Exploring the therapeutic potential of naturally occurring piceatannol in non-communicable diseases

Piceatannol is a naturally occurring hydroxylated resveratrol analogue that can be found in a variety of fruits and vegetables. It has been documented to have a wide range of beneficial effects, including anti-inflammatory, antioxidant, anti-aging, anti-allergic, antidiabetic, neuroprotective, cardioprotective, and chemopreventive properties. Piceatannol has significantly higher antioxidant activity than resveratrol. Piceatannol has been shown in preclinical studies to have the ability to inhibit or reduce the growth of cancers in various organs such as the brain, breast, lung, colon, cervical, liver, prostate, and skin. However, the bioavailability of Piceatannol is comparatively lower than resveratrol and other stilbenes. Several approaches have been reported in recent years to enhance its bioavailability and biological activity, and clinical trials are required to validate these findings. This review focuses on several aspects of natural stilbene Piceatannol, its chemistry, and its mechanism of action, and its promising therapeutic potential for the prevention and treatment of a wide variety of complex human diseases.

Piceatannol Alleviates Deoxynivalenol-Induced Damage in Intestinal Epithelial Cells via Inhibition of the NF-κB Pathway

Deoxynivalenol (DON) is a common mycotoxin that is widely found in various foods and feeds, posing a potential threat to human and animal health. This study aimed to investigate the protective effect of the natural polyphenol piceatannol (PIC) against DON-induced damage in porcine intestinal epithelial cells (IPEC-J2 cells) and the underlying mechanism. The results showed that PIC promotes IPEC-J2 cell proliferation in a dose-dependent manner. Moreover, it not only significantly relieved DON-induced decreases in cell viability and proliferation but also reduced intracellular reactive oxygen species (ROS) production. Further studies demonstrated that PIC alleviated DON-induced oxidative stress damage by increasing the protein expression levels of the antioxidant factors NAD(P)H quinone oxidoreductase-1 (NQO1) and glutamate-cysteine ligase modifier subunit (GCLM), and the mRNA expression of catalase (CAT), Superoxide Dismutase 1 (SOD1), peroxiredoxin 3 (PRX3), and glutathione S-transferase alpha 4 (GSTα4). In addition, PIC inhibited the activation of the nuclear factor-B (NF-κB) pathway, downregulated the mRNA expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) to attenuate DON-induced inflammatory responses, and further mitigated DON-induced cellular intestinal barrier injury by regulating the protein expression of Occludin. These findings indicated that PIC had a significant protective effect against DON-induced damage. This study provides more understanding to support PIC as a feed additive for pig production.

Piceatannol selectively inhibited the JNK3 enzyme and augmented apoptosis through inhibition of Bcl-2/Cyt-c/caspase-dependent pathways in the oxygen-glucose deprived SHSY-5Y cell lines: In silico and in vitro study

JNK3, a neuronal kinase activated by stress, plays a role in stress-induced apoptosis, leading to neuronal cell death following cerebral ischemia. This study investigates the neuroprotective effects of piceatannol (PCT) in SHSY-5Y neuroblastoma cells after hypoxic injury and its interaction with JNK3. We analyzed the crystal coordinates, interaction energies, and amino acid interactions to determine PCT's selectivity for JNK3. The electrostatic potential was computed using density functional theory, while molecular dynamics assessed the stability and structural consistency of the JNK3-PCT complex. We used SP600125 (SP6), a JNK3 inhibitor, as a reference compound. Additionally, we performed cell-free JNK 1, 2, and 3 kinase assays to evaluate the isoform selectivity of PCT. Cytotoxicity and cell viability were determined by an MTT test. To assess apoptosis, we used acridine orange/ethidium bromide dual fluorescent labeling and ANNEXIN A5-FITC flow cytometry. Western blot was used to evaluate the attenuation of JNK3 and apoptotic proteins. In silico studies revealed a stronger binding affinity between PCT and JNK3 compared to JNK1 and JNK2, which was further supported by the in vitro kinase assay. PCT-treated cells exhibited a decrease in Cyt-c and caspase-3 expression and an increase in Bcl-2 level, compared to hypoxic control (p < .001). PCT also demonstrated superior efficacy over SP6 in inhibiting JNK3 phosphorylation (p < .001). Furthermore, PCT significantly increased the expression of neuronal genes, including NgN1, neuroD2, and survivin (p < .001). In conclusion, PCT is a potential JNK3 inhibitor, since it inhibited phosphorylation and the Bcl-2/Cyt-C/caspase-3-dependent apoptotic pathway after ischemic/hypoxic insult.

The PKM2 inhibitor shikonin enhances piceatannol-induced apoptosis of glyoxalase I-dependent cancer cells

Glyoxalase I (GLO I), a major enzyme involved in the detoxification of the anaerobic glycolytic byproduct methylglyoxal, is highly expressed in various tumors, and is regarded as a promising target for cancer therapy. We recently reported that piceatannol potently inhibits human GLO I and induces the death of GLO I-dependent cancer cells. Pyruvate kinase M2 (PKM2) is also a potential therapeutic target for cancer treatment, so we evaluated the combined anticancer efficacy of piceatannol plus low-dose shikonin, a potent and specific plant-derived PKM2 inhibitor, in two GLO I-dependent cancer cell lines, HL-60 human myeloid leukemia cells and NCI-H522 human non-small-cell lung cancer cells. Combined treatment with piceatannol and low-dose shikonin for 48 h synergistically reduced cell viability, enhanced apoptosis rate, and increased extracellular methylglyoxal accumulation compared to single-agent treatment, but did not alter PKM1, PKM2, or GLO I protein expression. Taken together, these results indicate that concomitant use of low-dose shikonin potentiates piceatannol-induced apoptosis of GLO I-dependent cancer cells by augmenting methylglyoxal accumulation.

GPER/PKA-Dependent Enhancement of Hormone-Sensitive Lipase Phosphorylation in 3T3-L1 Adipocytes by Piceatannol

We previously reported that piceatannol (PIC) had an anti-obesity effect only in ovariectomized (OVX) postmenopausal obesity mice. PIC was found to induce the phosphorylation of hormone-sensitive lipase (pHSL) in OVX mice. To elucidate the mechanism by which PIC activates HSL, we investigated the effect of PIC using 3T3-L1 adipocytes. PIC induced HSL phosphorylation at Ser563 in 3T3-L1 cells, as in vivo experiments showed. pHSL (Ser563) is believed to be activated through the β-adrenergic receptor (β-AR) and protein kinase A (PKA) pathways; however, the addition of a selective inhibitor of β-AR did not inhibit the effect of PIC. The addition of a PKA inhibitor with PIC blocked pHSL (Ser563), suggesting that the effects are mediated by PKA in a different pathway than β-AR. The addition of G15, a selective inhibitor of the G protein-coupled estrogen receptor (GPER), reduced the activation of HSL by PIC. Furthermore, PIC inhibited insulin signaling and did not induce pHSL (Ser565), which represents its inactive form. These results suggest that PIC acts as a phytoestrogen and phosphorylates HSL through a novel pathway that activates GPER and its downstream PKA, which may be one of the inhibitory actions of PIC on fat accumulation in estrogen deficiency.

Extracts and Scirpusin B from Recycled Seeds and Rinds of Passion Fruits (Passiflora edulis var. Tainung No. 1) Exhibit Improved Functions in Scopolamine-Induced Impaired-Memory ICR Mice

In this paper, the seeds and rinds of passion fruit, which are the agricultural waste of juice processing, were recycled to investigate their biological activities for sustainable use. De-oiled seed powders (S) were successively extracted by refluxing 95% ethanol (95E), 50E, and hot water (HW), respectively, to obtain S-95EE, S-50EE, and S-HWE. Dried rind powders were successively extracted by refluxing HW and 95E to obtain rind-HWE and rind-95EE, respectively. S-50EE and S-95EE showed the most potent extracts, such as anti-amyloid-β1-42 aggregations and anti-acetylcholinesterase inhibitors, and they exhibited neuroprotective activities against amyloid-β25-35-treated or H2O2-treated SH-SY5Y cells. Scirpusin B and piceatannol were identified in S-95EE, S-50EE, and rind-HWE, and they showed anti-acetylcholinesterase activity at 50% inhibitory concentrations of 62.9 and 258.9 μM, respectively. Daily pretreatments of de-oiled seed powders and rind-HWE (600 mg/kg), S-95EE, and S-50EE (250 mg/kg) or scirpusin B (40 mg/kg) for 7 days resulted in improved learning behavior in passive avoidance tests and had significant differences (p < 0.05) compared with those of the control in scopolamine-induced ICR mice. The seeds and rinds of passion fruit will be recycled as materials for the development of functional foods, promoting neuroprotection and delaying the onset of cognitive dysfunctions.

