Activity of the antiestrogenic cajanin stilbene acid towards breast cancer

Cajaninstilbene Acid and Its Derivative as Multi-Therapeutic Agents: A Comprehensive Review

Pigeon pea (Cajanus cajan (L.) Millsp.) is a traditional Chinese medicinal plant widely utilized in folk medicine due to its significant pharmacological and nutritional properties. Cajaninstilbene acid (CSA), a stilbene compound derived from pigeon pea leaves, has been extensively investigated since the 1980s. A thorough understanding of CSA's mechanisms of action and its therapeutic effects on various diseases is crucial for developing novel therapeutic approaches. This paper presents an overview of recent research advancements concerning the biological activities and mechanisms of CSA and its derivatives up to February 2024. The review encompasses discussions on the in vivo metabolism of CSA and its derivatives, including antipathogenic micro-organisms activity, anti-tumor activity, systematic and organ protection activity (such as bone protection, cardiovascular protection, neuroprotection), anti-inflammatory activity, antioxidant activity, immune regulation as well as action mechanism of CSA and its derivatives. The most studied activities are antipathogenic micro-organisms activities. Additionally, the structure-activity relationships of CSA and its derivatives as well as the total synthesis of CSA are explored, highlighting the potential for developing new pharmaceutical agents. This review aims to provide a foundation for future clinical applications of CSA and its derivatives.

Enhanced Accumulation of Health-Promoting Cajaninstilbene Acid in Pigeon Pea Hairy Root Cultures Cocultured with an Endophytic Fungus during Early Stages of Colonization

Endophytic fungi can effectively regulate the biosynthesis of health-beneficial metabolites in plants. However, few studies have revealed how the accumulation of host metabolites varies during interactions with endophytic fungi. Here, pigeon pea hairy root cultures (PPHRCs) were cocultured with an endophytic fungus Penicillium rubens to explore the impact on the biosynthesis and accumulation of cajaninstilbene acid (CSA). The results showed that CSA accumulation in PPHRCs increased significantly (15.29-fold) during the early stages of P. rubens colonization (fungal attachment and invasion phases). Once P. rubens successfully colonized the intercellular gap of hairy roots to form a symbiotic relationship, the CSA levels in PPHRCs decreased drastically. Moreover, P. rubens could be recognized by plant pattern recognition receptors that regulate immunity/symbiosis, triggering the expression of genes related to pathogenesis, CSA biosynthesis, and ABC transporter. Overall, P. rubens could enhance the accumulation of health-promoting CSA in PPHRCs during the early stages of colonization.

A Dopamine-Modified Hyaluronic Acid-Based Mucus Carrying Phytoestrogen and Urinary Exosome for Thin Endometrium Repair

Thin endometrium (TE) is closely associated with infertility in reproductive medicine. Estrogen therapy gains unsatisfactory outcomes. In this study, an artificial mucus based on dopamine (L-DOPA)-modified hyaluronic acid combining phytoestrogen cajaninstilbene acid and rat urinary exosomes (CUEHD) is constructed for TE treatment using a rat TE model. In the rat TE model, the dominant elastic behavior and adhesive properties of CUEHD guarantee adequate retention, rendering superior synergistic treatment efficacy and favorable biosafety characteristics. CUEHD treatment significantly increases endometrial thickness and promotes receptivity and fertility. Mechanistically, estrogen homeostasis, inflammation inhibition, and endometrial regeneration are achieved through the crosstalk between ER-NLRP3-IL1β and Wnt-β catenin-TGFβ-smad signaling pathways. Moreover, the therapeutic potential of exosomes from human urine and adipose tissue-derived stem cells (ADSCs) and rat ADSCs are also demonstrated, indicating extensive use of the artificial mucus system. Thus, this study illustrates a platform combining phytoestrogen and exosomes with promising implications for TE treatment.

Cajanin stilbene acid: A direct inhibitor of colistin resistance protein MCR-1 that restores the efficacy of polymyxin B against resistant Gram-negative bacteria

BACKGROUND

The resistance of Gram-negative bacteria to polymyxin B, caused by the plasmid-mediated colistin resistance gene mcr-1, which encodes a phosphoethanolamine transferase (MCR-1), is a serious threat to global public health. Therefore, it is urgent to find new drugs that can effectively alleviate polymyxin B resistance. Through the screening of 78 natural compounds, we found that cajanin stilbene acid (CSA) can significantly restore the susceptibility of polymyxin B to mcr-1 positive Escherichia coli (E. coli).

