can be achieved with topical boswellic acid treatment. These findings suggest that boswellic acid has potential as a disease-modifying agent in OA.
doi:10.1016/j.joca.2013.10.012
PMCID: PMC3992997  PMID: 24185109
Osteoarthritis; Disease modifying anti-osteoarthritis drugs; Topical therapy summary
6.  Antistaphylococcal and biofilm inhibitory activities of acetyl-11-keto-β-boswellic acid from Boswellia serrata 
BMC Microbiology  2011;11:54.
Background
Boswellic acids are pentacyclic triterpenes, which are produced in plants belonging to the genus Boswellia. Boswellic acids appear in the resin exudates of the plant and it makes up 25-35% of the resin. β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid have been implicated in apoptosis of cancer cells, particularly that of brain tumors and cells affected by leukemia or colon cancer. These molecules are also associated with potent antimicrobial activities. The present study describes the antimicrobial activities of boswellic acid molecules against 112 pathogenic bacterial isolates including ATCC strains. Acetyl-11-keto-β-boswellic acid (AKBA), which exhibited the most potent antibacterial activity, was further evaluated in time kill studies, postantibiotic effect (PAE) and biofilm susceptibility assay. The mechanism of action of AKBA was investigated by propidium iodide uptake, leakage of 260 and 280 nm absorbing material assays.
Results
AKBA was found to be the most active compound showing an MIC range of 2-8 μg/ml against the entire gram positive bacterial pathogens tested. It exhibited concentration dependent killing of Staphylococcus aureus ATCC 29213 up to 8 × MIC and also demonstrated postantibiotic effect (PAE) of 4.8 h at 2 × MIC. Furthermore, AKBA inhibited the formation of biofilms generated by S. aureus and Staphylococcus epidermidis and also reduced the preformed biofilms by these bacteria. Increased uptake of propidium iodide and leakage of 260 and 280 nm absorbing material by AKBA treated cells of S aureus indicating that the antibacterial mode of action of AKBA probably occurred via disruption of microbial membrane structure.
Conclusions
This study supported the potential use of AKBA in treating S. aureus infections. AKBA can be further exploited to evolve potential lead compounds in the discovery of new anti-Gram-positive and anti-biofilm agents.
doi:10.1186/1471-2180-11-54
PMCID: PMC3066120  PMID: 21406118
7.  Boswellia Serrata, A Potential Antiinflammatory Agent: An Overview 
The resin of Boswellia species has been used as incense in religious and cultural ceremonies and in medicines since time immemorial. Boswellia serrata (Salai/Salai guggul), is a moderate to large sized branching tree of family Burseraceae (Genus Boswellia), grows in dry mountainous regions of India, Northern Africa and Middle East. Oleo gum-resin is tapped from the incision made on the trunk of the tree and is then stored in specially made bamboo basket for removal of oil content and getting the resin solidified. After processing, the gum-resin is then graded according to its flavour, colour, shape and size. In India, the States of Andhra Pradesh, Gujarat, Madhya Pradesh, Jharkhand and Chhattisgarh are the main source of Boswellia serrata. Regionally, it is also known by different names. The oleo gum-resins contain 30-60% resin, 5-10% essential oils, which are soluble in the organic solvents, and the rest is made up of polysaccharides. Gum-resin extracts of Boswellia serrata have been traditionally used in folk medicine for centuries to treat various chronic inflammatory diseases. The resinous part of Boswellia serrata possesses monoterpenes, diterpenes, triterpenes, tetracyclic triterpenic acids and four major pentacyclic triterpenic acids i.e. β-boswellic acid, acetyl-β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid, responsible for inhibition of pro-inflammatory enzymes. Out of these four boswellic acids, acetyl-11-keto-β-boswellic acid is the most potent inhibitor of 5-lipoxygenase, an enzyme responsible for inflammation.
doi:10.4103/0250-474X.93507
PMCID: PMC3309643  PMID: 22457547
Agent; antiinflammatory; Boswellia serrata; frankincense; olibanum; potential; Salai/Salai guggul
8.  Acetyl-11-keto-β-boswellic acid (AKBA); targeting oral cavity pathogens 
BMC Research Notes  2011;4:406.
Background
Boswellic acids mixture of triterpenic acids obtained from the oleo gum resin of Boswellia serrata and known for its effectiveness in the treatment of chronic inflammatory disease including peritumor edema. Boswellic acids have been extensively studied for a number of activities including anti inflammatory, antitumor, immunomodulatory, and inflammatory bowel diseases. The present study describes the antimicrobial activities of boswellic acid molecules against oral cavity pathogens. Acetyl-11-keto-β-boswellic acid (AKBA), which exhibited the most potent antibacterial activity, was further evaluated in time kill studies, mutation prevention frequency, postantibiotic effect (PAE) and biofilm susceptibility assay against oral cavity pathogens.
