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Betulinic acid and its derivatives: A patent review (2008-2013)
Abstract and Figures
Introduction:
Betulinic acid (BA) is a triterpenoid that can be obtained from renewable resources. BA is cytotoxic to many human tumor cell lines mainly by apoptosis but cell death might also be triggered by nonapoptotic pathways. Many derivatives have been synthesized to improve the very weak solubility of parent BA and to increase its cytotoxicity as well as its selectivity toward tumor cells.
Areas covered:
A brief introduction into cancer is given reflecting the different pathways this disease might be treated using chemotherapy using natural product analogs especially triterpenes. The different ways of action of BA in cancer cells are discussed. Finally, this review describes the main synthetic modifications that have been performed and discusses, in short, the structure-activity relationships of these analogs, investigated between 2008 and 2013 including some important publications from early 2014.
Expert opinion:
A number of patents on BA analogs for the chemotherapy of cancer have been reported between 2008 and 2013. Most of these patents deal with modifications at positions C-3, C-20 and C-28. There are only a few compounds meeting the needs of a sufficient hydrosolubility, while retaining high cytotoxicity and selectivity toward tumor cells. Thus, one might expect that there will be some efforts in developing molecules of improved solubility and to find new and more efficient forms of administration (liposomes, transdermal application and nanoemulsions). An important sideline might be the treatment of the age-dependent degeneration of the macula, a possible caveat of which might be a certain degree of CNS toxicity associated with several derivatives of BA.
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... Betulinic acid (BA) is a naturally occurring pentacyclic triterpene, widely distributed in the plant kingdom and obtained from birch tree bark. BA and its synthetic derivative, NVX-207 (3-acetyl-betulinic acid-2-amino-3-hydroxy-2-hydroxymethyl-propanoate), are known for their diverse properties, such as anti-inflammatory [27], anti-HIV [28], anthelminthic [29], immunomodulatory, antiangiogenic [30], antifibrotic and hepatoprotective effects [31,32]. Timeand dose-dependent [23,33] cytotoxicity of BA and NVX-207 against melanoma and various cancer cell lines from different species (e.g. ...
... Timeand dose-dependent [23,33] cytotoxicity of BA and NVX-207 against melanoma and various cancer cell lines from different species (e.g. human, horse, dog, mouse) has been repeatedly demonstrated in vitro and in vivo [23,31,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. The cytotoxic mechanism of BA and its derivates is based on a CD95-and p53-independent induction of apoptosis [50,51]. ...
... Selzer et al. demonstrated melanocytes to be less susceptible to inhibition by BA than melanoma cells [34]. In cell models of different species and different cancer types, this selectivity towards tumor cells has also been observed [31,34,40,42,44,46,52,53], although Weber et al. could not confirm these results in an equine cell culture model [38]. ...
Background
Gray horses are predisposed to equine malignant melanoma (EMM) with advancing age. Depending on the tumor’s location and size, they can cause severe problems (e.g., defaecation, urination, feeding). A feasible therapy for EMM has not yet been established and surgical excision can be difficult depending on the location of the melanoma. Thus, an effective and safe therapy is needed. Naturally occurring betulinic acid (BA), a pentacyclic triterpene and its synthetic derivate, NVX-207 (3-acetyl-betulinic acid-2-amino-3-hydroxy-2-hydroxymethyl-propanoate) are known for their cytotoxic properties against melanomas and other tumors and have already shown good safety and tolerability in vivo. In this study, BA and NVX-207 were tested for their permeation potential into equine skin in vitro in Franz-type diffusion cell (FDC) experiments after incubation of 5 min, 30 min and 24 h, aiming to use these formulations for prospective in vivo studies as a treatment for early melanoma stages. Potent permeation was defined as reaching or exceeding the half maximal inhibitory concentrations (IC50) of BA or NVX-207 for equine melanoma cells in equine skin samples. The active ingredients were either dissolved in a microemulsion (ME) or in a microemulsion gel (MEG). All of the formulations were transdermally applied but the oil-in-water microemulsion was administered with a novel oxygen flow-assisted (OFA) applicator (DERMADROP TDA).
Results
All tested formulations exceeded the IC50 values for equine melanoma cells for BA and NVX-207 in equine skin samples, independently of the incubation time NVX-207 applied with the OFA applicator showed a significant time-dependent accumulation and depot-effect in the skin after 30 min and 24 h (P < 0.05).
Conclusions
All tested substances showed promising results. Additionally, OFA administration showed a significant accumulation of NVX-207 after 30 min and 24 h of incubation. Further in vivo trials with OFA application are recommended.
