In vitro metabolism, permeation, and brain availability of six major boswellic acids from Boswellia serrata gum resins

Alpha-boswellic acid accelerates acute wound healing via NF-κB signaling pathway

BACKGROUND

Boswellic acids (BAs) showed promising effects in cancer treatment, immune response regulation, and anti-inflammatory therapy. We aimed to assess the roles of alpha-BA (α-BA) in treating acute wound healing.

METHODS

In vivo wound-healing models were established to evaluate the therapeutic effects of α-BA. Cell assays were conducted to assess the impact of α-BA on cellular biological functions. Western blot analysis was employed to validate the potential mechanisms of action of α-BA.

RESULTS

Animal models indicated that wound healing was notably accelerated in the α-BA group compared to the control group (P < 0.01). Hematoxylin and eosin (HE) staining and enzyme-linked immunosorbent assay (ELISA) assay preliminarily suggested that α-BA may accelerate wound healing by inhibiting excessive inflammatory reactions and increasing the protein levels of growth factors. Cell function experiments demonstrated that α-BA suppressed the proliferation and migration ability of human hypertrophic scar fibroblasts (HSFBs), thereby favoring wound healing. Additionally, α-BA exerted a significant impact on cell cycle progression. Mechanistically, the protein levels of key genes in nuclear factor kappa beta (NF-κB) signaling pathway, including cyclin D1, p65, IκBα, and p-IκBα, were downregulated by α-BA.

CONCLUSIONS

α-BA demonstrated the ability to counteract the abnormal proliferation of skin scar tissues, consequently expediting wound healing. These findings suggest its potential for development as a new agent for treating acute wound healing.

Efficacy evaluation of standardized Boswellia serrata extract (AflapinⓇ) in osteoarthritis: A systematic review and sub-group meta-analysis study

BACKGROUND AND PURPOSE

Osteoarthritis (OA) is a joint disease characterized by pain, inflammation, and physical disability. Boswellia serrata (BS) is widely studied for its effectiveness in OA condition. Our systematic review and meta-analysis study was aimed to evaluate BS extract efficacy in OA. A sub-group analysis was performed to compare the efficacy of a standardized BS extract (AflapinⓇ) with other BS extracts.

METHODS

Randomized controlled trials, identified from three online databases, evaluating the effect of BS extracts in OA were included. Quality of studies was assessed using PEDro scale and risk of bias was assessed using Cochrane Risk of Bias tool. Pooled effect was reported as mean difference (MD) and 95% confidence interval. Study was conducted as per the Cochrane guidelines (PROSPERO registration ID: CRD42023411356).

RESULTS

Nine RCTs with 712 participants were included. All studies (except one) were good quality studies. BS supplementation significantly reduced VAS (MD: -10.71; p<0.00001), LFI (MD: -2.99; p<0.00001), WOMAC-pain (MD: -10.69; p<0.0001), WOMAC-stiffness (MD: -5.49; p<0.00001), and WOMAC-function (MD: -10.69; p<0.00001) scores compared to control therapy. By sub-group analysis, AflapinⓇ supplementation showed greater reduction in VAS (MD: -16.09 vs -4.68), LFI (MD: -3.81 vs -2.01), WOMAC-pain (MD: -18.68 vs -7.07), WOMAC-stiffness (MD: -14.25 vs -3.78), and WOMAC-function (MD: -14.99 vs -8.41) scores as compared to other BS therapies.

CONCLUSIONS

BS supplementation is effective OA symptomatic management. Sub-group analysis revealed that AflapinⓇ supplementation may be better in improving the symptoms of OA which needs to be confirmed by more comparative clinical studies.

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.

Boswellic acid formulations are not suitable for treatment of pediatric high-grade glioma due to tumor promoting potential

Background and aim

Pediatric high-grade gliomas (pedHGG) comprise a very poor prognosis. Thus, parents of affected children are increasingly resorting to complementary and alternative medicine (CAM), among those Boswellia extracts. However, nothing is known about the therapeutic effectiveness of their active substances, Boswellic acids (BA) in pedHGG. Thus, we aimed to investigate if the three main Boswellic acids (BA) present in Boswellia plants, alpha-boswellic acid (α-BA), beta-boswellic acid (β-BA) and 3-acetyl-11-keto-beta-boswellic acid (AKBA) hold any promising potential for treatment of affected pedHGG patients.

Experimental procedure

Histone 3 (H3)-wildtype and H3.3K27M-mutant pedHGG cell lines were treated with BA, either alone or in combination with radio-chemotherapy with temozolomide. Cell viability, stemness properties, apoptosis, in ovo tumor growth and the transcriptome was investigated upon BA treatment.

Results and conclusion

Interestingly, α-BA and β-BA treatment promoted certain tumor properties in both pedHGG cells. AKBA treatment reduced cell viability and colony growth accompanied by induction of slight anti-inflammatory effects especially in H3.3K27M-mutant pedHGG cells. However, no effects on apoptosis and in ovo tumor growth were found. In conclusion, besides positive anti-tumor effects of AKBA, tumor promoting effects were observed upon treatment with α-BA and β-BA. Thus, only pure AKBA formulations may be used to exploit any potential positive effects in pedHGG patients. In conclusion, the use of commercially available supplements with a mixture of different BA cannot be recommended due to detrimental effects of certain BA whereas pure AKBA formulations might hold some potential as therapeutic supplement for treatment of pedHGG patients.

Efficacy and Safety of Aflapin®, a Novel Boswellia Serrata Extract, in the Treatment of Osteoarthritis of the Knee: A Short-Term 30-Day Randomized, Double-Blind, Placebo-Controlled Clinical Study

BACKGROUND AND OBJECTIVE

Aflapin^®, also known as AprèsFlex^® was developed as an enhanced bioavailable extract of Boswellia serrata gum resin, standardized to 20% 3-O-acetyl-11-keto-β-boswellic acid. This randomized, double-blind, placebo-controlled clinical trial confirms the efficacy of Aflapin in ameliorating the symptoms of osteoarthritis (OA) of the knee.