The fungal metabolite 4-hydroxyphenylacetic acid from Neofusicoccum parvum modulates defence responses in grapevine

In a consequence of global warming, grapevine trunk diseases (GTDs) have become a pertinent problem to viticulture, because endophytic fungi can turn necrotrophic upon host stress killing the plant. In Neofusicoccum parvum Bt-67, plant-derived ferulic acid makes the fungus release Fusicoccin aglycone triggering plant cell death. Now, we show that the absence of ferulic acid lets the fungus secrete 4-hydroxyphenylacetic acid (4-HPA), mimicking the effect of auxins on grapevine defence and facilitating fungal spread. Using Vitis suspension cells, we dissected the mode of action of 4-HPA during defence triggered by the bacterial cell-death elicitor, harpin. Early responses (cytoskeletal remodelling and calcium influx) are inhibited, as well as the expression of Stilbene Synthase 27 and phytoalexin accumulation. In contrast to other auxins, 4-HPA quells transcripts for the auxin conjugating GRETCHEN HAGEN 3. We suggest that 4-HPA is a key component of the endophytic phase of N. parvum Bt-67 preventing host cell death. Therefore, our study paves the way to understand how GTDs regulate their latent phase for successful colonisation, before turning necrotrophic and killing the vines.

Synergistic Power of Piceatannol and/or Vitamin D in Bleomycin-Induced Pulmonary Fibrosis In Vivo: A Preliminary Study

Oxidative stress and epigenetic alterations, including the overexpression of all class I and II histone deacetylases (HDACs), particularly HDAC2 and HDAC4, have been identified as key molecular mechanisms driving pulmonary fibrosis. Treatment with piceatannol (PIC) or vitamin D (Vit D) has previously exhibited mitigating impacts in pulmonary fibrosis models. The present study investigated the effects of PIC, Vit D, or a combination (PIC-Vit D) on the expression of HDAC2, HDAC4, and transforming growth factor-beta (TGF-β) in the lungs; the phosphatidylinositide-3-kinase (PI3K)/AKT signaling pathway; and the antioxidant status of the lungs. The objective was to determine if the treatments had protective mechanisms against pulmonary fibrosis caused by bleomycin (BLM) in rats. Adult male albino rats were given a single intratracheal dosage of BLM (10 mg/kg) to induce pulmonary fibrosis. PIC (15 mg/kg/day, oral (p.o.)), Vit D (0.5 μg/kg/day, intraperitoneal (i.p.)), or PIC-Vit D (15 mg/kg/day, p.o. plus 0.5 μg/kg/day, i.p.) were given the day following BLM instillation and maintained for 14 days. The results showed that PIC, Vit D, and PIC-Vit D significantly improved the histopathological sections; downregulated the expression of HDAC2, HDAC4, and TGF-β in the lungs; inhibited the PI3K/AKT signaling pathway; decreased extracellular matrix (ECM) deposition including collagen type I and alpha smooth muscle actin (α-SMA); and increased the antioxidant capacity of the lungs by increasing the levels of glutathione (GSH) that had been reduced and decreasing the levels of malondialdehyde (MDA) compared with the BLM group at a p-value less than 0.05. The concomitant administration of PIC and Vit D had a synergistic impact that was greater than the impact of monotherapy with either PIC or Vit D. PIC, Vit D, and PIC-Vit D exhibited a notable protective effect through their antioxidant effects, modulation of the expression of HDAC2, HDAC4, and TGF-β in the lungs, and suppression of the PI3K/AKT signaling pathway.

Resveratrol and Other Natural Oligomeric Stilbenoid Compounds and Their Therapeutic Applications

The use of natural compounds as an alternative to synthetic molecules has become a significant subject of interest in recent decades. Stilbenoids are a group of phenolic compounds found in many plant species and they have recently gained the focus of a multitude of studies in medicine and chemistry, resveratrol being the most representative molecule. In this review, we focused on the research that illustrates the therapeutic potential of this class of natural molecules considering various diseases with higher incidence rates. PubChem database was searched for bioactivities of natural stilbenoids, while several keywords (i.e., "stilbenoids", "stilbenoid anticancer") were used to query PubMed database for relevant studies. The diversity and the simplicity of stilbenes' chemical structures together with the numerous biological sources are key elements that can simplify both the isolation of these compounds and the drug design of novel bioactive molecules. Resveratrol and other related compounds are heterogeneously distributed in plants and are mainly found in grapes and wine. Natural stilbenes were shown to possess a wide range of biological activities, such as antioxidant, anti-inflammatory, antihyperglycemic, cardioprotective, neuroprotective, and antineoplastic properties. While resveratrol is widely investigated for its benefits in various disorders, further studies are warranted to properly harness the therapeutic potential of less popular stilbenoid compounds.

Cytotoxic and Apoptotic Effects of Pinostilbene and Bortezomib Combination Treatment on Human Multiple Myeloma Cells

Multiple myeloma (MM) is a cancer of plasma cells in the bone marrow characterized by bone lesions, hypercalcemia, anemia, and renal failure. Bortezomib (BTZ), a common treatment for MM, is a proteasome inhibitor that induces apoptosis in MM cells. However, high doses of BTZ can be very toxic, signifying a need for a synergistic drug combination to improve treatment efficacy. Resveratrol (RES), a phenolic compound found in grapes, has been shown to inhibit MM cell growth. We sought to identify a synergistic combination of BTZ with a RES derivative and analyze the effects on reducing viability and inducing apoptosis in human MM cells. BTZ as well as RES and its derivatives pinostilbene (PIN) and piceatannol (PIC) decreased MM cell viability in a dose- and time-dependent manner and increased expression of cleaved proapoptotic proteins poly(ADP-ribose) polymerase 1 (PARP1) and caspase-3 in a dose-dependent manner. The combination of 5 nM BTZ and 5 μM PIN was identified to have synergistic cytotoxic effects in MM RPMI 8226 cells. MM RPMI 8226 cells treated with this combination for 24 h showed increased cleaved PARP1 and caspase-3 expression and higher percentages of apoptotic cells versus cells treated with the individual compounds alone. The treatment also showed increased apoptosis induction in MM RPMI 8226 cells co-cultured with human bone marrow stromal HS-5 cells in a Transwell model used to mimic the bone marrow microenvironment. Expression of oxidative stress defense proteins (catalase, thioredoxin, and superoxide dismutase) in RPMI 8226 cells were reduced after 24 h treatment, and cytotoxic effects of the treatment were ameliorated by antioxidant N-acetylcysteine (NAC), suggesting the treatment impacts antioxidant levels in RPMI 8226 cells. Our results suggest that this combination of BTZ and PIN decreases MM cell viability synergistically by inducing apoptosis and oxidative stress in MM cells.

Modification of the 4-Hydroxyphenylacetate-3-hydroxylase Substrate Pocket to Increase Activity towards Resveratrol

4-Hydroxyphenylacetate-3-hydroxylase (4HPA3H; EC 1.14.14.9) is a heterodimeric flavin-dependent monooxygenase complex that catalyzes the ortho-hydroxylation of resveratrol to produce piceatannol. Piceatannol has various health benefits and valuable applications in food, medicine, and cosmetics. Enhancing the catalytic activity of 4HPA3H toward resveratrol has the potential to benefit piceatannol production. In this study, the critical amino acid residues in the substrate pocket of 4HPA3H that affect its activity toward resveratrol were identified using semi-rational engineering. Two key amino acid sites (I157 and A211) were discovered and the simultaneous "best" mutant I157L/A211D enabled catalytic efficiency (Kcat/Km-resveratrol) to increase by a factor of 4.7-fold. Molecular dynamics simulations indicated that the increased flexibility of the 4HPA3H substrate pocket has the potential to improve the catalytic activity of the enzyme toward resveratrol. On this basis, we produced 3.78 mM piceatannol by using the mutant I157L/A211D whole cells. In this study, we successfully developed a highly active 4HPA3H variant for the hydroxylation of resveratrol to piceatannol.

