Betulinic Acid Derivatives Research Articles

One-Pot Syntheses and Enzyme Inhibition Studies of New C-28 Ester Derivatives of Betulinic Acid

Betulinic acid and its various synthetic derivatives have been reported to possess diverse biological activities and some of these may serve as useful therapeutic agents for a variety of human disorders. In this perspective, we have now developed convenient one-pot syntheses of new C-28 esters (2-7) of betulinic acid by esterification of the carboxylic moiety of betulinic acid (1) with various alkylating agents. All the target compounds were subjected to enzyme inhibition studies to ascertain their possible therapeutic utility. Compound 5 showed very potent lipoxygenase inhibitory activity with an IC50 value of 13.2 μM, being much lower than the IC50 value of 22.4 μM of baicalein, which was used as the standard. Butulinic acid itself and compound 6 also showed significant inhibitory potential (IC50: 32.4 and 25.1 μM) against the same enzyme. The activities of both compounds 5 and 6 have been justified by intensive docking studies. Compounds 2 and 3 exhibited substantial inhibition (IC50: 18.4 and 21.5 μM) against the enzyme butrylcholinesterase, compared to serine used as the standard (IC50: 7.8 μM).

Synthesis of Betulonic and Betulinic Acids Derivatives with Sulfonamide Fragment Linked to the Triterpene Core by Amidoalkane Spaser

A series of potentially biologically active sulfonamides of betulonic and betulinic acids with a sulfonamide fragment containing residues of dibutylamine or N-heterocycles, which is linked to a triterpene core by an amidoethane or amidopropane spacer, was synthesized. Betulonic acid sulfonamides were obtained by chlorohydride conjugation of acid with 2-aminoethane and 3-aminopropanesulfonamides and used as precursor compounds for the transition to similar betulinic acid derivatives by selective reduction of the 3-keto group with the action of NaBH4 in EtOH. The structure of all synthesized triterpene sulfonamides was confirmed by 1D and 2D NMR spectroscopy and mass spectrometry.

Antiasthamatic Activity of Betulinic Acid as a Current Bioactive Compound in an Experimental Model

aims: The purpose of this study was to assess BA's effectiveness in treating bronchial asthma and to use molecular docking to find BA's binding energy with β-adrenoceptor. background: The natural triterpenoid molecule betulinic acid (BA) has many biological and therapeutic uses, one of which is the relief of asthma symptoms. objective: The purpose of this study was to assess BA's effectiveness in treating bronchial asthma and to use molecular docking to find BA's binding energy with β-adrenoceptor. method: Methods: The extraction technique involved the use of ethanol as a solvent and the herb Bacopa monnieri. Budesenoid was used as a standard drug. AutoDock vina in PyRx 0.8 was used for the molecular docking investigation. An acute toxicity examination was conducted according to OECD guideline 425. A guinea pig model of asthma called anaphylactic microshock was employed to ascertain the antiasthmatic efficacy of the medication under investigation. Antiasthmatic activity was performed by dividing the animals into four groups each containing six animals. Group 1 was the control group received only vehicle. Group 2 was the standard group received budesenoid. Group 3 was the test group received B. monnieri extract. Group 4 was the test group received betulinic acid (BA). result: Results: In terms of binding affinity, BA has a value of -7.45 kcal/mol. In line with earlier findings, molecular docking showed that BA bound to the hydrophobic cavity of LOX-5, and the formation of hydrogen bonds altered the micro-environment and structure of LOX-5. This resulted in a reduction in enzyme activity. The mean pre-convulsion time for Drug-1 was 506.66 in comparison to the control group as observed in guinea pig model of asthma. conclusion: Conclusion: It may be a good analytical approach to test BA or BA derivatives with a stronger antiasthmatic profile with the help of computed properties. BA was found effective in reducing anaphylaxis in animal model, thus, it may be useful against asthma. other: Conclusion: It may be a good analytical approach to test BA or BA derivatives with a stronger antiasthmatic profile with the help of computed properties. BA was found effective in reducing anaphylaxis in animal model, thus, it may be useful against asthma.

Enzymatic Synthesis of Novel Terpenoid Glycoside Derivatives Decorated with N-Acetylglucosamine Catalyzed by UGT74AC1.