METHODS

Based on the inclusion/exclusion criteria of the American College of Rheumatology, seventy subjects were recruited and randomized into Placebo (n = 35) and Aflapin (n = 35) groups. Subjects received either 100 mg Aflapin or a placebo for 30 days. All subjects were evaluated for pain and physical function using the standard tools i.e., Visual Analog Scale (VAS), Lequesne Functional Index (LFI), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at the baseline (Day 0), 5, and 30 days of treatment. Additionally, several inflammatory and cartilage biomarkers, including matrix metalloproteinase-3 (MMP-3), tumor necrosis factor-α (TNFα), high-sensitive C-reactive protein (hsCRP), Cartilage Oligomeric Matrix Protein (COMP), and collagen type II cleavage (C2C) were evaluated. Total blood chemistry analyses were conducted to affirm the safety of Aflapin.

RESULTS

Sixty-seven subjects completed the study. Aflapin conferred significant improvements in pain scores as early as five days of treatment. Post-trial, VAS, LFI, WOMAC pain, WOMAC stiffness, WOMAC function, and total WOMAC scores decreased in the Aflapin group by 45%, 40.9%, 44.4%, 66.3%, 44.4%, and 48%, respectively. Aflapin supplementation also reduced circulating MMP-3, TNFα, hsCRP, and C2C.

CONCLUSION

This investigation affirms that Aflapin is clinically efficacious, fast-acting, and safe in the management of osteoarthritis. No significant adverse effects were observed.

Beta-Boswellic Acid Protects Against Cerebral Ischemia/Reperfusion Injury via the Protein Kinase C Epsilon/Nuclear Factor Erythroid 2-like 2/Heme Oxygenase-1 Pathway

Ischemic strokes are associated with a high rate of disability and death globally. Cerebral ischemia/reperfusion (I/R) injury is a type of brain damage associated with oxidative stress after an ischemic stroke. Beta-boswellic acid (β-BA) reportedly exerts antioxidant and neuroprotective effects, but its role in cerebral I/R injury is unclear. The aim of this research was to investigate the neuroprotective effects, as well as the mechanisms of β-BA in cerebral I/R injury. In vivo experiments were conducted using a rat middle cerebral artery occlusion and reperfusion (MCAO/R) model, and in vitro experiments were performed using a rat neuronal oxygen-glucose deprivation and reoxygenation (OGD/R) model. Triphenyltetrazolium chloride staining, neurological function scores, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, hematoxylin and eosin staining, and antioxidant levels in the brain were used to assess the effects of β-BA. Flow cytometry was used to detect reactive oxygen species and apoptotic cells. Western blotting and immunofluorescence staining were used to measure protein levels. The results showed that β-BA markedly improved neurological deficits and decreased infarct volume and necrotic neurons in rats. The in vitro results showed that β-BA protected neurons against OGD/R-induced injury. Additionally, β-BA significantly increased the phosphorylation of protein kinase C epsilon (PRKCE) at S729, the translocation of nuclear factor erythroid 2-like 2 (NFE2L2), and expression of heme oxygenase-1 (HMOX1). This study demonstrates that β-BA exerts neuroprotective effects against cerebral I/R via the activation of the PRKCE/NFE2L2/HMOX1 pathway and is a potential therapeutic candidate for ischemic stroke.

The Biological Activity of 3-O-Acetyl-11-keto-β-Boswellic Acid in Nervous System Diseases

Frankincense is a hard gelatinous resin exuded by Boswellia serrata. It contains a complex array of components, of which acetyl-11-keto-beta-boswellic acid (AKBA), a pentacyclic triterpenoid of the resin class, is the main active component. AKBA has a variety of physiological actions, including anti-infection, anti-tumor, and antioxidant effects. The use of AKBA for the treatment of mental diseases has been documented as early as ancient Greece. Recent studies have found that AKBA has anti-aging and other neurological effects, suggesting its potential for the treatment of neurological diseases. This review focuses on nervous system-related diseases, summarizes the functions and mechanisms of AKBA in promoting nerve repair and regeneration after injury, protecting against ischemic brain injury and aging, inhibiting neuroinflammation, ameliorating memory deficits, and alleviating neurotoxicity, as well as having anti-glioma effects and relieving brain edema. The mechanisms by which AKBA functions in different diseases and the relationships between dosage and biological effects are discussed in depth with the aim of increasing understanding of AKBA and guiding its use for the treatment of nervous system diseases.

Safety and efficacy of a feed additive consisting of an extract of olibanum from Boswellia serrata Roxb. ex Colebr. for use in dogs and horses (FEFANA asbl)

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of olibanum extract from Boswellia serrata Roxb. ex Colebr., when used as a sensory additive (flavouring) in feed for all dogs and horses. The FEEDAP Panel concluded that the additive under assessment is safe for horses at the maximum proposed use level of 100 mg/kg in complete feed. For dogs, the calculated safe concentration in feed is 330 mg/kg complete feed. The additive is considered safe for consumers when used at the proposed conditions of use in horses. The additive under assessment should be considered as non-irritant to skin and eyes, but in the absence of data, no conclusion can be drawn on its potential to be a dermal and respiratory sensitiser. The use of the additive under the proposed conditions of use in feed for horses was not expected to pose a risk for the environment. Boswellia species and their preparations were recognised to flavour food. Since their function in feed would be essentially the same as that in food, no further demonstration of efficacy was considered necessary.