Findings
AKBA exhibited an inhibitory effect on all the oral cavity pathogens tested (MIC of 2-4 μg/ml). It exhibited concentration dependent killing of Streptococcus mutans ATCC 25175 up to 8 × MIC and also prevented the emergence of mutants of S.mutans ATCC 25175 at 8× MIC. AKBA demonstrated postantibiotic effect (PAE) of 5.7 ± 0.1 h at 2 × MIC. Furthermore, AKBA inhibited the formation of biofilms generated by S.mutans and Actinomyces viscosus and also reduced the preformed biofilms by these bacteria.
Conclusions
AKBA can be useful compound for the development of antibacterial agent against oral pathogens and it has great potential for use in mouthwash for preventing and treating oral infections.
doi:10.1186/1756-0500-4-406
PMCID: PMC3201914  PMID: 21992439
Streptococcus mutans; Biofilm; PAE; Boswellia serrata
9.  Structure-Dependent Inhibition of Bladder and Pancreatic Cancer Cell Growth by 2-Substituted Glycyrrhetinic and Ursolic Acid Derivatives 
Derivatives of oleanolic acid, ursolic acid and glycyrrhetinic acid substituted with electron withdrawing groups at the 2-position in the A-ring which also contains a 1-en-3-one structure are potent inhibitors of cancer cell growth. In this study, we have compared the effects of several 2-substituted analogs of triterpenoid acid methyl esters derived from ursolic and glycyrrhetinic acid on proliferation of KU7 and 253JB-V bladder and Panc-1 and Panc-28 pancreatic cancer cells. The results show that the 2-cyano and 2-trifluoromethyl derivatives were the most active compounds. The glycyrrhetinic acid derivatives with the rearranged C-ring containing the 9(11)-en-12-one structure were generally more active than the corresponding 12-en-11-one isomers. However, differences in growth inhibitory IC50 values were highly variable and dependent on the 2- substitutent (CN vs. CF3) and cancer cell context.
doi:10.1016/j.bmcl.2008.03.031
PMCID: PMC2408873  PMID: 18359628
glycyrrhetinate analogs; growth inhibition; bladder cancer; pancreatic cancer
10.  Urease inhibitory activities of β-boswellic acid derivatives 
Background and the purpose of the study
Boswellia carterii have been used in traditional medicine for many years for management different gastrointestinal disorders. In this study, we wish to report urease inhibitory activity of four isolated compound of boswellic acid derivative.
Methods
4 pentacyclic triterpenoid acids were isolated from Boswellia carterii and identified by NMR and Mass spectroscopic analysis (compounds 1, 3-O-acetyl-9,11-dehydro-β-boswellic acid; 2, 3-O-acetyl-11-hydroxy-β-boswellic acid; 3. 3-O- acetyl-11-keto-β-boswellic acid and 4, 11-keto-β-boswellic acid. Their inhibitory activity on Jack bean urease were evaluated. Docking and pharmacophore analysis using AutoDock 4.2 and Ligandscout 3.03 programs were also performed to explain possible mechanism of interaction between isolated compounds and urease enzyme.
Results
It was found that compound 1 has the strongest inhibitory activity against Jack bean urease (IC50 = 6.27 ± 0.03 μM), compared with thiourea as a standard inhibitor (IC50 = 21.1 ± 0.3 μM).
Conclusion
The inhibition potency is probably due to the formation of appropriate hydrogen bonds and hydrophobic interactions between the investigated compounds and urease enzyme active site and confirms its traditional usage.
doi:10.1186/2008-2231-21-2
PMCID: PMC3575251  PMID: 23351363
Boswellia carterii; Urease inhibitor; Boswellic acid; Docking; Autodock
11.  Tetra- and Pentacyclic Triterpene Acids from the Ancient Anti-inflammatory Remedy Frankincense as Inhibitors of Microsomal Prostaglandin E2 Synthase-1 
Journal of Natural Products  2014;77(6):1445-1451.