... Effects: Targets and Mechanisms References BA Inhibition of cyclic AMP-dependent protein kinase, sulfonylureas, stromelysin, and collagenase [3] B and BA Differential effects on cytokine production in human blood cell cultures [26] OA and derivatives Anticancer activity, target profiling, and mechanisms of action [27] L and derivatives Inhibitors of nitric oxide and prostaglandin E2 [28] B, BA, and L Stimulus-induced superoxide generation and tyrosyl phosphorylation of proteins in human neutrophils [29] TTs Induction of the mitochondrial pathway of apoptosis, especially in melanoma cells [30] TTs (Euonymus alatus twigs) Bioassay-guided isolation and antiproliferative effects [31] B Protects HT-22 hippocampal cells against ER stress by induction of heme oxygenase-1 and inhibition of ROS production [32] BA Cytotoxic against tumor cells and reduced cytotoxicity against normal dermal fibroblasts and blood lymphocytes [33] B extract (Acacia auricularis) ...
... Anti-proliferative effect via topoisomerase I and II inhibition in tumor cells (1), mitochondrial apoptosis (2), and anti-angiogenesis (3) in cancer cells [30] BA action on melanoma cells in vitro Induction of changes in the potential of the mitochondrial membrane, activation of caspases, and production of reactive oxygen species [61,62] BA distribution across various tissues was administered with a single intraperitoneal dose of 500 mg/kg, as determined by LC-ESI-/MS. ...
... Currently, the mechanisms involved in the anticancer activity of TTs, but especially of BA, are well known and involve BA. The most important is the BA's ability to induce apoptosis [30]. These are the extrinsic and intrinsic pathways involved in apoptosis, via the death receptor and the mitochondrial pathway. ...
Pentacyclic triterpenoids (TTs) represent a unique family of phytochemicals with interesting properties and pharmacological effects, with some representatives, such as betulinic acid (BA) and betulin (B), being mainly investigated as potential anticancer molecules. Considering the recent scientific and preclinical investigations, a review of their anticancer mechanisms, structure-related activity, and efficiency improved by their insertion in nanolipid vehicles for targeted delivery is presented. A systematic literature study about their effects on tumor cells in vitro and in vivo, as free molecules or encapsulated in liposomes or nanolipids, is discussed. A special approach is given to liposome-TTs and nanolipid-TTs complexes to be linked to microbubbles, known as contrast agents in ultrasonography. The production of such supramolecular conjugates to deliver the drugs to target cells via sonoporation represents a new scientific and applicative direction to improve TT efficiency, considering that they have limited availability as lipophilic molecules. Relevant and recent examples of in vitro and in vivo studies, as well as the challenges for the next steps towards the application of these complex delivery systems to tumor cells, are discussed, as are the challenges for the next steps towards the application of targeted delivery to tumor cells, opening new directions for innovative nanotechnological solutions.
... Many studies have been devoted to the methods of chemical modification of betulin derivatives with biological activity, including in reviews [8,[80][81][82][83]. Research on the targeted synthesis of betulin and betulinic acid derivatives with improved solubility began in 2000-2012, including the Gzuka review of patents [84]. ...
... 3. A special place among the methods for obtaining betulin derivatives is occupied by modification methods to give hydrophilicity and, accordingly, better solubility and bioavailability, which in turn makes it possible to prepare hydrophilic dosage forms, Many studies have been devoted to the methods of chemical modification of betulin derivatives with biological activity, including in reviews [8,[80][81][82][83]. Research on the targeted synthesis of betulin and betulinic acid derivatives with improved solubility began in 2000-2012, including the Gzuka review of patents [84]. ...
This scientific work presents practical and theoretical material on the methods of analysis and identification of betulin and its key derivatives. The properties of betulin and its derivatives, which are determined by the structural features of this class of compounds and their tendency to form dimers, polymorphism and isomerization, are considered. This article outlines ways to improve not only the bioavailability but also the solubility of triterpenoids, as well as any hydrophobic drug substances, through chemical transformations by introducing various functional groups, such as carboxyl, hydroxyl, amino, phosphate/phosphonate and carbonyl. The authors of this article summarized the physicochemical characteristics of betulin and its compounds, systematized the literature data on IR and NMR spectroscopy and gave the melting temperatures of key acids and aldehydes based on betulin.
