Acetyl-keto-beta-boswellic acid inhibits cellular proliferation through a p21-dependent pathway in colon cancer cells

Acetyl-11-keto-beta-boswellic acid inhibits cell proliferation and growth of oral squamous cell carcinoma via RAB7B-mediated autophagy

Natural products can overcome the limitations of conventional chemotherapy. Acetyl-11-keto-beta-boswellic acid (AKBA) as a natural product extracted from frankincense, exhibited chemotherapeutic activities in different cancers. However, whether AKBA exerts inhibiting effect of oral squamous cell carcinoma (OSCC) cells growth and the mechanism need to be explored. We attempted to investigate the therapeutic effects of AKBA against OSCC and explore the mechanism involved. Here we attempt to disclose the cell-killing effect of AKBA on OSCC cell lines and try to figure out the specifical pathway. The presence of increase autophagosome and the production of mitochondrial reactive oxygen species were confirmed after the application of AKBA on OSCC cells, and RAB7B inhibition enhanced autophagosome accumulation. Though the increase autophagosome was detected induced by AKBA, autophagic flux was inhibited as the failure fusion of autophagosome and lysosome. Cal27 xenografts were established to verify the role of anti-OSCC cells of AKBA in vivo. Based above findings, we speculate that natural product AKBA suppresses OSCC cells growth via RAB7B-mediated autophagy and may serve as a promising strategy for the therapy of OSCC.

The journey of boswellic acids from synthesis to pharmacological activities

There has been a lot of interest in using naturally occurring substances to treat a wide variety of chronic disorders in recent years. From the gum resin of Boswellia serrata and Boswellia carteri, the pentacyclic triterpene molecules known as boswellic acid (BA) are extracted. We aimed to provide a detailed overview of the origins, chemistry, synthetic derivatives, pharmacokinetic, and biological activity of numerous Boswellia species and their derivatives. The literature searched for reports of B. serrata and isolated BAs having anti-cancer, anti-microbial, anti-inflammatory, anti-arthritic, hypolipidemic, immunomodulatory, anti-diabetic, hepatoprotective, anti-asthmatic, and clastogenic activities. Our results revealed that the cytotoxic and anticancer effects of B. serrata refer to its triterpenoid component, including BAs. Three-O-acetyl-11-keto-BA was the most promising cytotoxic molecule among tested substances. Activation of caspases, upregulation of Bax expression, downregulation of nuclear factor-kappa B (NF-kB), and stimulation of poly (ADP)-ribose polymerase (PARP) cleavage are the primary mechanisms responsible for cytotoxic and antitumor effects. Evidence suggests that BAs have shown promise in combating a wide range of debilitating disease conditions, including cancer, hepatic, inflammatory, and neurological disorders.

Current stage of preclinical and clinical development of guggulsterone in cancers: Challenges and promises

Throughout human history, the utilization of medicinal herbs has been recognized as a crucial defense against various ailments, including cancer. Natural products with potential anticancer properties, capable of inducing apoptosis in cancer cells, have garnered substantial attention. One such agent under investigation is guggulsterone (GS), a phytosterol derived from the gum resin of the Commiphora mukul tree. This review aims to provide a comprehensive summary of recent studies elucidating the anticancer molecular mechanisms and molecular targets of GS, guiding future research and potential applications as an adjuvant drug in cancer therapy. Recent in vivo and in vitro studies have explored the biological activities of the active ingredients in Commiphora mukul. Specifically, GS emerges as a potential cancer chemopreventive and therapeutic agent. The investigations delve into the impact of GS on constitutively activated survival pathways, including Janus kinase/signal transducer and activator of transcription (JAK/STAT), nuclear factor-kappa B (NF-kB), and PI3-kinase/AKT signaling pathways. These pathways regulate antiapoptotic and proinflammatory genes, exerting control over growth and inflammatory responses. The findings highlight the potential of GS in disrupting survival pathways crucial for cancer cell viability. The inhibition of JAK/STAT, NF-kB, and PI3-kinase/AKT signaling pathways positions GS as a promising candidate for cancer therapy. The review synthesizes evidence from diverse studies, underscoring the multifaceted biological activities of GS in cancer prevention and treatment. To advance our understanding, future clinical and translational studies are imperative to determine effective doses in humans. Additionally, there is a need for the development of new pharmaceutical forms of GS to optimize therapeutic effects. This comprehensive review provides a foundation for ongoing research, offering insights into the potential of GS as a valuable addition to the armamentarium against cancer.

AKBA inhibits radiotherapy resistance in lung cancer by inhibiting maspin methylation and regulating the AKT/FOXO1/p21 axis

Acetyl-keto-b-boswellic acid (AKBA) functions in combating human malignant tumors, including lung cancer. However, the function of AKBA in regulating the radioresistance of lung cancer and its underlying mechanism still need to be elucidated. Radiation-resistant lung cancer cells (RA549) were established. Quantitative real-time polymerase chain reaction (QRT-PCR) and Western blot were employed to examine the messenger RNA (mRNA) and protein expressions. After being treated with AKBA and different doses of X-ray, cell proliferation and survival were examined using colony formation assay and cell-counting kit-8 (CCK-8) assay. The cellular localization of Forkhead box 1 (FOXO1) was measured by immunofluorescence (IF). Flow cytometry was employed to analyze cell cycle and apoptosis. In addition, in vivo experiment was performed to determine the effect of AKBA on the sensitivity of tumors to radiation. Herein, we found that AKBA could enhance the radiosensitivity in RA549, suppress cell proliferation, induce cell apoptosis and arrest cell cycle. It was observed that maspin was lowly expressed and hypermethylated in RA549 cells compared to that in A549 cells, while these changes were all eliminated by AKBA treatment. Maspin knockdown could reverse the regulatory effects of AKBA on radioresistance and cellular behaviors of RA549 cells. In addition, we found that AKBA treatment could repress the phosphorylation of Serine/Threonine Kinase (AKT), and FOXO1, increase the translocation of FOXO1 and p21 level in RA549 cells, which was abolished by maspin knockdown. Moreover, results of tumor xenograft displayed that AKBA could enhance the sensitivity of tumor to radiation through the maspin/AKT/FOXO1/p21 axis. We discovered that AKBA enhanced the radiosensitivity of radiation-resistant lung cancer cells by regulating maspin-mediated AKT/FOXO1/p21 axis.