The microsomal prostaglandin E2 synthase (mPGES)-1 is the terminal enzyme in the biosynthesis of prostaglandin (PG)E2 from cyclooxygenase (COX)-derived PGH2. We previously found that mPGES-1 is inhibited by boswellic acids (IC50 = 3–30 μM), which are bioactive triterpene acids present in the anti-inflammatory remedy frankincense. Here we show that besides boswellic acids, additional known triterpene acids (i.e., tircuallic, lupeolic, and roburic acids) isolated from frankincense suppress mPGES-1 with increased potencies. In particular, 3α-acetoxy-8,24-dienetirucallic acid (6) and 3α-acetoxy-7,24-dienetirucallic acid (10) inhibited mPGES-1 activity in a cell-free assay with IC50 = 0.4 μM, each. Structure–activity relationship studies and docking simulations revealed concrete structure-related interactions with mPGES-1 and its cosubstrate glutathione. COX-1 and -2 were hardly affected by the triterpene acids (IC50 > 10 μM). Given the crucial role of mPGES-1 in inflammation and the abundance of highly active triterpene acids in frankincence extracts, our findings provide further evidence of the anti-inflammatory potential of frankincense preparations and reveal novel, potent bioactivities of tirucallic acids, roburic acids, and lupeolic acids.
doi:10.1021/np500198g
PMCID: PMC4074212  PMID: 24844534
12.  Molecular Determinants of the Response of Tumor Cells to Boswellic Acids 
Pharmaceuticals  2011;4(8):1171-1182.
Frankincense (Boswellia serrata, B. carterii) is used as traditional remedy to treat inflammatory diseases. The molecular effects of the active ingredients, the boswellic acids, on the immune system have previously been studied and verified in several clinical studies. Boswellic acids also inhibit cancer cell growth in vitro and in vivo. The molecular basis of the cytotoxicity of boswellic acids is, however, not fully understood as yet. By mRNA-based microarray, COMPARE, and hierarchical cluster analyses, we identified a panel of genes from diverse functional groups, which were significantly associated with sensitivity or resistance of α- or β-boswellic acids, such as transcription factors, signal transducers, growth regulating genes, genes involved in RNA and protein metabolism and others. This indicates that boswellic acids exert profound cytotoxicity on cancer cells by a multiplicity of molecular mechanisms.
doi:10.3390/ph4081171
PMCID: PMC4058665
apoptosis; Boswellia; ceramide; frankincense; natural products; olibanum; pharmacogenomics; sphingomyelin
13.  Synthetic Triterpenoid Cyano Enone of Methyl Boswellate (CEMB) activates intrinsic, extrinsic, & endoplasmic reticulum stress cell death pathways in tumor cell lines 
Molecular cancer therapeutics  2011;10(9):1635-1643.
We explored the effect of a novel synthetic triterpenoid compound Cyano Enone of Methyl Boswellates (CEMB) on various prostate cancer and glioma cancer cell lines. CEMB displayed concentration-dependent cytotoxic activity with submicromolar lethal dose 50% (LD50) values in ten of ten tumor cell lines tested. CEMB-induced cytotoxicity is accompanied by activation of downstream effector caspases (caspases 3 and 7) and by upstream initiator caspases involved in both the extrinsic (caspase 8) and intrinsic (caspase 9) apoptotic pathways. By using small interfering RNAs (siRNAs), we show evidence that knock down of caspase 8, death receptor 4 (DR4), Apaf-1, and Bid impairs CEMB-induced cell death. Similar to other proapoptotic synthetic triterpenoid compounds, CEMB-induced apoptosis involved endoplasmic reticulum (ER) stress, as demonstrated by partial rescue of tumor cells by siRNA-mediated knock-down of expression of genes involve in the unfolded protein response such as Ire1, Perk, and ATF6. Altogether our results suggest that CEMB stimulates several apoptotic pathways in cancer cells, suggesting that this compound should be evaluated further as a potential agent for cancer therapy.
doi:10.1158/1535-7163.MCT-10-0887
PMCID: PMC4174562  PMID: 21746806
Triterpenoid; Apoptosis; ER stress
14.  Frankincense essential oil prepared from hydrodistillation of Boswellia sacra gum resins induces human pancreatic cancer cell death in cultures and in a xenograft murine model 
Background
Regardless of the availability of therapeutic options, the overall 5-year survival for patients diagnosed with pancreatic cancer remains less than 5%. Gum resins from Boswellia species, also known as frankincense, have been used as a major ingredient in Ayurvedic and Chinese medicine to treat a variety of health-related conditions. Both frankincense chemical extracts and essential oil prepared from Boswellia species gum resins exhibit anti-neoplastic activity, and have been investigated as potential anti-cancer agents. The goals of this study are to identify optimal condition for preparing frankincense essential oil that possesses potent anti-tumor activity, and to evaluate the activity in both cultured human pancreatic cancer cells and a xenograft mouse cancer model.
