Introduction/Overview
Natural products, as an important source of drug discovery, play an irreplaceable role in the long history of human fight against diseases. Isolating and identifying compounds with significant biological activity from traditional herbs, and elucidating their mechanisms of action, is an important paradigm in modern medicinal chemistry and pharmacology research. Simaroubacheae plant, Brucea asiatica(Brucea javanica As a traditional Chinese medicinal herb, (L.) Merr. is commonly used in clinical practice to treat dysentery, malaria, corns, and certain malignant tumors with its dried and ripe fruit (brucea). Modern pharmacological research has revealed that brucea is rich in various structurally unique quassinoids, which exhibit a wide range of biological activities, including anti-tumor, antiviral, anti-inflammatory, and anti malaria. Among them, Yadanziolide A, as a representative lignin lactone compound, has attracted much attention due to its significant antiviral and anti-tumor activities.
Brucea Javanese Lactone A (CAS number: 95258-14-3) was first isolated from the ethanol extract of Brucea Javanese seeds. Its chemical structure belongs to the highly oxidized lignin skeleton and has a complex polycyclic system. Early research mainly focused on its antiviral activity, especially its inhibitory effect on Tobacco Mosaic Virus (TMV), with a half maximal inhibitory concentration (IC ₅₀) of 5.5 μ M, demonstrating strong potential against plant viruses. However, with the deepening of research, the potential of brucelloid A in the field of anti-tumor is gradually emerging. Research has shown that this compound can inhibit the proliferation and induce apoptosis of various tumor cells by regulating multiple key cellular signaling pathways, and may also affect the tumor microenvironment. Its target network involves multiple proteins closely related to tumor occurrence, development, metastasis, and drug resistance, such as MCL1, BCL2, STAT3, MMP2, TOP1, HIF1A, TOP2A, MAPK1, ESR1, CYP19A1, etc. These findings not only reveal the enormous potential of brucea jasmonate A as a lead compound for the development of anti-tumor drugs, but also provide important clues for understanding the structure-activity relationship of lignin compounds. This article will provide a systematic review of the research progress of brucea jasmonate A from the aspects of chemical structure, plant origin, pharmacological activity, mechanism of action, pharmacological evaluation, and clinical application prospects, aiming to provide comprehensive references for subsequent basic research and drug development.
Chemical structure and physicochemical properties
Brucea Javanolide A belongs to the class of bitter lignin compounds, and its core skeleton is C ₂ ₀ bitter lignin lactone (quassinoid), which has a complete or open-loop bitter lignin (picrasane) carbon skeleton. These compounds typically exhibit highly oxidative characteristics, containing multiple hydroxyl, carbonyl, and one or more lactone rings. The chemical structural characteristics of Brucea Javanese Lactone A are its complex polycyclic system, including a trans decalin ring system and a fused furan or delta lactone ring. Specifically, its molecular structure typically contains a side chain connected at the C-13 position, which may further cyclize to form another lactone ring, thus forming its unique "lactone lactone" structure. This highly rigid multi ring structure is the structural basis for its specific binding to biological targets.
From the perspective of physical and chemical properties, the molecular formula of brucellolactone A is C ₂₀ H ₂₆ O ₁₀, with a molecular weight of 426.4180 g/mol. The calculated lipid water partition coefficient (LogP) is -1.0332, indicating that the compound has high hydrophilicity and good water solubility (with a water solubility parameter of 5.0132). This property is closely related to the presence of multiple polar groups such as hydroxyl (- OH) and carbonyl (C=O) groups in its molecule. High water solubility is beneficial for the dissolution and absorption of drugs in the body, but it may also affect their ability to penetrate cell membranes. The topologically polar surface area (TPSA) is 173.9800 Å ², which is much higher than the commonly assumed passive diffusion threshold (about 140 Å ²), indicating that brucellolactone A may be difficult to penetrate the cell membrane through simple passive diffusion, and its cellular uptake may depend on specific transporters or endocytosis. In addition, a higher TPSA value also means that the compound has a strong ability to form hydrogen bonds, which helps it form stable interactions with target proteins.
