Potential Cancer Chemopreventive Activity of Protocatechuic Acid

Graphene Oxide⁻PEG⁻Protocatechuic Acid Nanocomposite Formulation with Improved Anticancer Properties

The treatment of cancer through chemotherapy is limited by its toxicity to healthy tissues and organs, and its inability to target the cancer site. In this study, we have designed an anticancer nanocomposite delivery system for protocatechuic acid (PCA) using graphene oxide–polyethylene glycol as the nanocarrier, and coated with folic acid (GO–PEG–PCA–FA) for targeting the cancer cells. The designed anticancer delivery system was found to show much better anticancer activity than the free drug PCA against liver cancer HEP-G2 cells and human colon cancer HT-29 cells; at same time, it was found to be less toxic to normal fibroblast 3T3 cells. The folate-coated anticancer delivery system was found to show better activity then the free drug and the uncoated anticancer delivery system. The in vitro release of the PCA was found to be sustained in human physiological pHs, i.e., blood pH 7.4 and intracellular lysosomal pH 4.8. These in vitro findings are highly encouraging for further in vivo evaluation studies.

Storage conditions modulate the metabolomic profile of a black raspberry nectar with minimal impact on bioactivity

Pre-clinical and clinical studies suggest black raspberries (BRBs) may inhibit the development of oral cancer. Lyophilized BRB powder is commonly used in these studies, but processed BRB products are more often consumed. The objective of this work was to understand how storage conditions influence the phytochemical profile and anti-proliferative activity of a BRB nectar beverage. Untargeted UHPLC-Q-TOF-MS based metabolomics analyses demonstrated that large chemical variation was introduced by storage above -20 °C over 60 days. However, minimal change in anti-proliferative activity was observed when stored nectar extracts were applied to SCC-83-01-82 premalignant oral epithelial cells. As proof of concept, cyanidin-3-O-rutinoside and its degradation product, protocatechuic acid, were administered in different ratios maintaining an equimolar dose, and anti-proliferative activity was maintained. This study shows the utility of metabolomics to profile global chemical changes in foods, while demonstrating that isolated phytochemicals do not explain the complete bioactivity of a complex food product.

Profiling the impact of thermal processing on black raspberry phytochemicals using untargeted metabolomics

Clinical and laboratory studies have implicated black raspberries (BRBs) and their associated phytochemicals in the modulation of several chronic diseases. Most research on the health benefits of BRBs is conducted using freeze-dried or otherwise minimally processed products, yet BRBs are typically consumed as thermally processed goods like jams and syrups. The objective of this work was to profile the chemical changes that result from thermal processing of BRB powder into a nectar beverage. Using an untargeted UHPLC-QTOF-MS metabolomics approach, key degradation products of anthocyanins were identified along with several other proposed phenolic degradants. The effects of processing on other key BRB compound groups, including ellagitannins, are also discussed. This work demonstrates the utility of an untargeted metabolomics approach in describing the chemistry of complex food systems and provides a foundation for future research on the impact of processing on BRB product bioactivity.

Mechanistic Study of the In Vitro and In Vivo Inhibitory Effects of Protocatechuic Acid and Syringic Acid on VEGF-Induced Angiogenesis

