Boswellic acids activate p42(MAPK) and p38 MAPK and stimulate Ca(2+) mobilization

Protection of Beta Boswellic Acid against Streptozotocin-induced Alzheimer's Model by Reduction of Tau Phosphorylation Level and Enhancement of Reelin Expression

Alzheimer's disease is a growing general health concern with huge implications for individuals and society. Beta boswellic acid, a major compound of the Boswellia serrata plant, has long been used for the treatment of various inflammatory diseases. The exact mechanism of beta boswellic acid action in Alzheimer's disease pathogenesis remains unclear. In the current study, the protective effect of beta boswellic acid on streptozotocin-induced sporadic Alzheimer's disease was surveyed. Alzheimer's disease model was induced using streptozotocin followed by an assessment of the treatment effects of beta boswellic acid in the presence of streptozotocin. The prevention effect of beta boswellic acid on Alzheimer's disease induction by streptozotocin was evaluated. Behavioral activities in the treated rats were evaluated. Histological analysis was performed. Phosphorylation of tau protein at residues Ser396 and Ser404 and the expression of reelin protein were determined. Glial fibrillary acidic protein immunofluorescence staining was applied in the hippocampus regions. Our findings indicated that beta boswellic acid decreased traveled distance and escape latency in the prevention (beta boswellic acid + streptozotocin) and treatment (streptozotocin + beta boswellic acid) groups compared to control during the acquisition test. It increased "time spent" (%) in the target quadrant. Reelin level was enhanced in rats treated with beta boswellic acid. Tau hyperphosphorylation (p-tau404) and glial fibrillary acidic protein were decreased in the prevention group while the expression of reelin protein in both groups was increased. We could suggest that the anti-inflammatory property of beta boswellic acid is one of the main factors involving in the improvement of learning and memory in rats. Therefore the antineurodegenerative effect of beta boswellic acid may be due to its ability to reactivate reelin protein.

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.

The major Boswellia serrata active 3-acetyl-11-keto-β-boswellic acid strengthens interleukin-1α upregulation of matrix metalloproteinase-9 via JNK MAP kinase activation

BACKGROUND

Boswellia serrata gum resin has attracted pharmacological interest as an alternative antinflammatory.

PURPOSE

We studied the application of an ethanolic extract of the resin and its main active 3-O-acetyl-11-keto-β-boswellic acid (AKBA) against inflammatory degeneration of skin extracellular matrix.

STUDY DESIGN

We compared the effects of the extract and AKBA on the activity of MMP-2 and MMP-9 (72-kDa and 92-kDa type IV collagenases) in HaCaT keratinocytes exposed to interleukin-1α (IL-1α) as a skin inflammation model.

METHODS

MMP activity in cell conditioned medium was assayed by gelatin zymography, while NF-kB and MAP kinase activations were evaluated by Western blotting.

RESULTS

IL-1α (10 ng/ml) upregulated MMP-9 but not MMP-2 in HaCaT cells. The extract, used at 2.3, 4.6 and 9.3 µg/ml, had no effect, but in combination with IL-1α showed MMP-9 inhibition at the lowest dose and increased upregulation at the highest one. AKBA alone, at the same concentrations (corresponding to 5, 10, and 20 µM), did not stimulate MMP-9, but together with IL-1α induced an increased upregulation at the lowest dose that progressively disappeared at higher doses. WB analysis showed that IL-1α induced phosphorylation of NF-κB p65, while AKBA abolished this effect at 20 µM, but conversely increased it at 5 µM. Screening of MAP kinase phosphorylation showed a combined activation of IL-1α/AKBA on JNK, while the JNK inhibitor SP600125 abolished MMP-9 upregulation induced by IL-1α/AKBA.