Comparative study of the cytotoxicity, apoptotic, and epigenetic effects of Boswellic acid derivatives on breast cancer

This study aimed to compare the effect of Boswellic acid derivatives on the viability, apoptosis, and epigenomic profiling of breast cancer. According to the viability assays, 3-O-acetyl-11-keto-β-Boswellic acid (AKBA) showed more toxicity against MDA-MB-231 cells when compared with the 3-O-acetyl-β-Boswellic acid (ABA). In contrast, ABA revealed less toxicity against MCF-10A. Cell cycle and apoptosis assays determined the maximum apoptotic effect of AKBA on MCF-7, and MDA-MB-231 cells. Interestingly, β-Boswellic acid (BA) and ABA did not promote the apoptosis in MCF-10A cells. Transwell migration assay indicated the greatest normalized inhibition (around 160%) in the migration of MDA-MB-231 cells induced by AKBA. The expression of P53, BAX, and BCL2 genes in cancerous cell lines has affirmed that both AKBA and ABA could induce the maximal apoptosis. Western-blot investigation demonstrated that the maximum over-expression of P53 protein (1.96 times) was caused by AKBA in MDA-MB-231 cells, followed by ABA in MCF-7 cells. The BCL2 protein expression was in agreement with the previously reported results. The global DNA methylation in both cancerous cells was reduced by ABA. These results suggest that ABA represented more epigenetic modulatory effect while AKBA shows more cytotoxic and apoptotic effect against breast cancer cell lines.

Perspectives on natural compounds in chemoprevention and treatment of cancer: an update with new promising compounds

Cancer is the second deadliest disease worldwide. Although recent advances applying precision treatments with targeted (molecular and immune) agents are promising, the histological and molecular heterogeneity of cancer cells and huge mutational burdens (intrinsic or acquired after therapy) leading to drug resistance and treatment failure are posing continuous challenges. These recent advances do not negate the need for alternative approaches such as chemoprevention, the pharmacological approach to reverse, suppress or prevent the initial phases of carcinogenesis or the progression of premalignant cells to invasive disease by using non-toxic agents. Although data are limited, the success of several clinical trials in preventing cancer in high-risk populations suggests that chemoprevention is a rational, appealing and viable strategy to prevent carcinogenesis. Particularly among higher-risk groups, the use of safe, non-toxic agents is the utmost consideration because these individuals have not yet developed invasive disease. Natural dietary compounds present in fruits, vegetables and spices are especially attractive for chemoprevention and treatment because of their easy availability, high margin of safety, relatively low cost and widespread human consumption. Hundreds of such compounds have been widely investigated for chemoprevention and treatment in the last few decades. Previously, we reviewed the most widely studied natural compounds and their molecular mechanisms, which were highly exploited by the cancer research community. In the time since our initial review, many promising new compounds have been identified. In this review, we critically review these promising new natural compounds, their molecular targets and mechanisms of anticancer activity that may create novel opportunities for further design and conduct of preclinical and clinical studies.

Biosynthetic diversity in triterpene cyclization within the Boswellia genus

This review is not intended to describe the triterpenes isolated from the Boswellia genus, since this information has been covered elsewhere. Instead, the aim is to provide insights into the biosynthesis of triterpenes in Boswellia. This genus, which has 24 species, displays fascinating structural diversity and produces a number of medicinally important triterpenes, particularly boswellic acids. Over 300 volatile components have been reported in the essential oil of Boswellia, and more than 100 diterpenes and triterpenes have been isolated from this genus. Given that no triterpene biosynthetic enzymes have yet been isolated from any members of the Boswellia genus, this review will cover the likely biosynthetic pathways as inferred from structures in nature and the probable types of biosynthetic enzymes based on knowledge of triterpene biosynthesis in other plant species. It highlights the importance of frankincense and the factors and threats affecting its production. It covers triterpene biosynthesis in the genus Boswellia, including dammaranes, tirucallic acids, lupanes, oleananes, ursanes and boswellic acids. Strategies for elucidating triterpene biosynthetic pathways in Boswellia are considered. Furthermore, the possible mechanisms behind wound-induced resin synthesis by the tree and related gene expression profiling are covered. In addition, the influence of the environment and the genotype on the biosynthesis of resin and on variations in the compositions and types of resins will also be reviewed.

Boswellic acids and their derivatives as potent regulators of glucocorticoid receptor actions

Glucocorticoid (GCs) hormones exert their actions via their cognate steroid receptors the Glucocorticoid Receptors (GR), by genomic or non-genomic mechanisms of actions. GCs regulate many cellular functions among them growth, metabolism, immune response and apoptosis. Due to their cell type specific induction of apoptosis GCs are used for the treatment of certain type of cancer. In addition, due to their anti-inflammatory actions, GCs are among the most highly prescribed drug to treat chronic inflammatory disorders, albeit to the many adverse side effects arising by their long term and high doses use. Thus, there is a high need for selective glucocorticoid receptor agonist - modulators (SEGRA- SGRMs) as effective as classic GCs, but with a reduced side effect profile. Boswellic acids (BAs) are triterpenes that show structural similarities with GCs and exhibit anti-inflammatory and anti-cancer activities. In this study we examined whether BA alpha and beta and certain BAs derivatives exert their actions, at least in part, through the regulation of GR activities. Applying docking analysis we found that BAs can bind stably into the deacylcortivazol (DAC) accommodation pocket of GR. Moreover we showed that certain boswellic acids derivatives induce glucocorticoid receptor nuclear translocation, no activation of GRE dependent luciferase gene expression, and suppression of the TNF-α induced NF-κB transcriptional activation in GR positive HeLa and HEK293 cells, but not in low GR level COS-7 cells. Furthermore, certain boswellic acids compounds exert antagonistic effect on the DEX-induced GR transcriptional activation and induce cell type specific mitochondrial dependent apoptosis. Our results indicate that certain BAs are potent selective glucocorticoid receptor regulators and could have great potential for therapeutic use.

Plant-Derived Natural Products in Cancer Research: Extraction, Mechanism of Action, and Drug Formulation

Cancer is one of the main causes of death globally and considered as a major challenge for the public health system. The high toxicity and the lack of selectivity of conventional anticancer therapies make the search for alternative treatments a priority. In this review, we describe the main plant-derived natural products used as anticancer agents. Natural sources, extraction methods, anticancer mechanisms, clinical studies, and pharmaceutical formulation are discussed in this review. Studies covered by this review should provide a solid foundation for researchers and physicians to enhance basic and clinical research on developing alternative anticancer therapies.

Antiproliferative effects of boswellic acid-loaded chitosan nanoparticles on human lung cancer cell line A549

Aim: In the present study boswellic acids-loaded chitosan nanoparticles were synthesized using ionic gelation technique. The influence of independent variables were studied and optimized on dependent variables using central composite design. Methodology & results: The designed nanoparticles were observed spherical in shape with an average size of 67.5-187.2 nm and have also shown an excellent entrapment efficiency (80.06 ± 0.48). The cytotoxicity assay revealed enhanced cytotoxicity for drug-loaded nanoparticles in contrast to the free drug having an IC₅₀ value of 17.29 and 29.59 μM, respectively. Flow cytometry confirmed that treatment of cells with 40 μg/ml had arrested 22.75 ± 0.3% at SubG₀ phase of the cell cycle when compared with untreated A459 cells. The observed results justified the boswellic acids-loaded chitosan nanoparticles were effective due to greater cellular uptake, sustained intercellular drug retention and enhanced antiproliferative effect by inducing apoptosis.