The addition of the O-linked N-acetylglucosamine (O-GlcNAc) is a significant modification for active molecules, such as proteins, carbohydrates, and natural products. However, the synthesis of terpenoid glycoside derivatives decorated with GlcNAc remains a challenging task due to the absence of glycosyltransferases, key enzymes for catalyzing the transfer of GlcNAc to terpenoids. In this study, we demonstrated that the enzyme mutant UGT74AC1T79Y/L48M/R28H/L109I/S15A/M76L/H47R efficiently transferred GlcNAc from uridine diphosphate (UDP)-GlcNAc to a variety of terpenoids. This powerful enzyme was employed to synthesize GlcNAc-decorated derivatives of terpenoids, including mogrol, steviol, andrographolide, protopanaxadiol, glycyrrhetinic acid, ursolic acid, and betulinic acid for the first time. To unravel the mechanism of UDP-GlcNAc recognition, we determined the X-ray crystal structure of the inactivated mutant UGT74AC1His18A/Asp111A in complex with UDP-GlcNAc at a resolution of 1.66 Å. Through molecular dynamic simulation and activity analysis, we revealed the molecular mechanism and catalytically important amino acids directly involved in the recognition of UDP-GlcNAc. Overall, this study not only provided a potent biocatalyst capable of glycodiversifying natural products but also elucidated the structural basis for UDP-GlcNAc recognition by glycosyltransferases.

Design, synthesis and biological evaluation of novel betulinic acid derivatives containing 1,2,4-triazole-derived schiff bases as α-glucosidase inhibitors

A series of novel betulinic acid (BA) derivatives containing 1,2,4-triazole- derived schiff base have been designed and synthesized as α-glucosidase inhibitors. All the title compounds showed higher α-glucosidase inhibitory activity than acarbose and BA, with compound f32 showing the highest α-glucosidase inhibitory activity (IC50 = 1.52±0.16 μM). Lineweaver-Burk plot analysis suggested that compound f32 was a non-competitive inhibitor for α-glucosidase. 3D fluorescence and circular dichroism spectroscopy disclosed the interaction of compound f32 with α-glucosidase by changing the secondary structure of α-glucosidase. Molecular docking showed that compound f32 could bind to the active site of α-glucosidase through hydrogen bonding and hydrophobic interaction. More importantly, compound f32 could not only reduce the level of fasting blood glucose and postprandial blood glucose in mice, but also ameliorate dyslipidemia. The current findings suggest that compound f32 may serve as a leading compound for the discovery of α-glucosidase inhibitors in the treatment of type 2 diabetes.

1,2,3-Triazole-based betulinic acid derivatives as α-glucosidase inhibitors: Synthesis and in vitro and in vivo biological evaluation

A series of 1, 2, 3-triazole-based betulinic acid derivatives d1–d31 were synthesized as α-glucosidase inhibitors with hypoglycemic activity. All the derivatives exhibited excellent inhibition against α-glucosidase, and compound d23 was the most active (IC50 = 2.83 ± 0.19 μM). Inhibition kinetics showed that compound d23 was a mixed-type inhibitor for α-glucosidase. Spectroscopic studies based on 3D fluorescence and circular dichroism spectra suggested that compound d23 exerted its inhibitory activity by changing the conformation of α-glucosidase. Molecular docking revealed that compound d23 was well nested into the active pocket of α-glucosidase through hydrogen-bonding and hydrophobic interactions. In vivo experiments showed that compound d23 could not only reduce the level of fasting blood glucose, but also improve glucose tolerance and dyslipidemia. The present findings strongly suggest that compound d23 is exploitable as a leading compound for the development of α-glucosidase inhibitors in the treatment of type 2 diabetes.

A New Potent Inhibitor against α-Glucosidase Based on an In Vitro Enzymatic Synthesis Approach.