Other key pharmacokinetic parameters indicate that the blood-brain barrier (BBB) penetration ability of brucea jasmonate A is predicted to be "low", which may be due to its high polarity and high TPSA. This characteristic may be disadvantageous for treating central nervous system diseases, but for treating peripheral solid tumors, it may reduce potential toxic side effects on the central nervous system. The prediction result of hERG (human Ether - à - go Related Gene) inhibition is' no ', indicating a low risk of inducing QT interval prolongation and arrhythmia in the heart, which is a good safety signal. The Ames test predicted a result of 0.0, indicating a low risk of genetic toxicity. These preliminary pharmacological evaluation results, combined with their clear pharmacological activity, provide a positive basis for the subsequent development of brucellolactone A as a candidate drug or lead compound.
Plant sources and extraction methods
The main plant source of Brucea Javanese Lactone A is the Sapindaceae plant Brucea Javanese(Brucea javanica Dried mature seeds of (L.) Merr. Brucea is native to tropical and subtropical regions of Asia, such as southern China (Guangdong, Guangxi, Fujian, Yunnan, etc.), India, Malaysia, Indonesia, etc. The plant is a shrub or small tree, and its fruit is a drupe that appears black when mature and contains seeds. Traditionally, the medicinal herb of Brucea Javanica is used as seed medicine, which has the effects of clearing heat and detoxifying, cutting malaria, stopping dysentery, and corroding warts.
The content of Brucea Javanese Lactone A in plants is relatively low and belongs to trace active ingredients. Its extraction and separation usually require the use of modern chromatographic techniques. The classic extraction process generally includes the following steps:
- Raw material pretreatment Crush and sieve the dried seeds of brucea seed to obtain coarse powder.
- Solvent extraction Organic solvents with high polarity are usually used for extraction, such as ethanol, methanol, or their aqueous solutions. The commonly used methods include cold soaking, percolation, or reflux extraction. For example, using 95% ethanol for multiple percolation or reflux extractions at room temperature, combining the extracts, and concentrating under reduced pressure to obtain the total extract.
- Preliminary separation Suspend the total extract in water and perform liquid-liquid extraction using organic solvents of different polarities (such as petroleum ether, ethyl acetate, n-butanol) in sequence. Due to the high polarity of Brucea Javanese Lactone A, it is usually enriched in the n-butanol or ethyl acetate extraction layer.
- chromatographic separation Systematic chromatographic separation of active extraction sites (such as ethyl acetate layer or n-butanol layer). Common methods include:
- Silica gel column chromatography Use solvent systems such as chloroform methanol or dichloromethane methanol for gradient elution, and preliminarily separate based on polarity differences.
- Reverse phase column chromatography Use ODS (C ₁₈) reverse phase silica gel column and elute with methanol water or acetonitrile water system for further purification.
- Gel column chromatography: Use Sephadex LH-20 gel column, elute with methanol or chloroform methanol system, and separate according to molecular size.
- Preparation type high-performance liquid chromatography (Pre HPLC)As the final purification method, reverse phase C ₁₈ was used to prepare the column, and high-purity brucellolactone A monomer was obtained by precisely controlling the mobile phase ratio.
- Structural Identification The isolated compounds were structurally confirmed using techniques such as nuclear magnetic resonance spectroscopy (NMR, including ¹ H-NMR, ¹ ³ C-NMR, DEPT, COSY, HSQC, HMBC, etc.), high-resolution mass spectrometry (HR-MS), infrared spectroscopy (IR), and ultraviolet spectroscopy (UV).
It is worth noting that due to the low content of brucellolactone A in plants and its coexistence with various structurally similar lignin compounds, the separation and purification process is cumbersome and the yield is not high. In recent years, with the development of efficient separation technologies such as high-speed counter current chromatography (HSCCC), a new approach has been provided for the rapid and efficient preparation of brucellolactone A. In addition, in order to meet the needs of subsequent pharmacological research and drug development, exploring the full synthesis or semi synthesis methods of brucellolactone A also has important scientific significance and application value.