Acetyl-11-keto-β-boswellic acid inhibits proliferation and induces apoptosis of gastric cancer cells through the phosphatase and tensin homolog /Akt/ cyclooxygenase-2 signaling pathway

BACKGROUND

Gastric cancer is one of the most common malignant tumors of the digestive system worldwide, posing a serious danger to human health. Cyclooxygenase (COX)-2 plays an important role in the carcinogenesis and progression of gastric cancer. Acetyl-11-keto-β-boswellic acid (AKBA) is a promising drug for cancer therapy, but its effects and mechanism of action on human gastric cancer remain unclear.

AIM

To evaluate whether the phosphatase and tensin homolog (PTEN)/Akt/COX-2 signaling pathway is involved in the anti-tumor effect of AKBA in gastric cancer.

METHODS

Human poorly differentiated BGC823 and moderately differentiated SGC7901 gastric cancer cells were routinely cultured in Roswell Park Memorial Institute 1640 medium supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin. Gastric cancer cell proliferation was determined by methyl thiazolyl tetrazolium colorimetric assay. Apoptosis was measured by flow cytometry. Cell migration was assessed using the wound-healing assay. Expression of Bcl-2, Bax, proliferating cell nuclear antigen, PTEN, p-Akt, and COX-2 were detected by Western blot analysis. A xenograft nude mouse model of human gastric cancer was established to evaluate the anti-cancer effect of AKBA in vivo.

RESULTS

AKBA significantly inhibited the proliferation of gastric cancer cells in a dose- and time-dependent manner, inhibited migration in a time-dependent manner, and induced apoptosis in a dose-dependent manner in vitro; it also inhibited tumor growth in vivo. AKBA up-regulated the expression of PTEN and Bax, and down-regulated the expression of proliferating cell nuclear antigen, Bcl-2, p-Akt, and COX-2 in a dose-dependent manner. The PTEN inhibitor bpv (Hopic) reversed the high expression of PTEN and low expression of p-Akt and COX-2 that were induced by AKBA. The Akt inhibitor MK2206 combined with AKBA down- regulated the expression of p-Akt and COX-2, and the combined effect was better than that of AKBA alone.

CONCLUSION

AKBA inhibits the proliferation and migration and promotes the apoptosis of gastric cancer cells through the PTEN/Akt/COX-2 signaling pathway.

A Validated LC-MS/MS Method for Simultaneous Determination of 3-O-Acetyl-11-Keto-β-Boswellic Acid (AKBA) and its Active Metabolite Acetyl-11-Hydroxy-β-Boswellic Acid (Ac-11-OH-BA) in Rat Plasma: Application to a Pharmacokinetic Study

The aim of this study was to develop and validate a new, rapid, sensitive, selective and reliable liquid chromatography-tandem mass spectrometry method for simultaneous determination of 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) and its active metabolite 3-O-Acetyl-11-hydroxy-β-boswellic acid (Ac-11-hydroxy-BA) in rat plasma. Both analytes (AKBA and Ac-11-hydroxy-BA) and the internal standard (IS, ursolic acid) were extracted from 100 μL of rat plasma by protein precipitation. Chromatographic separation was achieved on PRP-H1 RP-C18 column (75 mm × 2 mm, 1.6 μm) using acetonitrile-water (95.5 v/v) as the mobile phase. Mass detection was conducted by electrospray ionization in positive ion multiple reaction monitoring (MRM) mode. A linear dynamic range of 1-1,000 ng/mL for both AKBA and Ac-11-hydroxy-BA was established with mean correlation coefficient (r (1)) of 0.999. Intra- and inter-day precision (% CV) of analysis were found in the range of 1.9-7.4%. The accuracy determined for these analytes ranged from 92.4 to 107.2%. The extraction recoveries for both analytes ranged from 92.6 to 97.3% for spiked plasma samples and were consistent. The % change in stability samples compared to nominal concentration ranged from 0.4 to 4.2%. This method was successfully tested to a pharmacokinetic (PK) study for estimation of AKBA and acetyl-11-hydroxy-BA in rat plasma following oral administration of AKBA. This method has been validated with the advantage of shorter run time that can be used for high-throughput analysis and has been successfully applied to the pharmacokinetic study of AKBA in rats.

UV-responsive AKBA@ZnO nanoparticles potential for polymorphous light eruption protection and therapy

Polymorphous light eruption (PLE) is one of the acquired idiopathic photodermatosis mainly induced by immoderate UV radiation. In order to realize UV protection and medicine administration simultaneously for polymorphous light eruption protection and therapy, Acetyl-11-keto-β-boswellic acid (AKBA) loaded Zinc Oxide (ZnO) nanoparticles of which drug release behavior is UV-controlled has been successfully synthesized. Such nanoparticles can not only reflect UV but also transfer the energy to release AKBA which presents an excellent antioxidant and anti-inflammatory effects. In addition, they are biocompatible to HaCaT cells. As a result, they have a great potential in combining UV protection and medicine administration simultaneously for PLE protection and therapy.

An Update on Pharmacological Potential of Boswellic Acids against Chronic Diseases

Natural compounds, in recent years, have attracted significant attention for their use in the prevention and treatment of diverse chronic diseases as they are devoid of major toxicities. Boswellic acid (BA), a series of pentacyclic triterpene molecules, is isolated from the gum resin of Boswellia serrata and Boswellia carteri. It proved to be one such agent that has exhibited efficacy against various chronic diseases like arthritis, diabetes, asthma, cancer, inflammatory bowel disease, Parkinson’s disease, Alzheimer’s, etc. The molecular targets attributed to its wide range of biological activities include transcription factors, kinases, enzymes, receptors, growth factors, etc. The present review is an attempt to demonstrate the diverse pharmacological uses of BA, along with its underlying molecular mechanism of action against different ailments. Further, this review also discusses the roadblocks associated with the pharmacokinetics and bioavailability of this promising compound and strategies to overcome those limitations for developing it as an effective drug for the clinical management of chronic diseases.

Acetyl-11-keto-β-boswellic acid modulates membrane dynamics in benzo(a)pyrene-induced lung carcinogenesis

Membrane fluidity is the most important physiochemical property of cell membranes and governs its functional attributes. The current investigations were undertaken to understand the potential role of acetyl-11-keto-β-boswellic acid (AKBA), if any, on regulation of membrane dynamics under conditions of benzo(a)pyrene (BaP)-induced lung carcinogenesis in female rats. The animals were divided into five groups which included (I) Normal control, (II) Vehicle treated (olive oil), (III) BaP treated, (IV) AKBA treated and (V) BaP + AKBA treated. BaP was administered at a dose level of 50 mg/kg b.wt. in olive oil orally twice a week for 4 weeks. AKBA was given at a dose level of 50 mg/kg b.wt. in olive oil orally thrice a week for 24 weeks. In addition, AKBA was also administered at a similar dose to BaP-treated animals 4 weeks prior to BaP administration and continued for another 20 weeks. The lipid profile and membrane dynamics were analysed in lung tissue. Total lipids, phospholipids content, membrane fluidity, polarization and order of membrane were significantly (p ≤ 0.001) increased in BaP-exposed animals. However, significant decrease was observed in glycolipids, cholesterol, microviscosity and anisotropy levels compared with normal control animals. Appreciable improvements in above indices were recorded when AKBA was administered to BaP-treated animals. Moreover, the structural variations observed in Fourier-transform infrared spectroscopy spectrum were also normalized in BaP-treated rats with AKBA supplementation. This suggests that the AKBA has a potential role in improving membrane fluidity and associated lipid content in BaP-induced lung carcinogenesis.