Safety assessment of a novel water-soluble extract of Boswellia serrata gum resin: acute toxicity, 90-day sub-chronic toxicity, Ames' bacterial reverse mutation, and in vivo micronucleus assays

Boswellia serrata gum resin extracts have demonstrated potential benefits in alleviating joint pain and discomfort of osteoarthritis. The major objective of the present study was to assess the safety of a water-soluble B. serrata gum resin extract (LI51202F1) in diverse models of acute oral, acute dermal, primary dermal irritation, eye irritation, and 90-day sub-chronic repeated dose toxicity studies, as well as Ames' bacterial reverse mutation assay and in vivo micronucleus assay. The acute oral and dermal toxicity studies in Sprague Dawley (SD) rats demonstrated that the median lethal dose (LD₅₀) of LI51202F1 is >2000 mg/kg body weight (BW). The acute dermal and eye irritation tests in New Zealand white rabbits exhibited that LI51202F1 is non-irritating to the skin and mildly irritating to the eyes, respectively. The 90-days sub-chronic repeated oral dose study demonstrated that the LI51202F1-treated male and female SD rats did not show signs of toxicity on their BW, food intake, organ weights, thyroid hormones, and on the clinical pathology, gross pathology, and histopathological assessments. In male and female rats, the no-observed-adverse-effect level (NOAEL) of LI51202F1 was 500 mg/kg/day, the highest tested dose in the study. The results of the bacterial reverse mutation assay in Salmonella typhimurium TA98, TA100, TA1535, TA1537, and Escherichia coli WP2uvrA (pKM101) strains in the presence or absence of S9 metabolic activation system and a micro-nucleus assay in mouse bone marrow erythrocytes demonstrated that LI51202F1 is neither mutagenic nor clastogenic. In conclusion, under the conditions of these studies, LI51202F1 demonstrated broad-spectrum safety.

Mechanistic role of boswellic acids in Alzheimer's disease: Emphasis on anti-inflammatory properties

The resin/gum of Boswellia species belonging to the family of Burseraceae is a naturally occurring mixture of bioactive compounds, which was traditionally used as a folk medicine to treat conditions like chronic inflammation. Several research studies have also explored its' therapeutic potential against multiple neurodegenerative diseases such as Alzheimer's disease (AD). The main chemical constituents of this gum include boswellic acids (BAs) like 3-O-acetyl-11-keto-β boswellic acid (AKBA) that possess potent anti-inflammatory and neuroprotective properties in AD. It is also involved in inhibiting the acetylcholinesterase (AChE) activity in the cholinergic pathway and improve choline levels as well as its binding with nicotinic receptors to produce anti-inflammatory effects. Multiple shreds of evidence have demonstrated that BAs modulate key molecular targets and signalling pathways like 5-lipoxygenase/cyclooxygenase, Nrf2, NF-kB, cholinergic, amyloid-beta (Aβ), and neurofibrillary tangles formation (NFTs) that are involved in AD progression. The present review focuses on the possible mechanistic therapeutic role of BAs in modulating the 5-LOX/COX pathway in arachidonic acid metabolism, activating Nrf2 through binding of ARE, inhibiting NF-kB and AChE activity. In addition, an inhibition of amyloid plaques (Aβ) and neurofibrillary tangles (NFTs) induced neurotoxicity and neuroinflammation in AD by BAs is also discussed in this review. We have also highlighted that BAs possess beneficial effects in AD by targeting multiple molecular pathways and makes it an emerging drug candidate for treating neurodegenerative diseases.

Potential therapeutic effects of boswellic acids/Boswellia serrata extract in the prevention and therapy of type 2 diabetes and Alzheimer's disease

The link between diabetes and cognitive dysfunction has been reported in many recent articles. There is currently no disease-modifying treatment available for cognitive impairment. Boswellia serrata (B. serrata) is used traditionally to treat chronic inflammatory diseases such as type 2 diabetes (T2D), insulin resistance (IR), and Alzheimer's disease (AD). This review aims to highlight current research on the potential use of boswellic acids (BAs)/B. serrata extract in T2D and AD. We reviewed the published information through June 2021. Studies have been collected through a search on online electronic databases (Academic libraries as PubMed, Scopus, Web of Science, and Egyptian Knowledge Bank). Accumulating evidence in preclinical and small human clinical studies has indicated that BAs/B. serrata extract has potential therapeutic effect in T2D and AD. According to most of the authors, the potential therapeutic effects of BAs/B. serrata extract in T2D and AD can be attributed to immunomodulatory, anti-inflammatory, antioxidant activity, and elimination of the senescent cells. BAs/B. serrata extract may act by inhibiting the IκB kinase/nuclear transcription factor-κB (IKK/NF-κB) signaling pathway and increasing the formation of selective anti-inflammatory LOX-isoform modulators. In conclusion, BAs/B. serrata extract may have positive therapeutic effects in prevention and therapy of T2D and AD. However, more randomized controlled trials with effective, large populations are needed to show a definitive conclusion about therapeutic efficacy of BAs/B. serrata extract in T2D and AD.

Identification of Potential Antiseizure Agents in Boswellia sacra using In Vivo Zebrafish and Mouse Epilepsy Models

The resin of the tree Boswellia sacra Flueck. (synonym: B. carterii; Burseraceae), also known as "frankincense", is a traditional remedy used for central nervous system disorders in East Africa. Here we report the evaluation of its antiseizure activity in zebrafish and mouse epilepsy models to identify novel antiseizure compounds. The resin was extracted by solvents of increasing polarity. The hexane extract demonstrated the strongest antiseizure activity and was therefore subjected to bioactivity-guided isolation, which leaded to the isolation of eight terpene derivatives. A new prenylbicyclogermacrene derivative (2) was isolated along with seven other compounds (1, 3-8). Among them, the triterpene β-boswellic acid (5) showed the strongest activity and reduced 90% of pentylenetetrazole (PTZ)-induced seizures at 100 μg/mL. In parallel to B. sacra, a commercial extract of Boswellia serrata was also evaluated and showed moderate bioactivity (45% reduction at 30 μg/mL). The extract of B. serrata was subjected to targeted isolation of other boswellic acid derivatives (9-13), which were evaluated for antiseizure activity in comparison with 5. In the whole series, β-boswellic acid (5) was the most active (60% reduction at 200 μM), and its potency was also confirmed with its purchased standard (S5). Pure nanoparticles of S5 and a commercially formulated extract of B. serrata were tested in a PTZ-kindling mouse seizure model. This notably revealed that the S5 administration reduced seizures by 50% in this mouse model, which was consistent with its detection and quantification in plasma and brain samples. This study and the preclinical evaluation performed indicate that β-boswellic acid, common to various species of Boswellia, has some potential as an antiseizure agent.