Methods
Boswellia sacra gum resins were hydrodistilled at 78°C; and essential oil distillate fractions were collected at different durations (Fraction I at 0–2 h, Fraction II at 8–10 h, and Fraction III at 11–12 h). Hydrodistillation of the second half of gum resins was performed at 100°C; and distillate was collected at 11–12 h (Fraction IV). Chemical compositions were identified by gas chromatography–mass spectrometry (GC-MS); and total boswellic acids contents were quantified by high-performance liquid chromatography (HPLC). Frankincense essential oil-modulated pancreatic tumor cell viability and cytotoxicity were determined by colorimetric assays. Levels of apoptotic markers, signaling molecules, and cell cycle regulators expression were characterized by Western blot analysis. A heterotopic (subcutaneous) human pancreatic cancer xenograft nude mouse model was used to evaluate anti-tumor capability of Fraction IV frankincense essential oil in vivo. Frankincense essential oil-induced tumor cytostatic and cytotoxic activities in animals were assessed by immunohistochemistry.
Results
Longer duration and higher temperature hydrodistillation produced more abundant high molecular weight compounds, including boswellic acids, in frankincense essential oil fraactions. Human pancreatic cancer cells were sensitive to Fractions III and IV (containing higher molecular weight compounds) treatment with suppressed cell viability and increased cell death. Essential oil activated the caspase-dependent apoptotic pathway, induced a rapid and transient activation of Akt and Erk1/2, and suppressed levels of cyclin D1 cdk4 expression in cultured pancreatic cancer cells. In addition, Boswellia sacra essential oil Fraction IV exhibited anti-proliferative and pro-apoptotic activities against pancreatic tumors in the heterotopic xenograft mouse model.
Conclusion
All fractions of frankincense essential oil from Boswellia sacra are capable of suppressing viability and inducing apoptosis of a panel of human pancreatic cancer cell lines. Potency of essential oil-suppressed tumor cell viability may be associated with the greater abundance of high molecular weight compounds in Fractions III and IV. Although chemical component(s) responsible for tumor cell cytotoxicity remains undefined, crude essential oil prepared from hydrodistillation of Boswellia sacra gum resins might be a useful alternative therapeutic agent for treating patients with pancreatic adenocarcinoma, an aggressive cancer with poor prognosis.
doi:10.1186/1472-6882-12-253
PMCID: PMC3538159  PMID: 23237355
Apoptosis; Boswellia sacra, Boswellic acid; Essential oil; Frankincense; Hydrodistillation; Pancreatic cancer
15.  Boswellia sacra essential oil induces tumor cell-specific apoptosis and suppresses tumor aggressiveness in cultured human breast cancer cells 
Background
Gum resins obtained from trees of the Burseraceae family (Boswellia sp.) are important ingredients in incense and perfumes. Extracts prepared from Boswellia sp. gum resins have been shown to possess anti-inflammatory and anti-neoplastic effects. Essential oil prepared by distillation of the gum resin traditionally used for aromatic therapy has also been shown to have tumor cell-specific anti-proliferative and pro-apoptotic activities. The objective of this study was to optimize conditions for preparing Boswellea sacra essential oil with the highest biological activity in inducing tumor cell-specific cytotoxicity and suppressing aggressive tumor phenotypes in human breast cancer cells.
Methods
Boswellia sacra essential oil was prepared from Omani Hougari grade resins through hydrodistillation at 78 or 100 oC for 12 hours. Chemical compositions were identified by gas chromatography-mass spectrometry; and total boswellic acids contents were quantified by high-performance liquid chromatography. Boswellia sacra essential oil-mediated cell viability and death were studied in established human breast cancer cell lines (T47D, MCF7, MDA-MB-231) and an immortalized normal human breast cell line (MCF10-2A). Apoptosis was assayed by genomic DNA fragmentation. Anti-invasive and anti-multicellular tumor properties were evaluated by cellular network and spheroid formation models, respectively. Western blot analysis was performed to study Boswellia sacra essential oil-regulated proteins involved in apoptosis, signaling pathways, and cell cycle regulation.
Results
More abundant high molecular weight compounds, including boswellic acids, were present in Boswellia sacra essential oil prepared at 100 oC hydrodistillation. All three human breast cancer cell lines were sensitive to essential oil treatment with reduced cell viability and elevated cell death, whereas the immortalized normal human breast cell line was more resistant to essential oil treatment. Boswellia sacra essential oil hydrodistilled at 100 oC was more potent than the essential oil prepared at 78 oC in inducing cancer cell death, preventing the cellular network formation (MDA-MB-231) cells on Matrigel, causing the breakdown of multicellular tumor spheroids (T47D cells), and regulating molecules involved in apoptosis, signal transduction, and cell cycle progression.