Inhibiting the activity of intestinal α-glucosidase is considered an effective approach for treating type II diabetes mellitus (T2DM). In this study, we employed an in vitro enzymatic synthesis approach to synthesize four derivatives of natural products (NPs) for the discovery of therapeutic drugs for T2DM. Network pharmacology analysis revealed that the betulinic acid derivative P3 exerted its effects in the treatment of T2DM through multiple targets. Neuroactive ligand-receptor interaction and the calcium signaling pathway were identified as key signaling pathways involved in the therapeutic action of compound P3 in T2DM. The results of molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations indicate that compound P3 exhibits a more stable binding interaction and lower binding energy (-41.237 kcal/mol) with α-glucosidase compared to acarbose. In addition, compound P3 demonstrates excellent characteristics in various pharmacokinetic prediction models. Therefore, P3 holds promise as a lead compound for the development of drugs for T2DM and warrants further exploration. Finally, we performed site-directed mutagenesis to achieve targeted synthesis of betulinic acid derivative. This work demonstrates a practical strategy of discovering novel anti-hyperglycemic drugs from derivatives of NPs synthesized through in vitro enzymatic synthesis technology, providing potential insights into compound P3 as a lead compound for anti-hyperglycemic drug development.

Derivatives of Betulin and Betulinic Acid Containing a Phosphonate Group—In Silico Studies and Preliminary In Vitro Assessment of Antiviral Activity

Viral diseases affecting both humans and animals are a serious public problem. Chemical modifications of the structure of compounds of natural origin, e.g., betulin, seem to be a promising model in the search for new antiviral agents. The subject of our work was to conduct preliminary tests on the antiviral activity of phosphonic derivatives of betulin and betulinic acid and to assess the pharmacokinetic profile of target compounds. Human (HHV-1, HAdV-5) and animal viruses (BEV, VSV) were used in the in vitro tests. Additionally, this paper presents the results of research using in silico methods (ADMET and molecular docking). Two compounds (betulin 29-phosphonate 3 and 3-(3′,3′-dimethylsuccinyl)betulin acid 29-phosphonate 8a) showed antiviral activity against BEV, and compound 3 was also active against HAdV-5. For compound 3, which showed advantageous pharmacokinetic parameters, molecular docking was performed to determine possible interactions with the cellular target HAdV-5 endopeptidase, which plays an important role in various functions of the virus. Selecting the most active derivatives makes it possible to plan tests on an animal model.

One-pot Synthesis of Some New Betulinic Acid Derivatives with Cytotoxicity Against Human Pancreatic Cancer Cells

Background: One-pot synthesis of new and biologically important betulinic acid derivatives has been designed and efficiently achieved in this work. Methods: The utilization of the carboxylic and hydroxyl moieties of betulinic acid has resulted in the development of a one-pot strategy towards the synthesis of some target compounds. Results: One-pot synthesis of new betulinic acid derivatives 3-9 has been achieved in moderate to high yields by way of esterification of the carboxylic functionality with a variety of alkylating agents. These were fully characterized by spectroscopic techniques. Conclusion: The synthesized new derivatives of betulinic acid were screened for their cytotoxic effect against human pancreatic cancer cells.

Synthesis of Hydrazide Derivative of Betulinic Acid, Its Organometallic Complexes, Characterization and Bioassay.

Betulinic acid and its derivatives comprehend an immense prospective toward the development of cytotoxic, antiviral, antimicrobial and antioxidant agents. Cisplatin (cytotoxic drug) divert the attentions to develop organometallic compounds with pronounced biological activities. The current study was aimed for the first time to synthesize, characterize and evaluate biologically a series of metal (Fe, Cu, Zn, Sn and Sb) complexes of betulinic acid hydrazide. First step involved the formation of hydrazide derivative of betulinic acid (ligand) by modification at C-28 carboxylic acid moiety of betulinic acid with hydrazine followed by the synthesis of its metal complexes using salts of different metals (Fe, Cu, Zn, Sn and Sb). Physical state, melting point, Fourier-transform infrared (FT-IR) and 1 H nuclear magnetic resonance (1 H-NMR) spectral techniques were used to characterized the ligand and its metal complexes. Agar well diffusion method and agar tube dilution assay were performed to evaluate its antibacterial and antifungal activities respectively. DPPH assay was carried out to develop antioxidant properties by the reported methods.