Considerations to Be Taken When Carrying Out Medicinal Plant Research-What We Learn from an Insight into the IC50 Values, Bioavailability and Clinical Efficacy of Exemplary Anti-Inflammatory Herbal Components

Medicinal plants represent a big reservoir for discovering new drugs against all kinds of diseases including inflammation. In spite the large number of promising anti-inflammatory plant extracts and isolated components, research on medicinal plants proves to be very difficult. Based on that background this review aims to provide a summarized insight into the hitherto known pharmacologically active concentrations, bioavailability, and clinical efficacy of boswellic acids, curcumin, quercetin and resveratrol. These examples have in common that the achieved plasma concentrations were found to be often far below the determined IC50 values in vitro. On the other hand demonstrated therapeutic effects suggest a necessity of rethinking our pharmacokinetic understanding. In this light this review discusses the value of plasma levels as pharmacokinetic surrogates in comparison to the more informative value of tissue concentrations. Furthermore the need for new methodological approaches is addressed like the application of combinatorial approaches for identifying and pharmacokinetic investigations of active multi-components. Also the physiological relevance of exemplary in vitro assays and absorption studies in cell-line based models is discussed. All these topics should be ideally considered to avoid inaccurate predictions for the efficacy of herbal components in vivo and to unlock the "black box" of herbal mixtures.

SZB120 Exhibits Immunomodulatory Effects by Targeting eIF2α to Suppress Th17 Cell Differentiation

IL-17-secreting Th17 cells play an important role in the pathogenesis of various inflammatory and autoimmune diseases. IL-17-targeted biologics and small molecules are becoming promising treatments for these diseases. In this study, we report that SZB120, a derivative of the natural compound 3-acetyl-β-boswellic acid, inhibits murine Th17 cell differentiation by interacting with the α-subunit of eukaryotic initiation factor 2 (eIF2α). We showed that SZB120 directly interacts with eIF2α and contributes to serine 51 phosphorylation of eIF2α. The suppressive effect of SZB120 on Th17 cell differentiation was reversed by GSK2606414, an inhibitor of eIF2α phosphokinase. Phosphorylation of eIF2α induced by SZB120 decreased the protein expression of IκBζ, which is important for Th17 cell differentiation. Notably, interaction with eIF2α by SZB120 also impaired glucose uptake and glycolysis in T cells. In vivo, SZB120 treatment of C57BL/6 mice significantly attenuated IL-17/Th17-mediated autoimmune disease. Our study indicates that SZB120 is a promising drug candidate for IL-17/Th17-mediated inflammatory diseases.

Investigation of Molecular Properties that Influence the Permeability and Oral Bioavailability of Major β-Boswellic Acids

BACKGROUND AND OBJECTIVES

Boswellic acids (BAs) include β-boswellic acid (BA), 3-acetyl-β-boswellic acid, 11-keto-β-boswellic acid, 3-acetyl-11-keto-β-boswellic acid, β-boswellic alcohol, and 3-acetyl-11-hydroxy-β-BA from Boswellia species, and are the main active ingredients of Boswellia serrata extracts (BSE). BSE have been used for the treatment of different inflammatory diseases; however, their pharmaceutical development has been severely limited by their poor oral bioavailability. The aims of this study were to investigate the molecular properties of six BAs, and to determine their experimental aqueous solubility, partition coefficient (Log P), gastrointestinal stability, adsorption-desorption kinetics, and permeability studies.

METHODS

The physicochemical properties of six BAs were obtained from SMILES representations using ChemDraw, and MarvinSketch. The molecular properties were also determined experimentally. The permeability studies were performed using parallel artificial membrane permeability assay (PAMPA), and Caco-2 cells.

RESULTS

The experimental Log P values of BAs correlated well (R² = 0.94) with the calculated Log P values. Metabolic stability data confirmed that BAs were found to be unstable in simulated gastrointestinal fluids and intestinal S9 fractions. The apparent permeability (P_app) range of BAs in both PAMPA and Caco-2 for the apical (AP) to basolateral (BL) was in the range of 0.52 ± 0.05 × 10^-6 to 2.84 ± 0.14 × 10^-6cm/s. The efflux ratio of P_app (BL → AP) to P_app (AP → BL) for all BAs was < 2 in Caco-2 cells, suggesting greater permeability in the absorptive direction. Caco-2 cell adsorption studies confirmed the accumulation of BAs (35-55%) inside the enterocytes. These compounds exhibited a strong correlation between PAMPA and Caco-2 cell monolayer permeation data.

CONCLUSIONS

The results of the present study have shown an empirical relationship between the molecular properties and intestinal absorption of BAs for the first time.

Acetyl-α-boswellic acid and Acetyl-β-boswellic acid protects against caerulein-induced pancreatitis via down-regulating MAPKs in mice

This study is to investigate the protective effect of Acetyl-α-boswellic acid and Acetyl-β-boswellic mixture(α/β-ABA), which is the active ingredients isolated from Frankincense, on actue pancreatitis and its mechanism. Our experimental results showed that 2 μM α/β-ABA reduced production of NO, TNF-α, IL-6, IL-10 and IL-1β in RAW264.7 cells that were stimulated with lipopolysaccharide (LPS) which indicates its anti-inflammatory role. In pancreatitis model induced by caerulein, intra-gastrical administration of 100 mg/kg α/β-ABA relieved inflammatory cells infiltration significantly and attenuated the serum elevation of amylase TNF-α and IL-6 remarkably in mice. Furthermore, α/β-ABA down-regulated mitogen-activated protein kinase (MAPK) family phosphorylated proteins in pancreas, including phosphorylated p38, ERK1/2 and JNK, to reduce the serum inflammatory factors. Finally, α/β-ABA alleviated the pancreatic edema and inflammatory cell infiltration in pancreatitis mice model. This study suggests that α/β-ABA may be targeted for drug development against pancreatitis via modulating MAPKs pathway.