Simultaneous HPTLC Densitometric Estimation of KBA and AKBA from Boswellia serrata

Background:

Boswellic acids (BAs) are extracted from oleo gum of Boswellia serrata and are utilized as potential anti-inflammatory, hypolipidemic, immunomodulatory and antitumor specialists. The present examination was meant to assess KBA and AKBA in Boswellia serrata separate by High-Performance Thin Layer Chromatography (HPTLC).

Methods:

The separation of bioactive compounds was performed utilizing mobile phase glacial acetic acid, n-hexane, ethyl acetate and toluene (0.3: 1: 8: 2) (v/v/v/v) and distinguished at wavelength 254 nm. The technique was approved for linearity, precision, accuracy, limit of detection (LOD), limit of quantification (LOQ), and so forth by International Conference on Harmonization guidelines.

Results:

The calibration range was observed to be 2- 14 μg/band for both the bioactive compounds. KBA was isolated with an Rf estimation of 0.39 ± 0.02 and AKBA with an Rf estimation of 0.42 ± 0.02. The accuracy was seen to be as high as 99.17% and 97.42 for KBA and KBA, respectively. The percentage RSD value for intra-day and between day varieties was under 2%. The system indicated high affectability and specificity.

Conclusion:

The developed HPTLC method was simple, precise, robust, specific, rapid, and costeffective and could be used for quality control analysis and quantification of KBA and AKBA in different herbal formulations containing the plant species.

Design, synthesis and biological evaluation of ring A modified 11-keto-boswellic acid derivatives as Pin1 inhibitors with remarkable anti-prostate cancer activity

Pin1 (Protein interaction with never in mitosis A1) is a validated molecular target for anticancer drug discovery. Herein, we reported the design, synthesis, and structure-activity relationship study of novel ring A modified AKBA (3-acetyl-11-keto-boswellic acid) derivatives as Pin1 inhibitors. Most compounds showed superior Pin1 inhibitory activities to AKBA. One of the most promising compounds, 10a, potently inhibited Pin1 with IC₅₀ value of 0.46 μM, while it displayed excellent anti-proliferative effect against prostate cancer cells PC-3 with GI₅₀ value of 1.82 μM. Structure-activity relationship indicated that reasonable structural modifications in ring A had significant impact on improving activity. Further mechanism research revealed that 10a decreased the level of Cyclin D1 and caused cell cycle arrest at G0/G1 phase in PC-3 cancer cells. Thus, compound 10a may serve as potential anti-prostate cancer agent for further investigation through Pin1 inhibition.

Metabolomics approach for predicting response to neoadjuvant chemotherapy for colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is a clinically heterogeneous disease, which necessitates a variety of treatments and leads to different outcomes. Only some CRC patients will benefit from neoadjuvant chemotherapy (NACT).

OBJECTIVES

An accurate prediction of response to NACT in CRC patients would greatly facilitate optimal personalized management, which could improve their long-term survival and clinical outcomes.

METHODS

In this study, plasma metabolite profiling was performed to identify potential biomarker candidates that can predict response to NACT for CRC. Metabolic profiles of plasma from non-response (n = 30) and response (n = 27) patients to NACT were studied using UHPLC-quadruple time-of-flight)/mass spectrometry analyses and statistical analysis methods.

RESULTS

The concentrations of nine metabolites were significantly different when comparing response to NACT. The area under the receiver operating characteristic curve value of the potential biomarkers was up to 0.83 discriminating the non-response and response group to NACT, superior to the clinical parameters (carcinoembryonic antigen and carbohydrate antigen 199).

CONCLUSION

These results show promise for larger studies that could result in more personalized treatment protocols for CRC patients.

Googling the Guggul (Commiphora and Boswellia) for Prevention of Chronic Diseases

Extensive research during last 2 decades has revealed that most drugs discovered today, although costs billions of dollars for discovery, and yet they are highly ineffective in their clinical response. For instance, the European Medicines Agency has approved 68 anti-cancer drugs, and out of which 39 has reached the market level with no indication of increased survival nor betterment of quality of life. Even when drugs did improve survival rate compared to available treatment strategies, most of these were found to be clinically insignificant. This is a fundamental problem with modern drug discovery which is based on thinking that most chronic diseases are caused by alteration of a single gene and thus most therapies are single gene-targeted therapies. However, extensive research has revealed that most chronic diseases are caused by multiple gene products. Although most drugs designed by man are mono-targeted therapies, however, those designed by "mother nature" and have been used for thousands of years, are "multi-targeted" therapies. In this review, we examine two agents that have been around for thousands of years, namely "guggul" from Commiphora and Boswellia. Although we are all familiar with the search engine "google," this is another type of "guggul" that has been used for centuries and being explored for its various biological activities. The current review summarizes the traditional uses, chemistry, in vitro and in vivo biological activities, molecular targets, and clinical trials performed with these agents.

3-O-acetyl-11-keto-β-boswellic acid exerts anti-tumor effects in glioblastoma by arresting cell cycle at G2/M phase

Background

Glioblastoma (GBM) is the most common, malignant, and lethal primary brain tumor in adults accounting for about 50% of all gliomas. Up to now, the chemotherapy approaches for GBM were limited. 3-O-acetyl-11-keto-β-boswellic acid (AKBA), the major active ingredient of the gum resin from Boswellia serrata and Boswellia carteri Birdw., was reported to inhibit the growth of many types of cancer cells; however, the underlying mechanism of its anticancer effects are still unclear.

Methods

The effects of AKBA on cell viability and its cytotoxicity were determined using CCK8 and LDH kits respectively. The EdU-DNA synthesis assay was used to evaluate inhibition of cell proliferation by AKBA. The role of AKBA in glioblastoma cell functions such as migration/invasion, and colony formation was evaluated using transwell chambers and soft agar, respectively. Flow cytometry and western blotting were used to detect AKBA-induced apoptosis. Potential mechanisms of AKBA action were explored by RNA sequencing and the identified hub genes were validated by real-time quantitative PCR and western blotting. Finally, the in vivo anti-tumor activity of AKBA was evaluated against a human glioblastoma cell line, U87-MG, in a xenograft mouse model.

