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

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.

Unravelling the Therapeutic Potential of Nano-Delivered Functional Foods in Chronic Respiratory Diseases

Chronic inflammation of the respiratory tract is one of the most concerning public health issues, as it can lead to chronic respiratory diseases (CRDs), some of which are more detrimental than others. Chronic respiratory diseases include chronic obstructive pulmonary disease (COPD), asthma, lung cancer, and pulmonary fibrosis. The conventional drug therapies for the management and treatment of CRDs only address the symptoms and fail to reverse or recover the chronic-inflammation-mediated structural and functional damage of the respiratory tract. In addition, the low efficacy and adverse effects of these drugs have directed the attention of researchers towards nutraceuticals in search of potential treatment strategies that can not only ameliorate CRD symptoms but also can repair and reverse inflammatory damage. Hence, there is a growing interest toward investigating the medicinal benefits of nutraceuticals, such as rutin, curcumin, zerumbone, and others. Nutraceuticals carry many nutritional and therapeutic properties, including anti-inflammatory, antioxidant, anticancer, antidiabetic, and anti-obesity properties, and usually do not have as many adverse effects, as they are naturally sourced. Recently, the use of nanoparticles has also been increasingly studied for the nano drug delivery of these nutraceuticals. The discrete size of nanoparticles holds great potential for the level of permeability that can be achieved when transporting these nutraceutical compounds. This review is aimed to provide an understanding of the use of nutraceuticals in combination with nanoparticles against CRDs and their mechanisms involved in slowing down or reversing the progression of CRDs by inhibiting pro-inflammatory signaling pathways.

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.

Anti-inflammatory and anti-cancer activities of frankincense: Targets, treatments and toxicities

The oleogum resins of Boswellia species known as frankincense have been used for ages in traditional medicine in India, China and the Arabian world independent of its use for cultural and religious rituals in Europe. During the past two decades, scientific investigations provided mounting evidence for the therapeutic potential of frankincense. We conducted a systematic review on the anti-inflammatory and anti-cancer activities of Boswellia species and their chemical ingredients (e.g. 3-O-acetyl-11-keto-β boswellic acid, α- and β-boswellic acids, 11-keto-β-boswellic acid and other boswellic acids, lupeolic acids, incensole, cembrenes, triterpenediol, tirucallic acids, and olibanumols). Frankincense acts by multiple mechanisms, e.g. by the inhibition of leukotriene synthesis, of cyclooxygenase 1/2 and 5-lipoxygenase, of oxidative stress, and by regulation of immune cells from the innate and acquired immune systems. Furthermore, frankincense modulates signaling transduction responsible for cell cycle arrest and inhibition of proliferation, angiogenesis, invasion and metastasis. Clinical trials showed the efficacy of frankincense and its phytochemicals against osteoarthritis, multiple sclerosis, asthma, psoriasis and erythematous eczema, plaque-induced gingivitis and pain. Frankincense revealed beneficial effects towards brain tumor-related edema, but did not reduce glioma size. Even if there is no treatment effect on brain tumors itself, the management of glioma-associated edema may represent a desirable improvement. The therapeutic potential against other tumor types is still speculative. Experimental toxicology and clinical trials revealed only mild adverse side effects. More randomized clinical trials are required to estimate the full clinical potential of frankincense for cancer therapy.

Antioxidant, anti-inflammatory and anti-fibrotic effects of Boswellia serrate gum resin in CCl4-induced hepatotoxicity

