Artepillin C, drupanin, aromadendrin-4'-O-methyl-ether and kaempferide from Brazilian green propolis promote gastroprotective action by diversified mode of action

ETHOPHARMACOLOGICAL RELEVANCE

The propolis is extensively used in folk medicine in natura or to prepare pharmaceutical formulations since ancient time to improve health or prevent diseases, among them gastrointestinal disorders. Aiming to contribute in the scientific validation about the popular use of Brazilian Green propolis (BGP) against gastritis and gastric ulcer, this work evaluated the antiulcer potential of isolated compounds from BGP, three prenylated p-coumaric acid derivatives and two flavonoids, respectively named: 3,5 diprenyl-4-hydroxycinnamic acid (artepillin C) (1), 3-prenyl-4-dihydroxycinnamoiloxy cinnamic acid (baccharin) (2), 3-prenyl-4-hydroxycinnamic acid (drupanin) (3), aromadendrin-4'-O-methyl-ether (4) and kaempferide (5).

MATERIAL AND METHODS

The compounds were characterized by nuclear magnetic resonance and mass spectrometry. Their gastroprotective effects were evaluated against ethanol/HCl- and indomethacin-induced ulcer in mice. Further, histological, histochemical, oxidative and inflammatory parameters were analyzed at ulcerated tissue. Acid antisecretory activities also were also assessed.

RESULTS

Compound 2 did not reduce the ethanol/HCl- induced ulcer at 30 mg/kg (p.o), whereas the minimum oral gastroprotective doses of 1, 3, 4 and 5 were 0.3, 0.3, 3 and 3 mg/kg, respectively. Besides, these compounds prevented ethanol/HCl-induced ulcer by intraperitoneal route, as well as indomethacin-induced ulcer by oral route. The gastroprotection was accompanied by normalization of superoxide dismutase, catalase and glutathione-S-transferase activities and reduction in myeloperoxidase activity. Moreover, the compounds 4 and 5 increased the gastric mucin content and 1 reduced TNF amount. Furthermore, 1, 3, 4 and 5 decreased volume, pH, total acidity and pepsin activity of the gastric juice from rats.

CONCLUSIONS

Together, our findings showed a diversified mode of action elicited by 1, 3, 4 and 5 on the gastroprotection and contribute to explain the anti-ulcer activity reported for BGP.

Neuroprotective effects of Brazilian green propolis on oxytosis/ferroptosis in mouse hippocampal HT22 cells

Propolis is a sticky dark-colored substance produced by honey bees and comprises resin, balsam, wax, essential and aromatic oils, pollen, and several other substances; it is used in food and beverages to improve health and prevent diseases. We studied the neuroprotective effects of extracts of Brazilian green propolis in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis had a more potent preventive effect on oxidative stress-induced cell death, oxytosis/ferroptosis, in HT22 cells than water extracts of Brazilian green propolis, whereas it did not protect against anticancer drug-induced apoptotic cell death. Among the primary constituents of ethanol extracts of Brazilian green propolis, only artepillin C, kaempferide, and kaempferol demonstrated neuroprotective effects against oxytosis/ferroptosis. The flavonoid derivatives kaempferide and kaempferol are antioxidants with radical-scavenging abilities that additionally induce antioxidant response element-mediated transcriptional activity, suggesting that upregulation of endogenous antioxidant defense protects against oxidative stress. In contrast, artepillin C attenuated reactive oxygen species production; however, it did not induce antioxidant response element activation. These findings indicate that the ethanol extracts of Brazilian green propolis help to prevent oxidative stress-related neuronal cell death that is involved in the pathogenesis of several neurodegenerative diseases.

Artepillin C: A comprehensive review of its chemistry, bioavailability, and pharmacological properties

Artepillin C (ARC), a prenylated derivative of p-coumaric acid, is one of the major phenolic compounds found in Brazilian green propolis (BGP) and its botanical source Baccharis dracunculifolia. Numerous studies on ARC show that its beneficial health effects correlate with the health effects of both BGP and B. dracunculifolia. Its wide range of pharmacological benefits include antioxidant, antimicrobial, anti-inflammatory, anti-diabetic, neuroprotective, gastroprotective, immunomodulatory, and anti-cancer effects. Most studies have focused on anti-oxidation, inflammation, diabetic, and cancers using both in vitro and in vivo approaches. Mechanisms underlying anti-cancer properties of ARC are apoptosis induction, cell cycle arrest, and the inhibition of p21-activated kinase 1 (PAK1), a protein characterized in many human diseases/disorders including COVID-19 infection. Therefore, further pre-clinical and clinical studies with ARC are necessary to explore its potential as intervention for a wide variety of diseases including the recent pandemic coronaviral infection. This review summarizes the comprehensive data on the pharmacological effects of ARC and could be a guideline for its future study and therapeutic usage.