The antiangiogenic activities of two structurally similar phenolics, protocatechuic acid (PA) and syringic acid (SA), were investigated. In vitro study using HUVECs demonstrated that both PA and SA (at 25 μM) significantly ( p < 0.05) inhibited VEGF-induced cell proliferation by 22.68 ± 5.6% and 21.93 ± 2.0%, respectively; cell migration by 50.04 ± 3.3% and 39.72 ± 4.7%, respectively; cell invasion by 44.16 ± 4.23% and 51.90 ± 2.73%, respectively; and cellular ROS generation by 11.48 ± 6.32% and 21.17 ± 9.10%, respectively. Our mechanistic study revealed that PA and SA blocked the VEGFR2-dependent Akt/ MMP2 and ERK pathways in HUVECs. These inhibitory effects were further confirmed by a decrease of endogenous alkaline phosphatase activity for PA and SA (21.47 ± 1.77% and 10.37 ± 1.27%, respectively) and the suppression of subintestinal vessel plexus formation in Tg (fli1a:EGFP) y1-type transgenic zebrafish embryos. PA and SA down-regulated the angiogenesis-related signal transduction pathway of VEGFα-VEGFR2 or Ang2- Tie2 in zebrafish. Moreover, it was also found that PA demonstrated a better inhibition on VEGF-induced migration of HUVEC and zebrafish vasculature. This might be due to the different number of hydroxyl and methoxy substituents possessed by PA and SA. Taken together, these findings indicate that phenolics PA and SA have potent antiangiogenic activities and are potential targets for the design and development of anticancer agents.

Prenylated phloroglucinols from Hypericum scruglii, an endemic species of Sardinia (Italy), as new dual HIV-1 inhibitors effective on HIV-1 replication

In a search for new potential multitarget anti-HIV compounds from natural products, we have identified in Hypericum scruglii, an endemic and exclusive species of Sardinia (Italy), a potent plant lead. The phytochemical study of the hydroalcoholic extract obtained from its leaves led to the isolation of its most abundant secondary metabolites, belonging to different chemical classes. In particular, three phloroglucinols derivatives were identified, confirming their significance as chemotaxonomic markers of the Hypericum genus. Among them, the 3-(13-hydroxygeranyl)-1-(2'-methylbutanoyl)phloroglucinol was reported here for the first time. All six isolated compounds have been evaluated firstly for the inhibition of both Human Immunodeficiency Virus type 1 (HIV-1) Reverse Transcriptase (RT)-associated DNA Polymerase (RDDP) and Ribonuclease H (RNase H) activities, for the inhibition of HIV-1 integrase (IN) in biochemical assays, and also for their effect on viral replication. Among the isolated metabolites, three phloroglucinol derivatives and quercitrin were effective on both RT-associated RDDP and RNase H activities in biochemical assays. The same active compounds affected also HIV-1 IN strand transfer function, suggesting the involvement of the RNase H active site. Furthermore, phloroglucinols compounds, included the newly identified compound, were able to inhibit the HIV-1 replication in cell based assays.

Anatolian honey is not only sweet but can also protect from breast cancer: Elixir for women from artemis to present

