Pharmacokinetics of Boldine in Control and Mrp2-Deficient Rats

Boldine: a narrative review of the bioactive compound with versatile biological and pharmacological potential

OBJECTIVE

Boldine is a plant-derived bioactive compound that has a beneficial impact on human health. Boldine is an aporphine alkaloid mainly obtained from the leaves and bark of the Chilean Boldo tree (Peumus boldus, Family: Monimiaceae). There are plenty of preclinical evidence supports that boldine exerts its beneficial effects against various diseases. Lumiskin™, a patented and marketed formulation by Revitol Skincare for skin brightening, contains Dicetyl boldine, a boldine derivative.

CONTENT

All the available information on the Chilean boldo tree (P. boldus Molina) species was actualized by systematically searching the scientific databases (PubMed, SciFinder, Web of Science, Google Scholar, Scopus and others) and scientific literature. This article covers the recent advances in pharmacokinetic, toxicological, pharmacological/biological activities, and molecular mechanisms of the bioactive compound to understand health benefits of boldine better.

SUMMARY

Boldine exerts antioxidant, hepatoprotective, anti-atherosclerotic, anti-diabetic, analgesic, antipyretic, anti-inflammatory, anti-epileptic, neuroprotective, nephroprotective, anti-arthritis, anticancer and nootropic effects. Moreover, boldine exhibits its various pharmacological activities by altering antioxidant parameters (MDA, superoxide dismutase, glutathione), peroxynitrite, inflammatory markers apoptotic index, caspase-3, acetyl-cholinesterase, myeloperoxidase, TNF-α (Tumor necrosis factor-α), iNOS, Bcl-2-associated X protein (BAX), ACE-1(Angiotensin-converting enzyme-1), dopamine D2 receptors and nicotinic acetylcholine receptor. Boldine has the potential to modulate a variety of biological networks.

OUTLOOK

Due to its versatile pharmacological effects reported in various experimental animals as well as in randomized clinical trials for the treatment of facial melasma and for treatment of urinary stone lithotripsy in children as a complementary phytotherapy; in the future, this compound might be developed as a novel drug for a different indication.

An Overview of Chemistry, Kinetics, Toxicity and Therapeutic Potential of Boldine in Neurological Disorders

Boldine is an alkaloid obtained from the medicinal herb Peumus boldus (Mol.) (Chilean boldo tree; boldo) and belongs to the family Monimiaceae. It exhibits a wide range of pharmacological effects such as antioxidant, anticancer, hepatoprotective, neuroprotective, and anti-diabetic properties. There is a dearth of information regarding its pharmacokinetics and toxicity in addition to its potential pharmacological activity. Boldine belongs to the aporphine alkaloid class and possesses lipophilic properties which enable its efficient absorption and distribution throughout the body, including the central nervous system. It exhibits potent free radical scavenging activity, thereby reducing oxidative stress and preventing neuronal damage. Through a variety of neuroprotective mechanisms, including suppression of AChE and BuChE activity, blocking of connexin-43 hemichannels, pannexin 1 channel, reduction of NF-κβ mediated interleukin release, and glutamate excitotoxicity which successfully reduces neuronal damage. These results point to its probable application in reducing neuroinflammation and oxidative stress in epilepsy, Alzheimer's disease (AD), and Parkinson's disease (PD). Moreover, its effects on serotonergic, dopaminergic, opioid, and cholinergic receptors were further investigated in order to determine its applicability for neurobehavioral dysfunctions. The article investigates the pharmacokinetics of boldine and reveals that it has a low oral bioavailability and a short half-life, requiring regular dosage to maintain therapeutic levels. The review studies boldine's potential therapeutic uses and mode of action while summarizing its neuroprotective benefits.  Given the favorable results for boldine as a potential neurotherapeutic drug in laboratory animals, more research is required. However, in order to optimise its therapeutic potential, it must be more bioavailable with fewer detrimental side effects.

Inhibition of Gluconeogenesis by Boldine in the Perfused Liver: Therapeutical Implication for Glycemic Control