PURPOSE

In this study, we tried to evaluate the ability of CSA to restore the susceptibility of polymyxin B towards the E. coli, and explore the mechanism of sensitivity recovery.

STUDY DESIGN AND METHODS

Checkerboard MICs, time-killing curves, scanning electron microscope, lethal and semi-lethal models of infection in mice were used to assess the ability of CSA to restore the susceptibility of polymyxyn to E. coli. The interaction between CSA and MCR-1 was evaluated using surface plasmon resonance (SPR), and molecular docking experiments.

RESULTS

Here, we find that CSA, a potential direct inhibitor of MCR-1, effectively restores the sensitivity of E. coli to polymyxin B. CSA can restore the sensitivity of polymyxin B to drug-resistant E. coli, and the MIC value can be reduced to 1 μg/ml. The time killing curve and scanning electron microscopy results also showed that CSA can effectively restore polymyxin B sensitivity. In vivo experiments showed that the simultaneous use of CSA and polymyxin B can effectively reduce the infection of drug-resistant E. coli in mice. SPR and molecular docking experiments confirmed that CSA strongly bound to MCR-1. The 17-carbonyl oxygen and 12- and 18‑hydroxyl oxygens of CSA were the key sites binding to MCR-1.

CONCLUSION

CSA is able to significantly restore the sensitivity of polymyxin B to E. coli in vivo and in vitro. CSA inhibits the enzymatic activity of the MCR-1 protein by binding to key amino acids at the active center of the MCR-1 protein.

Cocultivation of pigeon pea hairy root cultures and Aspergillus for the enhanced production of cajaninstilbene acid

Pigeon pea hairy root cultures (PPHRCs) have been proven to be a promising alternative for the production of health-beneficial phenolic compounds, such as the most important health-promoting compound, i.e., cajaninstilbene acid (CSA). In this study, PPHRCs were cocultured with live Aspergillus fungi for further improving phenolic productivity via biological elicitation. Aspergillus oryzae CGMCC 3.951 (AO 3.951) was found to be the optimal fungus that could achieve the maximum increment of CSA (10.73-fold increase) in 42-day-old PPHRCs under the inoculum size of mycelia 0.50% and cocultivation time 36 h. More precisely, the contents of CSA in hairy roots and culture media after fungal elicitation increased by 9.87- and 62.18-fold over control, respectively. Meanwhile, the contents of flavonoid glycosides decreased, while aglycone yields increased upon AO 3.951 elicitation. Moreover, AO 3.951 could trigger the oxidative stress and pathogen defense response thus activating the expression of biosynthesis- and ABC transporter-related genes, which contributed to the intracellular accumulation and extracellular secretion of phenolic compounds (especially CSA) in PPHRCs. And PAL2, 4CL2, STS1, and I3'H were likely to be the potential key enzyme genes regulating the biosynthesis of CSA, and ABCB11X1-1, ABCB11, and ABCG24X2 were closely related to the transmembrane transport of CSA. Overall, the cocultivation approach could make PPHRCs more commercially attractive for the production of high-value phenolic compounds such as CSA and flavonoid aglycones in nutraceutical/medicinal fields. And the elucidation of crucial biosynthesis and transport genes was important for systematic metabolic engineering aimed at increasing CSA productivity. KEY POINTS: • Cocultivation of PPHRCs and live fungi was to enhance CSA production and secretion. • PPHRCs augmented CSA productivity 10.73-fold when cocultured with AO 3.951 mycelia. • Several biosynthesis and transport genes related to CSA production were clarified.

The use of African medicinal plants in cancer management

Cancer is the third leading cause of premature death in sub-Saharan Africa. Cervical cancer has the highest number of incidences in sub-Saharan Africa due to high HIV prevalence (70% of global cases) in African countries which is linked to increasing the risk of developing cervical cancer, and the continuous high risk of being infected with Human papillomavirus In 2020, the risk of dying from cancer amongst women was higher in Eastern Africa (11%) than it was in Northern America (7.4%). Plants continue to provide unlimited pharmacological bioactive compounds that are used to manage various illnesses, including cancer. By reviewing the literature, we provide an inventory of African plants with reported anticancer activity and evidence supporting their use in cancer management. In this review, we report 23 plants that have been used for cancer management in Africa, where the anticancer extracts are usually prepared from barks, fruits, leaves, roots, and stems of these plants. Extensive information is reported about the bioactive compounds present in these plants as well as their potential activities against various forms of cancer. However, information on the anticancer properties of other African medicinal plants is insufficient. Therefore, there is a need to isolate and evaluate the anticancer potential of bioactive compounds from other African medicinal plants. Further studies on these plants will allow the elucidation of their anticancer mechanisms of action and allow the identification of phytochemicals that are responsible for their anticancer properties. Overall, this review provides consolidated and extensive information not only on diverse medicinal plants of Africa but on the different types of cancer that these plants are used to manage and the diverse mechanisms and pathways that are involved during cancer alleviation.