Results

AKBA inhibited cell proliferation, caused the release of LDH, decreased DNA synthesis, and inhibited the migration, invasion, and colony formation of U251 and U87-MG human glioblastoma cell lines. AKBA increased apoptosis as well as the activity of caspase 3/7 and the protein expression of cleaved-caspase 3 and cleaved PARP, while decreasing mitochondrial membrane potential. RNA-sequencing analyses showed that AKBA suppressed the expression of pRB, FOXM1, Aurora A, PLK1, CDC25C, p-CDK1, cyclinB1, Aurora B, and TOP2A while increasing the expression of p21 and GADD45A. These findings were validated by qRT-PCR and western blotting. The data are consistent with a mechanism in which AKBA arrested the cell cycle in glioblastoma cells at the G2/M phase by regulating the p21/FOXM1/cyclin B1 pathway, inhibited mitosis by downregulating the Aurora B/TOP2A pathway, and induced mitochondrial-dependent apoptosis. Oral administration of AKBA (100 mg/kg) significantly suppressed the tumorigenicity of U87-MG cells in a xenograft mouse model.

Conclusions

Taken together, these results suggest that AKBA (molecular weight, 512.7 Da) might be a promising chemotherapy drug in the treatment of GBM.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0805-4) contains supplementary material, which is available to authorized users.

Transcriptomic Profiling of MDA-MB-231 Cells Exposed to Boswellia Serrata and 3-O-Acetyl-B-Boswellic Acid; ER/UPR Mediated Programmed Cell Death

BACKGROUND/AIM

Triple-negative breast cancer (TNBC) is characterized by the absence of hormone receptors (estrogen, progesterone and human epidermal growth factor receptor-2) and a relatively poor prognosis due to inefficacy of hormone receptor-based chemotherapies. It is imperative that we continue to explore natural products with potential to impede growth and metastasis of TNBC. In this study, we screened over 1,000 natural products for capacity to induce cell death in TNBC (MDA-MB -231) cells.

MATERIALS AND METHODS

Frankincense (Boswellia serrata extract (BSE)) and 3-O-Acetyl-β-boswellic acid (3-OAβBA) were relatively potent, findings that corroborate the body of existing literature. The effects of BSE and 3-OAβBA on genetic parameters in MDA-MB-231 cells were evaluated by examining whole-transcriptomic influence on mRNAs, long intergenic non-coding RNA transcripts (lincRNA) and non-coding miRNAs.

RESULTS

Bio-statistical analysis demarcates the primary effect of both BSE/3-OAβBA on the up-regulation of PERK (protein kinase RNA-like endoplasmic reticulum kinase)- endoplasmic reticulum (ER)/unfolded protein response (UPR) pathways that are closely tied to activated programmed cell death (APCD). Global profiling confirms concomitant effects of BSE/3-OAβBA on upwardly expressed ER/URP APCD key components PERK (EIF2AK3), XBP1, C/EBP homologous protein transcription factor (CHOP), ATF3 and DDIT3,4/DNA-damage-inducible transcript 3,4 (GADD34). Further, BSE and/or 3-OAβBA significantly down-regulated oncogenes (OG) which, heretofore, lack functional pathway mapping, but are capable of driving epithelial-mesenchymal transition (EMT), cell survival, proliferation, metastasis and drug resistance. Among these are cell migration-inducing protein hyaluronan binding (CEMIP) [-7.22]; transglutaminase 2 [-4.96], SRY box 9 (SOX9) [-4.09], inhibitor of DNA binding 1, dominant negative helix-loop-helix protein (ID1) [-6.56]; and endothelin 1 (EDN1, [-5.06]). Likewise, in the opposite manner, BSE and/or 3-OAβBA induced the robust overexpression of tumor suppressor genes (TSGs), including: glutathione-depleting ChaC glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1) [+21.67]; the mTOR inhibitors - sestrin 2 (SESN2) [+16.4] Tribbles homolog 3 (TRIB3) [+6.2], homocysteine-inducible, endoplasmic reticulum stress-inducible, ubiquitin-like domain member 1 (HERPUD1) [+12.01]; and cystathionine gamma-lyase (CTH) [+11.12].

CONCLUSION

The anti-cancer effects of the historically used frankincense sap (BSE) appear to involve major impact on the ER/UPR response, concomitant to effecting multiple targets counter to the growth, proliferation and metastasis of TNBC cancer cells. The microarray data are available at Expression Omnibus GEO Series accession number GSE102891.

Anti-Inflammatory Activity of Boswellia serrata Extracts: An In Vitro Study on Porcine Aortic Endothelial Cells

This study is aimed at investigating the cytotoxicity, anti-inflammatory, and angiogenic activities of two Boswellia serrata extracts on primary culture of porcine aortic endothelial cells (pAECs). Chemical characterization of a dry extract (extract A) and a hydroenzymatic extract (extract G) of B. serrata was performed by HPLC using pure boswellic acids (BAs) as standard. In cultured pAECs, extract G improved cell viability, following LPS challenge, in a dose-dependent manner and did not show any toxic effect. On the other hand, extract A was toxic at higher doses and restored pAEC viability after LPS challenge only at lower doses. Pure BAs, used at the same concentrations as those determined in the phytoextracts, did not contrast LPS-induced cytotoxicity. Extract A showed proangiogenic properties at the lowest dose, and the same result was observed using pure AKBA at the corresponding concentration, whereas extract G did not show any effect on the migration capacity of endothelial cells. In conclusion, an anti-inflammatory activity of B. serrata extracts on endothelial cells was reported, though cytotoxicity or proliferative stimulation can occur instead of a protective effect, depending on the dose and the formulation.

Characterization of New Bioactive Enzyme Inhibitors from Endophytic Bacillus amyloliquefaciens RWL-1

Endophytic bacteria are known to produce a wide array of bioactive secondary metabolites with beneficial effects on human health. In the current study, a novel endophytic bacterial strain, Bacillus amyloliquefaciens RWL-1, was isolated from the seeds of Oryza sativa. Initially, the crude extract of RWL-1 was assessed for potential biological effects of enzyme inhibition and cytotoxicity and was found to exhibit a broad spectrum inhibition for α-glucosidase (37 ± 0.09%) and urease (49.4 ± 0.53%). The screening results were followed by bioassay-guided isolation of secondary metabolite(s) from RWL-1. Extensive chromatographic and spectrophotometry analyses revealed the presence of compound 1 (S)-2-hydroxy-N-((S)-1-((S)-8-hydroxy-1-oxoisochroman-3-yl)-3-methylbutyl)-2-((S)-5-oxo-2,5-dihydrofuran-2-yl)acetamide. Further bioassays of compound 1 showed significant inhibition of α-glucosidase (52.98 ± 0.8%) and urease (51.27 ± 1.0%), compared with positive control values of 79.14 ± 1.9% and 88.24 ± 2.2%, and negative controls (0.08 ± 0.1% and 0.05 ± 0.01%), respectively. The current study suggests that bacterial endophytes are a rich source of novel bioactive compounds with high therapeutic value.