Piceatannol as an Antiviral Inhibitor of PRV Infection In Vitro and In Vivo

Pseudorabies virus (PRV) belongs to the family Herpesviridae. PRV has a wide host range and can cause cytopathic effects (CPEs) in PK-15 cells. Therefore, PRV was used as a model to study the antiviral activity of piceatannol. The results showed that piceatannol could restrain PRV multiplication in PK-15 cells in a dose-dependent manner. The 50% inhibitory concentration (IC₅₀) was 0.0307 mg/mL, and the selectivity index (SI, CC₅₀/IC₅₀) was 3.68. Piceatannol could exert an anti-PRV effect by reducing the transcription level of viral genes, inhibiting PRV-induced apoptosis and elevating the levels of IL-4, TNF-α and IFN-γ in the serum of mice. Animal experiments showed that piceatannol could delay the onset of disease, reduce the viral load in the brain and kidney and reduce the pathological changes in the tissues and organs of the mice to improve the survival rate of the mice (14.3%). Therefore, the anti-PRV activity of piceatannol in vivo and in vitro was systematically evaluated in this study to provide scientific data for developing a new alternative measure for controlling PRV infection.

The Antiproliferative Activity of Adiantum pedatum Extract and/or Piceatannol in Phenylhydrazine-Induced Colon Cancer in Male Albino Rats: The miR-145 Expression of the PI-3K/Akt/p53 and Oct4/Sox2/Nanog Pathways

Colon cancer is one of the most common types of cancer worldwide, and its incidence is increasing. Despite advances in medical science, the treatment of colon cancer still poses a significant challenge. This study aimed to investigate the potential protective effects of Adiantum pedatum (AP) extract and/or piceatannol on colon cancer induced via phenylhydrazine (PHZ) in terms of the antioxidant and apoptotic pathways and histopathologic changes in the colons of male albino rats. The rats were randomly divided into eight groups: control, AP extract, piceatannol (P), PHZ, PHZ and AP treatments, PHZ and P treatments, PHZ and both AP and P, and PHZ and prophylaxis with both AP and P. The results demonstrated that PHZ induced oxidative damage, apoptosis, and histopathological changes compared to the control group. However, the administration of AP or P or AP + P as therapy or prophylaxis significantly ameliorated these changes and upregulated the colonic mir-145 and mRNA expression of P53 and PDCD-4 while downregulating the colonic mRNA expression of PI3K, AKT, c-Myc, CK-20, SOX-2, OCT-4, and NanoG compared to the PHZ group. These findings suggest that the candidate drugs may exert their anti-cancer effects through multiple mechanisms, including antioxidant and apoptotic activities.

Piceatannol Protects PC-12 Cells against Oxidative Damage and Mitochondrial Dysfunction by Inhibiting Autophagy via SIRT3 Pathway

Oxidative stress has been identified as a major cause of cellular injury in a variety of neurodegenerative disorders. This study aimed to investigate the cytoprotective effects of piceatannol on hydrogen peroxide (H₂O₂)-induced pheochromocytoma-12 (PC-12) cell damage and explore the underlying mechanisms. Our findings indicated that piceatannol pre-treatment significantly attenuated H₂O₂-induced PC-12 cell death. Furthermore, piceatannol effectively improved mitochondrial content and mitochondrial function, including enhancing mitochondrial reactive oxygen species (ROS) elimination capacity and increasing mitochondrial transcription factor (TFAM), peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) and mitochondria Complex IV expression. Meanwhile, piceatannol treatment inhibited mitochondria-mediated autophagy as demonstrated by restoring mitochondrial membrane potential, reducing autophagosome formation and light chain 3B II/I (LC3B II/I) and autophagy-related protein 5 (ATG5) expression level. The protein expression level of SIRT3 was significantly increased by piceatannol in a concentration-dependent manner. However, the cytoprotective effect of piceatannol was dramatically abolished by sirtuin 3 (SIRT3) inhibitor, 3-(1H-1,2,3-Triazol-4-yl) pyridine (3-TYP), which led to an exacerbated mitochondrial dysfunction and autophagy in PC-12 cells under oxidative stress. In addition, the autophagy activator (rapamycin) abrogated the protective effects of piceatannol on PC-12 cell death. These findings demonstrated that piceatannol could alleviate PC-12 cell oxidative damage and mitochondrial dysfunction by inhibiting autophagy via the SIRT3 pathway.

Protective Effects of Piceatannol on DNA Damage in Benzo[a]pyrene-Induced Human Colon Epithelial Cells

Evidence shows that the dietary intake of polycyclic aromatic hydrocarbons (PAHs) from food processing induces the cellular DNA damage response and leads to the development of colorectal cancer (CRC). Therefore, protecting from cellular DNA damage might be an effective strategy in preventing CRC. Benzo[a]pyrene (B[a]P) was used as a CRC initiator in the present study. Compared with other stilbenoids, piceatannol (PIC) showed the most effective inhibition of B[a]P-induced cytochrome P450 1B1 (CYP1B1) protein expression in NCM460 normal human colon epithelial cells. PIC treatment alleviated DNA migration and enhanced the expression of DNA-repair-related proteins, including histone 2AX (H2AX), checkpoint kinase 1 (Chk1), and p53, in B[a]P-induced NCM460 cells. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, flow cytometry, and enzyme-linked immunosorbent assay (ELISA) revealed that PIC exerted antioxidative effects on NCM460 cells by increasing the glutathione (GSH) content and scavenging the excess intracellular reactive oxygen species (ROS) induced by B[a]P. Furthermore, PIC suppressed B[a]P-induced CYP1B1 protein expression and stimulated miR-27b-3p expression. The upregulation of phase II detoxification enzymes, such as nicotinamide adenine dinucleotide phosphate (NADPH) and quinone oxidoreductase 1 (NQO1), and the antioxidative enzyme, heme oxygenase 1 (HO-1), via the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was observed in the PIC-treated group. Our results suggest that PIC is a potential CRC-blocking agent due to its ability to alleviate DNA damage, decrease intracellular ROS production, modulate the metabolism and detoxification of B[a]P, and activate the Nrf2 signaling pathway in B[a]P-induced NCM460 cells.

The Degree of Hydroxylation of Phenolic Rings Determines the Ability of Flavonoids and Stilbenes to Inhibit Calcium-Mediated Membrane Fusion

This paper discusses the possibility of using plant polyphenols as viral fusion inhibitors with a lipid-mediated mechanism of action. The studied agents are promising candidates for the role of antiviral compounds due to their high lipophilicity, low toxicity, bioavailability, and relative cheapness. Fluorimetry of calcein release at the calcium-mediated fusion of liposomes, composed of a ternary mixture of dioleoyl phosphatidylcholine, dioleoyl phosphatidylglycerol, and cholesterol, in the presence of 4'-hydroxychalcone, cardamonin, isoliquiritigenin, phloretin, resveratrol, piceatannol, daidzein, biochanin A, genistein, genistin, liquiritigenin, naringenin, catechin, taxifolin, and honokiol, was performed. It was found that piceatannol significantly inhibited the calcium-induced fusion of negatively charged vesicles, while taxifolin and catechin showed medium and low antifusogenic activity, respectively. As a rule, polyphenols containing at least two OH-groups in both phenolic rings were able to inhibit the calcium-mediated fusion of liposomes. In addition, there was a correlation between the ability of the tested compounds to inhibit vesicle fusions and to perturb lipid packing. We suggest that the antifusogenic action of polyphenols was determined by the depth of immersion and the orientation of the molecules in the membrane.

Benefits of skin application of piceatannol-A minireview

The skin is the largest organ of the human body and has several functions such as barrier against external agents, the maintenance of temperature and homeostatic functions. Skin ageing is a natural process that can be influenced by environmental factors, intrinsic skin factors and lifestyle. UV light plays an important role in skin ageing and can cause spots, requiring the use of depigmenting agents. Nowadays, there is a great demand for ingredients that prevent skin ageing, with natural agents occupying a promising position. Among the natural agents, polyphenols, such as resveratrol and piceatannol, found in grapes, passion fruits and other fruits, have a huge relevance. Great benefits of piceatannol have been reported, so thus, this work focuses specifically on a review of the literature regarding the application of this polyphenol in skin care products. This polyphenol can be used in a wound-healing, or as anti-ageing, antioxidant, anti-acne and skin whitening, among other effects.