The alkaloid boldine occurs in the Chilean boldo tree (Peumus boldus). It acts as a free radical scavenger and controls glycemia in diabetic rats. Various mechanisms have been proposed for this effect, including inhibited glucose absorption, stimulated insulin secretion, and increased expression of genes involved in glycemic control. Direct effects on glucose synthesis and degradation were not yet measured. To fill this gap, the present study is aimed at ensuring several metabolic pathways linked to glucose metabolism (e.g., gluconeogenesis) in the isolated perfused rat liver. In order to address mechanistic issues, energy transduction in isolated mitochondria and activities of gluconeogenic key enzymes in tissue preparations were also measured. Boldine diminished mitochondrial ROS generation, with no effect on energy transduction in isolated mitochondria. It inhibited, however, at least three enzymes of the gluconeogenic pathway, namely, phosphoenolpyruvate carboxykinase, fructose-bisphosphatase-1, and glucose 6-phosphatase, starting at concentrations below 50 μM. Consistently, in the perfused liver, boldine decreased lactate-, alanine-, and fructose-driven gluconeogenesis with IC₅₀ values of 71.9, 85.2, and 83.6 μM, respectively. Conversely, the compound also increased glycolysis from glycogen-derived glucosyl units. The hepatic ATP content was not affected by boldine. It is proposed that the direct inhibition of hepatic gluconeogenesis by boldine, combined with the increase of glycolysis, could be an important event behind the diminished hyperglycemia observed in boldine-treated diabetic rats.

Pharmacokinetics of glaucine after intravenous and oral administrations and detection of systemic aporphine alkaloids after ingestion of tulip poplar shavings in horses

Glaucine, an aporphine alkaloid with anti-tussive, anti-inflammatory, and anti-nociceptive properties, has been identified in post-race samples from racehorses. To investigate pharmacokinetics of glaucine in horses, a three-way crossover study of intravenous and oral glaucine (0.1 mg/kg) and orally administered tulip poplar shavings (50 g shavings = 0.001 mg/kg glaucine) was performed in six horses. A two-compartment model best described IV administration with alpha ( t 1 / 2 α $$ {t}_{1/2\alpha } $$ ) and beta ( t 1 / 2 β $$ {t}_{1/2\beta } $$ ) half-life lives of 0.3 (0.1-0.7) and 3.1 (2.4-7.8) h, respectively. The area under the curve ( AUC 0 ∞ $$ {\mathrm{AUC}}_0^{\infty } $$ _iv ) was 45.4 (34.7-52.3) h*ng/ml, and the volume of distribution of the central (Vd_c ) and peripheral (Vd_p ) compartments was 2.7 (1.3-4.6) and 4.9 (4.3-8.2) L/kg, respectively. A one compartment model best described the oral administration of glaucine with absorption ( t 1 / 2 ka $$ {t}_{1/2 ka} $$ ) and elimination ( t 1 / 2 kel $$ {t}_{1/2 kel} $$ ) half-lives of 0.09 (0.05-0.15) and 0.7 (0.6-0.8) h, respectively. The area under the curve ( AUC 0 ∞ $$ {\mathrm{AUC}}_0^{\infty } $$ _PO ) was 15.1 (8.0-19.5) h·ng/ml. Bioavailability following oral administration was 17%-48%. Following ingestion of shavings, glaucine and liriodenine were detectable in plasma for up to 16 and 48 h, respectively. Glaucine was quantifiable briefly in the urine from two horses. Liriodenine was quantifiable in urine for 12-20 h in four horses and for 48 h in two horses. The presence of liriodenine indicates ingestion of tulip poplar tree parts, however, does not rule out co-administration of purified glaucine in horses.

Study on the pharmacokinetics, tissue distribution and excretion of laurolitsine from Litsea glutinosa in Sprague-Dawley rats

CONTEXT

Laurolitsine is an aporphine alkaloid and exhibits potent antihyperglycemic and antihyperlipidemic effects in ob/ob mice.

OBJECTIVE

To investigate the pharmacokinetics, tissue distribution and excretion of laurolitsine.

MATERIALS AND METHODS

A LC-MS/MS method was established and validated to determine laurolitsine concentrations in the biological matrix of rats (plasma, tissue homogenate, urine and faeces). 10 Sprague-Dawley (SD) rats were used for plasma exposure study: 5 rats were injected with 2.0 mg/kg of laurolitsine via the tail vein, and the other 5 rats were administered laurolitsine (10.0 mg/kg) by gavage. 25 SD rats used for tissue distribution study and 5 SD rats for urine and faeces excretion study: rats administered laurolitsine (10.0 mg/kg) by gavage. After administered, serial blood, tissue, urine and faeces were collected. Analytical quantification was performed by a previous LC-MS/MS method. The pharmacokinetics, bioavailability, tissue distribution and excretion of laurolitsine were described.

RESULTS

The pharmacokinetic parameters of oral and intravenous administration with T_max were 0.47 and 0.083 h, t_1/2 were 3.73 and 1.67 h, respectively. Oral bioavailability was as low as 18.17%. Laurolitsine was found at a high concentration in the gastrointestinal tract, liver, lungs and kidneys (26 015.33, 905.12, 442.32 and 214.99 ng/g at 0.5 h, respectively) and low excretion to parent laurolitsine in urine and faeces (0.03 and 1.20% in 36 h, respectively).