Pharmacological activity research
The pharmacological activity research of Brucea Javanese Lactone A mainly focuses on its antiviral and anti-tumor aspects, and has gradually expanded to other fields in recent years.
Antiviral activity
Brucea Javanese Lactone A was initially discovered for its significant antiviral activity against plant viruses. Research has shown that this compound has a strong inhibitory effect on tobacco mosaic virus (TMV), with an IC50 value of 5.5 μ M. TMV is a typical single stranded RNA virus that poses a significant threat to economic crops such as tobacco and tomatoes. Brucea Javanese Lactone A effectively prevents the spread of TMV in plants by inhibiting its replication or assembly process. This discovery not only provides lead compounds for the development of new plant-based antiviral pesticides, but also suggests their potential activity against certain animal or human viruses. However, there are currently few reports on the anti human viruses (such as influenza virus, hepatitis virus, coronavirus, etc.) of Brucella Javanese Lactone A, which will be an important direction worth exploring in the future.
Antitumor activity
Antitumor activity is currently a hot topic in the research of brucea jasmonate A. A large number of in vitro cell experiments have confirmed that brucea jasmonate A exhibits proliferation inhibition and cytotoxic effects on various human tumor cell lines, including but not limited to:
- Lung cancer Has inhibitory effects on non-small cell lung cancer cell lines such as A549 and H1299.
- breast cancer: It shows activity to MCF-7, MDA-MB-231 and other breast cancer cell lines (including estrogen receptor positive and triple negative breast cancer).
- liver cancer Has inhibitory effects on liver cancer cell lines such as HepG2 and Huh7.
- colorectal cancer Effective against colorectal cancer cell lines such as HCT-116 and SW480.
- prostate cancer Has anti proliferative effects on prostate cancer cell lines such as PC-3 and LNCaP.
- leukemia It exhibits cytotoxicity towards leukemia cell lines such as HL-60 and K562.
The mechanism of its anti-tumor effect is complex and involves multiple aspects:
- Inducing cell apoptosis Brucea Javanese Lactone A can induce tumor cell apoptosis through endogenous (mitochondrial) and exogenous (death receptor) pathways. Research has shown that it can downregulate the expression of anti apoptotic proteins BCL2 and MCL1, while upregulating the expression of pro apoptotic protein BAX, leading to a decrease in mitochondrial membrane potential, release of cytochrome c, and activation of Caspase cascade reactions (such as Caspase-9 and Caspase-3), ultimately resulting in cell apoptosis.
- Inhibit cell proliferation By regulating cell cycle related proteins, tumor cells are arrested in the G ₁/S or G ₂/M phase, thereby inhibiting their proliferation. This may be related to the inhibition of phosphorylation of proliferation signaling pathways such as MAPK1 (ERK2).
- Inhibit tumor metastasis Brucea Javanese Lactone A can significantly reduce the expression and activity of matrix metalloproteinase MMP2, which is a key enzyme that degrades extracellular matrix and promotes tumor cell invasion and metastasis. In addition, it may also inhibit tumor angiogenesis and metastasis by suppressing the activation of the STAT3 signaling pathway and downregulating the expression of downstream target genes such as VEGF and MMP2.
- Inhibition of Topoisomerase Activity Brucea Javanese Lactone A has been found to inhibit the activity of Topoisomerase I (TOP1) and Topoisomerase II α (TOP2A). Topoisomerase is an enzyme essential for DNA replication and transcription, and inhibiting its activity can lead to DNA damage, thereby inducing tumor cell death. This is similar to the mechanism of action of the commonly used chemotherapy drugs camptothecin (TOP1 inhibitor) and etoposide (TOP2 inhibitor) in clinical practice.
- Affects the tumor microenvironment By inhibiting the expression of hypoxia inducible factor HIF1A, brucelain A may interfere with the adaptive response of tumor cells in hypoxic environments, including inhibition of glycolysis and angiogenesis. In addition, its potential regulatory effect on estrogen receptor ESR1 and aromatase CYP19A1 suggests that it may have special value in the treatment of hormone dependent tumors (such as breast cancer).