Piceatannol enhances Beclin-1 activity to suppress tumor progression and its combination therapy strategy with everolimus in gastric cancer

The effects and regulation of Beclin-1-an autophagy-related protein-have not been fully defined, however, a negative correlation has been reported between Beclin-1 expression and carcinogenesis. Meanwhile, no compound has been shown to directly inhibit its activity. Here, we evaluate piceatannol, a naturally occurring polyphenolic compound, as a potential targeting agonist of Beclin-1, to assess its efficacy as an antitumor agent against gastric cancer. More specifically, we determine the effects of piceatannol treatment on cell viability using a monitoring system and colony forming assay. Piceatannol was found to efficiently inhibit the proliferation of several human gastric cancer cell lines. Autophagic flux is increased by piceatannol treatment, and correlates with inhibition of cell proliferation and colony formation. Additionally, microscale thermophoresis and surface plasmon resonance results show a direct interaction between piceatannol and Beclin-1, which reduces the phosphorylation activity of Beclin-1 at the Ser-295 site. Notably, piceatannol impairs the binding of Beclin-1 to Bcl-2 and enhances the recruitment of binding of UV radiation resistance-associated gene protein, which further triggers Beclin-1-dependent autophagy signaling. An increase in autophagic activity via treatment with the mTOR inhibitor, everolimus, effectively sensitizes piceatannol-induced antitumor effects. Xenograft models confirmed that piceatannol inhibits tumor development and elicits a potent synergistic effect with everolimus in vivo. Taken together, the findings of this study strongly support the application of combinatorial piceatannol and everolimus therapy in future clinical trials for gastric cancer patients.

Piceatannol and 3'-Hydroxypterostilbene Alleviate Inflammatory Bowel Disease by Maintaining Intestinal Epithelial Integrity and Regulating Gut Microbiota in Mice

Inflammatory bowel disease has become a significant health concern across the globe, causing frequent and long-term harm to the digestive system. This study evaluated the effect of piceatannol (PIC) and 3'-hydroxypterostilbene (HPSB) on dextran sulfate sodium (DSS)-induced colitis in mice and investigated whether their effects are exerted through the amelioration of gut barrier dysfunction to reduce the severity of colitis. The findings showed that both PIC and HPSB attenuated inflammation by inhibiting the TNF-α/NF-κB/MLC pathway and reducing NLRP3 inflammasome activation. However, PIC was comparably effective in modulating tight junctions. The results may be attributed to the effect of PIC on reducing cell apoptosis-associated protein expression, including Bax/Bcl-2 and caspase-3 activation. Furthermore, microbiota analysis revealed that both PIC and HPSB increased representative probiotic species, including Akkermansiaceae and Lactobacillus intestinalis, and exhibited inhibitory effects on several bacterial species (Spiroplasmataceae and Acholeplasmataceae). Based on linear discriminant analysis effect size, butyrate-producing bacteria were identified as a biomarker in the PIC group. Overall, the results demonstrated that PIC repressed inflammation, inhibited cell apoptosis, and regulated microbiota composition. Consequently, PIC is more effective in maintaining gut barrier integrity than HPSB, and it is a promising ingredient in the development of functional food for colitis prevention.

Protective Effects Against Brucella abortus 544 Infection in a Murine Macrophage Cell Line and in a Mouse Model via Treatment with Sirtuin 1 Activators Resveratrol, Piceatannol and Ginsenoside Rg3

Brucellosis is a contagious zoonotic disease that infects millions of people annually with hundreds of millions more being exposed. It is caused by Brucella, a highly infectious bacterial species capable of infecting humans with an estimated dose of 10-100 organisms. Sirtuin 1 (SIRT1) has been reported to contribute to prevention of viral diseases as well as a chronic infection caused by Mycobacterium bovis. Here, we investigated the role of SIRT1 in the establishment of Brucella abortus infection in both in vitro and in vivo systems using the reported SIRT1 activators resveratrol (RES), piceatannol (PIC), and ginsenoside Rg3 (Rg3). In RAW264.7 cells, SIRT1 activators did not alter the adherence of Brucella or Salmonella Typhimurium. However, reduced uptake of Brucella was observed in cells treated with PIC and Rg3, and survival of Brucella within the cells was only observed to decrease in cells that were treated with Rg3, while PIC treatment reduced the intracellular survival of Salmonella. SIRT1 treatment in mice via oral route resulted in augmented Brucella resistance for PIC and Rg3, but not RES. PIC treatment favors Th2 immune response despite reduced serum proinflammatory cytokine production, while Rg3-treated mice displayed high IL-12 and IFN-γ serum production. Overall, our findings encourage further investigation into the complete mechanisms of action of the different SIRT1 activators used as well as their potential benefit as an effective alternative approach against intracellular and extracellular pathogens.

The Potential of Stilbene Compounds to Inhibit M(pro) Protease as a Natural Treatment Strategy for Coronavirus Disease-2019

COVID-19 disease has had a global impact on human health with increased levels of morbidity and mortality. There is an unmet need to design and produce effective antivirals to treat COVID-19. This study aimed to explore the potential ability of natural stilbenes to inhibit the M^pro protease, an acute respiratory syndrome coronavirus-2 (SARS-CoV-2) enzyme involved in viral replication. The binding affinities of stilbene compounds against M^pro were scrutinized using molecular docking, prime molecular mechanics-generalized Born surface area (MM-GBSA) energy calculations, and molecular dynamic simulations. Seven stilbene molecules were docked with M^pro and compared with GC376 and N3, antivirals with demonstrated efficacy against M^pro. Ligand binding efficiencies and polar and non-polar interactions between stilbene compounds and M^pro were analyzed. The binding affinities of astringin, isorhapontin, and piceatannol were -9.319, -8.166, and -6.291 kcal/mol, respectively, and higher than either GC376 or N3 at -6.976 and -6.345 kcal/mol, respectively. Prime MM-GBSA revealed that these stilbene compounds exhibited useful ligand efficacy and binding affinity to M^pro. Molecular dynamic simulation studies of astringin, isorhapontin, and piceatannol showed their stability at 300 K throughout the simulation time. Collectively, these results suggest that stilbenes such as astringin, isorhapontin, and piceatannol could provide useful natural inhibitors of M^pro and thereby act as novel treatments to limit SARS-CoV-2 replication.

Mechanism of Synergy between Piceatannol and Ciprofloxacin against Staphylococcus aureus

Piceatannol (PIC) is a natural stilbene extracted from grape skins that exhibits biological activities such as antibacterial, antitumor, and antioxidant activities. The present study was carried out to further investigate the effect of PIC on the antibacterial activity of different antibiotics and to reveal the antibacterial mechanism of PIC. We found that PIC had an inhibitory effect against Staphylococcus aureus (S. aureus); its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 128 μg/mL and 256 μg/ mL, respectively. Additionally, we measured the fractional inhibitory concentration (FIC) of PIC combined with antibiotics via the checkerboard method. The results showed that when PIC and ciprofloxacin (CIP) were combined, they displayed a synergistic effect against S. aureus. Moreover, this synergistic effect was verified by time-kill assays. Further, the results of the membrane permeability assay and proton motive force assay revealed that PIC could enhance the sensitivity of S. aureus to CIP by dissipating the bacterial proton motive force (PMF), particularly the ∆ψ component, rather than increasing membrane permeability. PIC also inhibited bacterial adenosine triphosphate (ATP) synthesis and was less likely to induce bacterial resistance but exhibited slight hemolytic activity on mammalian erythrocytes. In summary, the combination of PIC and CIP is expected to become a new drug combination to combat S. aureus.

Piceatannol Alleviates Clostridium perfringens Virulence by Inhibiting Perfringolysin O

Clostridium perfringens (C. perfringens) is an important foodborne pathogen that can cause diseases such as gas gangrene and necrotizing enteritis in a variety of economic animals, seriously affecting public health and the economic benefits and healthy development of the livestock and poultry breeding industry. Perfringolysin O (PFO) is an important virulence factor of C. perfringens and plays critical roles in necrotic enteritis and gas gangrene, rendering it an ideal target for developing new drugs against infections caused by this pathogen. In this study, based on biological activity inhibition assays, oligomerization tests and computational biology assays, we found that the foodborne natural component piceatannol reduced pore-forming activity with an inhibitory ratio of 83.84% in the concentration of 16 µg/mL (IC₅₀ = 7.83 µg/mL) by binding with PFO directly and changing some of its secondary structures, including 3-Helix, A-helix, bend, and in turn, ultimately affecting oligomer formation. Furthermore, we confirmed that piceatannol protected human intestinal epithelial cells from the damage induced by PFO with LDH release reduced by 38.44% at 16 µg/mL, based on a cytotoxicity test. By performing an animal experiment, we found the C. perfringens clones showed an approximate 10-fold reduction in infected mice. These results suggest that piceatannol may be a candidate for anti-C. perfringens drug development.

Protective Effects of Piceatannol against Selenite-Induced Cataract and Oxidative Damage in Rats

PURPOSE

This study aimed to investigate the protective effects of piceatannol (PIC) on selenite-induced cataracts in Sprague-Dawley rats and explore its therapeutic effects as an antioxidant.

