11-Keto-β-Boswellic Acids Prevent Development of Autoimmune Reactions, Insulitis and Reduce Hyperglycemia During Induction of Multiple Low-Dose Streptozotocin (MLD-STZ) Diabetes in Mice

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.

Naturally-occurring carboxylic acids from traditional antidiabetic plants as potential pancreatic islet FABP3 inhibitors. A molecular docking-aided study

The antidiabetic action of traditional plants is mostly attributed to their antioxidant and anti-inflammatory properties. These plants are still having some secrets, making them an attractive source that allows for investigating new drugs or uncovering precise pharmacologic antidiabetic functions of their constituents. In diabetes, which is a lipid disease, long-term exposure of pancreatic islet beta cells to fatty acids (FAs) increases basal insulin release, reduces glucose-stimulated insulin secretion, causes islet beta cell inflammation, failure and apoptosis. Pancreatic islet beta cells express fatty acid binding protein 3 (FABP3) that receives long-chain FAs and traffics them throughout different cellular compartments to be metabolized and render their effects. Inhibition of this FABP3 may retard FA metabolism and protect islet beta cells. Since FAs interact with FABPs by their carboxylic group, some traditionally-known antidiabetic plants were reviewed in the present study, searching for their components that have common features of FABP ligands, namely carboxylic group and hydrophobic tail. Many of these carboxylic acids were computationally introduced into the ligand-binding pocket of FABP3 and some of them exhibited FABP3 ligand possibilities. Among others, the naturally occurring ferulic, cleomaldeic, caffeic, sinapic, hydroxycinnamic, 4-p-coumaroylquinic, quinoline-2-carboxylic, chlorogenic, 6-hydroxykynurenic, and rosmarinic acids in many plants are promising candidates for being FABP3-specific inhibitors. The study shed light on repurposing these phyto-carboxylic acids to function as FABP inhibitors. However, more in-depth biological and pharmacological studies to broaden the understanding of this function are needed.

The Anti-Inflammatory and Immunomodulatory Activities of Natural Products to Control Autoimmune Inflammation

Inflammation is an integral part of autoimmune diseases, which are caused by dysregulation of the immune system. This dysregulation involves an imbalance between pro-inflammatory versus anti-inflammatory mediators. These mediators include various cytokines and chemokines; defined subsets of T helper/T regulatory cells, M1/M2 macrophages, activating/tolerogenic dendritic cells, and antibody-producing/regulatory B cells. Despite the availability of many anti-inflammatory/immunomodulatory drugs, the severe adverse reactions associated with their long-term use and often their high costs are impediments in effectively controlling the disease process. Accordingly, suitable alternatives are being sought for these conventional drugs. Natural products offer promising adjuncts/alternatives in this regard. The availability of specific compounds isolated from dietary/medicinal plant extracts have permitted rigorous studies on their disease-modulating activities and the mechanisms involved therein. Here, we describe the basic characteristics, mechanisms of action, and preventive/therapeutic applications of 5 well-characterized natural product compounds (Resveratrol, Curcumin, Boswellic acids, Epigallocatechin-3-gallate, and Triptolide). These compounds have been tested extensively in animal models of autoimmunity as well as in limited clinical trials in patients having the corresponding diseases. We have focused our description on predominantly T cell-mediated diseases, such as rheumatoid arthritis, multiple sclerosis, Type 1 diabetes, ulcerative colitis, and psoriasis.

Anti-diabetic potential of β-boswellic acid and 11-keto-β-boswellic acid: Mechanistic insights from computational and biochemical approaches

β-Boswellic acid (β-BA) and 11-keto-β-boswellic acid (β-KBA) are crucial bioactive compounds, mostly isolated from frankincense. These compounds are known for their potent anticancer and anti-inflammatory activities. Herein, we have explored the complete anti-diabetic potential of β-BA and β-KBA with detailed parameters. This research revealed that treatment with β-BA and β-KBA at a dose of 1, 2, and 10 mg/kg body weight for 21 days significantly improved body weight loss, water consumption, and specifically the concentration of blood glucose level (BGL) in diabetic animals, which indicated that the β-BA and β-KBA possess strong anti-diabetic activities. Serum total superoxide dismutase (SOD) and malondialdehyde (MDA) assays were also performed to evaluate the antioxidant effects. The biochemical analysis revealed that these compounds improve an abnormal level of several biochemical parameters like serum lipid values including total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C) to a normal level and the high-density lipoprotein cholesterol level (HDL-C). To understand the mechanism of action of β-BA and β-KBA, their most probable biological targets were searched through the inverse docking approach. Our computational analysis reflects that among other probable targets, the Dipeptidyl peptidase 4 (DPP-4) enzyme could be one of the possible binders of β-BA and β-KBA to produce their anti-diabetic activities. These in-silico results were validated by an in-vitro experiment. It indicates that the anti-diabetic effects of β-BA and β-KBA are produced by the inhibition of DDP-4. Thus, these anti-diabetic, antioxidant, and anti-hyperlipidemic effects of β-BA and β-KBA suggest these compounds as potential therapeutics for diabetic conditions.