Natural products with bioactive components are widely studied on various cancer cell lines for their possible cytotoxic effects, recently. Among these products, honey stands out as a valuable bee product containing many active phenolic compounds and flavonoids. Numerous types of multifloral honey and honeydew honey are produced in Turkey owing to its abundant vegetation. Therefore, in this study, we investigated the cytotoxic effects of particular tree-originated honeys from chestnut, cedar, pine, and multifloral honey on cell lines representing different types of the most common cancer of women, breast cancer, MCF7, SKBR3, and MDAMB-231, and fibrocystic breast epithelial cell line, MCF10A as a control. All honey samples were analyzed biochemically. The dose- (1, 2.5, 5, 7.5, and 10 µg/mL) and time (24th, 48th, and 72nd hours)-dependent effects of ethanol/water solutions of the honey samples were scrutinized. Cell viability/cytotoxicity was evaluated by the water soluble tetrazolium Salt-1 (WST-1) method. Apoptotic status was detected by Annexin V-PI assay using FACSCalibur. The statistical analysis was performed using GraphPad Prism 6 and the clustering data analysis with the R programming language. The biochemical analyses of the honey samples showed that the tree-originated honey samples contained more total phenolic compounds than the multifloral honey. Phenolic content of the honey types increases in order of multifloral, pine, cedar, and chestnut, respectively, which is compatible with their cytotoxic affectivity and dark color. In addition, the antioxidant capacity of the studied honey types was observed to increase in order of multifloral < pine < cedar ≅ chestnut. According to the WST-1 data, chestnut honey induced cytotoxicity over 50% on all the cell lines, including the control MCF10A cells, even with low doses (honey concentrations starting from 1 µg/mL) (P < 0.0001). Similarly, Cedar honey was observed to be the second most effective honey in this study. Cedar honey, with the dose of 1 µg/mL, was detected statistically highly significant on MCF10A, MCF7, and SKBR3. In contrast, pine honey showed dramatically significant cytotoxicity only on the MDAMB 231 cells with a 1 µg/mL dose at the same time point (P = 0.018). While pine honey caused an anticancer effect on the MCF-7 and SKBR3 cancer cell lines with a 2.5-5 µg/mL dose (P < 0.0001), like cedar and chestnut honeys, it increased the viability of the MCF10A control cells with the doses of 2.5-5 µg/mL. It only showed cytotoxicity with higher doses (10 µg/mL) on the MCF10A cell line (P < 0.0001). Moreover, we have observed that the multifloral and artificial honey samples were mostly ineffective or increased cell viability with the doses of 1-5 µg/mL. Apoptotic effects of the other honey samples on the MCF-7 cell line were found as chestnut> pine> cedar> multifloral in the Annexin V-propidium iodide (PI) analysis. Chestnut, cedar, and pine honey displayed a remarkably cytotoxic effect on breast cancer cell lines, MCF7, SKBR3, and even on the most aggressive MDAMB 231, representing the triple negative breast cancer, which lacks of targeted anticancer therapy. The chestnut and cedar honeys stand out to be the most cytotoxic on all cell lines, while pine honey was found to be the least toxic on control cells with appropriate toxicity on the cancer cells. © 2017 IUBMB Life, 69(9):677-688, 2017.

Ethyl 3,4-dihydroxybenzoate (EDHB): a prolyl hydroxylase inhibitor attenuates acute hypobaric hypoxia mediated vascular leakage in brain

Sudden exposure to altitude hypoxia is responsible for acute mountain sickness (AMS) in un-acclimatized persons. If not treated in time, AMS can worsen and leads to high altitude cerebral edema, which can be fatal. Present study explores the efficacy of ethyl 3,4-dihydroxybenzoate (EDHB), a prolyl hydroxylase enzyme inhibitor, in modulating adaptive responses to hypobaric hypoxia (HH) in rat brain. Male Sprague-Dawley rats treated with EDHB (75 mg/kg for 3 days), were subjected to acute HH exposure at 9144 m (30,000 ft) for 5 h. Animals were assessed for transvascular leakage and edema formation in brain and role of key inflammatory markers along with hypoxia responsive genes. HH stress increased transvascular permeability and edema formation in conjunction with upregulation of nuclear factor-κB (NF-κB) and its regulated proteins. There was surge in pro-inflammatory cytokines tumor necrosis factor-α, interleukin-6, interferon-γ, monocyte chemoattractant protein-1 and decrement in anti-inflammatory cytokine interleukin-10. Further, upregulation of vascular endothelial growth factor (VEGF), a vascular permeability marker and down-regulation of antioxidant and anti-inflammatory proteins hemoxygenase (HO-1) and metallothionein (MT-1) was also observed under hypoxia. EDHB supplementation effectively scaled down HH induced cerebral edema with concomitant downregulation of brain NF-κB expression. There was significant curtailment of pro-inflammatory cytokines and cell adhesion molecules. There was significant downregulation of permeability factor VEGF by EDHB with concomitant increment in hypoxia inducible factor (HIF1α) and anti-inflammatory proteins HO-1 and MT-1 compared to HH control thus accentuating the potential of EDHB as effective hypoxic preconditioning agent in ameliorating HH mediated injury in brain.