... Despite having great potential as a therapeutic agent, it is hard for BA to fulfill the requirements for adequate water solubility, maintaining both significant cytotoxicity and selectivity for tumor cells. Consequently, endeavors have been made to enhance the solubility of existing molecules and explore new and more efficient modes of administration, such as liposomes, nanoconstructs, and ionic liquids, including for brain tissue access [16,91,92]. ...
Betulinic acid is a naturally occurring compound that can be obtained through methanolic or ethanolic extraction from plant sources, as well as through chemical synthesis or microbial biotransformation. Betulinic acid has been investigated for its potential therapeutic properties, and exhibits anti-inflammatory, antiviral, antimalarial, and antioxidant activities. Notably, its ability to cross the blood–brain barrier addresses a significant challenge in treating neurological pathologies. This review aims to compile information about the impact of betulinic acid as an antitumor agent, particularly in the context of glioblastoma. Importantly, betulinic acid demonstrates selective antitumor activity against glioblastoma cells by inhibiting proliferation and inducing apoptosis, consistent with observations in other cancer types. Compelling evidence published highlights the acid’s therapeutic action in suppressing the Akt/NFκB-p65 signaling cascade and enhancing the cytotoxic effects of the chemotherapeutic agent temozolomide. Interesting findings with betulinic acid also suggest a focus on researching the reduction of glioblastoma’s invasiveness and aggressiveness profile. This involves modulation of extracellular matrix components, remodeling of the cytoskeleton, and secretion of proteolytic proteins. Drawing from a comprehensive review, we conclude that betulinic acid formulations as nanoparticles and/or ionic liquids are promising drug delivery approaches with the potential for translation into clinical applications for the treatment and management of glioblastoma.
... Betulinic acid (BA) is a pentacyclic lupane-type triterpene found in the medicinal plant Ziziphus jujuba var. spinosa (Bunge) Hu ex H. F.Chow [65]. Gu et al. [66] used a methionine and choline-deficient L-amino acid diet (MCD) and HFD to induce NAFLD in female C57BL/6 mice for 12 weeks. ...
Background
Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition with significant clinical implications. Emerging research indicates endoplasmic reticulum (ER) stress as a critical pathogenic factor governing inflammatory responses, lipid metabolism and insulin signal transduction in patients with NAFLD. ER stress-associated activation of multiple signal transduction pathways, including the unfolded protein response, disrupts lipid homeostasis and substantially contributes to NAFLD development and progression. Targeting ER stress for liver function enhancement presents an innovative therapeutic strategy. Notably, the natural bioactive compounds of plant extracts have shown potential for treating NAFLD by reducing the level of ER stress marker proteins and mitigating inflammation, stress responses, and de novo lipogenesis. However, owing to limited comprehensive reviews, the effectiveness and pharmacology of these bioactive compounds remain uncertain.
Objectives
To address the abovementioned challenges, the current review categorizes the bioactive compounds of plant extracts by chemical structures and properties into flavonoids, phenols, terpenoids, glycosides, lipids and quinones and examines their ameliorative potential for NAFLD under ER stress.
Methods
This review systematically analyses the literature on the interactions of bioactive compounds from plant extracts with molecular targets under ER stress, providing a holistic view of NAFLD therapy.
Results
Bioactive compounds from plant extracts may improve NAFLD by alleviating ER stress; reducing lipid synthesis, inflammation, oxidative stress and apoptosis and enhancing fatty acid metabolism. This provides a multifaceted approach for treating NAFLD.
Conclusion
This review underscores the role of ER stress in NAFLD and the potential of plant bioactive compounds in treating this condition. The molecular mechanisms by which plant bioactive compounds interact with their ER stress targets provide a basis for further exploration in NAFLD management.
The Juá is a plant of the family of the Rhamnaceae, of scientific name ZIZIPHUS JOAZEIRO, also known like joá, joazeiro, juazeiro, among others. It is a tall tree, which reaches from 5m to 15m high, abundant, thorny. With coriaceous leaves, small flowers, globose fruit, about 3cm, yellow, edible. The barks of the bark of the juazeiro have several applications, the main one is to replace the soap in the places where the water is heavy, brackish (they keep a saponácea property). Tea and syrup made from zest and leaves can be used for medicinal purposes. Recently, various hygiene products and industrialized aesthetics have included juazeiro in the composition of its products. In a simple manner, drying is a process in which heat is supplied to a particular material for the purpose of peeling or evaporating the moisture content that exists in the core or surface thereof, thereby obtaining a moisture-free product, i.e. , dry. Foam-mat drying applies to the drying of liquid or semi-liquid foodstuffs, which are transformed into stable foam by the incorporation of air into their structure and the addition of emulsifying / stabilizing agents (when necessary ) and has the characteristic of adding high commercial value and quality to the products, offering great possibilities of commercialization and uses. The objective of this work is to define parameters for foam-mat drying in juá to obtain juá powder. The use of this method for the drying of juá showed good results. It was verified that all variables studied (agitation time, stirring speed and drying temperature) influenced the behavior of juá. The stirring speed and the time of agitation of the juice are the variables that most influence the drying of the juá.