The present study aims to investigate the potential antioxidant, anti-inflammatory and anti-fibrotic effects of Boswellia serrate (BS) gum resin against carbon tetrachloride (CCl₄)-induced liver damage. Four groups consisting of eight rats each were designated: Group I, normal healthy control; group II, CCl₄-induced liver fibrosis; group III, CCl₄-induced liver fibrosis followed by BS treatment daily for two weeks; and group IV, CCl₄-induced liver fibrosis followed by silymarin treatment daily for two weeks. Expression of tumor necrosis factor-α (TNF-α) and nuclear factor κB (NF-κB), interleukin-6 (IL-6), transforming growth factor-β (TGF-β) and cyclooxygenase-2 (COX-2) were assessed, in addition to histopathological and fibrotic changes in liver tissues isolated from the rats. BS significantly ameliorated CCl₄-induced increases in serum aspartate (AST) and alanine transaminase (ALT) levels, reduced lactate dehydrogenase (LDH) activities in addition to restoring total bilirubin, triglyceride and albumin levels. BS treatment also alleviated oxidative stress and improved total antioxidant capacity in the liver, and reduced the expression of TNF-α, NF-κB, TGF-β, IL-6 and COX-2. On a histopathological level, BS treatment also exhibited antifibrotic activity. In conclusion, these findings suggest that BS contains potentially hepatoprotective effects against CCl4-induced liver injury via its antioxidant, anti-inflammatory and antifibrotic characteristics.

Triterpene Acids from Frankincense and Semi-Synthetic Derivatives That Inhibit 5-Lipoxygenase and Cathepsin G

Age-related diseases, such as osteoarthritis, Alzheimer’s disease, diabetes, and cardiovascular disease, are often associated with chronic unresolved inflammation. Neutrophils play central roles in this process by releasing tissue-degenerative proteases, such as cathepsin G, as well as pro-inflammatory leukotrienes produced by the 5-lipoxygenase (5-LO) pathway. Boswellic acids (BAs) are pentacyclic triterpene acids contained in the gum resin of the anti-inflammatory remedy frankincense that target cathepsin G and 5-LO in neutrophils, and might thus represent suitable leads for intervention with age-associated diseases that have a chronic inflammatory component. Here, we investigated whether, in addition to BAs, other triterpene acids from frankincense interfere with 5-LO and cathepsin G. We provide a comprehensive analysis of 17 natural tetra- or pentacyclic triterpene acids for suppression of 5-LO product synthesis in human neutrophils. These triterpene acids were also investigated for their direct interference with 5-LO and cathepsin G in cell-free assays. Furthermore, our studies were expanded to 10 semi-synthetic BA derivatives. Our data reveal that besides BAs, several tetra- and pentacyclic triterpene acids are effective or even superior inhibitors of 5-LO product formation in human neutrophils, and in parallel, inhibit cathepsin G. Their beneficial target profile may qualify triterpene acids as anti-inflammatory natural products and pharmacological leads for intervention with diseases related to aging.

Drug-Herb Interactions in the Elderly Patient with IBD: a Growing Concern

OPINION STATEMENT

Inflammatory bowel disease (IBD), which includes conditions such as Crohn's disease and ulcerative colitis, is becoming more prevalent with the elderly being the fastest growing group. Parallel to this, there is an increasing interest in the use of complementary and alternative medicine (CAM). Nearly half of patients with IBD have used CAM at one time. The elderly patients, however, are burdened by comorbid conditions, polypharmacy, and altered functional status. With increasing use of complementary and alternative medicine in our elderly patients with IBD, it is vital for the provider to provide counsel on drug-herb potential interactions. CAM includes herbal products, diet, dietary supplements, acupuncture, and prayer. In this paper, we will review common CAM, specifically herbs, that are used in patients with IBD including the herb background, suggested use, evidence in IBD, and most importantly, potential interactions with IBD medications used in elderly patients. Most important evidence-based adverse events and drug-herb interactions are summarized. The herbs discussed include Triticum aestivum (wheat grass), Andrographis paniculata (chiretta), Boswellia serrata, tormentil, bilberry, curcumin (turmeric), Plantago ovata (blond psyllium), Oenothera biennis (evening primrose oil), germinated barley foodstuff, an herbal preparation of myrrh, chamomile and coffee extract, chios mastic gum, wormwood (absinthe, thujone), Cannabis sativa (marijuana, THC), tripterygium wilfordii (thunder god vine), Ulmus rubra (slippery elm bark), trigonella foenugraecum (fenugreek), Dioscorea mexicana (wild yam), Harpagophytum procumbens (devil's claw), ginger, cinnamon, licorice, and peppermint.