Ameliorative Effect of Chronic Supplementation of Protocatechuic Acid Alone and in Combination with Ascorbic Acid in Aniline Hydrochloride Induced Spleen Toxicity in Rats

Background. Present study was designed to evaluate the protective effects of protocatechuic acid alone and in combination with ascorbic acid in aniline hydrochloride induced spleen toxicity in rats. Materials and Methods. Male Wistar rats of either sex (200-250 g) were used and divided into different groups. Spleen toxicity was induced by aniline hydrochloride (100 ppm) in drinking water for a period of 28 days. Treatment group received protocatechuic acid (40 mg/kg/day, p.o.), ascorbic acid (40 mg/kg/day, p.o.), and combination of protocatechuic acid (20 mg/kg/day, p.o.) and ascorbic acid (20 mg/kg/day, p.o.) followed by aniline hydrochloride. At the end of treatment period serum and tissue parameters were evaluated. Result. Rats supplemented with aniline hydrochloride showed a significant alteration in body weight, spleen weight, feed consumption, water intake, hematological parameters (haemoglobin content, red blood cells, white blood cells, and total iron content), tissue parameters (lipid peroxidation, reduced glutathione, and nitric oxide content), and membrane bound phosphatase (ATPase) compared to control group. Histopathology of aniline hydrochloride induced spleen showed significant damage compared to control rats. Treatment with protocatechuic acid along with ascorbic acid showed better protection as compared to protocatechuic acid or ascorbic acid alone in aniline hydrochloride induced spleen toxicity. Conclusion. Treatment with protocatechuic acid and ascorbic acid in combination showed significant protection in aniline hydrochloride induced splenic toxicity in rats.

Anticlastogenicity and Anticarcinogenicity of Purple Rice Extract in Rats

Oryza sativa L. var. indica cv. Kum Doi Saket is a pigmented rice variety grown in northern Thailand. Our previous study found that the methanol extract of purple rice seed had the highest level of antimutagenicity in a Salmonella mutation assay. The present study was designed to evaluate its in vivo anticlastogenic and anticarcinogenic potentials. The purple rice extract had no acute toxicity on rats. The oral administration of 1,000 mg/kg body weight (bw) of the extract for 28 days did not increase the number of micronucleated hepatocytes. Interestingly, it significantly reduced the amount of micronucleus formation in the liver of diethylnitrosamine (DEN)-treated rats. The inhibitory mechanism involved the induction of hepatic glutathione S-transferase (GST) activity. In addition, oral administration of 500 mg/kg bw extract for 10 weeks significantly decreased the number of hepatic GST placental form positive foci, but did not modulate the number of colonic aberrant crypt foci in DEN- and dimethylhydrazine-initiated rats. In conclusion, the methanol extract of purple rice seed showed no toxicity, clastogenicity, or carcinogenicity in laboratory rats. It did display chemopreventive activity against the early stages of rat hepatocarcinogenesis.

Comparison of free amino acids, antioxidants, soluble phenolic acids, cytotoxicity and immunomodulation of fermented mung bean and soybean

BACKGROUND

Mung bean and soybean have been individually reported previously to have antioxidant, cytotoxic and immunomodulatory effects, while fermentation is a well-known process to enhance the bioactive compounds that contribute to higher antioxidant, cytotoxic and immunomodulation effects. In this study, the free amino acids profile, soluble phenolic acids content, antioxidants, cytotoxic and immunomodulatory effects of fermented and non-fermented mung bean and soybean were compared.

RESULTS

Fermented mung bean was recorded to have the highest level of free amino acids, soluble phenolic acids (especially protocatechuic acid) and antioxidant activities among all the tested products. Both fermented mung bean and soybean possessed cytotoxicity activities against breast cancer MCF-7 cells by arresting the G0/G1 phase followed by apoptosis. Moreover, fermented mung bean and soybean also induced splenocyte proliferation and enhanced the levels of serum interleukin-2 and interferon-γ.