METHODS

Thirty-two eight-day-old rat pups were randomly divided into four groups, with eight pups in each of them. Group 1, as the control group, was injected with the same amount of saline, while Groups 2-4 were administered with sodium selenite (3.46 mg/kg) subcutaneously into the neck on postpartum day 10 for cataract induction. Without further treatment, Group 2 served as the control model, while Groups 3 and 4 (low- and high-dose PIC-treated) had intraperitoneal piceatannol from day 8 to day 17 at doses of 10 mg/kg and 20 mg/kg, respectively. On postpartum day 17, after the last injection, the rat pups were examined for cataract grade by slit lamp, and the lenses of every group were isolated for oxidative damage indicators and further analysis. SRA01/04 cells were exposed to 600 μM H₂O₂ for 24 hours with or without pretreatment with 10μМ piceatannol. Cell viability was tested by CCK-8 assay and cell apoptosis was evaluated by AnnexinV-PE/7AAD assay.

RESULTS

This study determined that compared with the model group, the degree of lens opacity was significantly reduced in PIC-treated groups. The histopathological damage of the lenses in the PIC-treated groups improved compared to the model group. There were fewer signs of lesions, such as vacuoles and atrophy. The biochemical results indicated that malondialdehyde (MDA) content of the PIC-treated groups were downregulated and the antioxidant enzyme activities (GSH and catalase) and antioxidant status (SOD) were upregulated compared with the model group. In vitro, piceatannol significantly restored cell viability and cell apoptosis under H₂O₂ injury.

CONCLUSION

Pretreatment with piceatannol may achieve a protective effect on cataract development through upregulating antioxidant enzyme activity.

Piceatannol, a Dietary Polyphenol, Alleviates Adipose Tissue Loss in Pre-Clinical Model of Cancer-Associated Cachexia via Lipolysis Inhibition

Cancer-associated cachexia (CAC) is the nutrition-independent loss of lean muscle and adipose tissues, and results in reduced chemotherapy effectiveness and increased mortality. Preventing adipose loss is considered a key target in the early stages of cachexia. Lipolysis is considered the central driver of adipose loss in CAC. We recently found that piceatannol, but not its analogue resveratrol, exhibits an inhibitory effect on lipolysis. The objective of this study was to investigate the role of piceatannol in cancer-associated lipolysis and cachexia-induced weight loss. Cancer cell-induced lipolysis in adipocytes was stimulated using cancer-conditioned media (CCM) or co-culture with human pancreatic cancer cells and the cachexia-associated cytokines TNF-α and interleukin-6 in 3T3-L1 adipocytes. C26 colon carcinoma-bearing mice were modeled using CAC in vivo. Piceatannol reduced cancer-associated lipolysis by at least 50% in both CCM and cytokine-induced lipolysis in vitro. Further gene and protein analysis confirmed that piceatannol modulated the stability of lipolytic proteins. Moreover, piceatannol protected tumor-bearing mice against weight-loss in early stages of CAC largely through preserving adipose tissue, with no effect on survival. This study demonstrates the use of a dietary compound to preserve adipose in models of early stage CAC and provides groundwork for further investigation of piceatannol or piceatannol-rich foods as alternative medicine in the preservation of body fat mass and future CAC therapy.

Piceatannol Prevents Colon Cancer Progression via Dual-Targeting to M2-Polarized Tumor-Associated Macrophages and the TGF-β1 Positive Feedback Signaling Pathway

SCOPE

M2 phenotype tumor-associated macrophages (M2-TAMs) play a key role in distant metastasis and poor clinical outcomes. Herein, a specific molecular mechanism that contributes to malignant progression is illuminated and investigates whether piceatannol (PIC) can target the crosstalk between M2-TAMs and cancer cells for potential colorectal cancer (CRC) therapy.

METHODS AND RESULTS

To mimic the tumor microenvironment (TME), direct and indirect coculture systems in vitro and in vivo mouse xenograft models are established. The results demonstrate that post-treatment with PIC in TME more effectively prevented the aggressive features and stemness of SW480 cells by restricting the polarization of M2-like macrophages and blocking the transforming growth factor β1 (TGF-β1) positive feedback autocrine/paracrine loop that exists between M2-like polarized macrophages and cancer cells. Furthermore, xenograft assays also observe significant repression in tumor growth and lung metastases with the administration of PIC. The key mechanism underlying the antimetastasis effects of PIC may include its directly inhibitory activity against TGF-β receptor type-1 (TGF-βR1) in the M2-like TAMs-created TME.

CONCLUSION

These novel findings demonstrate that PIC is a potent TGF-β1/TGF-βR1 pathway inhibitor and TME modulator for preventing tumor progression and metastasis in CRC by reeducating TAMs.

Passion fruit seed extract protects beta-amyloid-induced neuronal cell death in a differentiated human neuroblastoma SH-SY5Y cell model

Alzheimer's disease (AD) is a progressive neurodegenerative disease with accompanying perceptive disorder. We previously reported that decreasing levels of brain-derived neurotrophic factor (BDNF) promoted beta-amyloid (Aβ)-induced neuronal cell death in neuron-like differentiated SH-SY5Y (ndSH-SY5Y) human neuroblastoma cells in an AD mimic cell model. We investigated the neuroprotective effects of passion fruit seed extract (PFSE) and one of the main stilbene compounds, piceatannol, in an AD cell model using ndSH-SY5Y cells. Both PFSE and piceatannol were found to protect Aβ-induced neurite fragmentation in the cell model (protection efficacy; 34% in PFSE and 36% in piceatannol). In addition, both PFSE and piceatannol suppress Aβ-induced neuronal cell death in the cell model (inhibitory effect; 27% in PFSE and 32% in piceatannol). Our study is the first to report that piceatannol-rich PFSE can repress Aβ-induced neuronal cell death by protecting against neurite fragmentation in the AD human cell model. These findings suggest that piceatannol-rich PFSE can be considered a potentially neuroprotective functional food for both prevention and treatment of AD.

Piceatannol Antagonizes Lipolysis by Promoting Autophagy-Lysosome-Dependent Degradation of Lipolytic Protein Clusters in Adipocytes

Overly elevated circulating non-esterified fatty acids (NEFAs) is an emerging health concern of obesity-associated energy disorders. However, methods to reduce circulating NEFAs remain elusive. The present study determined the effect of piceatannol, a naturally occurring stilbene, on adipocyte lipolysis and its underlying mechanism. Differentiated 3T3-L1 adipocytes and brown adipocytes and isolated white adipose tissue were treated with various concentrations of piceatannol for 1.5-hr both in the basal and stimulated lipolysis conditions. Piceatannol significantly inhibited NEFAs and glycerol release with a concomitant reduction of ATGL, CGI-58 and PLIN1 expression in adipocytes. Using a series of inhibitor assays, piceatannol-induced degradation of these proteins was found to be mediated by upregulation of the autophagy-lysosome pathway. Moreover, we demonstrated that piceatannol is capable of stimulating autophagy in vitro. Importantly, piceatannol administration tended to lower fasting-induced serum glycerol levels in healthy mice. Furthermore, piceatannol administration lowered lipolysis, central adiposity and hyperinsulinemia in diet-induced obese mice. Our study provides profound evidence of a novel inhibitory role of piceatannol in lipolysis through autophagy-lysosome-dependent degradation of the key lipolytic proteins in adipocytes. This study offers a mechanistic foundation for investigating the potential of piceatannol-containing foods in reducing lipolysis and its associated metabolic disorders.

Piceatannol suppresses inflammation and promotes apoptosis in rheumatoid arthritis‑fibroblast‑like synoviocytes by inhibiting the NF‑κB and MAPK signaling pathways

Rheumatoid arthritis (RA) is a chronic inflammatory disease that mainly targets the synovial membrane, thus causing stiffness, deformity and dysfunction of joints. To date, no effective anti-inflammatory treatments are available for RA. Piceatannol (PIC) is a natural derivative of resveratrol, which has been reported to attenuate the inflammatory response. To evaluate the effect of PIC on RA and to determine the underlying molecular target of PIC, both in vitro and in vivo experiments were performed in the present study. A CIA rat model was established to evaluate the therapeutic effects of PIC. TNF-α, IL-1β and IL-6 levels in blood were measured by ELISA. Western blotting, immunofluorescence analysis and reverse transcription-quantitative PCR (RT-qPCR) were used to analyze the expression levels of protein and mRNA. In vitro, RA-fibroblast-like synoviocytes (FLSs) were pretreated with PIC and subsequently stimulated with TNF-α. The results revealed that PIC significantly upregulated the expression levels of proapoptotic proteins such as Bax and cleaved caspase-3. PIC also significantly reduced the production of proinflammatory cytokines, including PGE2, IL-6 and IL-1β, and significantly downregulated the expression of cyclooxygenase-2 at both the mRNA and protein expression levels. Furthermore, PIC downregulated the expression of MMP-3 and MMP-13, which have been found to be highly expressed in the synovium of patients with RA. Mechanistically, PIC was capable of significantly downregulating the expression levels of proteins involved in the NF-κB and MAPK signaling pathways. The results of the in vivo experiments using a rat collagen-induced arthritis model demonstrated that PIC decreased the arthritis score and exerted beneficial effects in cartilage and significantly reduced the expression of MMP-13. In conclusion, the findings of the present study revealed that PIC could suppress the inflammatory response, promote apoptosis, and exert a significant regulatory effect on the NF-κB and MAPK signaling pathways in RA-FLSs. Therefore, PIC may represent a potential drug for the future treatment of RA.