The Effects of Vinegar Processing on the Changes in the Physical Properties of Frankincense Related to the Absorption of the Main Boswellic Acids

Boswellic acids (BAs), as the main components of frankincense, exhibit notable anti-inflammatory properties. However, their pharmaceutical development has been severely limited by their poor oral bioavailability. Traditional Chinese medicinal processing, called Pao Zhi, is believed to improve bioavailability, yet the mechanism is still completely unclear. Previous research suggested that the bioavailability of a drug can be influenced by physical properties. This paper was designed to investigate the physical properties of frankincense and processed frankincense, including the surface morphology, particle size, polydispersity index (PDI), zeta potential (ZP), specific surface area, porosity, and viscosity. The differences in the intestinal absorption characteristics and equilibrium solubilities between frankincense and processed frankincense were determined by an ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UHPLC-TQ-MS) analysis method. The results showed that vinegar processing can alter the surface morphology, decrease the particle size and PDI, raise the absolute values of the ZP, specific surface area and porosity, and drop the viscosity of frankincense. Meanwhile, the rates of absorption and dissolution of the main BAs were increased after the processing of frankincense. The present study proves that the physical properties were changed after processing, in which case the bioavailability of frankincense was enhanced.

Seeing the Unseen of the Combination of Two Natural Resins, Frankincense and Myrrh: Changes in Chemical Constituents and Pharmacological Activities

For the treatment of diseases, especially chronic diseases, traditional natural drugs have more effective therapeutic advantages because of their multi-target and multi-channel characteristics. Among many traditional natural medicines, resins frankincense and myrrh have been proven to be effective in the treatment of inflammation and cancer. In the West, frankincense and myrrh have been used as incense in religious and cultural ceremonies since ancient times; in traditional Chinese and Ayurvedic medicine, they are used mainly for the treatment of chronic diseases. The main chemical constituents of frankincense and myrrh are terpenoids and essential oils. Their common pharmacological effects are anti-inflammatory and anticancer. More interestingly, in traditional Chinese medicine, frankincense and myrrh have been combined as drug pairs in the same prescription for thousands of years, and their combination has a better therapeutic effect on diseases than a single drug. After the combination of frankincense and myrrh forms a blend, a series of changes take place in their chemical composition, such as the increase or decrease of the main active ingredients, the disappearance of native chemical components, and the emergence of new chemical components. At the same time, the pharmacological effects of the combination seem magically powerful, such as synergistic anti-inflammation, synergistic anticancer, synergistic analgesic, synergistic antibacterial, synergistic blood-activation, and so on. In this review, we summarize the latest research on the main chemical constituents and pharmacological activities of these two natural resins, along with chemical and pharmacological studies on the combination of the two.

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.

Kinetic and thermodynamic study of beta-Boswellic acid interaction with Tau protein investigated by surface plasmon resonance and molecular modeling methods

Introduction: Beta-Boswellic acid (BBA) is a pentacyclic terpene which has been obtained from frankincense and its beneficial effects on neurodegenerative disorders such as Alzheimer’s disease (AD) have been addressed.

Methods: In the present study, thermodynamic and kinetic aspects of BBA interaction with Tau protein as one of the important proteins involved in AD in the absence and presence of glucose has been investigated using surface plasmon resonance (SPR) method. Tau protein was immobilized onto the carboxy methyl dextran chip and its binding interactions with BBA were studied at physiological pH at various temperatures. Glucose interference with these interactions was also investigated.

Results: Results showed that BBA forms a stable complex with Tau (K_D=8.45×10^-7 M) at 298 K. Molecular modeling analysis showed a hydrophobic interaction between BBA and HVPGGG segment of R₂ and R₄ repeated domains of Tau.

Conclusion: The binding affinity increased by temperature enhancement, while it decreased significantly in the presence of glucose. Both association and dissociation of the BBA-Tau complex were accompanied with an entropic activation barrier; however, positive enthalpy and entropy changes revealed that hydrophobic bonding is the main force involved in the interaction.

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.

Pentacyclic Triterpene Bioavailability: An Overview of In Vitro and In Vivo Studies

Pentacyclic triterpenes are naturally found in a great variety of fruits, vegetables and medicinal plants and are therefore part of the human diet. The beneficial health effects of edible and medicinal plants have partly been associated with their triterpene content, but the in vivo efficacy in humans depends on many factors, including absorption and metabolism. This review presents an overview of in vitro and in vivo studies that were carried out to determine the bioavailability of pentacyclic triterpenes and highlights the efforts that have been performed to improve the dissolution properties and absorption of these compounds. As plant matrices play a critical role in triterpene bioaccessibility, this review covers literature data on the bioavailability of pentacyclic triterpenes ingested either from foods and medicinal plants or in their free form.

Nanoparticle formulation of 11-keto-β-boswellic acid (KBA): anti-inflammatory activity and in vivo pharmacokinetics

CONTEXT

The oleo-gum-resin of Boswellia serrata Roxb. (Burseraceae) is widely used for the treatment of inflammatory diseases such as osteoarthritis, rheumatoid arthritis and cancer. Anti-inflammatory activity of 11-keto-β-boswellic acid (KBA) is impeded by poor oral bioavailability due to its high lipid solubility, rapid phase-1 metabolism and poor intestinal permeability.

OBJECTIVE

This study developed a poly-dl-lactide-co-glycolide-based nanoparticle formulation of KBA to improve its oral bioavailability and in vivo anti-inflammatory activity.

MATERIALS AND METHODS

KBA was isolated from the oleo-gum resin of B. serrata, and its nanoparticle formulation (KBA-NPs) was prepared by the emulsion-diffusion-evaporation method. Oral bioavailability of KBA and KBA-NPs was studied at 50 mg/kg p.o. dose in Sprague-Dawley rats, and further evaluated for in vivo anti-inflammatory activity in carrageenan-induced rat paw oedema assay at the same dose level.