Discovery of betulinic acid derivatives as gut-restricted TGR5 agonists: Balancing the potency and physicochemical properties

The pleiotropic effects of TGR5 make it an appealing target for intervention of metabolic and inflammatory disorders, but systemic activation of TGR5 faces challenges of on-target side effects, especially gallbladder filling. Gut-restricted agonists were proved to be sufficient to circumvent these side effects, but extremely low systemic exposure may not be effective in activating TGR5 since it is located on the basolateral membrane. Herein, to balance potency and physicochemical properties, a series of gut-restricted TGR5 agonists with diversified kinetophores had been designed and synthesized. Compound 22-Na exhibited significant antidiabetic effect, and showed favorable gallbladder safety after 7 days of oral administration in humanized TGR5H88Y mice, confirming that gut-restricted agonism of TGR5 is a viable strategy to alleviate systemic target-related effects.

Enhanced Cytotoxicity and Antimelanoma Activity of Novel Semisynthetic Derivatives of Betulinic Acid with Indole Conjugation.

The prevalence and severity of skin cancer, specifically malignant melanoma, among Caucasians remains a significant concern. Natural compounds from plants have long been explored as potential anticancer agents. Betulinic acid (BI) has shown promise in its therapeutic properties, including its anticancer effects. However, its limited bioavailability has hindered its medicinal applications. To address this issue, two recently synthesized semisynthetic derivatives, N-(2,3-indolo-betulinoyl)diglycylglycine (BA1) and N-(2,3-indolo-betulinoyl)glycylglycine (BA2), were compared with previously reported compounds N-(2,3-indolo-betulinoyl)glycine (BA3), 2,3-indolo-betulinic acid (BA4), and BI. These compounds were evaluated for their effects on murine melanoma cells (B164A5) using various in vitro assays. The introduction of an indole framework at the C2 position of BI resulted in an increased cytotoxicity. Furthermore, the cytotoxicity of compound BA4 was enhanced by conjugating its carboxylic group with an amino acid residue. BA2 and BA3, with glycine and glycylglycine residues at C28, exhibited approximately 2.20-fold higher inhibitory activity compared to BA4. The safety assessment of the compounds on human keratinocytes (HaCaT) has revealed that concentrations up to 10 µM slightly reduced cell viability, while concentrations of 75 µM resulted in lower cell viability rates. LDH leakage assays confirmed cell membrane damage in B164A5 cells when exposed to the tested compounds. BA2 and BA3 exhibited the highest LDH release, indicating their strong cytotoxicity. The NR assay revealed dose-dependent lysosome disruption for BI and 2,3-indolo-betulinic acid derivatives, with BA1, BA2, and BA3 showing the most cytotoxic effects. Scratch assays demonstrated concentration-dependent inhibition of cell migration, with BA2 and BA3 being the most effective. Hoechst 3342 staining revealed that BA2 induced apoptosis, while BA3 induced necrosis at lower concentrations, confirming their anti-melanoma properties. In conclusion, the semisynthetic derivatives of BI, particularly BA2 and BA3, show promise as potential candidates for further research in developing effective anti-cancer therapies.

Design, synthesis and biological evaluation of betulinic acid derivatives as potential inhibitors of 3CL-protease of SARS-CoV-2

During the coronavirus reproduction process, 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro) are accountable for the fragmentation of two polyprotein precursors (pp1a/pp1ab) into substructural proteins. These two proteins are vital for the replication and transcription of the viral genome. Therefore, 3CLpro is a key protein and target for the design of coronavirus inhibitors. In previous studies, we found that betulinic acid has an inhibitory effect on 3CLpro, with 51.5 % inhibition of 3CLpro at 20 µM. Then, series of betulinic acid derivatives were designed, synthesized, and evaluated for their inhibition activities. The results showed that BA02 and BA05 showed significant inhibitory activity on 3CLpro with inhibitory rates of 78.1 % and 82.5 % at 20 µM, respectively. Further evaluation of these two compounds shows that their IC50 values are 7.22 ± 0.14 μM and 6.40 ± 0.14 μM, respectively.