Pentacyclic triterpenoids are a diverse subclass of naturally occurring terpenes with various biological activities and applications. These compounds are broadly distributed in natural plant resources, but their low abundance and the slow growth cycle of plants pose challenges to their extraction and production. The biosynthesis of pentacyclic triterpenoids occurs through two main pathways, the mevalonic acid (MVA) pathway and the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway, which involve several enzymes and modifications. Plant in vitro cultures, including elicited and hairy root cultures, have emerged as an effective and sustainable system for pentacyclic triterpenoid production, circumventing the limitations associated with natural plant resources. Bioreactor systems and controlling key parameters, such as media composition, temperature, light quality, and elicitor treatments, have been optimized to enhance the production and characterization of specific pentacyclic triterpenoids. These systems offer a promising bioprocessing tool for producing pentacyclic triterpenoids characterized by a low carbon footprint and a sustainable source of these compounds for various industrial applications.
Terpenoids, also known as isoprenoids, are the most numerous and structurally diverse natural products found in many plants. Several studies, in vitro, preclinical, and clinical, have confirmed that this class of compounds displays a wide array of very important pharmacological properties. The diverse collection of terpenoid structures and functions has evoked increased interest in their commercial use resulting in some with established medical applications being registered as drugs on the market. This chapter herewith outlines the classification of terpenoids providing brief descriptions of each group, the methods of extraction and their chemical identification, and discusses their range of pharmacological activities and pharmaceutical applications.
Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the “Hallmarks of cancer”. Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.
HIV-1 maturation inhibitors are compounds other than HIV-1 protease inhibitors that inhibit HIV-1 maturation. This review focuses on triterpene derivatives, as their preclinical and clinical pharmacological profiles have been relatively well studied. Among the triterpene anti-HIV-1 maturation inhibitors, the betulinic acid derivative bevirimat dimeglumine (MPC-4326, formerly PA-457) is at the most advanced stage of drug development. Myriad Pharmaceuticals acquired all rights to bevirimat from Panacos Pharmaceuticals and continues to develop it under the new name MPC-4326. Although bevirimat is a potent HIV-1 maturation inhibitor, the results from phase II clinical trials indicate that it is less effective in a subset (30-40%) of HIV-1-positive individuals due to Gag polymorphisms in the glutamine-valine-threonine (QVT) motif of spacer peptide SP1. In addition to clinical development, recent medicinal chemistry approaches to obtain HIV-1 maturation inhibitors that are more potent than bevirimat are summarized. Copyright © 2009 Prous Science, S.A.U. or its licensors. All rights reserved.
Betulin was esterified with (±)-citronellic and geranic acids to resp. 28-O-esters at 0°C, 3,28-O-diesters at room temp. and to 3-O-esters via 28-O-acetates with following hydrolysis of acetoxy group. Similarly, betulinic acid was esterified to resp. diastereoisomeric esters. The substrates and products were studied for cytotoxic activity. Neither terpenic acids used, nor betulin monoesters, nor betulin dicitronellate were cytotoxic. Betulin digeranylate showed some cytotoxic activity but lower than that of betulin. In contrary, betulinic acid citronellate showed cytotoxic activity in some cases even higher that of unsubstituted betulinic acid (toward murine lymphoblasts and T-cell human leukemia). All esters were obtained as oils (except for betulinic acids citronellate m. p. 143–145°) and identified by NMR and IR spectroscopies.
New derivatives of lupane triterpenoids, viz., 20,29-dihydrobetulinic and 3-epi-20,29-dihydrobetulinic acid derivatives containing triphenylphosphonium fragments as substituents were synthesized. These compound considerably exceed betulinic acid in antitumor activity.
Using neoglycosylation, the impact of differential glycosylation upon the divergent anticancer and anti-HIV properties of the triterpenoid betulinic acid (BA) was examined. Each member from a library of 37 differentially glycosylated BA variants was tested for anticancer and anti-HIV activities. Enhanced analogs for both desired activities were discovered with the corresponding antitumor or antiviral enhancements diverging, based upon the appended sugar, into two distinct compound subsets.