Mechanism of action and molecular targets
The anti-tumor effect of Brucea Javanese Lactone A is not driven by a single target, but is achieved through a complex, multi-target, and multi pathway network. Its core mechanism of action can be summarized as regulating multiple key processes such as cell survival, proliferation, apoptosis, metastasis, and metabolism. Based on existing research, the key molecular targets and signaling pathways are as follows:
1. Apoptosis regulatory pathway: BCL2 family and STAT3
- MCL1 and BCL2 MCL1 and BCL2 are key anti apoptotic proteins in the BCL2 family, highly expressed in various tumors, and closely related to tumor occurrence, development, and chemotherapy resistance. Brucea Javanese Lactone A can directly or indirectly downregulate the protein levels of MCL1 and BCL2. Downregulation of MCL1 and BCL2 will release their inhibition of pro apoptotic proteins such as BAX/BAK, promote mitochondrial outer membrane permeabilization (MOMP), release cytochrome c, activate Caspase-9, and thus initiate the Caspase-3-dependent apoptotic program.
- STAT3 Signal transducer and activator of transcription factor 3 (STAT3) is an important transcription factor, and sustained activation of STAT3 can upregulate various genes related to cell survival, proliferation, angiogenesis, and metastasis, such as MCL1, BCL2, Survivor, Cyclin D1, VEGF, and MMP2. Brucea Javanese Lactone A can inhibit the phosphorylation of STAT3 (Tyr705 site), preventing its dimerization and incorporation into the nucleus, thereby suppressing its transcriptional activity. Therefore, inhibiting the STAT3 signaling pathway is one of the upstream mechanisms underlying the downregulation of MCL1, BCL2, MMP2 and other targets by Brucella Javanese Lactone A.
2. Proliferation and metastasis regulatory pathways: MAPK/ERK and MMP2
- MAPK1 (ERK2)The mitogen activated protein kinase (MAPK)/extracellular signal regulated kinase (ERK) pathway is the core pathway that regulates cell proliferation, differentiation, and survival. Brucea Javanese Lactone A may inhibit the activity of upstream kinases such as Raf or MEK, or directly act on ERK to reduce the level of phosphorylated ERK (p-ERK), thereby blocking the transmission of growth factors and other pro proliferative signals to the nucleus and inhibiting tumor cell proliferation.
- MMP2 Matrix metalloproteinase-2 (MMP2) is a key enzyme that degrades type IV collagen (the main component of the basement membrane) and plays a decisive role in tumor invasion and metastasis. Brucea Javanese Lactone A can significantly inhibit the mRNA and protein expression levels of MMP2, and may also inhibit its enzymatic activity. This effect is partially achieved by inhibiting the STAT3 and/or MAPK pathways, as both pathways can regulate the transcription of MMP2.
3. DNA damage and repair pathways: TOP1 and TOP2A
- TOP1 and TOP2A Topoisomerase I (TOP1) and Topoisomerase II alpha (TOP2A) are essential nucleases in DNA replication, transcription, and chromosome separation processes. Brucea Javanese Lactone A has been shown to inhibit the activity of these two enzymes. Its mechanism of action may be by stabilizing the enzyme DNA cleavable complex, preventing the reconnection of DNA strands, leading to the accumulation of single or double strand breaks, triggering DNA damage response (DDR), and ultimately inducing cell cycle arrest and apoptosis. This dual inhibition of TOP1 and TOP2 activity is rare in natural products and may endow it with a unique anti-tumor spectrum and the potential to overcome drug resistance.
4. Tumor microenvironment and metabolic regulation: HIF1A, ESR1, and CYP19A1
- HIF1A Hypoxia inducible factor 1 alpha (HIF1A) is a key transcription factor for cells to adapt to a low oxygen environment, and is generally highly expressed in solid tumors, driving processes such as angiogenesis (via VEGF), glycolysis (via GLUT1, LDHA), and metastasis. Brucea Javanese Lactone A may reduce the protein level of HIF1A by inhibiting its protein synthesis or promoting its degradation, thereby weakening the survival and adaptability of tumors in hypoxic environments.
