Pharmacological properties of protocatechuic Acid and its potential roles as complementary medicine

Polyphenol characterisation of Phoenix dactylifera L. (date) seeds using HPLC-mass spectrometry and its bioaccessibility using simulated in-vitro digestion/Caco-2 culture model

The polyphenolic content in date seeds, a promising functional ingredient for food, was characterised in three forms viz., date seed powder (DSP), date seed pita bread (DSB) and date seed extract (DSE). Bioaccessibility of the polyphenols from the samples was assessed by in-vitro digestion coupled with transport using Caco-2 cells. HPLC-ESI-UV/MS/MS-(IT) analysis recorded the presence of phenolic acids, flavanols, flavonols and flavones. Flavan-3-ols was the most significant group with the highest concentration in DSP, 47.91 ± 0.13 g/kg, after depolymerisation. Phenolic acids such as protocatechuic acid, vanillic acid and caffeoylshikimic acid were recovered from DSP and DSE after in-vitro digestion. In comparison, the recovery was significantly lower in the bread sample. Similarly, transport of protocatechuic acid, p-hydroxybenzoic acid, caffeoylshikimic acid, p-coumaric acid, syringic acid hexoside and diosmin through Caco-2 monolayer was observed in DSP and DSE, while protocatechuic acid and p-hydroxybenzoic acid were the only polyphenols transported from digested DSB.

The pharmacokinetics of flavanones

The intake of flavanones, the predominant flavonoid in the Citrus genus in human diets is variable but considerable. It is thus unsurprising that they have attracted interest for their claimed positive effects on health. However, to substantiate any purported impact on health and decipher the underlying mechanism(s), knowledge of pharmacokinetics is crucial. The aim of this article is to review currently known aspects of the fate of flavanones in the organism including absorption, metabolism, distribution, and excretion as well as possible kinetic interactions with clinically used drugs. There are three principal keynotes: (1) The level of parent flavanones in plasma is negligible. The major reason for this is that although flavanones are absorbed into enterocytes after oral intake, they are rapidly metabolized, in particular, into conjugates, sulfates and glucuronides, which are the major forms circulating in plasma. (2) A large fraction reaches the colon where it is efficiently metabolized into small absorbable phenolics. (3) The form (aglycone vs. glycoside) and species (e.g. human vs. rat) have important impact. In conclusion, knowledge of the pharmacokinetics of flavanones, in particular of metabolites, their achievable plasma concentration and half-lives, should be borne in mind when their biological effects are investigated.

Fatty Acids Predominantly Affect Anti-Hydroxyl Radical Activity and FRAP Value: The Case Study of Two Edible Mushrooms

Compared to plants, nowadays mushrooms attract more attention as functional foods, due to a number of advantages in manipulating them. This study aimed to screen the chemical composition (fatty acids and phenolics) and antioxidant potential (OH•, 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and ferric reducing ability of plasma (FRAP)) of two edible mushrooms, Coprinus comatus and Coprinellus truncorum, collected from nature and submerged cultivation. Partial least square regression analysis has pointed out the importance of some fatty acids—more precisely, unsaturated fatty acids (UFAs) followed by fatty acids possessing both short (C6:0 and C8:0) and long (C23:0 and C24:0) saturated chains—and phenolic compounds (such as protocatechuic acid, daidzein, p-hydroxybenzoic acid, genistein and vanillic acid) for promising anti-OH•, FRAP and anti-DPPH• activities, respectively. However, other fatty acids (C16:0, C18:0 and C18:3n3) along with the flavonol isorhamnetin are actually suspected to negatively affect (by acting pro-oxidative) the aforementioned parameters, respectively. Taken together, design of new food supplements targeting oxidative stress might be predominantly based on the various UFAs combinations (C18:2n6, C20:1, C20:2, C20:4n6, C22:2, C22:1n9, etc.), particularly if OH• is suspected to play an important role.

Comparative analysis of phenolic compounds in four taxa of Erigeron acris s. l. (Asteraceae)