Piceatannol Protects Brain Endothelial Cell Line (bEnd.3) against Lipopolysaccharide-Induced Inflammation and Oxidative Stress

Dysfunction of the blood-brain barrier (BBB) is involved in the pathogenesis of many cerebral diseases. Oxidative stress and inflammation are contributing factors for BBB injury. Piceatannol, a natural ingredient found in various plants, such as grapes, white tea, and passion fruit, plays an important role in antioxidant and anti-inflammatory responses. In this study, we examined the protective effects of piceatannol on lipopolysaccharide (LPS) insult in mouse brain endothelial cell line (bEnd.3) cells and the underlying mechanisms. The results showed that piceatannol mitigated the upregulated expression of adhesion molecules (ICAM-1 and VCAM-1) and iNOS in LPS-treated bEnd.3 cells. Moreover, piceatannol prevented the generation of reactive oxygen species in bEnd.3 cells stimulated with LPS. Mechanism investigations suggested that piceatannol inhibited NF-κB and MAPK activation. Taken together, these observations suggest that piceatannol reduces inflammation and oxidative stress through inactivating the NF-κB and MAPK signaling pathways on cerebral endothelial cells in vitro.

Piceatannol alleviates glucolipotoxicity induced vascular barrier injury through inhibition of the ROS/NF-kappa B signaling pathway

Vascular barrier dysfunction is considered as the initial and critical event in atherosclerosis progression. Recent studies have revealed that treatment with piceatannol (PIC) alleviates both acute and chronic responses to vascular injury. We investigated whether PIC treatment would have beneficial effects on glucolipotoxicity-induced endothelial barrier dysfunction. Target proteins of PIC were identified from several online databases. Then, we confirmed the effect of PIC on endothelial barrier function. PIC treatment mitigated the impairment of endothelial cell motility, adhesion and migration ability associated with high glucose/lipid stimulation. PIC stabilized cytoskeletal reorganization and expression of cell cytoskeletal associated proteins GTPase. PIC reversed changes in critical vascular junction proteins and thus preserved endothelial barrier function and permeability. Finally, we confirmed that reducing of nuclear factor kappa B (NF-κB)/p65 activation and elimination of reactive oxygen species (ROS) were involved in the protective effect of PIC against glucolipotoxicity-induced vascular barrier injury. We identify PIC as a promising therapeutic strategy for glucolipotoxicity-induced endothelial barrier injury.

The Anti-Obesity Potential of Cyperus rotundus Extract Containing Piceatannol, Scirpusin A and Scirpusin B from Rhizomes: Preclinical and Clinical Evaluations

PURPOSE

Obesity is a complex medical problem that increases the risk of other diseases like diabetes, cardiovascular diseases, and fatty liver disease. The present study evaluated the efficacy and safety of Cyperus rotundus rhizome extract (CRE), standardized to contain Piceatannol, Scirpusin A, and Scirpusin B (5% total Stilbenoids) in overweight individuals. The mechanism of activity was evaluated in a diet-induced mice model of obesity and adipocytes in vitro.

MATERIALS AND METHODS

The efficacy, safety, and tolerability of CRE were evaluated in 30 obese individuals with a BMI of 30 to 40 kg/m² for 90 days in a randomized, double-blind, parallel-group, placebo-controlled study. In vitro studies were carried out in differentiated 3T3 L1 adipocytes, and the therapeutic efficacy was evaluated in high-fat diet-induced obese mice.

RESULTS

The pilot clinical study showed a reduction in body weight with a significant decrease in waist circumference and BMI. The serum lipid profile showed a significant improvement in CRE-treated individuals. The extract was well tolerated, and no adverse effects were reported at the end of the study. CRE showed a dose-dependent adipogenesis reduction in vitro with an IC₅₀ value of 9.39 μg/mL, while oral administration of CRE reduced weight gain in diet-induced obese mice. The efficacy in mice was associated with reduced levels of leptin, corticosteroids, and serum lipid levels, with no adverse effects.

CONCLUSION

CRE has anti-adipogenic properties, is safe for human consumption, and effectively manages weight and hypercholesterolemia in overweight individuals.

Transforming Tea Catechins into Potent Anticancer Compound: Analysis of Three Boronated-PEG Delivery System

Chemotherapy has led to many undesirable side effects, as these are toxic drugs that are unable to differentiate between cancer and normal cells. Polyphenols (tea catechins) are an ideal option as alternative chemotherapeutics owing to their inherent anticancer properties, antioxidant properties and being naturally occurring compounds, are deemed safe for consumption. However, without proper administration, the bioavailability of these compounds is low and inefficient. Therefore, proper delivery of these phenolic compounds is vital for cancer therapy. Herein, we analyzed three potential solutions to creating nanoparticle drugs using naturally occurring phenolic compounds (piceatannol (PIC), epigallocatechin gallate hydrophilic (EGCG) and l-epicatechin (EPI)). By using a simple pi-pi stacking mechanism, we utilized boronated PEG (PEG-Br) as an anchor to efficiently load EPI, PIC and EGCG, respectively, to produce three effective phenolic compound-based nanoparticles, which could be delivered safely in systemic circulation, yet detach from its cargo intracellularly to exert its anticancer effect for effective cancer therapy.

Constituent Characteristics and Functional Properties of Passion Fruit Seed Extract

The genus Passiflora L. is widely cultivated in tropical and subtropical regions. The major species, Passiflora edulis Sims, is known as 'passion fruit' and is widely used in processed foods as well as eaten raw. P. edulis fruits are eaten for their pulp together with the seeds; however, the seeds are often discarded when used in processed foods. P. edulis seeds contain a variety of nutrients and functional components, and their industrial use is desirable from the perspective of waste reduction. Previous studies have analyzed the constituents of P. edulis and their physiological functions. P. edulis seeds contain various types of polyphenols, especially those rich in stilbenes (e.g., piceatannol). P. edulis seed extracts and isolated compounds from seeds have been reported to exhibit various physiological functions, such as antioxidant effects, improvement of skin condition, fat-burning promotion effects, and hypoglycemic effects. This review summarizes the nutritional characteristics, polyphenol content, and physiological functions of P. edulis seeds.

The Bark of the Spruce Picea jezoensis Is a Rich Source of Stilbenes

Stilbenes are plant phenolic secondary metabolites that show beneficial effects on human health and possess high antifungal activity against plant pathogens. Currently, a search for plant sources with high stilbene levels is relevant, since stilbene content in various plant species can vary substantially and is often at a low level. In this paper, the bark and wood of Picea jezoensis were analyzed for the content and composition of stilbenes and compared with other known stilbene sources. The HPLC-MS analysis of P. jezoensis bark and wood extracted with different solvents and at different temperatures revealed the presence of 11 and 5 stilbenes, respectively. The highest number of stilbenes of 171 and 229 mg per g of the dry weight (mg/g DW) was extracted from the bark of P. jezoensis using methanol or ethanol at 60 °C for 2 h. Trans-astringin, trans-piceid, and trans-isorhapontin prevailed over other stilbenoids (99% of all detected stilbenes). The most abundant stilbene was trans-isorhapontin, reaching 217 mg/g DW or 87% of all stilbenes. An increase in the extraction time from 2 to 6 h did not considerably increase the detected level of stilbenes, while lower extraction temperatures (20 and 40 °C) significantly lowered stilbene yield. The content of stilbenes in the P. jezoensis bark considerably exceeded stilbene levels in other stilbene-producing plant species. The present data revealed that the bark of P. jezoensis is a rich source of stilbenes (primarily trans-isorhapontin) and provided effective stilbene extraction procedures.