Conclusions
Similar to our previous observations in human bladder cancer cells, Boswellia sacra essential oil induces breast cancer cell-specific cytotoxicity. Suppression of cellular network formation and disruption of spheroid development of breast cancer cells by Boswellia sacra essential oil suggest that the essential oil may be effective for advanced breast cancer. Consistently, the essential oil represses signaling pathways and cell cycle regulators that have been proposed as therapeutic targets for breast cancer. Future pre-clinical and clinical studies are urgently needed to evaluate the safety and efficacy of Boswellia sacra essential oil as a therapeutic agent for treating breast cancer.
doi:10.1186/1472-6882-11-129
PMCID: PMC3258268  PMID: 22171782
16.  Boswellic Acid Inhibits Growth and Metastasis of Human Colorectal Cancer in Orthotopic Mouse Model By Downregulating Inflammatory, Proliferative, Invasive, and Angiogenic Biomarkers 
Numerous cancer therapeutics were originally identified from natural products used in traditional medicine. One such agent is acetyl-11-keto-beta-boswellic acid (AKBA), derived from the gum resin of the Boswellia serrata known as Salai guggal or Indian frankincense. Traditionally it has been used in Ayurvedic medicine to treat proinflammatory conditions. In the present report, we hypothesized that AKBA can affect the growth and metastasis of colorectal cancer (CRC) in orthotopically-implanted tumors in nude mice. We found that the oral administration of AKBA (50-200 mg/kg) dose-dependently inhibited the growth of CRC tumors in mice, resulting in decrease in tumor volumes than those seen in vehicle-treated mice without significant decreases in body weight. In addition, we observed that AKBA was highly effective in suppressing ascites and distant metastasis to the liver, lungs, and spleen in orthotopically-implanted tumors in nude mice. When examined for the mechanism, we found that markers of tumor proliferation index Ki-67 and the microvessel density CD31; were significantly downregulated by AKBA treatment. We also found that AKBA significantly suppressed NF-κB activation in the tumor tissue and expression of pro-inflammatory (COX2), tumor survival (bcl-2, bcl-xL, IAP-1, survivin), proliferative (cyclin D1), invasive (ICAM-1, MMP-9) and angiogenic (CXCR4 and VEGF) biomarkers. When examined for serum and tissue levels of AKBA, a dose-dependent increase in the levels of the drug was detected, indicating its bioavailability. Thus, our findings suggest that this boswellic acid analogue can inhibit the growth and metastasis of human CRC in vivo through downregulation of cancer-associated biomarkers.
doi:10.1002/ijc.26251
PMCID: PMC3246525  PMID: 21702037
AKBA; colorectal cancer; NF-κB; growth; metastasis
17.  Induction of Apoptosis and Nonsteroidal Antiinflammatory Drug-Activated Gene 1 in Pancreatic Cancer Cells By A Glycyrrhetinic Acid Derivative 
Molecular carcinogenesis  2009;48(8):692-702.
Methyl 2-cyano-3,11-dioxo-18β-olean-1,12-dien-30-oate (CDODA-Me) is a synthetic triterpenoid derived from glycyrrhetinic acid, a bioactive phytochemical in licorice, CDODA-Me inhibits growth of Panc1 and Panc28 pancreatic cancer cell lines and activates peroxisome proliferator-activated receptor γ (PPARγ)-dependent transactivation in these cells. CDODA-Me also induced p21 and p27 protein expression and downregulates cyclin D1; however, these responses were receptor-independent. CDODA-Me induced apoptosis in Panc1 and Panc28 cells, and this was accompanied by receptor-independent induction of the proapoptotic proteins early growth response-1 (Egr-1), nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1), and activating transcription factor-3 (ATF3). Induction of NAG-1 and Egr-1 by CDODA-Me was dependent on activation of phosphatidylinositol-3-kinase (PI3-K) and/or p42 and p38 mitogen-activated protein kinase (MAPK) pathways but there were differences between Panc28 and Panc1 cells. Induction of NAG-1 in Panc28 cells was p38-MAPK- and PI3-K-dependent but Egr-1-independent, whereas induction in Panc1 cells was associated with activation of p38-MAPK, PI3-K and p42-MAPK and was only partially Egr-1-dependent. This is the first report of the induction of the proapoptotic protein NAG-1 in pancreatic cancer cells.
doi:10.1002/mc.20518
PMCID: PMC2746008  PMID: 19125423
CDODA-Me; pancreatic cancer; apoptosis
18.  Dietary phytochemicals as potent chemotherapeutic agents against breast cancer: Inhibition of NF-κB pathway via molecular interactions in rel homology domain of its precursor protein p105 
Pharmacognosy Magazine  2013;9(33):51-57.