Selected Plant Triterpenoids and Their Derivatives as Antiviral Agents

The results of the most recent investigation of triterpenoid-based antiviral agents namely in the HIV-1 and HSV-1 treatment were reviewed and summarized. Several key historical achievements are included to stress consequences and continuity in this research. Most of the agents studied belong to a series of compounds derived from betulin or betulinic acid, and their synthetic derivative is called bevirimat. A termination of clinical trials of bevirimat in Phase IIb initiated a search for more successful compounds partly derived from bevirimat or designed independently of bevirimat structure. Surprisingly, a majority of bevirimat mimics are derivatives of betulinic acid, while other plant triterpenoids, such as ursolic acid, oleanolic acid, glycyrrhetinic acid, or other miscellaneous triterpenoids, are relatively rarely involved in a search for a novel antiviral agent. Therefore, this review article is divided into three parts based on the leading triterpenoid core structure.

Synthesis and Cytotoxicity of Monomethylated Betulinic Acid 3-O-α-l-Rhamnopyranosides.

Three original derivatives of the cytotoxic betulinic acid 3-O-α-l-rhamnopyranoside featuring a monomethylated rhamnoside residue were synthesized. An improved catalytic procedure was involved to functionalize the O-3 position of the monosaccharide in a site-selective fashion. The cytotoxicity of the novel compounds was evaluated in vitro to highlight the moderate impact of carbohydrate monomethylation on the biological activity of betulinic acid 3-O-α-l-rhamnopyranoside.

Construction of a UDP-Arabinose Regeneration System for Efficient Arabinosylation of Pentacyclic Triterpenoids.

Glycosylation is an important method of modifying natural products and is usually catalyzed by uridine 5'-diphosphate (UDP)-glycosyltransferase. UDP-β-l-arabinose (UDP-Ara) confers specific functions to natural products such as pentacyclic triterpenoids. However, UDP-arabinosyltransferase with high regioselectivity toward pentacyclic triterpenoids has rarely been reported. In addition, UDP-Ara is mainly biosynthesized from UDP-α-d-glucose (UDP-Glc) through several reaction steps, resulting in the high cost of UDP-Ara. Herein, UGT99D1 was systematically characterized for specifically transferring one moiety of arabinose to the C-3 position of typical pentacyclic triterpenoids. Subsequently, 15 enzymes from plants, mammals, and microorganisms were characterized, and a four-enzyme cascade comprising sucrose synthase, UDP-Glc dehydrogenase, UDP-α-d-glucuronic acid decarboxylase, and UDP-Glc 4-epimerase was constructed to transform sucrose into UDP-Ara with UDP recycling. This system was demonstrated to efficiently produce the arabinosylated derivative (Ara-BA) of typical pentacyclic triterpenoid betulinic acid (BA). Finally, the in vitro cytotoxicity tests indicated that Ara-BA showed much higher anticancer activities than BA. The established arabinosylation platform shows the potential to enhance the pharmacological activity of natural products.

Dynamics simulation and in vitro studies of betulinic acid derivative with liver X receptor

Molecular dynamics simulation of the dominant conformational conjugate was performed for 40 ns and 100 ns via Amber software based on molecular docking by Sybyl software. Because the RMSD and RMSF of 100 ns MD simulation were higher than that of 40 ns MD simulation, the 40 ns was reasonable and credible for MD simulation. The binding free energy and decomposition free energy of the two systems of betulinic acid, com3 with liver X receptor was calculated by the MM_GBSA and MM_PBSA methods, respectively. The results showed that the two systems reached equilibrium and convergence at 20 ns, both stable at about 2 Å, and exhibited low volatility in the range of amino acid 270 to 370 (RMSF <1 Å). The binding energy of com3 (ΔGbind = −68.02 kcal/mol by the MM_GBSA method or −55.50 kcal/mol by the MM_PBSA method) with the liver X receptor was lower than that of betulinic acid (ΔGbind = −55.70 kcal/mol or −42.73 kcal/mol) respectively, and van der Waals force was the most important main driving force, which was consistent with molecular docking and previous experiments. Hydrophobic groups and aromatic rings can be introduced appropriately in structure optimization to increase the van der Waals force and π-π accumulation effect of betulinic acid and liver X receptor, which is conducive to binding and thereby increasing antitumor activity. The clone formation assay and results of western blotting indicated that BA derivative com3 exposure inhibited cell proliferation may relate to the regulation of the AKT/mTOR pathway in 7721 cells. This study clarifies the dynamic interaction mode and potential mechanism of betulinic acid and its derivatives with the liver X receptor, which provides a new idea for the rapid screening of liver X receptor agonists from traditional Chinese medicines. Communicated by Ramaswamy H. Sarma