Cajaninstilbene Acid Ameliorates Acetaminophen-Induced Liver Injury Through Enhancing Sestrin2/AMPK-Mediated Mitochondrial Quality Control

Acetaminophen (APAP)-induced liver injury (AILI) is the main cause of acute liver failure in the developed countries. The present study aimed to evaluate the therapeutic efficacy of cajaninstilbene acid (CSA), a major stilbene compound derived from the leaves of pigeon pea [Cajanus cajan (L.) Millsp.], against AILI. CSA (50, 75 mg/kg, p. o.) was administered to male C57BL/6 N mice 0.5 h after a toxic dose of APAP (300 mg/kg, i. p.). The direct effect of CSA on hepatocytes was tested on primary mouse hepatocytes. Serum transaminases, hematoxylin and eosin staining, TUNEL and propidium iodide staining were used to assess hepatic damage and cell death. The results demonstrated that APAP-induced liver injury was ameliorated by CSA, as evidenced by decreased alanine aminotransferase and aspartate aminotransferase levels in the serum, and fewer necrotic and apoptotic hepatocytes in vitro and in vivo. Consequently, the inflammation in response to APAP overdose was inhibited by CSA. Without affecting APAP metabolic activation, CSA interrupted the sustained JNK-Sab-ROS activation loop and alleviated oxidative stress. Additionally, CSA promoted mitochondrial quality control, including mitochondrial biogenesis and mitophagy, as revealed by increased PGC-1α, TFAM, LC3-Ⅱ, PINK1 and mitochondrial Parkin expression and decreased p62 expression. Further mechanistic investigations showed that independent of CAMKK2, LKB1-mediated AMPK activation, which was promoted by Sestrin2, might be responsible for the protective effect of CSA. Our study demonstrates that CSA alleviates APAP-induced oxidative stress and enhanced mitochondrial quality control through Sestrin2/AMPK activation, thereby protecting against AILI,.

Application of UV-B radiation for enhancing the accumulation of bioactive phenolic compounds in pigeon pea [Cajanus cajan (L.) Millsp.] hairy root cultures

UV-B radiation is an ideal elicitation strategy for promoting phytochemical accumulation in plant in vitro cultures, associated with various advantages of easy manipulation, cost-effectiveness, no residue, and instantaneous termination. For the first time, UV-B radiation was used to enhance the production of bioactive phenolic compounds (flavonoids and stilbenes) in pigeon pea hairy root cultures (PPHRCs). The total yield of eight flavonoids (414.95 ± 50.68 μg/g DW) in 42-day-old PPHRCs exposed to 4 h of UV-B radiation increased by 1.49-fold as against control, whereas the yield of cajaninstilbene acid (6566.01 ± 702.14 μg/g DW) in PPHRCs undergoing 10 h of UV-B radiation significantly increased by 2.31-fold over control. UV-B radiation was found to induce the oxidative stress in PPHRCs and cause the tissue damage to hairy roots, which improved the levels of endogenous salicylic acid thus triggering the expression of genes involved in phenylpropanoid biosynthesis pathway. And, a regulation competition in metabolic flow dominated by CHS and STS was responsible for the difference in accumulation trends of flavonoids and cajaninstilbene acid. Results of this study not only provide a feasible and simple UV-B supplementation strategy for the enhanced production of bioactive phenolic compounds (especially the high-value cajaninstilbene acid) in PPHRCs, but also contributed to the understanding of photobiological responses related to secondary metabolism.