Piceatannol, a Structural Analog of Resveratrol, Is an Apoptosis Inducer and a Multidrug Resistance Modulator in HL-60 Human Acute Myeloid Leukemia Cells

Acute myeloid leukemia is characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells. Despite recent advances in the treatment of this disease, the prognosis and overall long-term survival for patients remain poor, which drives the search for new chemotherapeutics and treatment strategies. Piceatannol, a polyphenolic compound present in grapes and wine, appears to be a promising chemotherapeutic agent in the treatment of leukemia. The aim of the present study was to examine whether piceatannol induces autophagy and/or apoptosis in HL-60 human acute myeloid leukemia cells and whether HL-60 cells are able to acquire resistance to piceatannol toxicity. We found that piceatannol at the IC90 concentration of 14 µM did not induce autophagy in HL-60 cells. However, it induced caspase-dependent apoptosis characterized by phosphatidylserine externalization, disruption of the mitochondrial membrane potential, caspase-3 activation, internucleosomal DNA fragmentation, PARP1 cleavage, chromatin condensation, and fragmentation of cell nuclei. Our findings also imply that HL-60 cells are able to acquire resistance to piceatannol toxicity via mechanisms related to MRP1 activity. Our results suggest that the use of piceatannol as a potential chemotherapeutic agent may be associated with the risk of multidrug resistance, warranting its use in combination with other chemotherapeutic agents.

Piceatannol ameliorates behavioural, biochemical and histological aspects in cisplatin-induced peripheral neuropathy in rats

Peripheral neurotoxicity is a dose-limiting and a potentially lifelong persistent toxicity of cisplatin. This study investigated the possible protective effect of piceatannol (PIC) in a model of cisplatin-induced peripheral neuropathy in rats. PIC (10 mg/kg, i.p.) was given for 7 days, starting 2 days before cisplatin single injection (7 mg/kg, i.p.). Behavioural, biochemical and histological examinations were conducted. Cisplatin administration resulted in thermal hypoalgesia evidenced by increased paw and tail withdrawal latency times in the hotplate and tail flick tests, respectively, and reduced the abdominal constrictions in response to the acetic acid injection. Moreover, cisplatin treatment decreased rat locomotor activity and grip strength. These behavioural alterations were reversed by PIC coadministration. In addition, PIC decreased cisplatin-induced elevation in serum neurotensin and platinum accumulation in sciatic nerve. Also, PIC reversed, to a large extent, cisplatin-induced microscopical alterations in nerve axons and restored normal myelin thickness. Therefore, PIC may protect against cisplatin-induced peripheral neuropathy.

Systemic antioxidant and anti-inflammatory effects of yellow passion fruit bagasse extract during prostate cancer progression

We evaluated the impact of yellow passion fruit (Passiflora edulis sp.) bagasse extract (PFBE) administration in systemic oxidative and inflammatory parameters in vivo, considering prostate cancer progression in transgenic mice (TRAMP). Piceatannol, scirpusin-B, dicaffeoylquinic acid, citric acid, and (+)-catechin were identified in PFBE, and the extract showed high in vitro antioxidant capacity. Some alterations in systemic parameters were verified during prostate cancer progression, as the increase in ALT and MDA levels, and SOD and GPx activities in the plasma. In the liver, higher MDA, TNF-α, and NF-κB levels, and GR and GPx activities were verified. Compared to their respective controls, the short- and long-term PFBE administration reduced MDA levels in the liver and plasma. The long-term treatment increased the catalase activity in the plasma, while the short-term treatment increased the hepatic SOD and catalase activities. Still, a reduction in hepatic TNF-α and NF-κB levels was verified after long-term treatment. PRACTICAL APPLICATIONS: Prostate cancer progression is associated with changes in systemic redox status and inflammation markers. Moreover, the intake of polyphenols with antioxidant properties, besides delaying prostate carcinogenesis, may improve the systemic antioxidant defenses and inflammatory response. In vitro studies pointed to a promising antioxidant and anti-inflammatory potential of yellow passion fruit bagasse. However, in vivo studies are scarce. Our results provided information about in vivo impacts of PFBE oral consumption on antioxidant defense and inflammation, indicating its potential as an adjuvant during the initial steps of prostate cancer.

Diversity and characteristics of culturable endophytic bacteria from Passiflora edulis seeds

Defense compounds generally inhibit microbial colonization of plants. In this study, we examined the presence of endophytes in Passiflora edulis seeds that accumulate resveratrol and piceatannol at extremely high levels as defense compounds. Interestingly, although no microbial colonies appeared on an agar growth medium from the cut or homogenized seeds, colonies were generated from cut seedlings derived from the seeds. A total of 19 bacterial strains were isolated, of which 15 were classified as Gram-positive. As we hypothesized that extremely high levels of piceatannol in the seeds would inhibit the growth of endophytes cultured directly from the seeds, we examined the antimicrobial activity of this compound against the isolated bacteria. Piceatannol exerted bacteriostatic rather than bactericidal effects on most of the bacteria tested. These results suggest that the bacteria remain static in the seeds due to the presence of piceatannol and are transmitted to the seedlings during the germination process, enabling colonies to be established from the seedlings on the agar medium. We also investigated the biocatalytic activity of the isolated bacteria toward resveratrol and piceatannol. One bacterium, Brevibacterium sp. PE28-2, converted resveratrol and piceatannol to their respective derivatives. This strain is the first endophyte shown to exhibit such activity.

Effect of piceatannol against malignant melanoma in vivo and in vitro

OBJECTIVES

To study the antitumor effect of piceatannol (PIC) on malignant melanoma in vitro and in vivo.

METHODS

B16F10 cells were cultured in vitro and treated with gradient concentrations of PIC. Cell viability was detected with methyl thiazolyl tetrazolium (MTT) assay; matrix metalloproteinase (MMP)-2, MMP-9, vascular endothelial growth factor (VEGF), spleen tyrosine kinase (Syk), and p-Syk were detected with Western blot; migration ability was detected with wound healing assay; invasion ability was detected with Transwell assay. Syk expression was suppressed through RNA interference for the detection of the possible mechanism of PIC in melanoma. An in vivo study was established by creating B16F10-bearing mice with intraperitoneal injection of PIC.

RESULTS

The cell viability of B16F10 decreased with increasing PIC concentration. The results of the Transwell assay showed that invasion ability decreased with increasing PIC concentration, and healing time was prolonged at increased PIC concentration in the wound healing assay. Western blot results showed that PIC mainly inhibited the phosphorylation of Syk and inhibited the expression of MMP-2, MMP-9, and VEGF. RNA interference pointed out that blocking the expression of Syk can reveal the same inhibition effect on B16F10 cells as PIC. In vivo study revealed that different concentrations of PIC cangreatly inhibit melanoma progression.

CONCLUSIONS

PIC might block the progression of malignant melanoma by inhibiting spleen tyrosine kinase.

Piceatannol alleviate ROS-mediated PC-12 cells damage and mitochondrial dysfunction through SIRT3/FOXO3a signaling pathway

Oxidative stress-associated mitochondrial dysfunction has been identified as a major mechanism in multiple neurodegenerative diseases. This study aims to investigate the cytoprotective effects of piceatannol on ROS-mediated PC-12 cells damage and related mitochondrial dysfunction. Piceatannol treatment could significantly attenuate PC-12 cells oxidative damage and ROS-mediated cells apoptosis. Moreover, pretreatment with piceatannol effectively decreased mitochondrial membrane depolarization, cleaved-caspase 3, and increased Bcl-2 and Bcl-2/Bax compared with control H₂ O₂ group. Meanwhile, piceatannol treatment improved mitochondrial respiration function which led to an enhancement in the maximal respiration and spare respiratory capacity. Further mechanisms analysis showed that the protein expression of SIRT3 and its downstream protein FOXO3a were significantly increased after piceatannol addition in a dose-dependent manner. Whereas the cytoprotective role of piceatannol was markedly abolished by the SIRT3 inhibitor 3-TYP, suggesting that SIRT3/FOXO3a signaling pathway played a vital role in mediating the neuronal cytoprotective effects of piceatannol. PRACTICAL APPLICATIONS: The results of our study provide a novel insight that piceatannol could be potentially used as a promising bioactive component against oxidative damage and neurocyte apoptosis. The findings may provide theoretical basis for brain health of piceatannol consumption in some extent.