CONCLUSION

The enhancing effect of IL-1α/AKBA on MMP-9 at low AKBA concentration seems to involve the activation of JNK-mediated NF-κB pathway. Conversely, the extract inhibits the IL-1α effect at low doses, but not at higher ones, where AKBA and possibly other β-boswellic acids reach concentrations that potentiate the effect of IL-1α. The extract at low doses could protect the skin against degenerative processes of extracellular matrix, while keto-β-boswellic acids seem unsuitable for this purpose.

Cancer Prevention and Therapy: Integrating Traditional Korean Medicine Into Modern Cancer Care

In spite of billions of dollars spent on cancer research each year, overall cancer incidence and cancer survival has not changed significantly in the last half century. Instead, the recent projection from the World Health Organization suggests that global cancer incidence and death is expected to double within the next decade. This requires an "out of the box" thinking approach. While traditional medicine used for thousands of years is safe and affordable, its efficacy and mechanism of action are not fully reported. Demonstrating that traditional medicine is efficacious and how it works can provide a "bed to bench" and "bench to bed" back approach toward prevention and treatment of cancer. This current review is an attempt to describe the contributions of traditional Korean medicine (TKM) to modern medicine and, in particular, cancer treatment. TKM suggests that cancer is an outcome of an imbalance of body, mind, and spirit; thus, it requires a multimodal treatment approach that involves lifestyle modification, herbal prescription, acupuncture, moxibustion, traditional exercise, and meditation to restore the balance. Old wisdoms in combination with modern science can find a new way to deal with the "emperor of all maladies."

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.

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 acids from frankincense inhibit lipopolysaccharide functionality through direct molecular interference

Lipophilic extracts of gum resins of Boswellia species (BSE) are used in folk medicine to treat various inflammatory disorders and infections. The molecular background of the beneficial pharmacological effects of such extracts is still unclear. Various boswellic acids (BAs) have been identified as abundant bioactive ingredients of BSE. Here we report the identification of defined BAs as direct inhibitors of lipopolysaccharide (LPS) functionality and LPS-induced cellular responses. In pull-down experiments, LPS could be precipitated using an immobilized BA, implying direct molecular interactions. Binding of BAs to LPS leads to an inhibition of LPS activity which was observed in vitro using a modified limulus amoebocyte lysate assay. Analysis of different BAs revealed clear structure-activity relationships with the classical β-BA as most potent derivative (IC(50)=1.8 μM). In RAW264.7 cells, LPS-induced expression of inducible nitric oxide synthase (iNOS, EC 1.14.13.39) was selectively inhibited by those BAs that interfered with LPS activity. In contrast, interferon-γ-induced iNOS induction was not affected by BAs. We conclude that structurally defined BAs are LPS inhibiting agents and we suggest that β-BA may contribute to the observed anti-inflammatory effects of BSE during infections by suppressing LPS activity.

Clinical evaluation of Boswellia serrata (Shallaki) resin in the management of Sandhivata (osteoarthritis)

Sandhigata vata is described under Vatavyadhi in all Ayurvedic texts. Charaka was the first to describe separately "Sandhigata anila", but it was not included under 80 types of nanatmaja vatavyadhi. Osteoarthritis is the most common degenerative joint disease that begins asymptomatically in middle age with progressive symptoms in advancing age. Majority of people by the age 40 years may develop osteoarthritis, especially in weight bearing joints. Females are prone with 25% prevalence, whereas males have a prevalence of 16%. In the present study, 56 patients fulfilling the diagnostic criteria of Sandhigata vata, divided into two groups. Patients of first group were administered with 500 mg capsule of Shallaki, 6 g per day (in three divided doses) with lukewarm water (n=29) and the second group) capsule Shallaki as above along with local application of Shallaki ointment on the affected joints (n=23). After a course of therapy for 2 months, symptomatic improvement was observed in both the groups at various levels with promising results in the patients of first group.