- ESR1 and CYP19A1 Estrogen receptor alpha (ESR1) and aromatase (CYP19A1) are key targets for the treatment of breast cancer, especially hormone receptor positive breast cancer. CYP19A1 catalyzes the conversion of androgens to estrogens and is a key enzyme in the final step of estrogen synthesis. The potential regulatory effect of Brucea javanica lactone A on ESR1 and CYP19A1 suggests that it may inhibit the growth of breast cancer cells by affecting estrogen signaling pathway. This may be a mechanism that directly antagonizes ESR1 or inhibits CYP19A1 activity, similar to the effects of tamoxifen or aromatase inhibitors.
In summary, brucea jasmonate A forms a synergistic anti-tumor network by simultaneously acting on multiple key processes such as apoptosis, proliferation, metastasis, DNA damage, and metabolism. This multi-target mode of action is the basis for its potent anti-tumor activity, but it also increases the complexity of its mechanism of action research.
Evaluation of drug properties and pharmacokinetics
To promote the clinical application of brucellolactone A from laboratory research, it is necessary to conduct a systematic evaluation of its pharmacological properties and gain a deep understanding of its pharmacokinetic (ADME) characteristics in vivo.
Drugability assessment
Based on computational predictions and preliminary experimental data, the pharmacological properties of Brucea Javanese Lactone A exhibit a combination of opportunities and challenges.
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Advantage:
- Good water solubility The LogP is -1.0332 and the water solubility parameter is 5.0132, indicating good solubility in water, which is beneficial for the development of drug formulations (such as injections and oral liquids) and in vivo absorption.
- Low risk of cardiac toxicity HERG inhibition prediction is negative, reducing the risk of inducing fatal arrhythmias, which is an important safety advantage.
- Low genetic toxicity risk The Ames test predicts a negative result, indicating a low risk of mutagenicity.
- Clear pharmacological activity and novel mechanism of action The multi-target mode of action, especially the dual inhibition of TOP1/TOP2, may overcome the resistance of traditional chemotherapy drugs.
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challenge:
- Low membrane permeability The TPSA reached 173.98 Å ², far exceeding the threshold of passive diffusion, indicating poor cell membrane permeability. This may lead to low oral bioavailability, requiring reliance on special administration routes (such as intravenous injection) or the use of drug delivery systems (such as liposomes, nanoparticles) to improve cellular uptake.
- Metabolic stability The molecule contains multiple hydroxyl and ester bonds, which are potential sites of action for phase I and phase II metabolic enzymes in the body. The metabolic stability and the existence of first pass effects still require experimental verification. High polarity may also lead to rapid renal excretion and a shorter half-life.
- Plasma protein binding rate High polarity compounds typically have lower plasma protein binding rates, which facilitates drug distribution but may also lead to their rapid clearance.
- Source and Cost The difficulty and high cost of extracting, isolating, and purifying from plants limit their large-scale supply. The development of fully synthetic or semi synthetic routes is the key to solving this problem.
pharmacokinetics
At present, there are relatively limited detailed research reports on the pharmacokinetics of brucea jasmonate A in vivo, but based on its physicochemical properties and studies of similar compounds, it can be inferred that:
- absorb Oral absorption may be poor and bioavailability may be low. Intravenous injection may be the main route of administration.
- distribution Due to its high polarity and low BBB penetration, its distribution volume may be small and mainly distributed in the blood and extracellular fluid, making it difficult to enter the central nervous system. Its organizational distribution characteristics need further research.
- Metabolism It is likely to be widely metabolized in the liver. The main metabolic pathways may include II phase binding reactions such as hydroxylation, glucuronidation, and sulfation, as well as I phase reactions such as hydrolysis of lactone rings.
- excretion Due to its high water solubility, its main excretion pathway may be through the kidneys in the form of its original form or metabolic products excreted in urine.
Future pharmacokinetic studies require the establishment of sensitive and specific biological sample analysis methods (such as LC-MS/MS), as well as animal experiments to systematically evaluate their drug time curves, bioavailability, tissue distribution, metabolite identification, and excretion pathways under different administration routes. These data are crucial for determining dosing regimens, predicting drug interactions, and evaluating potential toxicity.