RESULTS

The prepared KBA-NPs had a particle size of 152.6 nm with polydispersity index of 0.194, 79.7% entrapment efficiency and a cumulative 61.5% release of KBA from KBA-NPs, at 72 h. KBA-NPs showed 60.8% inhibition of rat paw oedema at 5 h as compared to 34.9% as that of KBA. The results of oral bioavailability study and in vivo anti-inflammatory activity showed 7- and 1.7-fold increase in bioavailability and anti-inflammatory activity, respectively, of KBA in KBA-NPs as compared to KBA alone.

CONCLUSION

The results of improved oral bioavailability and in vivo anti-inflammatory activity of KBA-NPs suggested successful development of KBA nanoparticle formulation.

A single-dose, randomized, cross-over, two-way, open-label study for comparing the absorption of boswellic acids and its lecithin formulation

BACKGROUND

The oral administration of the gum resin extracts of Indian frankincense (Boswellia serrata Roxb. ex Colebr) results in very low plasma concentrations of boswellic acids (BAs), being far below the pharmacologically active concentrations required in vitro for anti-inflammatory activity. For that reason the use of Indian frankincense in clinical practice and pharmaceutical development has substantially lagged behind. Recently the application of new formulation technologies resulted in a formulation of frankincense extract with lecithin, which revealed improved absorption and tissue penetration of BAs in a rodent study, leading for the first time to plasma concentrations of BAs in the range of their anti-inflammatory activity.

PURPOSE

In order to verify these encouraging results in humans, the absorption of a standardized Boswellia serrata extract (BE) and its lecithin formulation (CSP) was comparatively investigated in healthy volunteers.

STUDY DESIGN

According to a randomized cross-over design with two treatments, two sequences and two periods, 12 volunteers alternatively received the lecithin-formulated Boswellia extract (CSP) or the non-formulated Boswellia extract (BE) at a dosage of 2×250mg capsules.

METHODS

The plasma concentrations of the six major BAs (KBA, AKBA, βBA, αBA, AβBA, AαBA) were determined using LC/MS.

RESULTS

With the exception of KBA, a significantly higher (both in terms of weight-to-weight and molar comparison) and quicker absorption of BAs from the lecithin formulation was observed, leading to C_max in the range required for the interaction with their molecular targets.

CONCLUSION

These findings pave the way to further studies evaluating the clinical potential of BAs, and verify the beneficial effect of lecithin formulation to improve the absorption of poorly soluble phytochemicals.

β-Boswellic acid, a bioactive substance used in food supplements, inhibits protein synthesis by targeting the ribosomal machinery

The Boswellia gum resin extracts have been used in traditional medicines because of their remarkable anti-inflammatory properties. Nowadays, these extracts are on the market as food supplements. β-Boswellic acid (βBA) is one of the main pentacyclic triterpene components, among the family of BAs, of the Boswellia gum resins. BAs have been broadly studied and are well known for their wide anti-inflammatory and potential anticancer properties. In this paper, a mass spectrometry-based chemoproteomic approach has been applied to characterize the whole βBA interacting profile. Among the large numbers of proteins fished out, proteasome, 14-3-3 and some ribosomal proteins were considered the most interesting targets strictly connected to the modulation of the cancer progression. In particular, because of their recent assessment as innovative chemotherapeutic targets, the ribosomal proteins were considered the most attractive βBA partners, and the biological role of their interaction with the natural compound has been evaluated. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous quantification of triterpenoic acids by high performance liquid chromatography method in the extracts of gum resin of Boswellia serrata obtained by different extraction techniques

Background

Boswellia serrata, also known as Indian frankincense is a commercially important medicinal plant which has been used for hundreds of years as an Ayurvedic medicine for the attempted treatment of arthritis. It contains naturally occurring triterpenoic acids, called as boswellic acids (BA’s).

Results

A highly reproducible High performance liquid chromatography-ultraviolet diode array detection (HPLC-UV-DAD) method was developed for the simultaneous determination and quantitative analysis of eight major triterpenoic acids in Boswellia serrata gum resin obtained by different extraction techniques. All the calibration curves exhibited good linear regression (R² > 0.997) within the test ranges. The established method showed good precision and overall recoveries of the boswellic acids.

Conclusions

The eight triterpenoic acids coded as BS-1 (11-keto-beta-boswellic acid), BS-2 (3-O-acetyl-11-keto-beta-boswellic acid), BS-3 (3-keto tirucallic acid), BS-4 (3-O-acetyl-alpha-tirucallic acid), BS-5 (3-O-acetyl-beta-tirucallic acid), BS-6 (alpha-boswellic acid), BS-7 (beta-boswellic acid) and BS-8 (3-O-acetyl-beta-boswellic acid) were isolated from the processed gum resin of Boswellia serrata by column chromatography. The proposed HPLC method is simple, reliable and has been very useful for the qualitative as well as quantitative analysis of boswellic acids in the gum resin of Boswellia serrata. The proposed method allows to quantify boswellic acids in appreciable amounts by HPLC-UV (DAD) method in the extracts and the available marketed formulations.Graphical abstract

Boswellic acid activity against glioblastoma stem-like cells

Boswellic acids (BAs) have long been considered as useful adjunct pharmacological agents for the treatment of patients with malignant brain tumors, notably glioblastoma. Two principal modes of action associated with BAs have been postulated: i) Anti-inflammatory properties, which are useful for containing edema formation, and ii) intrinsic antitumor cell properties, with a hitherto ill-defined mode of action. The present study assessed the effects of various BA derivatives on the viability and clonogenicity of a panel of nine long-term glioma cell lines and five glioma-initiating cell lines, studied cell cycle progression and the mode of cell death induction, and explored potential synergy with temozolomide (TMZ) or irradiation. BA induced the concentration-dependent loss of viability and clonogenicity that was independent of tumor protein 53 status and O6-methylguanine DNA methyltransferase expression. The treatment of glioma cells with BA resulted in cell death induction, prior to or upon S phase entry, and exhibited features of apoptotic cell death. Synergy with irradiation or TMZ was detected at certain concentrations; however, the inhibitory effects were mostly additive, and never antagonistic. While the intrinsic cytotoxic properties of BA at low micromolecular concentrations were confirmed and the potential synergy with irradiation and TMZ was identified, the proximate pharmacodynamic target of BA remains to be identified.