CONCLUSION

Augmented amounts of free amino acids and phenolic acids content after fermentation enhanced the antioxidants, cytotoxicity and immunomodulation effects of mung bean and soybean. More specifically, fermented mung bean showed the best effects among all the tested products. This study revealed the potential of fermented mung bean and soybean as functional foods for maintenance of good health.

3,4-Dihydroxyphenylacetic acid, a microbiota-derived metabolite of quercetin, attenuates acetaminophen (APAP)-induced liver injury through activation of Nrf-2

1. Acetaminophen (APAP) overdose leads to severe hepatotoxicity. 3,4-dihydroxyphenylacetic acid (DOPAC) is a scarcely studied microbiota-derived metabolite of quercetin. The aim of this study was to determine the protective effect of DOPAC against APAP-induced liver injury. 2. Mice were treated intragastrically with DOPAC (10, 20 or 50 mg/kg) for 3 days before APAP (300 mg/kg) injection. APAP alone caused increase in serum aminotransferase levels and changes in hepatic histopathology. APAP also promoted oxidative stress by increasing lipid peroxidation and decreasing anti-oxidant enzyme activities. These events led to hepatocellular necrosis and reduced liver function. DOPAC increased nuclear factor erythroid 2-related factor 2 (Nrf-2) translocation to the nucleus and enhanced the expression of phase II enzymes and anti-oxidant enzymes, and thereby reduced APAP hepatotoxicity and enhanced anti-oxidant ability. 3. Our data provide evidence that DOPAC protected the liver against APAP-induced injury, which is involved in Nrf-2 activation, implying that DOPAC can be considered as a potential natural hepatoprotective agent.

Modulatory effect of protocatechuic acid on cadmium induced nephrotoxicity and hepatoxicity in rats in vivo

Introduction

This study sought to investigate the effect of protocatechuic acid (PCA); a phenolic compound readily available in most plant foods on cadmium-induced nephrotoxicity and hepatoxicity in rats.

Case description

Thirty six adult male rats weighing about 150–160 g were acclimatized for 2 weeks and subsequently divided into six groups: Group 1 rats received normal saline (control group), group 2 rats were administered 5 mg Cd/kg body weight in form of solution orally (induced group), groups 3 and 4 received cadmium solution and different doses of PCA (10 and 20 mg/kg body weight) respectively, while groups 5 and 6 were the normal rats administered different doses of PCA (10 and 20 mg/kg) respectively in an experiment that lasted for twenty one days. The animals were sacrificed, the blood was collected and the serum was subsequently prepared. Furthermore, the liver was excised, homogenized and centrifuged to obtain the tissue homogenate used for the analyses. The serum was used for the determination of the total protein, urea, creatinine and uric acid levels while the liver homogenate was used for the estimation of alanine aminotransferase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP).

Discussion and evaluation

The result revealed that total protein level was reduced in cadmium induced toxicity rat group which was elevated upon treatment with PCA. Conversely, the elevated levels of urea, uric acid and creatinine in cadmium induced toxicity kidney rats were significantly (p < 0.05) reduced in PCA treated groups. Similarly, marked elevation in the ALT, AST and ALP activity were observed in cadmium induced toxicity rat group when compared with the control group. However, significant (p < 0.05) decrease in ALT, AST and ALP activity were noticed in groups administered different doses of PCA.

Conclusions

The results from this study suggest that PCA may protect against cadmium-induced toxicity in the kidney and liver.