The weak hydrosolubility of betulinic acid (3) hampers the clinical development of this natural anticancer agent. In order to circumvent this problem and to enhance the pharmacological properties of betulinic acid (3) and the lupane-type triterpenes lupeol (1), betulin (2), and methyl betulinate (7), glycosides (beta-D-glucosides, alpha-L-rhamnosides, and alpha-D-arabinosides) were synthesized and in vitro tested for cytotoxicity against three cancerous (A-549, DLD-1, and B16-F1) and one healthy (WS1) cell lines. The addition of a sugar moiety at the C-3 or C-28 position of betulin (2) resulted in a loss of cytotoxicity. In contrast, the 3-O-beta-D-glucosidation of lupeol (1) improved the activity by 7- to 12-fold (IC(50) 14-15.0 mu M). Moreover, the results showed that cancer cell lines are 8- to 12-fold more sensitive to the 3-O-alpha-L-rhamnopyranoside derivative of betulinic acid (IC(50) 2.6-3.9 mu M, 22) than the healthy cells (IC(50) 31 mu M). Thus, this study indicates that 3-O-glycosides of lupane-type triterpenoids represent an interesting class of potent in vitro cytotoxic agents. (c) 2006 Elsevier Ltd. All rights reserved.
Lipase catalyzed synthesis reaction of betulinic acid with 3-methylphthalic anhydride in presence of Novozyme 435 as biocatalyst gave 3β-(3- methylphthalyl)-lup-20(29)-ene-28-oic acid, which is a new candidate for anticancer agent. The reaction was carried out in chloroform at 37 °C for 24 h. 3β-(3-methylphthalyl)-lup-20(29)-ene-28-oic acid showed a higher cytotoxicity as compare to parent compound.
Betulinic acid is a natural product that can be found in abundance in the outer bark of the white birch tree (Betula pendula Roth, Betulaceae). The experimental study was intended to extract betulinic acid from the white birch tree leaves and its derivatization to obtain dipeptide compounds with potential biologic activity. For this purpose, three dipeptides were used: alanyl-glycine, glycyl-leucine and leucyl-glycine. The biological activity of betulinoil- glycyl-leucine has been tested on several cancer cells lines, HeLa, MCF-7, A431 and A2780.
A novel series of 17-carboxylic acid modified amide derivatives of 23-hydroxy betulinic acid (1) were prepared and tested in vitro against five cell lines: A549 (human lung carcinoma), BEL-7402 (human hepatoma), SF-763 (human cerebroma), B16 (mice melanoma) and HL-60 (human leukaemia). Within this series of compounds, 4a (IC50=21.08 μM in SF-763, IC50=21.63 μM in HL-60), 4b (IC50=28.45 μM in HL-60,IC50=29.32 μM in BEL-7402) and 6g (IC50=26.09 (μM in BEL-7402, IC50=22.65 (μM in HL-60) have the more potent cytotoxic activity than lead compound 1. The preliminary structure-activity relationship analysis of the C-28 amide derivatives is also discussed.
The anticancer properties of the derivatives of natural pentacyclic triterpenoids have received much attention recently. Here we present the preparation and the evaluation of the anticancer activity of a novel group of derivatives: quaternary ammonium esters. The esters were synthesized by quaternization of the respective 2-bromoethyl esters of betulinic, dihydrobetulinic, platanic, oleanolic, ursolic, and 3 beta-acetoxy-21-oxolup-18-en-28-oic acids with common low-molecular-weight tertiary amines, namely trimethylamine, triethylamine, pyridine, and triethanolamine. However, the desired quaternary salts were obtained only from trimethylamine, triethylamine, and pyridine. In case of the reaction with triethanolamine the elimination of one of the 2-hydroxyethyl groups occurred and only tertiary amines were formed. Most of the prepared compounds showed significant in vitro cytotoxic activity on the CEM T-lymfoblastic leukaemia cell line. Three of the six selected compounds {2-(triethylammonio) ethyl 3 beta-hydroxylup-20(29)-en-28oate bromide, 2-(triethylammonio) ethyl 3 beta-hydroxylupan-28-oate bromide and 2-[bis(2-hydroxyethyl) amino] ethyl 3 beta-hydroxylupan-28- oate] exhibited strong cytotoxic activity on a panel of ten cell lines, including drug resistant.
Betulinic acid is a naturally occurring pentacyclic lupane-type triterpene. It shows a broad range of biological and medicinal properties. This review provides the various botanical sources of betulinic acid.