CONCLUSIONS

This study established a simple, rapid and accurate LC-MS/MS method to determine laurolitsine in different rat samples and successful application in a pharmacokinetic study.

Natural Aporphine Alkaloids with Potential to Impact Metabolic Syndrome

The incidence and prevalence of metabolic syndrome has steadily increased worldwide. As a major risk factor for various diseases, metabolic syndrome has come into focus in recent years. Some natural aporphine alkaloids are very promising agents in the prevention and treatment of metabolic syndrome and its components because of their wide variety of biological activities. These natural aporphine alkaloids have protective effects on the different risk factors characterizing metabolic syndrome. In this review, we highlight the activities of bioactive aporphine alkaloids: thaliporphine, boldine, nuciferine, pronuciferine, roemerine, dicentrine, magnoflorine, anonaine, apomorphine, glaucine, predicentrine, isolaureline, xylopine, methylbulbocapnine, and crebanine. We particularly focused on their impact on metabolic syndrome and its components, including insulin resistance and type 2 diabetes mellitus, endothelial dysfunction, hypertension and cardiovascular disease, hyperlipidemia and obesity, non-alcoholic fatty liver disease, hyperuricemia and kidney damage, erectile dysfunction, central nervous system-related disorder, and intestinal microbiota dysbiosis. We also discussed the potential mechanisms of actions by aporphine alkaloids in metabolic syndrome.

Anti-parasitic drugs modulate the non-selective channels formed by connexins or pannexins

The proteins connexins, innexins, and pannexins are the subunits of non-selective channels present in the cell membrane in vertebrates (connexins and pannexins) and invertebrates (innexins). These channels allow the transfer of ions and molecules across the cell membrane or, and in many cases, between the cytoplasm of neighboring cells. These channels participate in various physiological processes, particularly under pathophysiological conditions, such as bacterial, viral, and parasitic infections. Interestingly, some anti-parasitic drugs also block connexin- or pannexin-formed channels. Their effects on host channels permeable to molecules that favor parasitic infection can further explain the anti-parasitic effects of some of these compounds. In this review, the effects of drugs with known anti-parasitic activity that modulate non-selective channels formed by connexins or pannexins are discussed. Previous studies that have reported the presence of these proteins in worms, ectoparasites, and protozoa that cause parasitic infections have also been reviewed.

Preparation, Characterization and In Vitro Antioxidant Potential of Boldine-phospholipid Complex

Background:

Boldine, is an aporphine alkaloid that possesses potent antioxidant activity. Despite having enormous potential, the clinical application of boldine was restricted because of its poor bioavailability attributed to its poor aqueous solubility and rapid clearance from the body. The drug phospholipid complexation techniques were frequently employed to overcome the limitation of low bioavailability of phytoconstituents/herbal extract.

Objective:

The boldine phospholipid complex (BOL-PC) formulation was developed for enhancing antioxidant potential of boldine by preparing its phospholipid complex.

Methods:

Boldine loaded phospholipid (BOL-PC) complex was prepared by refluxing followed by solvent evaporation method and subjected to various physicochemical and spectral analysis. Further, the in-vitro antioxidant activity was evaluated by DPPH free radical scavenging method.

Results:

The formation of the complex was confirmed by 1H NMR and thermal analysis. SEM and PXRD revealed partial amorphization of drug in complex formed. The BOL-PC dissolution rate and solubility was significantly improved compared to the parent compound. The maximum % yield and % EE was found to be 95.92± 0.01732 and 95.89±0.3502 respectively in the optimized formulation (F3) which exhibited concentration-dependent antioxidant property.

Conclusion:

It was concluded from the study that the phospholipid complexation of boldine has better antioxidant potential and improved the solubility, dissolution profile which may facilitate its oral absorption and enhances its chances for clinical application.

Inhibition of Acetylcholinesterase and Butyrylcholinesterase by a Plant Secondary Metabolite Boldine

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are two enzymes sensitive to various chemical compounds having ability to bind to crucial parts of these enzymes. Boldine is a natural alkaloid and it was mentioned in some older works that it can inhibit some kinds of AChE. We reinvestigated this effect on AChE and also on BChE using acetyl (butyryl) thiocholine and Ellman's reagents as standard substances for spectrophotometric assay. We found out IC₅₀ of AChE equal to 372 μmol/l and a similar level to BChE, 321 μmol/l. We conclude our experiment by a finding that boldine is cholinesterase inhibitor; however we report significantly weaker inhibition than that suggested in literature. Likewise, we tried to investigate the mechanism of inhibition and completed it with in silico study. Potential toxic effect on cholinesterases in real conditions is also discussed.