Boswellia serrata: an overall assessment of in vitro, preclinical, pharmacokinetic and clinical data

Non-steroidal anti-inflammatory drug (NSAID) intake is associated with high prevalence of gastrointestinal or cardiovascular adverse effects. All efforts to develop NSAIDs that spare the gastrointestinal tract and the cardiovasculature are still far from achieving a breakthrough. In the last two decades, preparations of the gum resin of Boswellia serrata (a traditional ayurvedic medicine) and of other Boswellia species have experienced increasing popularity in Western countries. Animal studies and pilot clinical trials support the potential of B. serrata gum resin extract (BSE) for the treatment of a variety of inflammatory diseases like inflammatory bowel disease, rheumatoid arthritis, osteoarthritis and asthma. Moreover, in 2002 the European Medicines Agency classified BSE as an 'orphan drug' for the treatment of peritumoral brain oedema. Compared to NSAIDs, it is expected that the administration of BSE is associated with better tolerability, which needs to be confirmed in further clinical trials. Until recently, the pharmacological effects of BSE were mainly attributed to suppression of leukotriene formation via inhibition of 5-lipoxygenase (5-LO) by two boswellic acids, 11-keto-β-boswellic acid (KBA) and acetyl-11-keto-β-boswellic acid (AKBA). These two boswellic acids have also been chosen in the monograph of Indian frankincense in European Pharmacopoiea 6.0 as markers to ensure the quality of the air-dried gum resin exudate of B. serrata. Furthermore, several dietary supplements advertise the enriched content of KBA and AKBA. However, boswellic acids failed to inhibit leukotriene formation in human whole blood, and pharmacokinetic data revealed very low concentrations of AKBA and KBA in plasma, being far below the effective concentrations for bioactivity in vitro. Moreover, permeability studies suggest poor absorption of AKBA following oral administration. In view of these results, the previously assumed mode of action - that is, 5-LO inhibition - is questionable. On the other hand, 100-fold higher plasma concentrations have been determined for β-boswellic acid, which inhibits microsomal prostaglandin E synthase-1 and the serine protease cathepsin G. Thus, these two enzymes might be reasonable molecular targets related to the anti-inflammatory properties of BSE. In view of the results of clinical trials and the experimental data from in vitro studies of BSE, and the available pharmacokinetic and metabolic data on boswellic acids, this review presents different perspectives and gives a differentiated insight into the possible mechanisms of action of BSE in humans. It underlines BSE as a promising alternative to NSAIDs, which warrants investigation in further pharmacological studies and clinical trials.

Boswellia resin: from religious ceremonies to medical uses; a review of in-vitro, in-vivo and clinical trials

Objectives

Despite its historical-religious, cultural and medical importance, Boswellia has not been thoroughly studied, and gaps still exist between our knowledge of the traditional uses of the resin and the scientific data available. Here we review the pharmacology of Boswellia resin and of the small molecules identified as the active ingredients of the resin.

Key findings

The resin of Boswellia species (‘frankincense’, ‘olibanum’) has been used as incense in religious and cultural ceremonies since the beginning of written history. Its medicinal properties are also widely recognized, mainly in the treatment of inflammatory conditions, as well as in some cancerous diseases, wound healing and for its antimicrobial activity. Until recently, work on Boswellia focused on the immunomodulatory properties of the resin and boswellic acids were considered to be the main, if not the only, active ingredients of the resin. Hence, this family of triterpenoids was investigated by numerous groups, both in vitro and in vivo. These compounds were shown to exert significant anti-inflammatory and pro-apoptotic activity in many assays: in vitro, in vivo and in clinical trials. We recently found incensole acetate and its derivatives, which are major components of Boswellia resin, to be nuclear factor-κB inhibitors, thus suggesting that they are, at least in part, responsible for its anti-inflammatory effects. Incensole acetate also exerts a robust neuroprotective effect after brain trauma in mice. Furthermore, it causes behavioural as well as anti-depressive and anxiolytic effects in mice. It is also a potent agonist of the transient receptor potential (TRP)V3 channel. It thus seems that incensole acetate and its derivatives play a significant role in the effects that Boswellia resin exerts on biological systems.