Background:
Dietary phytochemicals consist of a wide variety of biologically active compounds that are ubiquitous in plants, many of which have been reported to have anti-tumor as well as anti-inflammatory properties.
Objective:
In the present study, we aimed to validate these findings by using docking protocols and explicate the possible mechanism of action for a dataset of nine phytochemicals namely boswellic acid, 1-caffeoylquinic acid, ellagic acid, emodin, genistein, guggulsterone, quercetin, resveratrol, and sylibinin from different plants against the nuclear factor- kappaB (NF-κB) precursor protein p105, an important transcription factor reported to be overexpressed in breast cancer.
Materials and Methods:
2-D structures of all phytochemicals were retrieved from PubChem Compound database and their subsequent conversion into 3-D structures was performed by using online software system CORINA. The X-ray crystallographic structure of the NF-κB precursor p105 was extracted from Brookhaven Protein Data Bank. Molecular docking simulation study was carried out by using AutoDock Tools 4.0.
Results:
Our results showed significant binding affinity of different phytochemicals with the Rel homology domain of the NF-κB precursor protein p105. Quercetin and 1-caffeoylquinic acid were found to be very effective inhibitors against target molecule as they showed binding energy of −12.11 and −11.50 Kcal/mol, respectively. The order of affinity of other ligands with p105 was found as follows: guggulsterone > sylibinin > emodin > resveratrol > genistein > boswellic acid > ellagic acid.
Conclusion:
Our in silico study has explored the possible chemopreventive mechanism of these phytochemicals against the NF-κB precursor protein p105 and deciphered that quercetin, 1-caffeoylquinic acid and guggulsterone were the potent inhibitors against target molecule. In addition, large scale preclinical and clinical trials are needed to explore the role of these chemotherapeutic molecules against the NF-κB precursor protein p105 in cure and prevention of breast cancer.
doi:10.4103/0973-1296.108140
PMCID: PMC3647395  PMID: 23661994
1-Caffeoylquinic acid; boswellic acid; breast cancer; emodin; guggulsterone; molecular docking; NF-κB; rel homology domain; sylibinin
19.  Efficacy of boswellic acid on lysosomal acid hydrolases, lipid peroxidation and anti-oxidant status in gouty arthritic mice 
Objective
To evaluate the efficacy of boswellic acid against monosodium urate crystal-induced inflammation in mice.
Methods
The mice were divided into four experimental groups. Group I served as control; mice in group II were injected with monosodium urate crystal; group III consisted of monosodium urate crystal-induced mice who were treated with boswellic acid (30 mg/kg/b.w.); group IV comprised monosodium urate crystal-induced mice who were treated with indomethacin (3 mg/kg/b.w.). Paw volume and levels/activities of lysosomal enzymes, lipid peroxidation, anti-oxidant status and inflammatory mediator TNF-α were determined in control and monosodium urate crystal-induced mice. In addition, the levels of β-glucuronidase and lactate dehydrogenase were also measured in monosodium urate crystal-incubated polymorphonuclear leucocytes (PMNL) in vitro.
Results
The activities of lysosomal enzymes, lipid peroxidation, and tumour necrosis factor-α levels and paw volume were increased significantly in monosodium urate crystal-induced mice, whereas the activities of antioxidant status were in turn decreased. However, these changes were modulated to near normal levels upon boswellic acid administration. In vitro, boswellic acid reduced the level of β-glucuronidase and lactate dehydrogenase in monosodium urate crystal-incubated PMNL in concentration dependent manner when compared with control cells.
Conclusions
The results obtained in this study further strengthen the anti-inflammatory/antiarthritic effect of boswellic acid, which was already well established by several investigators.
doi:10.1016/S2221-1691(11)60206-2
PMCID: PMC3609259  PMID: 23569882
Boswellic acid; Gouty arthritis; Indomethacin; Lysosomal enzymes; Polymorphonuclear leucocytes; Monosodium urate; Lipid peroxidation; Antioxidant status; Anti-inflammatory effect; Antiarthritic effect; Inflammation
20.  Micropropagation and non-steroidal anti-inflammatory and anti-arthritic agent boswellic acid production in callus cultures of Boswellia serrata Roxb. 