Pretreatment with β-Boswellic Acid Improves Blood Stasis Induced Endothelial Dysfunction: Role of eNOS Activation

Vascular endothelial cells play an important role in modulating anti-thrombus and maintaining the natural function of vascular by secreting many active substances. β-boswellic acid (β-BA) is an active triterpenoid compound from the extract of boswellia serrate. In this study, it is demonstrated that β-BA ameliorates plasma coagulation parameters, protects endothelium from blood stasis induced injury and prevents blood stasis induced impairment of endothelium-dependent vasodilatation. Moreover, it is found that β-BA significantly increases nitric oxide (NO) and cyclic guanosine 3’, 5’-monophosphate (cGMP) levels in carotid aortas of blood stasis rats. To stimulate blood stasis-like conditions in vitro, human umbilical vein endothelial cells (HUVECs) were exposed to transient oxygen and glucose deprivation (OGD). Treatment of β-BA significantly increased intracellular NO level. Western blot and immunofluorescence as well as immunohistochemistry reveal that β-BA increases phosphorylation of enzyme nitric oxide synthase (eNOS) at Ser1177. In addition, β-BA mediated endothelium-dependent vasodilatation can be markedly blocked by eNOS inhibitor L-NAME in blood stasis rats. In OGD treated HUEVCs, the protective effect of β-BA is attenuated by knockdown of eNOS. In conclusion, the above findings provide convincing evidence for the protective effects of β-BA on blood stasis induced endothelial dysfunction by eNOS signaling pathway.

Boswellic acids target the human immune system-modulating antimicrobial peptide LL-37

The antimicrobial peptide LL-37 is the sole member of the human cathelicidin family with immune system-modulating properties and roles in autoimmune disease development. Small molecules able to interact with LL-37 and to modulate its functions have not been described yet. Boswellic acids (BAs) are pentacyclic triterpene acids that are bioactive principles of frankincense extracts used as anti-inflammatory remedies. Although various anti-inflammatory modes of action have been proposed for BAs, the pharmacological profile of these compounds is still incompletely understood. Here, we describe the identification of human LL-37 as functional target of BAs. In unbiased target fishing experiments using immobilized BAs as bait and human neutrophils as target source, LL-37 was identified as binding partner assisted by MALDI-TOF mass spectrometry. Thermal stability experiments using circular dichroism spectroscopy confirm direct interaction between BAs and LL-37. Of interest, this binding of BAs resulted in an inhibition of the functionality of LL-37. Thus, the LPS-neutralizing properties of isolated LL-37 were inhibited by 3-O-acetyl-β-BA (Aβ-BA) and 3-O-acetyl-11-keto-β-BA (AKβ-BA) in a cell-free limulus amoebocyte lysate assay with EC50=0.2 and 0.8 μM, respectively. Also, LL-37 activity was inhibited by these BAs in LL-37-enriched supernatants of stimulated neutrophils or human plasma derived from stimulated human whole blood. Together, we reveal BAs as inhibitors of LL-37, which might be a relevant mechanism underlying the anti-inflammatory properties of BAs and suggests BAs as suitable chemical tools or potential agents for intervention with LL-37 and related disorders.

Development and optimisation of 3-Acetyl-11-keto-β-boswellic acid loaded poly-lactic-co-glycolic acid-nanoparticles with enhanced oral bioavailability and in-vivo anti-inflammatory activity in rats

OBJECTIVES

3-Acetyl-11-keto-β-boswellic acid (AKBA) is a potent anti-inflammatory compound of Boswellia serrata. However, anti-inflammatory activity of AKBA is impeded by poor oral bioavailability due to its poor aqueous solubility. In this context, we aimed to develop poly lactic-co-glycolic acid (PLGA)-based nanoparticle formulation of AKBA (AKBA-NPs) in order to improve its oral bioavailability and in-vivo anti-inflammatory activity in rats.

METHODS

AKBA-NPs were prepared and characterised by analysing particle size and zeta potential using zeta sizer, surface morphology by scanning electron microscopy and transmission electron microscopy, and physical property using differential scanning calorimetry and X-ray diffraction techniques. The optimised nanoparticles were evaluated for in-vitro drug release and oral bioavailability studies, and in-vivo anti-inflammatory activity by carrageenan-induced rat paw oedema method.

KEY FINDINGS

The optimised AKBA-NPs showed the particle size of 179.6 nm with 0.276 polydispersity index and entrapment efficiency of 82.5%. AKBA-NPs showed increased in-vivo anti-inflammatory activity as compared with AKBA. Bioavailability study revealed about six times higher peak plasma concentration of AKBA in AKBA-NPs. Moreover, t1/2 and total area under the curve of AKBA were also enhanced by two and ninefold, respectively, in AKBA-NPs as compared with corresponding AKBA.

CONCLUSIONS

The promising results of improved oral bioavailability and in-vivo anti-inflammatory activity of AKBA suggested the successful nanoparticle formulation of AKBA.