Conclusions

Altogether, studies on Boswellia resin have provided an arsenal of bio-active small molecules with a considerable therapeutic potential that is far from being utilized.

Boswellic acids: a group of medicinally important compounds

This review, containing over 276 references, covers the progress made in the chemistry and bioactivity of this important group of triterpenoids. Though initially known for their anti-inflammatory and anti-arthritic activities through a unique 5-LO inhibition mechanism, boswellic acids have recently attained significance due to their anti-cancer properties. The phytochemistry and chemical modifications, including mechanism of action, are discussed.

Induction of central signalling pathways and select functional effects in human platelets by beta-boswellic acid

We have recently shown that in polymorphonuclear leukocytes, 11-keto boswellic acids (KBAs) induce Ca2+ mobilisation and activation of mitogen-activated protein kinases (MAPK). Here we addressed the effects of BAs on central signalling pathways in human platelets and on various platelet functions. We found that beta-BA (10 microM), the 11-methylene analogue of KBA, caused a pronounced mobilisation of Ca2+ from internal stores and induced the phosphorylation of p38 MAPK, extracellular signal-regulated kinase (ERK)2, and Akt. These effects of beta-BA were concentration dependent, and the magnitude of the responses was comparable to those obtained after platelet stimulation with thrombin or collagen. Based on inhibitor studies, beta-BA triggers Ca2+ mobilisation via the phospholipase (PL)C/inositol-1,4,5-trisphosphate pathway, and involves Src family kinase signalling. Investigation of platelet functions revealed that beta-BA (> or =10 microM) strongly stimulates the platelet-induced generation of thrombin in an ex-vivo in-vitro model, the liberation of arachidonic acid (AA), and induces platelet aggregation in a Ca2+-dependent manner. In contrast to beta-BA, the 11-keto-BAs (KBA or AKBA) evoke only moderate Ca2+ mobilisation and activate p38 MAPK, but fail to induce phosphorylation of ERK2 or Akt, and do not cause aggregation or significant generation of thrombin. In summary, beta-BA potently induces Ca2+ mobilisation as well as the activation of pivotal protein kinases, and elicits functional platelet responses such as thrombin generation, liberation of AA, and aggregation.

Boswellic acids stimulate arachidonic acid release and 12-lipoxygenase activity in human platelets independent of Ca2+ and differentially interact with platelet-type 12-lipoxygenase

Boswellic acids inhibit the transformation of arachidonic acid to leukotrienes via 5-lipoxygenase but can also enhance the liberation of arachidonic acid in human leukocytes and platelets. Using human platelets, we explored the molecular mechanisms underlying the boswellic acid-induced release of arachidonic acid and the subsequent metabolism by platelet-type 12-li-poxygenase (p12-LO). Both beta-boswellic acid and 3-O-acetyl-11-keto-boswellic acid (AKBA) markedly enhanced the release of arachidonic acid via cytosolic phospholipase A2 (cPLA2), whereas for generation of 12-hydro(pero)xyeicosatetraenoic acid [12-H(P)ETE], AKBA was less potent than beta-boswellic acid and was without effect at higher concentrations (> or =30 microM). In contrast to thrombin, beta-boswellic acid-induced release of ara-chidonic acid and formation of 12-H(P)ETE was more rapid and occurred in the absence of Ca2+. The Ca2+-independent release of arachidonic acid and 12-H(P)ETE production elicited by beta-boswellic acid was not affected by pharmacological inhibitors of signaling molecules relevant for agonist-induced arachidonic acid liberation and metabolism. It is noteworthy that in cell-free assays, beta-boswellic acid increased p12-LO catalysis approximately 2-fold in the absence but not in the presence of Ca2+, whereas AKBA inhibited p12-LO activity. No direct modulatory effects of boswellic acids on cPLA2 activity in cell-free assays were evident. Therefore, immobilized KBA (linked to Sepharose beads) selectively precipitated p12-LO from platelet lysates but failed to bind cPLA2. Taken together, we show that boswellic acids induce the release of arachidonic acid and the synthesis of 12-H(P)ETE in human platelets by unique Ca2+-independent routes, and we identified p12-LO as a selective molecular target of boswellic acids.