Relation of the IGF/IGF1R system to autophagy in colitis and colorectal cancer

Metabolic syndrome (MetS), as a chronic inflammatory disorder has a potential role in the development of inflammatory and cancerous complications of the colonic tissue. The interaction of DNA damage and inflammation is affected by the insulin-like growth factor 1 receptor (IGF1R) signaling pathway. The IGF1R pathway has been reported to regulate autophagy, as well, but sometimes through a bidirectional context. Targeting the IGF1R-autophagy crosstalk could represent a promising strategy for the development of new antiinflammatory and anticancer therapies, and may help for subjects suffering from MetS who are at increased risk of colorectal cancer. However, therapeutic responses to targeted therapies are often shortlived, since a signaling crosstalk of IGF1R with other receptor tyrosine kinases or autophagy exists, leading to acquired cellular resistance to therapy. From a pharmacological point of view, it is attractive to speculate that synergistic benefits could be achieved by inhibition of one of the key effectors of the IGF1R pathway, in parallel with the pharmacological stimulation of the autophagy machinery, but cautiousness is also required, because pharmacologic IGF1R modulation can initiate additional, sometimes unfavorable biologic effects.

Boswellia serrata resin extract alleviates azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon tumorigenesis

SCOPE

Boswellia serrata (BS) resin is a popular dietary supplement for joint nourishment. In this study, we investigated the chemopreventive effects of dietary BS extract and its impact of gut microbiota on azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colitis-associated colon cancer in mice.

METHODS AND RESULTS

Male ICR mice were injected with AOM and 2% DSS via drinking water. The mice were fed with 0.25 or 0.5% BS extract, and colonic tissue were collected at 15 weeks. The main effective components of BS supercritical CO₂ extraction were analyzed by LC-MS/MS are boswellic acids. We found that treatment with BS extract significantly reduce the colonic tumor formation. Western blot and histological analysis revealed that dietary BS extract could markedly reduce the inflammation associated protein levels expression. Furthermore, BS extract reduced cell proliferation via inhibiting phosphorylation level of protein kinase B (Akt), glycogen synthase kinase 3β (GSK3β), and downregulation of cyclin D1. In addition, BS extract also altered the composition of gut microbiota by enhancing the proportion of Clostridiales and reducing the percentage of Bacteroidales.

CONCLUSION

In summary, BS extract decreased the protein levels of inflammative enzymes such as inducible nitric oxide synthase and cyclooxygenase-2 in colonic mucosa. It also mediated Akt/GSK3β/cyclin D1 signaling pathway and altered the composition of gut microbiota to alleviate tumor growth. Taken together, this study suggests that BS extract has great potential to suppress colon tumorigenesis.

Anti-inflammatory and neuroprotective activity of boswellic acids in rotenone parkinsonian rats

There is evidence that inflammation and oxidative stress contribute to the neurodegenerative changes observed in Parkinson's disease. Unfortunately, there is a lack of curative treatment for this debilitating movement disorder. Boswellic acids (BAs) are pentacyclic triterpene molecules of plant origin that have been utilized for treating many inflammatory conditions. The current study was conducted to explore the protective role of BAs against rotenone-induced experimental parkinsonism. Twenty-four rats were assigned to one of four treatment groups. The first two groups were a vehicle group (no rotenone) and a rotenone control group in which rats received rotenone (1 mg/kg) every 48 h. The next 2 groups received rotenone (1 mg/kg every 48 h) plus protective oral doses of BAs (125 or 250 mg/kg daily). Rats in the rotenone group showed motor dysfunction when tested in the open-field arena and cylinder and rotarod tests. Moreover, inflammatory markers increased, whereas the dopamine level was lower in the striata of rats in the rotenone group versus those in the vehicle group. BAs taken by rats with rotenone-induced parkinsonism showed enhanced general motor performance, reduced inflammatory markers, and increased striatal dopamine level and nigral tyrosine hydroxylase immunostaining. In conclusion, BAs are promising agents in slowing the progression of Parkinson's disease if appropriate data become available about their safety and efficacy in humans.

Nrf2- and Bach1 May Play a Role in the Modulation of Ultraviolet A-Induced Oxidative Stress by Acetyl-11-Keto-β-Boswellic Acid in Skin Keratinocytes

BACKGROUND

Exposure of human skin to solar ultraviolet A (UVA) irradiation causes severe oxidative stress with damage to various cellular components and concomitant inflammation and carcinogenesis.

OBJECTIVE

The aim of this study is to investigate the protective effect of acetyl-11-keto-β-boswellic acid (AKBA) against UVA radiation on human skin keratinocytes.

METHODS

HaCaT cells were pretreated with AKBA followed by UVA irradiation. Radiation effects on cell morphology, cell viability, intracellular reactive oxygen species (ROS) levels, and antioxidant enzymes were examined.

RESULTS

AKBA reduces UVA irradiation-induced cell viability loss, accompanied by a decreased production of UVA-induced ROS, decreased malondialdehyde, and increased superoxide dismutase expression. In addition, AKBA increased basal and UVA-induced levels of Nrf2 (NF-E2-related factor 2), the redox-sensitive factor, and its target genes NQO1 and heme oxygenase-1 (HO-1), whereas expression of the transcriptional repressor Bach1 (BTB and CNC homology 1) was reduced. Furthermore, the cytoprotective effects of AKBA against UVA-derived oxidative damage were accompanied by modulating expression of inflammatory mediators (i.e., cyclooxygenase-2 and nuclear factor-κB) and NOX1.

CONCLUSIONS

AKBA protects skin cells from UVA-induced damage by modulating inflammatory mediators and/or ROS production. Therefore, AKBA has potential in the development of skin care products.

Design and synthesis of novel 2-substituted 11-keto-boswellic acid heterocyclic derivatives as anti-prostate cancer agents with Pin1 inhibition ability

A series of novel acetyl-11-keto-β-boswellic acid (AKBA) derivatives with a different electron-withdrawing group on ring A and a nitrogen heterocycle at C-24 were designed and synthesized. These semi-synthetic compounds showed improved anti-proliferative activity against prostate cancer cells over AKBA. Compound 8f bearing 2-cyano-3,11-dioxo moiety and piperazine was the most potent to inhibit growth of prostate cancer PC-3 (IC₅₀ = 0.04 μM) and LNCaP (IC₅₀ = 0.27 μM) cell lines. 8f caused cell cycle arrest in G2/M and induced apoptosis. 8f decreased the protein levels of anti-apoptosis protein Mcl-1, c-FLIP and cell cycle regulating protein cyclin D1. 8f inhibited the activity of Pin1, a peptidyl-prolyl cis-trans isomerase to stabilize cyclin D1. 8f represented a compound with improved anti-proliferative effects for prostate cancer therapy working through new mechanisms.