Natural deep eutectic solvents and aqueous solutions as an alternative extraction media for propolis

Ethanolic extracts of propolis are consumed for their health benefits even though direct consumption of alcoholic extracts is not always ideal. Natural Deep Eutectic Solvents (NADES) can potentially extract similar compounds as alcoholic extracts while being better for direct consumption. Therefore, in this work alternative solvents for the extraction of green propolis including its biomarker artepillin C were examined. Sixteen NADES made from low toxicity chemicals, including the essential amino acid l-lysine, were explored along with twelve individual NADES components and honey, which showed similar physical-chemical properties to NADES. At 50 °C NADES made from choline chloride-propylene glycol or lactic acid proved to be equal or better than the benchmark EtOH:Water 7:3 (v/v). Alternatively, aqueous l-lysine appeared as a potential solvent for the preparation of aqueous propolis extracts. From these findings NADES, honey and aqueous l-lysine solutions all demonstrated the potential to replace ethanol or water for extracting green propolis.

Effect of light, oxygen and temperature on the stability of artepillin C and p-coumaric acid from Brazilian green propolis

Brazilian Green Propolis (BGP) is an important bee product, which displays important biological activities, making it valuable in the international market. The major prenylated phenolic compound in BPG is (E)-artepillin C, along with its precursor (E)-p-coumaric acid, both contributing to the biological effects of BGP. Taking that into account, it was evaluated the effect of light, temperature and air oxygen in their content to establish the best storage and transport conditions for crude BGP and the pure compounds. For that, (E)-artepillin C and (E)-p-coumaric acid were initially submitted to degradation for five days under sunlight and high temperature (50 °C), furnishing three major (E)-Artepillin C isomers and one from (E)-p-coumaric acid. Then, it was developed and validated a Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for quantifying these compounds in crude BGP and in its extracts. In the stability studies, it was used a Full Factorial and Central Composite Design to establish the desirable storage conditions. (E)-Artepillin C, both pure and in BGP should be kept protected from light and storage below -2.5 °C. (E)-p-Coumaric acid can be stored at room temperature. Therefore, the best storage and transport conditions to keep the content of both compounds in BGP are protection from light at low temperatures.

Artepillin C, is it a good marker for quality control of Brazilian green propolis?

As commercialisation of Brazilian green propolis is going on, quality evaluation and authenticity are important. The result demonstrated that artepillin C found by far in Brazilian green propolis by HPLC-ESI-MS/MS analysis, while a small interferent may be mistaken as artepillin C in some propolis from China. A new HPLC quality control method as artepillin C for marker was developed, which is the primary assessment criteria for quality control of Brazilian green propolis.

Artepillin C Induces Selective Oxidative Stress and Inhibits Migration and Invasion in a Comprehensive Panel of Human Cervical Cancer Cell Lines

BACKGROUND

Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is the main bioactive component of Brazilian green propolis, and possesses, among other things, anticancer properties. However, to the best of our knowledge, there are no studies of artepillin C in cervical cancer.

METHOD

To explore a new therapeutic candidate for cervical cancer, we have evaluated the effects of artepillin C on cellular viability in a comprehensive panel of human cervical cancer-derived cell lines including HeLa (human papillomavirus/HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16- and 18-positive) and C33A (HPV-negative) cells compared to a spontaneously immortalized human epithelial cell line (HaCaT).

RESULTS

Our results demonstrated that artepillin C had a selective effect on cellular viability and could induce apoptosis possibly by intrinsic pathway, likely a result of oxidative stress, in all cancer-derived cell lines but not in HaCaT. Additionally, artepillin C was able to inhibit the migration and invasion of cancer cells.

CONCLUSION

Thus, artepillin C appears to be a promising new candidate as an anticancer drug for cervical cancer induced by different HPV types.

Chemical composition and antimycoplasma activity of a brown propolis from southern Brazil

Extracts of a sample of brown propolis produced in the district of Itapará (Southern Brazil) were obtained with solvents with increasing polarity. The extracts were analyzed by RPHPLC-DAD-ESI-MS/MS and evaluated toward activity against Mycoplasma bovis, M. gallisepticum, M. genitalium, M. hominis, M. hyorinis, M. penetrans and M. pneumonieae. Typical components of "alecrim-do-campo" propolis (e.g. prenylated phenylpropanoids and caffeoyl-quinic acids) were characterized in the analyzed extraccts, in addition to several flavonols. Less polar extracts showed higher anti-mycoplasma activity (MIC value commonly 3.9 μg/mL) than alcoholic and aqueous extracts (MIC value often 7.8-250 μg/mL). The results indicate that Itapará propolis is a promising source for the development of therapeutic drugs.