Regulation of vascular responses to inflammation: inducible matrix metalloproteinase-3 expression in human microvascular endothelial cells is sensitive to antiinflammatory Boswellia

Endothelial cells are critical elements in the pathophysiology of inflammation. Tumor necrosis factor (TNF) alpha potently induces inflammatory responses in endothelial cells. Recently we have examined the genetic basis of the antiinflammatory effects of Boswellia extract (BE) in a system of TNFalpha-induced gene expression in human microvascular endothelial cells (HMECs). Of the 522 genes induced by TNFalpha in HMECs, 113 genes were sensitive to BE. BE prevented the TNFalpha-induced expression of matrix metalloproteinases (MMPs). In the current work, we sought to test the effects of BE on TNFalpha-inducible MMP expression in HMECs. Acetyl-11-ketobeta- boswellic acid (AKBA) is known to be an active principle in BE. To evaluate the significance of AKBA in the antiinflammatory properties of BE, effects of BE containing either 3% (BE3%) or 30% (BE30%, 5- Loxin) were compared. Pretreatment of HMECs for 2 days with BE potently prevented TNFalpha-induced expression and activity of MMP-3, MMP-10, and MMP-12. In vivo, BE protected against experimental arthritis. In all experiments, both in vitro and in vivo, BE30% was more effective than BE3%. In sum, this work lends support to our previous report that BE has potent antiinflammatory properties both in vitro as well as in vivo.

3-O-acetyl-11-keto-boswellic acid decreases basal intracellular Ca2+ levels and inhibits agonist-induced Ca2+ mobilization and mitogen-activated protein kinase activation in human monocytic cells

Previously, we showed that 11-keto-boswellic acid and 3-O-acetyl-11-keto-BA (AKBA) stimulate Ca(2+) mobilization and activate mitogen-activated protein kinases (MAPKs) in human polymorphonuclear leukocytes (PMNLs). Here, we addressed the effects of boswellic acids on the intracellular Ca(2+) concentration ([Ca(2+)](i)) and on the activation of p38(MAPK) and extracellular signal-regulated kinase (ERK) in the human monocytic cell line Mono Mac (MM) 6. In contrast to PMNLs, AKBA concentration dependently (1-30 microM) decreased the basal [Ca(2+)](i) in resting MM6 cells but also in cells where [Ca(2+)](i) had been elevated by stimulation with platelet-activating factor (PAF). AKBA also strongly suppressed the subsequent elevation of [Ca(2+)](i) induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), PAF, or by the direct phospholipase C activator 2,4, 6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide, but AKBA failed to prevent Ca(2+) signals induced by thapsigargin or ionomycin. Suppression of Ca(2+) homeostasis by AKBA was also observed in primary monocytes, isolated from human blood. Moreover, AKBA inhibited the activation of p38(MAPK) and ERKs in fMLP-stimulated MM6 cells. Although the effects of AKBA could be mimicked by the putative phospholipase C (PLC) inhibitor U-73122 (1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione), AKBA appears to operate independent of PLC activity since the release of intracellular inositol-1,4,5-trisphosphate evoked by 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide was hardly diminished by AKBA. Inhibitor studies indicate that AKBA may decrease [Ca(2+)](i) by blocking store-operated Ca(2+) and/or nonselective cation channels. Together, AKBA interferes with pivotal signaling events in monocytic cells that are usually required for monocyte activation by proinflammatory stimuli. Interruption of these events may represent a possible mechanism underlying the reported anti-inflammatory properties of AKBA.