Kinome-Wide Profiling Identifies Human WNK3 as a Target of Cajanin Stilbene Acid from Cajanus cajan (L.) Millsp

Pigeon Pea (Cajanus cajan (L.) Millsp.) is a common food crop used in many parts of the world for nutritional purposes. One of its chemical constituents is cajanin stilbene acid (CSA), which exerts anticancer activity in vitro and in vivo. In an effort to identify molecular targets of CSA, we performed a kinome-wide approach based on the measurement of the enzymatic activities of 252 human kinases. The serine-threonine kinase WNK3 (also known as protein kinase lysine-deficient 3) was identified as the most promising target of CSA with the strongest enzymatic activity inhibition in vitro and the highest binding affinity in molecular docking in silico. The lowest binding affinity and the predicted binding constant pKi of CSA (−9.65 kcal/mol and 0.084 µM) were comparable or even better than those of the known WNK3 inhibitor PP-121 (−9.42 kcal/mol and 0.123 µM). The statistically significant association between WNK3 mRNA expression and cellular responsiveness to several clinically established anticancer drugs in a panel of 60 tumor cell lines and the prognostic value of WNK3 mRNA expression in sarcoma biopsies for the survival time of 230 patients can be taken as clues that CSA-based inhibition of WNK3 may improve treatment outcomes of cancer patients and that CSA may serve as a valuable supplement to the currently used combination therapy protocols in oncology.

In silico profiling of histone deacetylase inhibitory activity of compounds isolated from Cajanus cajan

Background

Cancer is responsible for high morbidity and mortality globally. Because the overexpression of histone deacetylases (HDACs) is one of the molecular mechanisms associated with the development and progression of some diseases such as cancer, studies are now considering inhibition of HDAC as a strategy for the treatment of cancer. In this study, a receptor-based in silico screening was exploited to identify potential HDAC inhibitors among the compounds isolated from Cajanus cajan, since reports have earlier confirmed the antiproliferative properties of compounds isolated from this plant.

Results

Cajanus cajan-derived phytochemicals were docked with selected HDACs, with givinostat as the reference HDAC inhibitor, using AutodockVina and Discovery Studio Visualizer, BIOVIA, 2020. Furthermore, absorption, distribution, metabolism and excretion (ADME) drug-likeness analysis was done using the Swiss online ADME web tool. From the results obtained, 4 compounds; betulinic acid, genistin, orientin and vitexin, were identified as potential inhibitors of the selected HDACs, while only 3 compounds (betulinic acid, genistin and vitexin) passed the filter of drug-likeness. The molecular dynamic result revealed the best level of flexibility on HDAC1 and HDAC3 compared to the wild-type HDACs and moderate flexibility of HDAC7 and HDAC8.

Conclusions

The results of molecular docking, pharmacokinetics and molecular dynamics revealed that betulinic acid might be a suitable HDAC inhibitor worthy of further investigation in order to be used for regulating conditions associated with overexpression of HDACs. This knowledge can be used to guide experimental investigation on Cajanus cajan-derived compounds as potential HDAC inhibitors.

Integrated bioinformatics analysis of core regulatory elements involved in keloid formation

BACKGROUND

Keloid is a benign fibro-proliferative dermal tumor formed by an abnormal scarring response to injury and characterized by excessive collagen accumulation and invasive growth. The mechanism of keloid formation has not been fully elucidated, especially during abnormal scarring. Here, we investigated the regulatory genes, micro-RNAs (miRNAs) and transcription factors (TFs) that influence keloid development by comparing keloid and normal scar as well as keloid and normal skin.

METHODS

Gene expression profiles (GSE7890, GSE92566, GSE44270 and GSE3189) of 5 normal scar samples, 10 normal skin samples and 18 keloid samples from the Gene Expression Omnibus (GEO) database were interrogated. Differentially expressed genes (DEGs) were identified between keloid and normal skin samples as well as keloid and normal scar samples with R Project for Statistical Computing. Gene Ontology (GO) functional enrichment analysis was also performed with R software. DEG-associated protein-protein interaction (PPI) network was constructed by STRING, followed by module selection from the PPI network based on the MCODE analysis. Regulatory relationships between TF/miRNA and target genes were predicted with miRnet and cytoscape. Core regulatory genes were verified by RT-qPCR.