Boswellia serrata Protects Against Glutamate-Induced Oxidative Stress and Apoptosis in PC12 and N2a Cells

This study was designed to investigate whether the extract from Boswellia serrata oleo-gum resin (BSE) can protect against glutamate-induced oxidative damage and cytotoxicity in PC12 and N2a cell lines. Using a simple and reliable reverse-phase high-performance liquid chromatography (HPLC), the amount of 3-acetyl-11-keto-β-boswellic acid (AKBA) in the BSE was found to be 18.5% w/w. The results confirmed that BSE and AKBA, at concentrations as high as 100 μg/mL or 10 μM, respectively, caused no significant cytotoxicity or apoptotic cell death. Co- and pretreatment with BSE (25-100 μg/mL) or AKBA (5 μM) restored the viability of PC12 and N2a cells under glutamate toxicity (8 mM). Treatment with BSE and AKBA also attenuated the toxic effects of glutamate on intracellular reactive oxygen species, lipid peroxidation, superoxide dismutase activity, and oxidative DNA damage compared with the untreated glutamate-injured cells. Furthermore, BSE and AKBA decreased the apoptotic cell population in the sub-G1 region and the rate of both early and late-stage apoptosis induced by glutamate in the cells. Our data suggest that the protective effects of Boswellia extract and AKBA against glutamate toxicity in PC12 and N2a cells may be mediated through the amelioration of the oxidative stress and the resultant apoptosis.

A cosmeceutical formulation based on boswellic acids for the treatment of erythematous eczema and psoriasis

Background

Boswellic acids (BAs) show anti-inflammatory properties in a variety of inflammatory diseases, including rheumatoid arthritis, osteoarthritis, and asthma. A topical administration route is currently used to deliver active compounds in psoriatic and eczematous patients. In this double-blind study we compare a novel BA formulation (containing Bosexil^®, INCI [International Nomenclature of Cosmetic Ingredients]: lecithin, Boswellia serrata resin extract) with a placebo formulation. A third arm of the trial received a formulation of Vaccinium myrtillus seed oil, previously demonstrated as an effective local treatment for psoriatic lesions.

Methods

Patients with psoriasis or erythematous eczema were randomly assigned, in a 1:1:1 ratio, to Bosexil^®, V. myrtillus seed oil, or placebo. In order to evaluate the effects of treatment, the changes of scales and erythema from diagnosis to the end of treatment were scored in psoriatic patients, while changes in itch and erythema were analyzed for erythematous eczema patients. Psoriasis Area Severity Index and Eczema Area and Severity Index scores were also calculated.

Results

In patients with psoriasis, scales and erythema improved both with Bosexil^® and the V. myrtillus seed oil treatment in comparison with placebo. In particular, the treatment with Bosexil^® formulation improved scales (70% of cases) and erythema (50% of cases) without any case of worsening. In patients with eczema, the administration of placebo did not result in any improvement in 90% of cases, and in the remaining 10% worsened both itch and erythema. Bosexil^® formulation improved both itch (60% of cases) and erythema (60% of cases) without any case of worsening. V. myrtillus seed oil improved itch and erythema in 66.7% and 77.8% of patients, respectively.

Conclusion

A topical formulation of Bosexil^® may be promising for the treatment of psoriasis and erythematous eczema. Long-term studies are recommended to evaluate the adherence to this topical treatment and its clinical benefits in real life.