Antioxidant activity of protocatechuates evaluated by DPPH, ORAC, and CAT methods

Hibiscus sabdariffa L. is a worldwide consumed plant, principally after infusion of its dried sepals and calyces, which are usually discarded. Nevertheless, they represent a potential source of natural bioactive compounds, e.g. polyphenols, which could add value to this under-exploited plant. Protocatechuic acid (PA) was chosen as a model of the phenolic acids that can be extracted from H. sabdariffa. In order to modify PA hydrophilic character, which limits its use in lipid-rich food products, PA was esterified to C1-C18 alcohols, and the impact of lipophilization on its antioxidant activity was evaluated in both, an homogeneous (DPPH and ORAC methods) and an heterogeneous (CAT method) system. Results herein obtained showed that, depending on the grafted alkyl chain length, lipophilization could positively affect the antioxidant activity of PA in heterogeneous media; therefore, support its use as an innovative way to synthesize molecules with an improved antioxidant capacity and potential to be used as multifunctional preservatives in food.

Induction of Apoptosis in MCF-7 Cells via Oxidative Stress Generation, Mitochondria-Dependent and Caspase-Independent Pathway by Ethyl Acetate Extract of Dillenia suffruticosa and Its Chemical Profile

Dillenia suffruticosa, which is locally known as Simpoh air, has been traditionally used to treat cancerous growth. The ethyl acetate extract of D. suffruticosa (EADs) has been shown to induce apoptosis in MCF-7 breast cancer cells in our previous study. The present study aimed to elucidate the molecular mechanisms involved in EADs-induced apoptosis and to identify the major compounds in the extract. EADs was found to promote oxidative stress in MCF-7 cells that led to cell death because the pre-treatment with antioxidants α-tocopherol and ascorbic acid significantly reduced the cytotoxicity of the extract (P<0.05). DCFH-DA assay revealed that treatment with EADs attenuated the generation of intracellular ROS. Apoptosis induced by EADs was not inhibited by the use of caspase-inhibitor Z-VAD-FMK, suggesting that the cell death is caspase-independent. The use of JC-1 dye reflected that EADs caused disruption in the mitochondrial membrane potential. The related molecular pathways involved in EADs-induced apoptosis were determined by GeXP multiplex system and Western blot analysis. EADs is postulated to induce cell cycle arrest that is p53- and p21-dependent based on the upregulated expression of p53 and p21 (P<0.05). The expression of Bax was upregulated with downregulation of Bcl-2 following treatment with EADs. The elevated Bax/Bcl-2 ratio and the depolarization of mitochondrial membrane potential suggest that EADs-induced apoptosis is mitochondria-dependent. The expression of oxidative stress-related AKT, p-AKT, ERK, and p-ERK was downregulated with upregulation of JNK and p-JNK. The data indicate that induction of oxidative-stress related apoptosis by EADs was mediated by inhibition of AKT and ERK, and activation of JNK. The isolation of compounds in EADs was carried out using column chromatography and elucidated using the nuclear resonance magnetic analysis producing a total of six compounds including 3-epimaslinic acid, kaempferol, kaempferide, protocatechuic acid, gallic acid and β-sitosterol-3-O-β-D-glucopyranoside. The cytotoxicity of the isolated compounds was determined using MTT assay. Gallic acid was found to be most cytotoxic against MCF-7 cell line compared to others, with IC50 of 36 ± 1.7 μg/mL (P<0.05). In summary, EADs generated oxidative stress, induced cell cycle arrest and apoptosis in MCF-7 cells by regulating numerous genes and proteins that are involved in the apoptotic signal transduction pathway. Therefore, EADs has the potential to be developed as an anti-cancer agent against breast cancer.

Protocatechuic acid inhibits oleic acid-induced vascular smooth muscle cell proliferation through activation of AMP-activated protein kinase and cell cycle arrest in G0/G1 phase