Pharmacological evidences for cytotoxic and antitumor properties of Boswellic acids from Boswellia serrata

ETHNOPHARMACOLOGICAL RELEVANCE

Increasing research on traditional herbal medicines and their phytoconstituents has recognized their usefulness in complementary as adjuvant to chemotherapy in various types of cancers. The oleo-gum resin of Boswellia serrata tree is one such folk medicine, which has been traditionally used for religious, cosmetic as well as medical purposes since ages. The oleo-gum resin of the plant has been used in traditional medicine to treat variety of conditions including inflammatory diseases like arthritis, asthma, chronic pain, bowel conditions and many other diseases. This review presents an overview of scientific studies on cytotoxic and antitumor properties of B. serrata and its constituents.

MATERIALS AND METHODS

Literature search was carried out for activities of B. serrata and various isolated boswellic acids such as β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid reported in various cancer types in vitro as well as in vivo.

RESULTS

The triterpenoidal fraction of B. serrata (containing boswellic acids) is responsible for the cytotoxic and antitumor properties. Among the screened compounds, 3-O-acetyl-11-keto-β-boswellic acid has been found to be most promising cytotoxic molecule. The cytotoxic and antitumor effects are mainly due to induction of apoptosis through caspase activation, increased Bax expression, NF-κB down regulation and induction of poly (ADP)-ribose polymerase (PARP) cleavage.

CONCLUSIONS

Boswellic acids appear to be promising candidates for anticancer drug development in future. However, further in vivo studies are needed. Studies in combination with clinically used anticancer drugs and QSAR studies on individual boswellic acid also need to be carried out.

Phytochemical Analysis and Anti-cancer Investigation of Boswellia serrata Bioactive Constituents In Vitro

Cancer is a major health obstacle around the world, with hepatocellular carcinoma (HCC) and colorectal cancer (CRC) as major causes of morbidity and mortality. Nowadays, there isgrowing interest in the therapeutic use of natural products for HCC and CRC, owing to the anticancer activity of their bioactive constituents. Boswellia serrata oleo gum resin has long been used in Ayurvedic and traditional Chinese medicine to alleviate a variety of health problems such as inflammatory and arthritic diseases. The current study aimed to identify and explore the in vitro anticancer effect of B. Serrata bioactive constituents on HepG2 and HCT 116 cell lines. Phytochemical analysis of volatile oils of B. Serrata oleo gum resin was carried out using gas chromatography- mass spectrometry (GC/MS). Oleo-gum-resin of B. Serrata was then successively extracted with petroleum ether (extract 1) and methanol (extract 2). Gas-liquid chromatography (GLC) analysis of the lipoidal matter was also performed. In addition, a methanol extract of B. Serrata oleo gum resin was phytochemically studied using column chromatography (CC) and thin layer chromatography (TLC) to obtain four fractions (I, II, III and IV). Sephadex columns were used to isolate β-boswellic acid and identification of the pure compound was done using UV, mass spectra, 1H NMR and 13C NMR analysis. Total extracts, fractions and volatile oils of B. Serrata oleo-gum resin were subsequently applied to HCC cells (HepG2 cell line) and CRC cells (HCT 116 cell line) to assess their cytotoxic effects. GLC analysis of the lipoidal matter resulted in identification of tricosane (75.32%) as a major compound with the presence of cholesterol, stigmasterol and β-sitosterol. Twenty two fatty acids were identified of which saturated fatty acids represented 25.6% and unsaturated fatty acids 74.4% of the total saponifiable fraction. GC/MS analysis of three chromatographic fractions (I,II and III) of B. Serrata oleo gum resin revealed the presence of pent-2-ene-1,4-dione, 2-methyl- levulinic acid methyl ester, 3,5- dimethyl- 1- hexane, methyl-1-methylpentadecanoate, 1,1- dimethoxy cyclohexane, 1-methoxy-4-(1-propenyl)benzene and 17a-hydroxy-17a-cyano, preg-4-en-3-one. GC/MS analysis of volatile oils of B. Serrata oleo gum resin revealed the presence of sabinene (19.11%), terpinen-4-ol (14.64%) and terpinyl acetate (13.01%) as major constituents. The anti-cancer effect of two extracts (1 and 2) and four fractions (I, II, III and IV) as well as volatile oils of B. Serrata oleo gum resin on HepG2 and HCT 116 cell lines was investigated using SRB assay. Regarding HepG2 cell line, extracts 1 and 2 elicited the most pronounced cytotoxic activity with IC50 values equal 1.58 and 5.82 μg/mL at 48 h, respectively which were comparable to doxorubicin with an IC50 equal 4.68 μg/mL at 48 h. With respect to HCT 116 cells, extracts 1 and 2 exhibited the most obvious cytotoxic effect; with IC50 values equal 0.12 and 6.59 μg/mL at 48 h, respectively which were comparable to 5-fluorouracil with an IC50 equal 3.43 μg/ mL at 48 h. In conclusion, total extracts, fractions and volatile oils of B. Serrata oleo gum resin proved their usefulness as cytotoxic mediators against HepG2 and HCT 116 cell lines with different potentiality (extracts > fractions > volatile oil). In the two studied cell lines the cytotoxic acivity of each of extract 1 and 2 was comparable to doxorubicin and 5-fluorouracil, respectively. Extensive in vivo research is warranted to explore the precise molecular mechanisms of these bioactive natural products in cytotoxicity against HCC and CRC cells.

Nutraceuticals as potential therapeutic agents for colon cancer: a review

Colon cancer is a world-wide health problem and the second-most dangerous type of cancer, affecting both men and women. The modern diet and lifestyles, with high meat consumption and excessive alcohol use, along with limited physical activity has led to an increasing mortality rate for colon cancer worldwide. As a result, there is a need to develop novel and environmentally benign drug therapies for colon cancer. Currently, nutraceuticals play an increasingly important role in the treatment of various chronic diseases such as colon cancer, diabetes and Alzheimer׳s disease. Nutraceuticals are derived from various natural sources such as medicinal plants, marine organisms, vegetables and fruits. Nutraceuticals have shown the potential to reduce the risk of colon cancer and slow its progression. These dietary substances target different molecular aspects of colon cancer development. Accordingly, this review briefly discusses the medicinal importance of nutraceuticals and their ability to reduce the risk of colorectal carcinogenesis.