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.

Evaluation of the solubility of 11-keto-β-boswellic acid and its histological effect on the diabetic mice liver using a novel technique

Background and Aim:

The literature is scant on the effect of 11-keto-β-boswellic acid (KBA) on the liver of diabetes-induced mice. This study was designed to develop a rapid, sensitive, accurate, and inexpensive detection technique for evaluating the solubility of KBA obtained from the gum resin of Omani frankincense (Boswellia sacra) in the liver of streptozotocin-induced diabetic mice using Fourier transform infrared (FTIR) reflectance spectroscopy coupled with principal components analysis (PCA). It also aimed to investigate the effect of KBA on histological changes in the hepatocytes of diabetic mice.

Materials and Methods:

Eighteen mice were assigned to the healthy control group, the diabetic control group, or the KBA-treated diabetic group. Liver tissue samples from all groups were scanned using an FTIR reflectance spectrophotometer in reflection mode. FTIR reflectance spectra were collected in the wavenumber range of 400-4000 cm⁻¹ using an attenuated total reflectance apparatus.

Results:

FTIR reflectance spectra were analyzed using PCA. The PCA score plot, which is an exploratory multivariate data set, revealed complete segregation among the three groups’ liver samples based on changes in the variation of wavenumber position in the FTIR reflectance spectra, which indicated a clear effect of KBA solubility on treatments. Histological analysis showed an improvement in the liver tissues, with normal structures of hepatocytes exhibiting mild vacuolation in their cytoplasm.

Conclusion:

KBA improved the morphology of liver tissues in the diabetic mice and led to complete recovery of the damage observed in the diabetic control group. FTIR reflectance spectroscopy coupled with PCA could be deployed as a rapid, low-cost, and non-destructive detection method for evaluating treatment effects in diseased liver tissue based on the solubility of KBA.

Serjanic Acid Improves Immunometabolic Markers in a Diet-Induced Obesity Mouse Model

Plant extracts from Cecropia genus have been used by Latin-American traditional medicine to treat metabolic disorders and diabetes. Previous reports have shown that roots of Cecropia telenitida that contains serjanic acid as one of the most prominent and representative pentacyclic triterpenes. The study aimed to isolate serjanic acid and evaluate its effect in a prediabetic murine model by oral administration. A semi-pilot scale extraction was established and serjanic acid purification was followed using direct MALDI-TOF analysis. A diet induced obesity mouse model was used to determine the impact of serjanic acid over selected immunometabolic markers. Mice treated with serjanic acid showed decreased levels of cholesterol and triacylglycerols, increased blood insulin levels, decreased fasting blood glucose and improved glucose tolerance, and insulin sensitivity. At transcriptional level, the reduction of inflammation markers related to adipocyte differentiation is reported.

Boswellic extracts and 11-keto-ß-boswellic acids prevent type 1 and type 2 diabetes mellitus by suppressing the expression of proinflammatory cytokines

BACKGROUND

Type 1 diabetes is an autoimmune disease directed to the pancreatic islets where inflammation leads to the death of insulin-producing ß cells and insulin deficiency. Type 2 diabetes, which is closely related to overweight, is characterized by insulin resistance. In both cases, proinflammatory cytokines play an important role by causing insulitis and insulin resistance. The gum resin of Boswellia species and its pharmacologically active compounds, including 11-keto-ß-boswellic acids have been shown to suppress the expression of proinflammatory cytokines in various immune-competent cells.

PURPOSE

To review the present evidence of the therapeutic effects of boswellic extracts (BE) and/or 11-keto-ß-boswellic acids in the prevention/treatment of diabetes mellitus and to provide comprehensive insights into the underlying molecular mechanisms.

METHODS

This review considers all available informations from preclinical and clinical studies concerning BEs, 11-keto-ß-boswellic acids, proinflammatory cytokines and diabetes mellitus collected via electronic search (PubMed) and related publications of the author.

RESULTS

Type 1 diabetes: Studies in mice with autoimmune diabetes revealed that in the model of multiple injections of low doses of streptozotocin (MLD-STZ), an extract of the gum resin of Boswellia serrata and 11-keto-ß-boswellic acid (KBA) suppressed the increase in proinflammatory cytokines in the blood, infiltration of lymphocytes into pancreatic islets and increase in blood glucose. In a second model, i.e. the nonobese diabetic (NOD) mouse, KBA prevented the infiltration of lymphocytes into pancreatic islets. Regarding the clinical effects, a case report provided evidence that BE suppressed the blood levels of tyrosine phosphatase antibody (IA₂-A), a marker for insulitis, in a patient with late-onset autoimmune diabetes of the adult (LADA). Type 2 diabetes: In a preclinical study in rats where obesity was alimentary induced, the administration of BE significantly reduced food intake, overweight, proinflammatory cytokines such as interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNF-α) and ameliorated the parameters of glucose and lipid metabolism. Similar results were obtained in a second animal study, where type 2 diabetes was induced by a combination of a high-fat/high-fructose diet and a single dose of streptozotocin. Two clinical trials with patients with type 2 diabetes receiving the resin of Boswellia serrata demonstrated improvement in the blood glucose, HbA_1c and lipid parameters.