Interference of boswellic acids with the ligand binding domain of the glucocorticoid receptor

Boswellic acids (BAs) possess anti-inflammatory properties in various biological models with similar features to those of glucocorticoids (GCs), such as suppression of the release of pro-inflammatory cytokines. Hence, the molecular mechanism of BAs responsible for their anti-inflammatory features might be attributable to interference with the human glucocorticoid receptor (GR). Due to obvious structural similarities with GCs, we conducted pharmacophore studies as well as molecular docking simulations of BAs as putative ligands at the ligand binding site (LBS) of the GR in distinct functional states. In order to verify receptor binding and functional activation of the GR by BAs, radiometric binding assays as well as GR response element-dependent luciferase reporter assay were performed with dexamethasone (DEX) as a functional positive control. With respect to the observed position of GCs in GR crystal complexes in the active antagonist state, BAs docked in a flipped orientation with estimated binding constants reflecting nanomolar affinities. For validation, DEX and other steroids were successfully redocked into their crystal poses in similar ranges as reported in the literature. In line with the pharmacophore and docking models, the BAs were strong GR binders (radiometric binding assay), albeit none of the BAs activated the GR in the reporter gene assay, when compared to the GC agonist DEX. The flipped scaffolds of all BAs dislodge the known C-11 function from its receiving amino acid (Asn564), which may explain the silencing effects of receptor-bound BAs in the reporter gene assay. Together, our results constitute a compelling example of rigid keys acting in an adaptable lock qualifying as a reversed induced fit mechanism, thereby extending the hitherto published knowledge about molecular target interactions of BAs.

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.

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.

Evaluation of systemic administration of Boswellia papyrifera extracts on spatial memory retention in male rats

Time-dependent effects of ethanolic extract of Boswellia papyrifera, administered systemically, on spatial memory retention in the Morris water maze were investigated in male rats. A total extract of Boswellia papyrifera (300 mg/kg) was administered every eight hours to three groups of rats by gavage for 1, 2 and 4 weeks. In a separate set of experiments, three doses of a fraction of the extract, called the boswellic acids (100, 200 and 300 mg/kg) were administered by gavage to three groups of rats three times a day for 2 weeks. Following these applications, animals were trained for 4 days. Behavioral testing for evaluation of spatial memory retention was performed 48 h after completion of training. Boswellia papyrifera extracts and boswellic acids caused a significant reduction in escape latency and distance traveled but had no influence on swimming speed. These findings provide evidence that Boswellia papyrifera extracts affect spatial memory retention irrespective of the treatment period. In addition our data show that systemic administration of the boswellic acids fraction enhanced spatial memory retention in a dose-dependent manner. These improving effects may be due to some extent to the interactions of these products with inflammatory mediators, neurotransmitter signaling cascades or protein kinase pathways in the brain.

Evidence of effectiveness of herbal medicinal products in the treatment of arthritis. Part I: Osteoarthritis

Herbal medicinal products (HMPs) are used in a variety of oral and topical forms for the treatment of osteoarthritis. The aim of this study was to update a previous systematic review published in 2000. We searched electronic databases (MEDLINE, EMBASE, CISCOM, AMED, CINAHL, Cochrane registers) to June 2007, unrestricted by date or language, and included randomized controlled trials that compared HMPs with inert (placebo) or active controls in patients with osteoarthritis. Five reviewers contributed to data extraction. Disagreements were discussed and resolved by consensus with reference to Cochrane guidelines and advice from the Cochrane Collaboration.Thirty-five studies (30 studies identified for this review update, and 5 studies included in the original review) evaluating the effectiveness of 22 HMPs were included. However, due to differing HMPs, interventions, comparators, and outcome measures, meta-analysis was restricted to data from studies of three HMPs: topical capsaicin, avocado-soybean unsaponifiables, and the Chinese herbal mixture SKI306X showed benefit in the alleviation of osteoarthritic pain.Several studies investigating products from devil's claw, and a powder from rose hip and seed, reported favorable effects on osteoarthritic pain, whereas two studies of a willow bark extract returned disparate results. Three studies of Phytodolor N(R) were of limited use because doses and measures were inconsistent among trials. The remaining single studies for each HMP provided moderate evidence of effectiveness. No serious side effects were reported with any herbal intervention.Despite some evidence, the effectiveness of none of the HMPs is proven beyond doubt. The obvious potential benefits of HMPs in the treatment of osteoarthritis are reduced reliance on synthetic medications with the associated risks of harmful adverse events, but further clinical trials are necessary before HMPs can be adopted in osteoarthritis treatment guidelines.

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.