RESULTS

We identified 628 DEGs, of which 626 were up-regulated and 2 were down-regulated. Seven core genes [neuropeptide Y(NPY), 5-hydroxytryptamine receptor 1A(HTR1A), somatostatin (SST), adenylate cyclase 8 (ADCY8), neuromedin U receptor 1 (NMUR1), G protein subunit gamma 3 (GNG3), and G protein subunit gamma 13 (GNG13)] all belong to MCODE1 and were enriched in the "G protein coupled receptor signaling pathway" of the GO biological process category. Furthermore, nine core miRNAs (hsa-mir-124, hsa-let-7, hsa-mir-155, hsa-mir-26a, hsa-mir-941, hsa-mir-10b, hsa-mir-20, hsa-mir-31 and hsa-mir-372), and two core TFs (SP1 and TERT) were identified to play important roles in keloid formation. In the TF/miRNA-target gene network, both hsa-mir-372 and hsa-mir-20 had a regulatory effect on GNG13, ADCY8 was predicted to be target by hsa-mir-10b, and HTR1A and NPY were potentially by SP1. Furthermore, the expression of core regulatory genes (GNG13, ADCY8, HTR1A and NPY) was validated in clinical samples.

CONCLUSIONS

GNG13, ADCY8, NPY and HTR1A may act as core genes in keloid formation and these core genes establish relationship with SP1 and miRNA (hsa-mir-372, hsa-mir-20, hsa-mir-10b), which may influence multiple signaling pathways in the pathogenesis of keloid.

Simultaneous quantification of eleven bioactive phenolic compounds in pigeon pea natural resources and in vitro cultures by ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-QqQ-MS/MS)

Bioactive phenolics primarily contribute to versatile health benefits of pigeon pea. For the first time, an UPLC-QqQ-MS/MS method was developed for the quantitative analysis of eleven bioactive phenolic compounds in pigeon pea natural resources (seeds, leaves, and roots) and in vitro cultures (calli and hairy roots). The proposed method could be achieved within 6 min of running time, and displayed the satisfactory linearity, sensitivity, precision, accuracy, and stability. According to analytical results, the distribution of eleven target compounds in different organs of pigeon pea was clarified. Also, it was surprisingly found that pigeon pea in vitro cultures exhibited superiority in contents of genistin and cajaninstilbene acid as compared with natural resources. Overall, the present work provided a rapid and sensitive analysis approach, which could be useful not only for quality control of pigeon pea natural resources, but also for applicability and safety evaluation of pigeon pea in vitro cultures.

Effective Production of Phenolic Compounds with Health Benefits in Pigeon Pea [Cajanus cajan (L.) Millsp.] Hairy Root Cultures

Phenolic compounds in pigeon pea possess various biological properties beneficial to human health. In this study, pigeon pea hairy root cultures (PPHRCs) were developed as an effective in vitro platform for the production of phenolic compounds. A high-productive hairy root line was screened and characterized, and its culture conditions were optimized in terms of biomass productivity and phenolic yield. The comparative profiling of 10 phenolic compounds in PPHRCs and pigeon pea natural resources (seeds, leaves, and roots) was achieved by ultra-high-performance liquid chromatography-tandem mass spectrometry analysis. The total phenolic yield in PPHRCs (3278.44 μg/g) was much higher than those in seeds (68.86 μg/g) and roots (846.03 μg/g), and comparable to leaves (3379.49 μg/g). Notably, PPHRCs exhibited superiority in the yield of the most important health-promoting compound cajaninstilbene acid (2996.23 μg/g) against natural resources (4.42-2293.31 μg/g). Overall, PPHRCs could serve as promising potential alternative sources for the production of phenolic compounds with nutraceutical/medicinal values.

Cajanin Stilbene Acid Inhibited Vancomycin-Resistant Enterococcus by Inhibiting Phosphotransferase System

Antimicrobial resistance has become a serious threat to human and animal health, and vancomycin-resistant Enterococcus has become an important nosocomial infection pathogen, causing thousands of deaths each year. In this study, after screening a variety of natural products, we found that cajanin stilbene acid (CSA) had significant inhibitory effect on sensitive and vancomycin-resistant Enterococcus (VRE) in vitro. And we also confirmed that CSA had significant anti-VRE infection ability in vivo. Subsequently, we studied the antibacterial mechanism of CSA through proteomics experiments, and the results showed that CSA killed Enterococcus by inhibiting the phosphotransferase system of Enterococcus, thus hinders the normal growth and metabolic functions of bacteria. The results of this study provided evidence for the in-depth study on the mechanism of the antibacterial action of CSA and also provided a candidate for the development of anti-VRE drugs.

Identification of key pathways and genes in PTEN mutation prostate cancer by bioinformatics analysis

Background

Prostate cancer (Pca) remains one of the leading adult malignancies. PTEN (Phosphatase and Tensin Homolog) mutant is the top common mutated genes in prostate cancer, which makes it a promising biomarker in future individualized treatment.