CONCLUSION

Preclinical and clinical data suggest that BE and/or 11-keto-ß-boswellic acids by inhibiting the expression of proinflammatory cytokines from immune-competent cells, may prevent insulitis and insulin resistance in type 1 and type 2 diabetes, respectively, and therefore may be an option in the treatment/prevention of type 1 and type 2 diabetes. It is hypothesized that molecularly, BE and 11-keto-ß-boswellic acids act via interference with the IκB kinase/Nuclear Transcription Factor-κB (IKK/NF-κB) signaling pathway through inhibition of the phosphorylation activity of IKK. However, further investigations and well-designed clinical studies are required.

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.

Protective effect of triterpenes against diabetes-induced β-cell damage: An overview of in vitro and in vivo studies

Accumulative evidence shows that chronic hyperglycaemia is a major factor implicated in the development of pancreatic β-cell dysfunction in diabetic patients. Furthermore, most of these patients display impaired insulin signalling that is responsible for accelerated pancreatic β-cell damage. Indeed, prominent pathways involved in glucose metabolism such as phosphatidylinositol 3-kinase/ protein kinase B (PI3-K/AKT) and 5' AMP-activated protein kinase (AMPK) are impaired in an insulin resistant state. The impairment of this pathway is associated with over production of reactive oxygen species and pro-inflammatory factors that supersede pancreatic β-cell damage. Although several antidiabetic drugs can improve β-cell function by modulating key regulators such as PI3-K/AKT and AMPK, evidence of their β-cell regenerative and protective effect is scanty. As a result, there has been continued exploration of novel antidiabetic therapeutics with abundant antioxidant and antiinflammatory properties that are essential in protecting against β-cell damage. Such therapies include triterpenes, which have displayed robust effects to improve glycaemic tolerance, insulin secretion, and pancreatic β-cell function. This review summarises most relevant effects of various triterpenes on improving pancreatic β-cell function in both in vitro and in vivo experimental models. A special focus falls on studies reporting on the ameliorative properties of these compounds against insulin resistance, oxidative stress and inflammation, the well-known factors involved in hyperglycaemia associated tissue damage.

Boswellic Acids and Their Role in Chronic Inflammatory Diseases

Boswellic acids, which are pentacyclic triterpenes belong to the active pharmacological compounds of the oleogum resin of different Boswellia species. In the resin, more than 12 different boswellic acids have been identified but only KBA and AKBA received significant pharmacological interest. Biological Activity: In an extract of the resin of Boswellia species multiple factors are responsible for the final outcome of a therapeutic effect, be it synergistic or antagonistic. Moreover, the anti-inflammatory actions of BAs are caused by different mechanisms of action. They include inhibition of leukotriene synthesis and to a less extend prostaglandin synthesis. Furthermore inhibition of the complement system at the level of conversion of C3 into C3_a and C3_b. A major target of BAs is the immune system. Here, BEs as well as BAs including KBA and AKBA, have been shown to decrease production of proinflammatory cytokines including IL-1, IL-2, IL-6, IFN-γ and TNF-α which finally are directed to destroy tissues such as cartilage, insulin producing cells, bronchial, intestinal and other tissues. NFĸB is considered to be the target of AKBA. The complex actions of BEs and BAs in inflamed areas may be completed by some effects that are localized behind the inflammatory process as such tissue destruction. In this case, in vitro- and animal studies have shown that BAs and BEs suppress proteolytic activity of cathepsin G, human leucocyte elastase, formation of oxygen radicals and lysosomal enzymes.

PHARMACOKINETICS

Whereas KBA is absorbed reaching blood levels being close to in vitro IC_50, AKBA which is more active in in vitro studies than KBA, but undergoes much less absorption than KBA. However, absorption of both is increased more than twice when taken together with a high-fat meal.Clinical Studies There are a variety of chronic inflammatory diseases which respond to treatment with extracts from the resin of Boswellia species. Though, the number of cases is small in related clinical studies, their results are convincing and supported by the preclinical data. These studies include rheumatoid arthritis, osteoarthritis, chronic colitis, ulcerative colitis, collagenous colitis, Crohn's disease and bronchial asthma. It can not be expected that there is cure from these diseases but at least improvement of symptoms in about 60-70 % of the cases. Side Effects The number and severity of side effects is extremely low. The most reported complaints are gastrointestinal symptoms. Allergic reactions are rare. And most authors report, that treatment with BEs is well tolerated and the registered side effects in BE- and placebo groups are similar.