Incensole Acetate, a Novel Anti-Inflammatory Compound Isolated fromBoswelliaResin, Inhibits Nuclear Factor-κB Activation

Boswellia resin is a major anti-inflammatory agent in herbal medical tradition, as well as a common food supplement. Its anti-inflammatory activity has been attributed to boswellic acid and its derivatives. Here, we re-examined the anti-inflammatory effect of the resin, using inhibitor of nuclear factor-kappaB alpha (IkappaB alpha) degradation in tumor necrosis factor (TNF) alpha-stimulated HeLa cells for a bioassay-guided fractionation. We thus isolated two novel nuclear factor-kappaB (NF-kappaB) inhibitors from the resin, their structures elucidated as incensole acetate (IA) and its nonacetylated form, incensole (IN). IA inhibited TAK/TAB-mediated IkappaB kinase (IKK) activation loop phosphorylation, resulting in the inhibition of cytokine and lipopolysaccharide-mediated NF-kappaB activation. It had no effect on IKK activity in vitro, and it did not suppress IkappaB alpha phosphorylation in costimulated T-cells, indicating that the kinase inhibition is neither direct nor does it affect all NF-kappaB activation pathways. The inhibitory effect seems specific; IA did not interfere with TNFalpha-induced activation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase. IA treatment had a robust anti-inflammatory effect in a mouse inflamed paw model. Cembrenoid diterpenoids, specifically IA and its derivatives, may thus constitute a potential novel group of NF-kappaB inhibitors, originating from an ancient anti-inflammatory herbal remedy.

Evidence of effectiveness of herbal antiinflammatory drugs in the treatment of painful osteoarthritis and chronic low back pain

Treatment with herbal medicines is very popular in Europe. In order to get information on the evidence of effectiveness of oral herbal medicines in the treatment of pain in the joints or lower back, OVID(MEDLINE), PUBMED and COCHRANE COLLABORATION LIBRARY were searched back to 1985 for systematic reviews. The level of evidence of effectiveness was defined as strong - at least two confirmatory studies demonstrating a clinical relevant effect, moderate - one confirmatory study with a clinical relevant effect and/or multiple exploratory studies of good quality; otherwise the evidence was insufficient or conflicting in the case of inconsistent findings. Fifteen systematic reviews were identified. The evidence of effectiveness was strong for a proprietary unsaponifiable avocado soybean fraction and Harpagophytum preparations containing > 50 mg harpagoside in the daily dosage, moderate for ginger and a proprietary rose hip and seed powder, insufficient for Boswellia serrata gum resin and other herbal preparations and inconsistent for a proprietary willow bark extract. Further rigorous studies are required to confirm the usefulness of herbal medicines in the treatment of osteoarthritic complaints and chronic low back pain in order to enable acceptance of the herbal medicines into the treatment guidelines.

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.

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.

5-Lipoxygenase regulates senescence-like growth arrest by promoting ROS-dependent p53 activation

5-Lipoxygenase (5LO) is involved in the production of leukotrienes and reactive oxygen species (ROS) from arachidonic acid. Its strong activation has been associated with several diseases like cancer and neurodegeneration. Here we show that 5LO activity increases during senescence-like growth arrest induced by oncogenic ras or culture history in both human and mouse embryo fibroblasts. Overexpression of 5LO promotes senescence-like growth arrest via a p53/p21-dependent pathway, and this occurs independently of telomerase activity. 5LO stabilizes p53 through phosphorylation at Ser15 and increases expression of the p53-transcriptional target p21. This is achieved by regulating ROS production. Indeed, ROS are increased in 5LO-arrested cells. Antioxidants and a low oxygen environment prevent 5LO-induced growth arrest. Finally, 5LO inhibition reduces the growth arrest induced by oncogenic ras or culture history and these effects are neutralized by the addition of exogenous ROS. These data link the 5LO pathway to oxidative crises of primary fibroblast and suggest that the ability of 5LO to induce senescence-like growth arrest may be important in the pathogenesis of 5LO-associated disorders.