Artepillin C, a major component of Brazilian green propolis, inhibits endoplasmic reticulum stress and protein aggregation

Propolis, a compound produced by honeybees, has long been used in food and beverages to improve health and prevent diseases. We previously reported that the ethanol extracts of Brazilian green propolis and its constituents artepillin C, kaempferide, and kaempferol mitigate oxidative stress-induced cell death via oxytosis/ferroptosis. Here, we investigated the potential of Brazilian green propolis and its constituents to protect against endoplasmic reticulum stress in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis, artepillin C, and kaempferol attenuated tunicamycin-induced unfolded protein response and cell death. Interestingly, artepillin C inhibited both tunicamycin-induced protein aggregation in HT22 cells and the spontaneous protein aggregation of mutant canine superoxide dismutase 1 (E40K-SOD1-EGFP) in Neuro2a cells. These findings indicate that in addition to oxidative stress, the ethanol extracts of Brazilian green propolis help prevent endoplasmic reticulum stress-related neuronal cell death, which is proposedly involved in several neurodegenerative diseases. Moreover, artepillin C, a major constituent of Brazilian green propolis, may exhibit chemical chaperone-like properties.

Artepillin C overcomes apalutamide resistance through blocking androgen signaling in prostate cancer cells

Prostate cancer has a relatively good prognosis, but most cases develop resistance to hormone therapy, leading to castration-resistant prostate cancer (CRPC). Androgen receptor (AR) antagonists and a cytochrome P450 17A1 inhibitor have been used to treat CRPC, but cancer cells readily develop resistance to these drugs. In this study, to improve the therapy of CRPC, we searched for natural compounds which block androgen signaling. Among cinnamic acid derivatives contained in Brazilian green propolis, artepillin C (ArtC) suppressed expressions of androgen-induced prostate-specific antigen and transmembrane protease serine 2 in a dose-dependent manner. Reporter assays revealed that ArtC displayed AR antagonist activity, albeit weaker than an AR antagonist flutamide. In general, aberrant activation of the androgen signaling is involved in the resistance of prostate cancer cells to hormone therapy. Recently, apalutamide, a novel AR antagonist, has been in clinical use, but its drug-resistant cases have been already reported. To search for compounds which overcome the resistance to apalutamide, we established apalutamide-resistant prostate cancer 22Rv1 cells (22Rv1/APA). The 22Rv1/APA cells showed higher AR expression and androgen sensitivity than parental 22Rv1 cells. ArtC inhibited androgen-induced proliferation of 22Rv1/APA cells by suppressing the enhanced androgen signaling through blocking the nuclear translocation of AR. In addition, ArtC potently sensitized the resistant cells to apalutamide by inducing apoptotic cell death due to mitochondrial dysfunction. These results suggest that the intake of Brazilian green propolis containing ArtC improves prostate cancer therapy.

pH-Dependence Cytotoxicity Evaluation of Artepillin C against Tumor Cells

Brazilian green propolis is a well-known product that is consumed globally. Its major component, Artepillin C, showed potential as an antitumor product. This study explored the impact of Artepillin C on fibroblast and glioblastoma cell lines, used as healthy and very aggressive tumor cell lines, respectively. The focus of the study was to evaluate the pH-dependence of Artepillin C cytotoxicity, since tumor cells are known to have a more acidic extracellular microenvironment compared to healthy cells, and Artepillin C was shown to become more lipophilic at lower pH values. Investigations into the pH-dependency of Artepillin C (6.0-7.4), through viability assays and live cell imaging, revealed compelling insights. At pH 6.0, MTT assays showed the pronounced cytotoxic effects of Artepillin C, yielding a notable reduction in cell viability to less than 12% among glioblastoma cells following a 24 h exposure to 100 µM of Artepillin C. Concurrently, LDH assays indicated significant membrane damage, affecting approximately 50% of the total cells under the same conditions. Our Laurdan GP analysis suggests that Artepillin C induces autophagy, and notably, provokes a lipid membrane packing effect, contributing to cell death. These combined results affirm the selective cytotoxicity of Artepillin C within the acidic tumor microenvironment, emphasizing its potential as an effective antitumor agent. Furthermore, our findings suggest that Artepillin C holds promise for potential applications in the realm of anticancer therapies given its pH-dependence cytotoxicity.

Vibrational Spectroscopic Characterization and Coherent Anti-Stokes Raman Spectroscopy (CARS) Imaging of Artepillin C

In the following work, the vibrational spectroscopic characteristics of artepillin C are reported by means of Fourier transform infrared (FT-IR) and Raman spectroscopies, surface-enhanced Raman scattering (SERS), and coherent anti-Stokes Raman scattering (CARS) microscopy. Artepillin C is an interesting compound due to its pharmacological properties, including antitumor activity. It is found as the major component of Brazilian green propolis, a resinous mixture produced by bees to protect their hives against intruders. Vibrational spectroscopic techniques have shown a strong peak at 1599 cm^-1, assigned to C=C stretching vibrations from the aromatic ring of artepillin C. From these data, direct visualization of artepillin C could be assessed by means of CARS microscopy, showing differences in the film hydration obtained for its neutral and deprotonated states. Raman-based methods show potential to visualize the uptake and action of artepillin C in biological systems, triggering its interaction with biological systems that are needed to understand its mechanism of action.