Protocatechuic acid (PCA) has been implicated in the progression of atherosclerosis. The proliferation of vascular smooth muscle cells (VSMC) may play a crucial role in the pathogenesis of atherosclerosis. Adenosine 5′-monophosphate-activated protein kinase (AMPK) additionally exerts several beneficial effects on vascular function and improves vascular abnormalities. The current study sought to determine whether PCA has an inhibitory effect on VSMC proliferation under oleic acid (OA) treatment. A7r5 cells were treated with OA (150 μM) or cotreated with OA and PCA (150 μg/mL) for 24 and 48 h. PCA-treated cells were found to cause an increase in G0/G1 cell cycle arrest. Western blotting showed that PCA increased the expressions of p53 and p21Cip1, subsequently decreasing the expression of cyclin E1 and Cdk2. In addition, PCA induced phosphorylation of AMPK and inhibited the expression of fatty acid synthase, Akt-p, and Skp2 after stimulation with OA. After treatment with AMPK inhibitor, the effects of PCA mentioned above were reversed. Taken together, PCA inhibited OA-induced VSMC proliferation through AMPK activation and down-regulation of FAS and AKT signals, which then blocks G0/G1 phase cell cycle progression. These findings provide a new insight into the protective properties of PCA on VSMC, which may constitute a novel effective antiatherosclerosis agent.

Phenolic acid composition, antiatherogenic and anticancer potential of honeys derived from various regions in Greece

The phenolic acid profile of honey depends greatly on its botanical and geographical origin. In this study, we carried out a quantitative analysis of phenolic acids in the ethyl acetate extract of 12 honeys collected from various regions in Greece. Our findings indicate that protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid and p-coumaric acid are the major phenolic acids of the honeys examined. Conifer tree honey (from pine and fir) contained significantly higher concentrations of protocatechuic and caffeic acid (mean: 6640 and 397 µg/kg honey respectively) than thyme and citrus honey (mean of protocatechuic and caffeic acid: 437.6 and 116 µg/kg honey respectively). p-Hydroxybenzoic acid was the dominant compound in thyme honeys (mean: 1252.5 µg/kg honey). We further examined the antioxidant potential (ORAC assay) of the extracts, their ability to influence viability of prostate cancer (PC-3) and breast cancer (MCF-7) cells as well as their lowering effect on TNF- α-induced adhesion molecule expression in endothelial cells (HAEC). ORAC values of Greek honeys ranged from 415 to 2129 µmol Trolox equivalent/kg honey and correlated significantly with their content in protocatechuic acid (p<0.001), p-hydroxybenzoic acid (p<0.01), vanillic acid (p<0.05), caffeic acid (p<0.01), p-coumaric acid (p<0.001) and their total phenolic content (p<0.001). Honey extracts reduced significantly the viability of PC-3 and MCF-7 cells as well as the expression of adhesion molecules in HAEC. Importantly, vanillic acid content correlated significantly with anticancer activity in PC-3 and MCF-7 cells (p<0.01, p<0.05 respectively). Protocatechuic acid, vanillic acid and total phenolic content correlated significantly with the inhibition of VCAM-1 expression (p<0.05, p<0.05 and p<0.01 respectively). In conclusion, Greek honeys are rich in phenolic acids, in particular protocatechuic and p-hydroxybenzoic acid and exhibit significant antioxidant, anticancer and antiatherogenic activities which may be attributed, at least in part, to their phenolic acid content.

A review on protocatechuic Acid and its pharmacological potential

Flavonoids and polyphenols are heterocyclic molecules that have been associated with beneficial effects on human health, such as reducing the risk of various diseases like cancer, diabetes, and cardiovascular and brain diseases. Protocatechuic acid (PCA) is a type of widely distributed naturally occurring phenolic acid. PCA has structural similarity with gallic acid, caffeic acid, vanillic acid, and syringic acid which are well-known antioxidant compounds. More than 500 plants contain PCA as active constituents imparting various pharmacological activity and these effects are due to their antioxidant activities, along with other possible mechanisms, such as anti-inflammatory properties and interaction with several enzymes. Over the past two decades, there have been an increasing number of publications on polyphenols and flavonoids, which demonstrate the importance of understanding the chemistry behind the antioxidant activities of both natural and synthesized compounds, considering the benefits from their dietary ingestion as well as pharmacological use. This work aims to review the pharmacological effects of PCA molecules in humans and the structural aspects that contribute to these effects.