Selective Extraction of Piceatannol from Passiflora edulis by-Products: Application of HSPs Strategy and Inhibition of Neurodegenerative Enzymes

Passiflora edulis by-products (PFBP) are a rich source of polyphenols, of which piceatannol has gained special attention recently. However, there are few studies involving environmentally safe methods for obtaining extracts rich in piceatannol. This work aimed to concentrate piceatannol from defatted PFBP (d-PFBP) by means of pressurized liquid extraction (PLE) and conventional extraction, using the bio-based solvents selected with the Hansen solubility parameters approach. The relative energy distance (Ra) between solvent and solute was: Benzyl Alcohol (BnOH) < Ethyl Acetate (EtOAc) < Ethanol (EtOH) < EtOH:H₂O. Nonetheless, EtOH presented the best selectivity for piceatannol. Multi-cycle PLE at 110 °C was able to concentrate piceatannol 2.4 times more than conventional extraction. PLE exhibited a dependence on kinetic parameters and temperature, which could be associated with hydrogen bonding forces and the dielectric constant of the solvents. The acetylcholinesterase (AChE) and lipoxygenase (LOX) IC₅₀ were 29.420 μg/mL and 27.682 μg/mL, respectively. The results reinforce the demand for processes to concentrate natural extracts from food by-products.

Active Components from Cassia abbreviata Prevent HIV-1 Entry by Distinct Mechanisms of Action

Cassia abbreviata is widely used in Sub-Saharan Africa for treating many diseases, including HIV-1 infection. We have recently described the chemical structures of 28 compounds isolated from an alcoholic crude extract of barks and roots of C. abbreviata, and showed that six bioactive compounds inhibit HIV-1 infection. In the present study, we demonstrate that the six compounds block HIV-1 entry into cells: oleanolic acid, palmitic acid, taxifolin, piceatannol, guibourtinidol-(4α→8)-epiafzelechin, and a novel compound named as cassiabrevone. We report, for the first time, that guibourtinidol-(4α→8)-epiafzelechin and cassiabrevone inhibit HIV-1 entry (IC₅₀ of 42.47 µM and 30.96 µM, respectively), as well as that piceatannol interacts with cellular membranes. Piceatannol inhibits HIV-1 infection in a dual-chamber assay mimicking the female genital tract, as well as HSV infection, emphasizing its potential as a microbicide. Structure-activity relationships (SAR) showed that pharmacophoric groups of piceatannol are strictly required to inhibit HIV-1 entry. By a ligand-based in silico study, we speculated that piceatannol and norartocarpetin may have a very similar mechanism of action and efficacy because of the highly comparable pharmacophoric and 3D space, while guibourtinidol-(4α→8)-epiafzelechin and cassiabrevone may display a different mechanism. We finally show that cassiabrevone plays a major role of the crude extract of CA by blocking the binding activity of HIV-1 gp120 and CD4.

Piceatannol-Loaded Bilosome-Stabilized Zein Protein Exhibits Enhanced Cytostatic and Apoptotic Activities in Lung Cancer Cells

Piceatannol (PIC) is a naturally occurring polyphenolic stilbene, and it has pleiotropic pharmacological properties. Moreover, PIC has cytotoxic actions among various cancer cells. In this work, preparations of PIC-loaded bilosome-zein (PIC-BZ) were designed, formulated, and characterized, and the optimized PIC-BZ cytotoxic activities, measured as half maximal inhibitory concentration (IC₅₀), against lung cancer cell line was investigated. Box-Behnken design was utilized in order to examine the effect of preparation factors on drug entrapment and particle size. PIC-BZ showed a spherical shape after optimization, and its particle size was determined as 157.45 ± 1.62 nm. Moreover, the efficiency of drug entrapment was found as 93.14 ± 2.15%. The cytotoxic activity evaluation revealed that the adjusted formulation, which is PIC-BZ formula, showed a substantially smaller IC₅₀ versus A549 cells. Cell cycle analysis showed accumulation of cells in the G2-M phase. Moreover, it showed in the sub-G1 phase, a rise of cell fraction suggestion apoptotic improving activity. Increased early and late phases of apoptosis were demonstrated by staining of cells with annexin V. Furthermore, the cellular caspase-3 protein expression was significantly raised by PIC-BZ. In addition, the wound healing experiment confirmed the results. To conclude, compared to pure PIC, PIC-BZ demonstrated a higher cell death-inducing activity against A549 cells.

Profile of Stilbenes and Other Phenolics in Fanagoria White and Red Russian Wines

Grapes and wines represent the most important source of edible stilbenes and other phenolic metabolites, which demonstrate a wide range of valuable biological activities. However, there is no information about the profile and content of phenolic compounds in Russian wines. We firstly analyzed phenolics (stilbenes, phenolic acids, and flavonols) in some representatives of Russian wines, including eleven red and seven white Russian wines from Fanagoria, Krasnodarsky Territory. The Russian red wines contained six stilbenes (trans-resveratrol, cis-resveratrol, trans-, cis-piceid, trans-piceatannol, δ-viniferin), while the white wines contained only five stilbenes (cis-resveratrol, trans-, cis-piceid, trans-piceatannol, trans-resveratrol). More than a half of the total stilbenes in the wines (65% of all stilbenes) were presented by trans-piceid and cis-piceid, while trans-resveratrol reached 16% of all the stilbenes. The red wines also contained six phenolic acids and six flavonols, while the white wines contained six phenolic acids and only three flavonols. Myrecitin-3-O-glucoside, quercetin-3-O-glucoside, and myricetin were the major flavonols in the red wines, while dihydroquercetin-3-O-rhamnoside was the major flavonol in the white wines. The red wines contained markedly higher amounts of stilbenes, phenolic acids, and flavonols than the white wines. Thus, the data showed that young red Russian Fanagoria wines represent a rich source of phenolic compounds. The study also revealed that younger wines were more abundant in phenolics, and wine storage for six months in the dark at +10 °C led to a decrease in the total content of phenolics, primarily monomeric stilbenes and quercetin-3-O-glucoside and quercetin flavonols.

Piceatannol inhibits pyroptosis and suppresses oxLDL-induced lipid storage in macrophages by regulating miR-200a/Nrf2/GSDMD axis

As a major bioactive compound from grapes, piceatannol (PIC) has been reported to exert anti-atherosclerotic activity in various studies. Nevertheless, the mechanism underlying the effect of piceatannol against atherosclerosis (AS) is elusive. Our study identified miR-200a/Nrf2/GSDMD signaling pathway as critical mediators in the effect of piceatannol on macrophages. In the present study, we confirmed that treatment of piceatannol repressed the oxLDL-induced lipid storage in macrophages. Compared with control group, piceatannol inhibited TG storage and the activity of caspase1. It is noting that in response to oxLDL challenge, piceatannol abated the pyroptosis in RAW264.7 cells, with a decreased expression of caspase1, gasdermin D (GSDMD), IL-18, IL-1β and NLRP3. Moreover, we investigated the role of microRNA (miR)-200a/Nrf2 signaling pathway in the effect of piceatannol. The results declared that after transfection of si-miR-200a or si-Nrf2 plasmids, the effects of piceatannol on macrophages were converted, including lipid storage and pyroptosis. Importantly, si-miR-200a plasmid reduced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), indicating that miR-200a acted as an enhancer of Nrf2 in macrophages. Collectively, our findings demonstrate that piceatannol exerts anti-atherosclerotic activity on RAW264.7 cells by regulating miR-200a/Nrf2/GSDMD signaling. The present study is the first time to identify miR-200a as a candidate target in AS and declared an association between miR-200a and pyroptosis, which provides a novel therapy for the treatment of AS.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Comparison of Ferroptosis-Inhibitory Mechanisms between Ferrostatin-1 and Dietary Stilbenes (Piceatannol and Astringin)

Synthetic arylamines and dietary phytophenolics could inhibit ferroptosis, a recently discovered regulated cell death process. However, no study indicates whether their inhibitory mechanisms are inherently different. Herein, the ferroptosis-inhibitory mechanisms of selected ferrostatin-1 (Fer-1) and two dietary stilbenes (piceatannol and astringin) were compared. Cellular assays suggested that the ferroptosis-inhibitory and electron-transfer potential levels decreased as follows: Fer-1 >> piceatannol > astringin; however, the hydrogen-donating potential had an order different from that observed by the antioxidant experiments and quantum chemistry calculations. Quantum calculations suggested that Fer-1 has a much lower ionization potential than the two stilbenes, and the aromatic N-atoms were surrounded by the largest electron clouds. By comparison, the C4'O-H groups in the two stilbenes exhibited the lowest bond disassociation enthalpies. Finally, the three were found to produce corresponding dimer peaks through ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry analysis. In conclusion, Fer-1 mainly depends on the electron transfer of aromatic N-atoms to construct a redox recycle. However, piceatannol and astringin preferentially donate hydrogen atoms at the 4'-OH position to mediate the conventional antioxidant mechanism that inhibits ferroptosis, and to ultimately form dimers. These results suggest that dietary phytophenols may be safer ferroptosis inhibitors for balancing normal and ferroptotic cells than arylamines with high electron-transfer potential.