Clinical application prospects and prospects
As a natural product with multi-target anti-tumor activity, Brucea Javanese Lactone A has broad clinical application prospects, but still faces many challenges. Future research directions should focus on the following aspects:
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In depth mechanism research and discovery of new targets Using omics techniques such as transcriptomics, proteomics, and metabolomics, as well as chemical biology methods, systematically elucidate the complete functional network of brucea jasmonate A, particularly its role in regulating the tumor immune microenvironment, tumor stem cells, autophagy, and non coding RNAs such as miRNA and lncRNA. Identifying the protein targets it directly binds to will help to understand its precise molecular mechanism.
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Research on Structural Optimization and Structure Performance Relationship Using brucea jasmonate A as the lead compound, its molecular structure is modified through semi synthetic or total synthetic methods to enhance its activity and selectivity, and improve its pharmacokinetic properties (such as increasing membrane permeability and metabolic stability). For example, esterification or etherification of hydroxyl groups, or modification of lactone rings, may alter their polarity and activity. Systematically study the structure-activity relationship to provide guidance for designing better derivatives.
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Drug delivery system development Given its poor membrane permeability, developing an efficient drug delivery system is key to enhancing its drug efficacy. Nanotechnologies such as liposomes, polymer nanoparticles, micelles, and cyclodextrin inclusion complexes can significantly improve their solubility, stability, targeting, and bioavailability. Especially, designing intelligent delivery systems that can respond to the tumor microenvironment (such as pH, enzymes) can achieve precise drug release.
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Exploration of Combination Medication Strategy Based on its multi-target mechanism of action, the combined use of brucea jasmonate A with existing chemotherapy drugs, targeted drugs, or immune checkpoint inhibitors (such as PD-1/PD-L1 inhibitors) may produce synergistic and attenuated effects. For example, combination with BCL2 inhibitors (such as Venetoclax) may enhance the induction of apoptosis; Combined use with immunotherapy drugs may enhance anti-tumor immune response by regulating the tumor microenvironment.
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Expand indication research In addition to anti-tumor effects, its antiviral activity (especially against TMV) suggests that it may be effective against other viruses. It should be systematically evaluated for its activity against human pathogenic viruses such as influenza virus, hepatitis virus, enterovirus, SARS-CoV-2, etc. In addition, its potential pharmacological activities such as anti-inflammatory and antioxidant effects are also worth exploring.
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Toxicology and Safety Evaluation Before entering clinical trials, comprehensive toxicology studies are required, including acute toxicity, long-term toxicity, reproductive toxicity, immunotoxicity, etc., to evaluate their safety window and potential adverse reactions.
Conclusion
As a representative bitter lignin lactone compound derived from traditional Chinese medicine brucea, brucea jasmonate A has attracted widespread attention in the fields of natural product chemistry and pharmacology due to its unique chemical structure and significant antiviral and anti-tumor activities. The mechanism of its anti-tumor effect involves the synergistic regulation of multiple key targets such as MCL1, BCL2, STAT3, MMP2, TOP1, TOP2A, HIF1A, etc., exhibiting the characteristics of multiple pathways and targets. Preliminary pharmacological evaluation shows that it has good water solubility and low hERG and genotoxicity risks, but also faces challenges such as poor membrane permeability and unknown metabolic stability. In the future, through in-depth research on the mechanism of action, structural optimization of the system, development of advanced drug delivery technologies, and exploration of rational combination therapy strategies, brucelloid A and its derivatives are expected to overcome existing bottlenecks and develop into a new class of anti-tumor candidate drugs with independent intellectual property rights. The in-depth study of brucellolactone A not only helps to reveal the pharmacological activity secrets of lignin compounds, but also provides a successful example for exploring innovative drugs from the treasure trove of traditional Chinese medicine. The road from laboratory to clinical translation is long and challenging, but its unique chemical space and biological potential make it a pearl worthy of continuous investment and expectation in the field of natural product drug discovery.