Human genome screen to identify the genetic basis of the anti-inflammatory effects of Boswellia in microvascular endothelial cells

Inflammatory disorders represent a substantial health problem. Medicinal plants belonging to the Burseraceae family, including Boswellia, are especially known for their anti-inflammatory properties. The gum resin of Boswellia serrata contains boswellic acids, which inhibit leukotriene biosynthesis. A series of chronic inflammatory diseases are perpetuated by leukotrienes. Although Boswellia extract has proven to be anti-inflammatory in clinical trials, the underlying mechanisms remain to be characterized. TNF alpha represents one of the most widely recognized mediators of inflammation. One mechanism by which TNFalpha causes inflammation is by potently inducing the expression of adhesion molecules such as VCAM-1. We sought to test the genetic basis of the antiinflammatory effects of BE (standardized Boswellia extract, 5-Loxin) in a system of TNF alpha-induced gene expression in human microvascular endothelial cells. We conducted the first whole genome screen for TNF alpha- inducible genes in human microvascular cells (HMEC). Acutely, TNF alpha induced 522 genes and downregulated 141 genes in nine out of nine pairwise comparisons. Of the 522 genes induced by TNF alpha in HMEC, 113 genes were clearly sensitive to BE treatment. Such genes directly related to inflammation, cell adhesion, and proteolysis. The robust BE-sensitive candidate genes were then subjected to further processing for the identification of BE-sensitive signaling pathways. The use of resources such as GenMAPP, KEGG, and gene ontology led to the recognition of the primary BE-sensitive TNF alpha-inducible pathways. BE prevented the TNF alpha-induced expression of matrix metalloproteinases. BE also prevented the inducible expression of mediators of apoptosis. Most strikingly, however, TNF alpha-inducible expression of VCAM-1 and ICAM-1 were observed to be sensitive to BE. Realtime PCR studies showed that while TNF alpha potently induced VCAM-1 gene expression, BE completely prevented it. This result confirmed our microarray findings and built a compelling case for the anti-inflammatory property of BE. In an in vivo model of carrageenan-induced rat paw inflammation, we observed a significant antiinflammatory property of BE consistent with our in vitro findings. These findings warrant further research aimed at identifying the signaling mechanisms by which BE exerts its anti-inflammatory effects.

Coupling of boswellic acid-induced Ca2+ mobilisation and MAPK activation to lipid metabolism and peroxide formation in human leucocytes

1. We have previously shown that 11-keto boswellic acids (11-keto-BAs), the active principles of Boswellia serrata gum resins, activate p38 MAPK and p42/44(MAPK) and stimulate Ca(2+) mobilisation in human polymorphonuclear leucocytes (PMNL). 2. In this study, we attempted to connect the activation of MAPK and mobilisation of Ca(2+) to functional responses of PMNL, including the formation of reactive oxygen species (ROS), release of arachidonic acid (AA), and leukotriene (LT) biosynthesis. 3. We found that, in PMNL, 11-keto-BAs stimulate the formation of ROS and cause release of AA as well as its transformation to LTs via 5-lipoxygenase. 4. Based on inhibitor studies, 11-keto-BA-induced ROS formation is Ca(2+)-dependent and is mediated by NADPH oxidase involving PI 3-K and p42/44(MAPK) signalling pathways. Also, the release of AA depends on Ca(2+) and p42/44(MAPK), whereas the pathways stimulating 5-LO are not readily apparent. 5. Pertussis toxin, which inactivates G(i/0) protein subunits, prevents MAPK activation and Ca(2+) mobilisation induced by 11-keto-BAs, implying the involvement of a G(i/0) protein in BA signalling. 6. Expanding studies on differentiated haematopoietic cell lines (HL60, Mono Mac 6, BL41-E-95-A) demonstrate that the ability of BAs to activate MAPK and to mobilise Ca(2+) may depend on the cell type or the differentiation status. 7. In summary, we conclude that BAs act via G(i/0) protein(s) stimulating signalling pathways that control functional leucocyte responses, in a similar way as chemoattractants, that is, N-formyl-methionyl-leucyl-phenylalanine or platelet-activating factor.