Micropropagation through cotyledonary and leaf node and boswellic acid production in stem callus of a woody medicinal endangered tree species Boswellia serrata Roxb. is reported. The response for shoots, roots and callus formation were varied in cotyledonary and leafy nodal explants from in vitro germinated seeds, if inoculated on Murshige and Skoog’s (MS) medium fortified with cytokinins and auxins alone or together. A maximum of 8.0 ± 0.1 shoots/cotyledonary node explant and 6.9 ± 0.1 shoots/leafy node explants were produced in 91 and 88 % cultures respectively on medium with 2.5 μM 6-benzyladenine (BA) and 200 mg l−1 polyvinylpyrrolidone (PVP). Shoots treated with 2.5 μM IBA showed the highest average root number (4.5) and the highest percentage of rooting (89 %). Well rooted plantlets were acclimatized and 76.5 % of the plantlets showed survival upon transfer to field conditions. Randomly amplified polymorphic DNA (RAPD) analysis of the micropropagated plants compared with mother plant revealed true-to-type nature. The four major boswellic acid components in calluses raised from root, stem, cotyledon and leaf explants were analyzed using HPLC. The total content of four boswellic acid components was higher in stem callus obtained on MS with 15.0 μM IAA, 5.0 μM BA and 200 mg l−1 PVP. The protocol reported can be used for conservation and exploitation of in vitro production of medicinally important non-steroidal anti-inflammatory metabolites of B. serrata.
doi:10.1007/s12298-012-0137-3
PMCID: PMC3550693  PMID: 24381442
Anti-arthritic; Anti-inflammatory; Boswellia serrata; Boswellic acid; Burseraceae; Callus; Indian olibanum; Micropropagation; Salai guggul; Steroids
21.  Oncogenic MicroRNA-27a Is A Target For Anticancer Agent Methyl 2-Cyano-3,11-dioxo-18β-olean-1,12-dien-30-oate in Colon Cancer Cells 
Methyl 2-cyano-3,11-dioxo-18β-olean-1,12-dien-30-oate (CDODA-Me) is a synthetic derivative of glycyrrhetinic acid, a triterpenoid phytochemical found in licorice extracts. CDODA-Me inhibited growth of RKO and SW480 colon cancer cells and this was accompanied by decreased expression of Sp1, Sp3 and Sp4 protein and mRNA and several Sp-dependent genes including survivin, vascular endothelial growth factor (VEGF), and VEGF receptor 1 (VEGFR1 or Flt-1). CDODA-Me also induced apoptosis, arrested RKO and SW480 cells at G2/M, and inhibited tumor growth in athymic nude mice bearing RKO cells as xenografts. CDODA-Me decreased expression of microRNA-27a (miR-27a), and this was accompanied by increased expression of two miR-27a-regulated mRNAs, namely ZBTB10 (an Sp repressor) and Myt-1 which catalyzes phosphorylation of cdc2 to inhibit progression of cells through G2/M. Both CDODA-Me and antisense miR-27a induced comparable responses in RKO and SW480 cells, suggesting that the potent anticarcinogenic activity of CDODA-Me is due to repression of oncogenic miR-27a.
doi:10.1002/ijc.24530
PMCID: PMC2766353  PMID: 19582879
CDODA-Me; anticarcinogenicity; miR-27a; colon cancer; cell cycle
22.  Discovery of cyclooxygenase inhibitors from medicinal plants used to treat inflammation 
Eleven authenticated botanicals used in the traditional Chinese medicine Huo-Luo-Xiao-Ling Dan were screened for ligands to cyclooxygenase (COX) using pulsed ultrafiltration liquid chromatography-mass spectrometry, and a mass spectrometry-based enzyme assay was used to determine the concentration of each of 17 ligands that inhibited COX-1 or COX-2 by 50% (IC50). Acetyl-11-keto-β-boswellic -boswellic acid, acid, acetyl-α-boswellic acid, acetyl-β-boswellic acid, and betulinic acid were COX-1 selective inhibitors with IC50 values of approximately 10 μM. Senkyunolide O and cryptotanshinone were COX-2 selective inhibitors with IC50 values of 5 and 22 μM, respectively. Roburic acid and phenethyl-trans-ferulate inhibited COX-1 and COX-2 equally. COX inhibition and the IC50 values of most of these natural product ligands have not been reported previously.
doi:10.1016/j.phrs.2010.02.007
PMCID: PMC2860736  PMID: 20188172
Cyclooxygenase; COX-2; drug discovery; botanical dietary supplements; senkyunolide O; cryptotanshinone
23.  Antitumor Agents 255. Novel Glycyrrhetinic Acid-Dehydrozingerone Conjugates as Cytotoxic Agents 
Bioorganic & medicinal chemistry  2007;15(18):6193-6199.