Ultra-high-performance liquid chromatography using a fused-core particle column for fast analysis of propolis phenolic compounds

Propolis is a bee product with a complex chemical composition formed by several species from different geographical origins. The complex propolis composition requires an accurate and reproducible characterization of samples to standardize the quality of the material sold to consumers. This work developed an ultra-high-performance liquid chromatography with a photodiode array detector method to analyze propolis phenolic compounds based on the two key propolis biomarkers, Artepillin C and p-Coumaric acid. This choice was made due to the complexity of the sample with the presence of several compounds. The optimized method was hyphenated with mass spectrometry detection allowing the detection of 23 different compounds. A step-by-step strategy was used to optimize temperature, flow rate, mobile phase composition, and re-equilibration time. Reverse-phase separation was achieved with a C18 fused-core column packed with the commercially available smallest particles (1.3 nm). Using a fused-core column with ultra-high-performance liquid chromatography allows highly efficient, sensitive, accurate, and reproducible determination of compounds extracted from propolis with an outstanding sample throughput and resolution. Optimized conditions permitted the separation of the compounds in 5.50 min with a total analysis time (sample-to-sample) of 6.50 min.

Antitumoral Potential of Artepillin C, a Compound Derived from Brazilian Propolis, against Breast Cancer Cell Lines

BACKGROUND

Breast cancer is the most commonly diagnosed cancer among women worldwide with limited treatment options. Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is one of the main constituents of Brazilian propolis presenting different activities, including antitumoral effects against various types of cancer.

OBJECTIVE

We evaluated the antitumoral potential and mechanisms of action of artepillin C against two distinct human breast cancer cell lines, MCF-7 and MDA-MB-231, to explore a new therapeutic candidate.

METHODS

Cell viability was assessed by MTT assay and the long-term cytotoxicity was performed by clonogenic assay. The morphological changes were observed by light microscopy, analysis of cell death pathway by Annexin V FITC/propidium iodide (PI), lactate dehydrogenase (LDH) by colorimetry, DNA fragmentation by agarose gel and senescence by β-galactosidase. Detection of total reactive oxygen species (ROS) by fluorescence microscopy and determination of mitochondrial transmembrane potential by flow cytometry were also performed.

RESULTS

Artepillin C presented a strong and dose-time-dependent cytotoxic effect on MCF-7 and MDA-MB-231 cell lines, with cytotoxicity more evident in MCF-7. In both cancer cell lines, the clonogenic potential was significantly reduced and the morphology of the cells was changed. The treatment also induced death by necrosis and late apoptosis in MCF-7 and MDA-MB-231 and induced cell senescence in MCF-7. Also, artepillin C increased total ROS in both cancer cells and decreased mitochondrial membrane potential in MDA-MB-231 cells.

CONCLUSION

Artepillin C presented antitumoral potential in two human breast cancer cell lines, MCF-7, and MDA-MB-231, suggesting a new promising option for the treatment and/or chemopreventive strategy for breast cancer.

Countercurrent chromatography isolation of green propolis biomarkers: Potential blockers of SARS-COV-2 RBD and ACE2 interaction

Propolis is a natural resinous mixture produced by honeybees with numerous biological activities. Considering the recently reported potential of propolis as an adjuvant in COVID-19 treatment, a methodology for the fractionation of the hexane extract of Brazilian green propolis (HEGP) was developed for the obtention of prenylated biomarkers by countercurrent chromatography. The inhibition of the interaction between the receptor binding domain (RBD) of spike and ACE2 receptor was evaluated by the Lumitᵀᴹ immunoassay. Fractionation of HEGP was performed by both normal (CCC1 and CCC2, with extended elution) and reversed (CCC3) phase elution-extrusion modes with the solvent system hexane-ethanol-water 4:3:1. The normal elution mode of CCC1 (471 mg HEGP in a 80 mL column volume, 1.6 mm id) was scaled-up (CCC5, 1211 mg HEGP in a 112 mL column volume, 2.1 mm id), leading to the isolation of 89.9 mg of artepillin C, 1; 52.7 mg of baccharin, 2; and 26.6 mg of chromene, with purities of 93 %, 83 % and 88 %, respectively, by HPLC-PDA. Among the isolated compounds, artepillin C, 1, and baccharin, 2, presented the best results in the Lumitᵀᴹ immunoassay, showing 67% and 51% inhibition, respectively, at the concentration of 10 μM. This technique proved to be of low operational cost and excellent reproducibility.