Prevention and Treatment of Colorectal Cancer by Natural Agents From Mother Nature

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States after cancers of the lung and the breast/prostate. While the incidence of CRC in the United States is among the highest in the world (approximately 52/100,000), its incidence in countries in India is among the lowest (approximately 7/100,000), suggesting that lifestyle factors may play a role in development of the disease. Whereas obesity, excessive alcohol consumption, a high-calorie diet, and a lack of physical activity promote this cancer, evidence indicates that foods containing folates, selenium, Vitamin D, dietary fiber, garlic, milk, calcium, spices, vegetables, and fruits are protective against CRC in humans. Numerous agents from "mother nature" (also called "nutraceuticals,") that have potential to both prevent and treat CRC have been identified. The most significant discoveries relate to compounds such as cardamonin, celastrol, curcumin, deguelin, diosgenin, thymoquinone, tocotrienol, ursolic acid, and zerumbone. Unlike pharmaceutical drugs, these agents modulate multiple targets, including transcription factors, growth factors, tumor cell survival factors, inflammatory pathways, and invasion and angiogenesis linked closely to CRC. We describe the potential of these dietary agents to suppress the growth of human CRC cells in culture and to inhibit tumor growth in animal models. We also describe clinical trials in which these agents have been tested for efficacy in humans. Because of their safety and affordability, these nutraceuticals provide a novel opportunity for treatment of CRC, an "old age" disease with an "age old" solution.

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.

Boswellic acid exerts antitumor effects in colorectal cancer cells by modulating expression of the let-7 and miR-200 microRNA family

Colorectal cancer (CRC) is a complex disease with genetic and epigenetic alterations in many key oncogenes and tumor suppressor genes. The active principle of a gum resin from Boswellia serrata, 3-acetyl-11-keto-β-boswellic acid (AKBA), has recently gained attention as a chemopreventive compound due to its ability to target key oncogenic proteins such as 5-lipoxygenase and nuclear factor-kappaB. AKBA has been shown to inhibit the growth of CRC cells; however, the precise molecular mechanisms underlying its anticancer activities in CRC remain unclear. We hypothesized that boswellic acids may achieve their chemopreventive effects by modulating specific microRNA (miRNA) pathways. We found that AKBA significantly up-regulated expression of the let-7 and miR-200 families in various CRC cell lines. Both let-7 and miR-200 are putative tumor-suppressive miRNAs. AKBA modulated the expression of several downstream targets of the let-7 and miR-200 families, such as CDK6, vimentin and E-cadherin. These data were further strengthened by miRNA knockdown studies, which revealed that inhibition of let-7i facilitated enhanced cancer cell proliferation, migration and invasion. In addition, AKBA also induced similar modulation of the let-7 and miR-200 downstream genes in CRC tumors orthotopically implanted in nude mice. These results indicate that AKBA-induced antitumor effects in CRC occur, at least partly through the up-regulation of specific miRNA pathways. Our data provide novel evidence that anticancer effects of boswellic acids are due in part to their ability to regulate cellular epigenetic machinery and further highlight the promise for this phytochemical in the preventative and therapeutic applications of CRC.

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

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

Boswellic acid induces epigenetic alterations by modulating DNA methylation in colorectal cancer cells

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.

Targeted inhibition of tumor proliferation, survival, and metastasis by pentacyclic triterpenoids: potential role in prevention and therapy of cancer

Over the last two decades, extensive research on plant-based medicinal compounds has revealed exciting and important pharmacological properties and activities of triterpenoids. Fruits, vegetables, cereals, pulses, herbs and medicinal plants are all considered to be biological sources of these triterpenoids, which have attracted great attention especially for their potent anti-inflammatory and anti-cancer activities. Published reports in the past have described the molecular mechanism(s) underlying the various biological activities of triterpenoids which range from inhibition of acute and chronic inflammation, inhibition of tumor cell proliferation, induction of apoptosis, suppression of angiogenesis and metastasis. However systematic analysis of various pharmacological properties of these important classes of compounds has not been done. In this review, we describe in detail the pre-clinical chemopreventive and therapeutic properties of selected triterpenoids that inhibit multiple intracellular signaling molecules and transcription factors involved in the initiation, progression and promotion of various cancers. Molecular targets modulated by these triterpenoids comprise, cytokines, chemokines, reactive oxygen intermediates, oncogenes, inflammatory enzymes such as COX-2, 5-LOX and MMPs, anti-apoptotic proteins, transcription factors such as NF-κB, STAT3, AP-1, CREB, and Nrf2 (nuclear factor erythroid 2-related factor) that regulate tumor cell proliferation, transformation, survival, invasion, angiogenesis, metastasis, chemoresistance and radioresistance. Finally, this review also analyzes the potential role of novel synthetic triterpenoids identified recently which mimic natural triterpenoids in physical and chemical properties and are moving rapidly from bench to bedside research.

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.

Boswellic acid suppresses growth and metastasis of human pancreatic tumors in an orthotopic nude mouse model through modulation of multiple targets

Pancreatic cancer (PaCa) is one of the most lethal cancers, with an estimated 5-year survival of <5% even when patients are given the best treatment available. In addition, these treatments are often toxic and expensive, thus new agents which are safe, affordable and effective are urgently needed. We describe here the results of our study with acetyl-11-keto-β-boswellic acid (AKBA), an agent obtained from an Ayurvedic medicine, gum resin of Boswellia serrata. Whether AKBA has an activity against human PaCa, was examined in in vitro models and in an orthotopic nude mouse model of PaCa. We found that AKBA inhibited the proliferation of four different PaCa cell lines (AsPC-1, PANC-28, and MIA PaCa-2 with K-Ras and p53 mutations, and BxPC-3 with wild-type K-Ras and p53 mutation). These effects correlated with an inhibition of constitutively active NF-κB and suppression of NF-κB regulating gene expression. AKBA also induced apoptosis, and sensitized the cells to apoptotic effects of gemcitabine. In the orthotopic nude mouse model of PaCa, p.o. administration of AKBA alone (100 mg/kg) significantly inhibited the tumor growth; this activity was enhanced by gemcitabine. In addition, AKBA inhibited the metastasis of the PaCa to spleen, liver, and lungs. This correlated with decreases in Ki-67, a biomarker of proliferation, and CD31, a biomarker of microvessel density, in the tumor tissue. AKBA produced significant decreases in the expression of NF-κB regulating genes in the tissues. Immunohistochemical analysis also showed AKBA downregulated the expression of COX-2, MMP-9, CXCR4, and VEGF in the tissues. Overall these results demonstrate that AKBA can suppress the growth and metastasis of human pancreatic tumors in an orthotopic nude mouse model that correlates with modulation of multiple targets.

Two new triterpenoids from the resin of Boswellia carterii

Two new triterpenoids, 3-oxotirucalla-7,9(11),24-trien-21-oic acid (1) and 18Hα,3β,20β-ursanediol (2), along with 15 known triterpenes, α-amyrin, α-boswellic acid, β-boswellic acid, acetyl α-boswellic acid, acetyl β-boswellic acid, 9,11-dehydro-β-boswellic acid, 9,11-dehydro-α-boswellic acid, acetyl 11α-methoxy-β-boswellic acid, 11-keto-β-boswellic acid, acetyl 11-keto-β-boswellic acid, acetyl α-elemolic acid, 3β-hydroxytirucalla-8,24-dien-21-oic acid, elemonic acid, 3α-hydroxytirucalla-7,24-dien-21-oic acid, and 3α-hydroxytirucall-24-en-21-oic acid, were isolated from the resin of Boswellia carterii Birdw.