Esterification of glycyrrhetinic acid (GA) with dehydrozingerone (DZ) resulted in a novel cytotoxic GA-DZ conjugate. Based on this exciting finding, we conjugated eleven different DZ analogs with GA or other triterpenoids, including oleanoic acid (OA) or ursolic acid (UA). In an in vitro anticancer assay using nine different human tumor cell lines, most of the GA-DZ conjugates showed significant potency. Particularly, compounds 5, 29, and 30 showed significant cytotoxic effects against LN-Cap, 1A9, and KB cells with ED50 values of 0.6, 0.8, and 0.9 μM, respectively. Similar conjugates between DZ and OA or UA were inactive suggesting that the GA component is critical for activity. Notably, although GA-DZ conjugates showed potent cytotoxic activity, the individual components (GA and DZ analogs) were inactive. Thus, GA-DZ conjugates are new chemical entities and represent interesting hits for anticancer drug discovery and development.
doi:10.1016/j.bmc.2007.06.027
PMCID: PMC2034305  PMID: 17591444
Glycyrrhetinic acid; Dehydrozingerone; Conjugation; Cytotoxicity
24.  Glycyrrhetinic acid-modified chitosan nanoparticles enhanced the effect of 5-fluorouracil in murine liver cancer model via regulatory T-cells 
Modified chitosan nanoparticles are a promising platform for drug, such as 5-fluorouracil (5-FU), gene, and vaccine delivery. Here, we used chitosan and hepatoma cell-specific binding molecule glycyrrhetinic acid (GA) to synthesize glycyrrhetinic acid-modified chitosan (GA-CTS). The synthetic product was confirmed by infrared spectroscopy and hydrogen nuclear magnetic resonance. By combining GA-CTS and 5-FU, we obtained a GA-CTS/5-FU nanoparticle, with a particle size of 193.7 nm, drug loading of 1.56%, and a polydispersity index of 0.003. The GA-CTS/5-FU nanoparticle provided a sustained-release system comprising three distinct phases of quick, steady, and slow release. In vitro data indicated that it had a dose- and time-dependent anticancer effect. The effective drug exposure time against hepatic cancer cells was increased in comparison with that observed with 5-FU. In vivo studies on an orthotropic liver cancer mouse model demonstrated that GA-CTS/5-FU significantly inhibited cancer cell proliferation, resulting in increased survival time. The antitumor mechanisms for GA-CTS/5-FU nanoparticle were possibly associated with an increased expression of regulatory T-cells, decreased expression of cytotoxic T-cell and natural killer cells, and reduced levels of interleukin-2 and interferon gamma.
doi:10.2147/DDDT.S52809
PMCID: PMC3810199  PMID: 24187487
hepatic carcinoma; regulatory T cells; glycyrrhetinic acid; targeted therapy; 5-fluorouracil
25.  18beta-Glycyrrhetinic Acid Inhibits Periodontitis Via Glucocorticoid-Independent NF–κB Inactivation In IL-10 Deficient Mice 
Journal of periodontal research  2010;45(6):757-763.
Background and objective
18beta-glycyrrhetinic acid (GA) is a natural anti-inflammatory compound derived from licorice root extract (Glycyrrhiza glabra). The effect of GA on experimental periodontitis and its mechanism of action were determined in the present study.
Methods
Periodontitis was induced by oral infection with Porphyromonas gingivalis W83 in IL-10 deficient mice. The effect of GA, which was delivered by subcutaneous injections in either prophylactic or therapeutic regimens, on alveolar bone loss and gingival gene expressions was determined on day 42 after initial infection. The effect of GA on LPS-stimulated macrophages, T cell proliferation, and osteoclastogenesis was also examined in vitro.
Results
GA administered either prophylactically or therapeutically dramatically reduced infection-induced bone loss in IL-10 deficient mice, which are highly disease-susceptible. Although GA has been reported to exert its anti-inflammatory activity via down-regulation of 11-beta hydroxysteroid dehydrogenase-2 (HSD2), which converts active glucocorticoids (GC) to their inactive forms, GA did not reduce HSD2 gene expression in gingival tissue. Rather, under GC-free conditions, GA potently inhibited LPS-stimulated proinflammatory cytokine production and RANKL-stimulated osteoclastogenesis, both of which are NF–κB-dependent. GA furthermore suppressed LPS- and RANKL-stimulated phosphorylation of NF–κB p105 in vitro.
Conclusion
These findings indicate that GA inhibits periodontitis by inactivation of NF–κB in an IL-10 and GC-independent fashion.
doi:10.1111/j.1600-0765.2010.01296.x
PMCID: PMC3075584  PMID: 20682015
18beta-glycyrrhetinic acid; periodontal disease; NF–κB; IL-10 deficient mouse

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