Identification in Rat Plasma and Urine by Linear Trap Quadrupole-Orbitrap Mass Spectrometry of the Metabolites of Maslinic Acid, a Triterpene from Olives

Maslinic acid is a natural pentacyclic triterpenoid widely distributed in edible and medicinal plants with health-promoting activities. The identification and quantification of its metabolites is a requirement for a better understanding of the biological effects of this triterpene. Therefore, maslinic acid was orally administered to Sprague-Dawley rats at a dose of 50 mg/kg of body weight. Blood and urine were withdrawn at 45 min. Samples were extracted with ethyl acetate prior to liquid chromatography-atmospheric pressure chemical ionization-linear trap quadrupole-Orbitrap (LC-APCI-LTQ-Orbitrap) analysis. Screening of plasma yielded four monohydroxylated derivatives (M1-M4), one monohydroxylated and dehydrogenated metabolite (M5), and two dihydroxylated and dehydrogenated compounds (M6 and M7). In urine, M1, M4, M5, and M6 were detected. Quantification by LC-APCI-mass spectrometry (MS) revealed maslinic acid as the prevalent compound in both plasma (81.8%) and urine (73.9%), which indicates that metabolism is low and mainly attributable to phase I reactions.

Comparative pharmacokinetic study of two boswellic acids in normal and arthritic rat plasma after oral administration of Boswellia serrata extract or Huo Luo Xiao Ling Dan by LC-MS

Huo Luo Xiao Ling Dan (HLXLD), a Chinese herbal formula composed of 11 different herbs, has been used traditionally for the treatment of arthritis and other chronic inflammatory diseases. However, the pharmacokinetic profile of its anti-inflammatory bioactive compounds has not been elucidated. Boswellic acids are the bioactive compounds with potent anti-inflammatory activity isolated from Boswellia serrate which is one of the 11 herbs of HLXLD. The objective of the study was to compare the pharmacokinetics of the two bioactive bowsellic acids: 11-keto-β-boswellic acid and 3-O-acetyl-11-keto-β-boswellic following oral administration of HLXLD or Boswellia serrata extract alone in normal and arthritic rats. An LC-MS method was developed and validated for the determination of 11-keto-β-boswellic acid and 3-O-acetyl-11-keto-β-boswellic in the comparative pharmacokinetic study. The results showed that there were significant differences in pharmacokinetic parameters between normal and arthritic groups. Interestingly, the absorptions of two boswellic acids were significantly higher in HLXLD than Boswellia serrata extract alone, indicating the synergistic effect of other herbal ingredients in HLXLD. This comparative pharmacokinetic study provided direct evidence supporting the notion that the efficacy of a complex mixture such as HLXLD is better than that of single components in treating human diseases.

Investigating permeability related hurdles in oral delivery of 11-keto-β-boswellic acid

11-Keto-β-boswellic acid (KBA) is an important and potent boswellic acids responsible for anti-inflammatory action of Boswellia extract. However, its pharmaceutical development has been severely limited by its poor oral bioavailability. The present work aims to investigate the permeability related hurdles in oral delivery of KBA. Gastrointestinal stability, gastrointestinal metabolism, adsorption-desorption kinetics and Caco-2 permeability studies have been carried out. KBA was found poorly permeable with Papp value of 2.85 ± 0.14 × 10(-6)cm/s. Higher absorptive transport indicated role of carrier mediated transport. Moreover, KBA transport across monolayer showed saturation kinetics at higher concentrations. KBA exposed to 1α,25-(OH)2 vitamin D3 treated cell monolayer showed the lowest Papp value of 2.01×10(-6) ± 0.02 × 10(-6)cm/s indicating role of CYP3A4 mediated metabolism during KBA transport. Metabolic stability experiments in jejunum S9 fractions further confirmed this. KBA was found unstable in simulated gastrointestinal fluids and also got accumulated in the enterocytes. Sorption and desorption kinetic studies using Caco-2 cells further confirmed accumulation of KBA inside the enterocytes. KBA also showed pH dependent permeability with higher flux at gradient pH condition of pH 6.5 at apical and 7.4 at basolateral. Taken as whole, the major permeability related hurdles that hampered oral bioavailability of KBA included its gastrointestinal instability, CYP3A4 mediated intestinal metabolism, accumulation within the enterocytes and saturable kinetics. The present investigation may help in designing novel drug delivery system for KBA.

Inhibitors of cathepsin G: a patent review (2005 to present)

INTRODUCTION

Cathepsin G (CatG) is a neutral proteinase originating from human neutrophils. It displays a unique dual specificity (trypsin- and chymotrypsin-like); thus, its enzymatic activity is difficult to control. CatG is involved in the pathophysiology of several serious human diseases, such as chronic obstructive pulmonary disease (COPD), Crohn's disease, rheumatoid arthritis, cystic fibrosis and other conditions clinically manifested by excessive inflammatory reactions. For mentioned reasons, CatG was considered as good molecular target for the development of novel drugs. However, none of them have yet entered the market as novel therapeutic agents.

AREAS COVERED

This article presents an in-depth and detailed analysis of the therapeutic potential of CatG inhibitors based on a review of patent applications and academic publishing disclosed in patents and patent applications (1991 - 2012), with several exceptions for inhibitors retrieved from academic articles.

EXPERT OPINION

Among the discussed inhibitors of CatG, examples corresponding to derivatives of β-ketophosphonic acids, aminoalkylphosphonic esters and boswellic acids (BAs) could be regarded as the most promising. The most promising one seems to be analogues of compounds of Nature's origin (peptidic and BA derivates). Nevertheless, nothing is currently known about the clinical disposition of any of the CatG inhibitors discovered so far. This latter point suggests that there is still a lot of work to do in the design of stable, pharmacologically active compounds able to specifically regulate the in vivo activity of cathepsin G.

Triterpenoid resinous metabolites from the genus Boswellia: pharmacological activities and potential species-identifying properties

The resinous metabolites commonly known as frankincense or olibanum are produced by trees of the genus Boswellia and have attracted increasing popularity in Western countries in the last decade for their various pharmacological activities. This review described the pharmacological specific details mainly on anti-inflammatory, anti-carcinogenic, anti-bacterial and apoptosis-regulating activities of individual triterpenoid together with the relevant mechanism. In addition, species-characterizing triterpenic markers with the methods for their detection, bioavailability, safety and other significant properties were reviewed for further research.