Methods

We obtained gene expression data of prostate cancer from TCGA (The Cancer Genome Atlas) database for analysis. We analyzed the DEGs (differentially expressed genes), and used online tools or software to analyze Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene set enrichment analysis (GSEA), Search Tool for the Retrieval of Interacting Genes/Proteins, and Molecular Complex Detection.

Results

Latest TCGA data showed PTEN mutation in about 22% patients. 1736 DEGs in total were identified. Results of gene functional enrichment analyses showed that muscle contraction, negative regulation of growth and multiple metabolic progression were significantly enriched. GNG13, ACTN2, POTEE, ACTA1, MYH6, MYH3, MYH7, MYL1, TNNC1 and TNNC2 were the top ten hub genes. Patients with PTEN mutation showed relatively decreased mRNA expression level of PTEN. Survival analysis indicated the risk of disease recurrence in patients with PTEN mutation.

Conclusions

Our findings suggested that PTEN mutation in prostate cancer may induce changes in a variety of genes and pathways and affect disease progression, suggesting the significance of PTEN mutation in individualized treatment of prostate cancer.

The Cholesterol-Modulating Effect of Methanol Extract of Pigeon Pea (Cajanus cajan (L.) Millsp.) Leaves on Regulating LDLR and PCSK9 Expression in HepG2 Cells

Pigeon pea (Cajanus cajan (L.) Millsp.) is a legume crop consumed as an indigenous vegetable in the human diet and a traditional medicinal plant with therapeutic properties. The current study highlights the cholesterol-modulating effect and underlying mechanisms of the methanol extract of Cajanus cajan L. leaves (MECC) in HepG2 cells. We found that MECC increased the LDLR expression, the cell-surface LDLR levels and the LDL uptake activity in HepG2 cells. We further demonstrated that MECC suppressed the proprotein convertase subtilisin/kexin type 9 (PCSK9) mRNA and protein expression, but not affected the expression of other cholesterol or lipid metabolism-related genes including inducible degrader of LDLR (IDOL), HMG-CoA reductase (HMGCR), fatty acid synthase (FASN), acetyl-CoA carboxylase (ACC1), and liver X receptor-α (LXR-α) in HepG2 cells. Furthermore, we demonstrated that MECC down-regulated the PCSK9 gene expression through reducing the amount of nuclear hepatocyte nuclear factor-1α (HNF-1α), a major transcriptional regulator for activation of PCSK9 promoter, but not that of nuclear sterol-responsive element binding protein-2 (SREBP-2) in HepG2 cells. Finally, we identified the cajaninstilbene acid, a main bioactive stilbene component in MECC, which significantly modulated the LDLR and PCSK9 expression in HepG2 cells. Our current data suggest that the cajaninstilbene acid may contribute to the hypocholesterolemic activity of Cajanus cajan L. leaves. Our findings support that the extract of Cajanus cajan L. leaves may serve as a cholesterol-lowering agent.

Phytochemicals: Current strategies for treating breast cancer

Females with early-stage metastatic, estrogen-dependent breast cancer are generally treated with surgery, radiation and chemotherapy, or with more targeted approaches such as aromatase inhibitors (anastrozole or letrozole) or anti-estrogens (tamoxifen). Despite widespread successful usage of these agents for the treatment of breast cancer, resistance, tumor relapse and metastasis remain the principal causes of mortality for patients with breast cancer. While numerous groups have made major contributions toward an improved understanding of resistance mechanisms, the currently insufficient grasp of the most critical pathways involved in resistance is evident in the inability to adequately treat and drastically improve patient outcomes in females with hormone-refractory breast cancer, including triple negative breast cancer. Therefore, further investigation of novel therapeutic approaches is paramount to reveal previously unconsidered agents that could be utilized to treat metastatic disease. Numerous naturally occurring phytochemicals have recently gained interest as potential therapeutic breast cancer agents appear to directly affect estrogen-dependent and estrogen-independent breast cancer cell proliferation, potentially via affecting breast cancer stem cell populations. While numerous natural compounds have exhibited promise, they are limited by their bioavailability. Therefore, to effectively treat future hormone-refractory breast tumors, it is critical to adequately refine and formulate these agents for effective therapeutic use and delivery. Herein, the literature on the current state of phytochemicals is reviewed, including their limitations and potential as targeted therapies for breast cancer.