Antioxidant and phenolic acid profiles of tissue cultured and acclimatized Merwilla plumbea plantlets in relation to the applied cytokinins

Merwilla plumbea (Lindl.) Speta is an important medicinal plant widely used in traditional medicine. We evaluated the effect of five cytokinins [benzyladenine (BA), 2-isopentenyladenine (2iP), meta-topolin (mT), meta-topolin riboside (mTR), and meta-methoxy-9-tetrahydropyran-2-yl-topolin (MemTTHP)] on the level of phenolic acids and antioxidant activity of M. plumbea during the tissue culture and acclimatization stages. Two cytokinins (mT and mTR) significantly improved the antioxidant activity of tissue culture plantlets while the control plantlets were better after acclimatization. Using UPLC-MS/MS, the levels of hydroxybenzoic and hydroxycinnamic acid derivatives (phenolic acids) varied significantly during tissue culture and acclimatization, depending on the cytokinin and plant part analyzed. Vanillic acid (24.9 μg g⁻¹) detected in underground parts of tissue culture plants supplemented with BA was the most abundant phenolic acid detected. The current findings indicate that the phytochemicals together with the bioactivity during in vitro propagation of M. plumbea is influenced by the cytokinin type used and the stage of plant material collection.

Protective effects of protocatechuic acid on TCDD-induced oxidative and histopathological damage in the heart tissue of rats

2,3,7,8-Tetracholorodibenzo- p-dioxin (TCDD) is a highly toxic environmental contaminant that causes severe toxic effects in animal and human. In this study, we investigated the toxic effects of TCDD and the preventive effects of protocatechuic acid (PCA), a widespread phenolic compound, in the heart tissue of rats. For this purpose, 3–4 months old 28 rats with 280–310 g body weights were equally divided into 4 groups (control, TCDD, PCA, TCDD + PCA group). A 2 μg/kg dose of 2,3,7,8-TCDD and 100 mg/kg dose of PCA were dissolved in corn oil and given orally to the rats for 45 days. The results indicated that TCDD induced oxidative stress by increasing the level of thiobarbituric acid reactive substance and by decreasing the levels of glutathione, catalase, glutathione peroxidase and superoxide dismutase in the heart tissue of rats. In contrast, PCA treatment prevents the toxic effects of TCDD on oxidative stress. In addition, histopathological alterations such as necrosis and hemorrhage occurred in TCDD group, and PCA treatment partially prevents these alterations in heart tissue. In this study, it was concluded that TCDD exposure led to toxic effects in heart tissue and PCA treatment could prevent the toxicity of TCDD.

Protocatechuic acid prevents reproductive damage caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in male rats

In this study, it was aimed to determinate beneficial effects of protocatechuic acid (PCA) against reproductive toxicity caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an environmental contaminant. For this purpose, 28 rats were equally divided into four groups (control, TCDD 2 μg kg(-1) per week, PCA 100 mg kg(-1) per day and TCDD + PCA group), and compounds were orally administered for 45 days. The results indicated that TCDD induced oxidative stress via an increase in thiobarbituric acid-reactive substances levels and a decrease in reduced glutathione, catalase, glutathione peroxidise and SOD levels in male rats. In contrast, PCA treatment prevented toxic effects of TCDD in terms of oxidative stress. Additionally, sperm motility, sperm concentration and serum testosterone levels significantly decreased, and pathologic testicular damage increased with TCDD exposure. However, these effects of TCDD on sperm characteristics, histopathological changes and hormone levels were reversed by PCA treatment. In conclusion, it was found that TCDD exposure induced reproductive toxicity (oxidative, hormonal, histopathological and spermatological alternations) in male rats and PCA treatment could prevent toxic effects of TCDD. Thus, PCA may be useful for the prevention and treatment of reproductive toxicity caused by TCDD.