Synthesis of hybrid compounds of 24-nor-lupane triterpene and amino acids via C-28 amide linkage

Betulinic acid derivatives exhibit different biological activity against diversified targets, such as anticarcinogenic activity in experimental animals, anti-HIV, antihyperglycemia, and anti-inflammatory in humans. In this work, we investigated the synthetic procedure of 24-nor-3-oxo-20(29)-lupen-28-oic acid (1) derivatives. Starting from compound 1 and L-leucine methyl ester, we proceeded with amidification, reduction, and hydrolysis under basic conditions. Finally, three hybrid compounds were successfully synthesised and elucidated with spectral means.

Discovery, structural optimization, and anti-tumor bioactivity evaluations of betulinic acid derivatives as a new type of RORγ antagonists

Betulinic acid (BA) is a natural pentacyclic triterpenoid that has a wide range of biological and pharmacological effects. Here, computational methods such as pharmacophore screening and reverse docking were used to predict the potential target for BA. Retinoic acid receptor-related orphan receptor gamma (RORγ) was confirmed as its target by several molecular assays as well as crystal complex structure determination. RORγ has been the focus of metabolic regulation, but its potential role in cancer treatment has only recently come to the fore. In this study, rationale optimization of BA was performed and several new derivatives were generated. Among them, the compound 22 showed stronger binding affinity with RORγ (KD = 180 nM), good anti-proliferative activity against cancer cell lines, and potent anti-tumor efficacy with a TGI value of 71.6% (at a dose of 15 mg/kg) in the HPAF-II pancreatic cancer xenograft model. Further RNA-seq analysis and cellular validation experiments supported that RORγ antagonism was closely related to the antitumor activity of BA and 22, resulting in suppression of the RAS/MAPK and AKT/mTORC1 pathway and inducing caspase-dependent apoptosis in pancreatic cancer cells. RORγ was highly expressed in cancer cells and tissues and positively correlated with the poor prognosis of cancer patients. These results suggest that BA derivatives are potential RORγ antagonists worthy of further exploration.

VCE-005.1, an hypoxia mimetic betulinic acid derivative, induces angiogenesis and shows efficacy in a murine model of traumatic brain injury

One of the main global causes of mortality and morbidity is traumatic brain injury (TBI). Neuroinflammation and brain-blood barrier (BBB) disruption play a pivotal role in the pathogenesis of acute and chronic TBI onset. The activation of the hypoxia pathway is a promising approach for CNS neurodegenerative diseases, including TBI. Herein, we have studied the efficacy of VCE-005.1, a betulinic acid hydroxamate, against acute neuroinflammation in vitro and on a TBI mouse model. The effect of VCE-005.1 on the HIF pathway in endothelial vascular cells was assessed by western blot, gene expression, in vitro angiogenesis, confocal analysis and MTT assays. In vivo angiogenesis was evaluated through a Matrigel plug model and a mouse model of TBI induced by a controlled cortical impact (CCI) was used to assess VCE-005.1 efficacy. VCE-005.1 stabilized HIF-1α through a mechanism that involved AMPK and stimulated the expression of HIF-dependent genes. VCE-005.1 protected vascular endothelial cells under prooxidant and pro-inflammatory conditions by enhancing TJ protein expression and induced angiogenesis both in vitro and in vivo. Furthermore, in CCI model, VCE-005.1 greatly improved locomotor coordination, increased neovascularization and preserved BBB integrity that paralleled with a large reduction of peripheral immune cells infiltration, recovering AMPK expression and reducing apoptosis in neuronal cells. Taken together, our results demonstrate that VCE-005.1 is a multitarget compound that shows anti-inflammatory and neuroprotective effects mainly by preventing BBB disruption and has the potential to be further developed pharmacologically in TBI and maybe other neurological conditions that concur with neuroinflammation and BBB disruption.