The aim of the present work was to investigate and compare the content of phenolic compounds in four taxa of Erigeron acris L. s. l.: E. acris (EAA), E. acris subsp. droebachiensis (O.F. Müll.) Arcang. (EAD), E. acris subsp. serotinus (Weihe) Greuter (EAS) and E. ×huelsenii Vatke (EH), a hybrid between E. acris and E. canadensis L. The total flavonoid content was determined by Christ-Müller method and the total phenolic acid content was determined by the method utilizing Arnov’s reagent. The method using ultra high performance liquid chromatography with photodiode array detection (UHPLC-PDA) was applied for the separation, identification and quantification of nine phenolic compounds (protocatechuic acid, chlorogenic acid, caffeic acid, 6′-O-caffeoylerigeroside, scutellarein-7-O-β-D-glucuronide, quercetin 3-O-glucoside, 4,5-dicaffeoylquinic acid, quercetin and luteolin) in the aerial parts of E. acris s. l. The chromatographic separation was carried out using a BEH C18 column packed with 1.7-μm particles and gradient elution with a mobile phase of water and methanol, both containing 0.02% (v/v) trifluoroacetic acid. The four investigated taxa of E. acris s. l. differed in the composition and the content of phenolic compounds. The main substances determined in the methanolic herbal extracts were: scutellarein-7-O-β-D-glucuronide (EAA, EAS, EAD and EH), 6′-O-caffeoylerigeroside (EAA, EAD and EH) and chlorogenic acid (EAS and EH). Moreover, the results indicated that five of the nine tested compounds were found in all investigated extracts from herbs of E. acris s. l. Two of them (6′-O-caffeoylerigeroside and scutellarein-7-O-β-D-glucuronide) could be selected as potential chemotaxonomic markers of the genus Erigeron L.

Relationship of the Phytochemicals from Coffee and Cocoa By-Products with their Potential to Modulate Biomarkers of Metabolic Syndrome In Vitro

This study aimed to compare the phytochemicals from coffee and cocoa by-products and their relationship with the potential for reducing markers of inflammation, oxidative stress, adipogenesis, and insulin resistance in vitro. We characterized the phytochemical profile of extracts from coffee husk, coffee silverskin, and cocoa shell and evaluated their in vitro biological activity in RAW264.7 macrophages and 3T3-L1 adipocytes. Pearson correlations and principal component regressions were performed to find the contribution of phytochemicals and underlying mechanisms of action. Coffee husk and silverskin extracts were mainly composed of caffeine and chlorogenic acid. Major components in cocoa shell included theobromine and protocatechuic acid. Both coffee and cocoa by-product extracts effectively reduced inflammatory markers in macrophages and adipocytes (NO, PGE2, TNF-α, MCP-1, and IL-6) and the production of reactive oxygen species (21.5-66.4%). Protocatechuic and chlorogenic acids, together with caffeine, were suggested as main contributors against inflammation and oxidative stress. Furthermore, extracts reduced lipid accumulation (4.1-49.1%) in adipocytes by regulating lipolysis and inducing adipocyte browning. Gallic and chlorogenic acids were associated with reduced adipogenesis, and caffeine with adipocyte browning. Extracts from coffee and cocoa by-products also modulated the phosphorylation of insulin receptor signaling pathway and stimulated GLUT-4 translocation (52.4-72.9%), increasing glucose uptake. The insulin-sensitizing potential of the extracts was mainly associated with protocatechuic acid. For the first time, we identified the phytochemicals from coffee and cocoa by-products and offered new insights into their associations with biomarkers of inflammation, oxidative stress, adipogenesis, and insulin resistance in vitro.

Cannabinoid system involves in the analgesic effect of protocatechuic acid

BACKGROUND

Protocatechuic acid is an antioxidant which is shown to have analgesic activity in limited studies. However, the mechanisms of action remain unclear.

OBJECTIVES

It is aimed to investigate the possible contribution of cannabinoid system that supresses the nociceptive process by the activation of CB1 and CB2 receptors in central and peripheral levels of pain pathways, to the analgesic activity of protocatechuic acid.

METHODS

The analgesic activity of protocatechuic acid was determined at the doses of 75, 150 and 300 mg/kg (i.p.) by acetic acid-induced writhing and tail-immersion tests in mice. The results were compared to the analgesic effect of 300 mg/kg (i.p.) dipyrone and non-specific CB receptor agonist 5 mg/kg (i.p.) WIN 55,212-2. For investigating the contribution of cannabinoid system to protocatechuic acid analgesia; pre-treatment with 8 mg/kg (i.p.) CB1 antagonist AM251 and 8 mg/kg (i.p.) CB2 antagonist AM630 were performed separately before 300 mg/kg protocatechuic acid administration.

RESULTS

It was determined that protocatechuic acid has dose-dependent analgesic effect independently from locomotor activity and is comparable with effects of dipyrone and WIN 55,212-2. Pre-treatment with CB1 receptor antagonist AM251 significantly antagonized the protocatechuic acid-induced analgesia in the tail-immersion and writhing tests, whereas pre-treatment of CB2 receptor antagonist AM630 was found to be effective only in the tail-immersion test.

CONCLUSION

It is concluded that cannabinoid modulation contributes to the analgesic effect of protocatechuic acid in spinal level rather than peripheral. CB1 receptor stimulation rather than CB2 receptor stimulation mediates the analgesic effect of protocatechuic acid in both levels, especially peripheral. Graphical abstract Protocatechuic acid inhibits pain response via cannabinoidergic system.

Protective mechanisms of protocatechuic acid against doxorubicin-induced nephrotoxicity in rat model

Background Doxorubicin (DOX) induces toxicity in many tissues/organs, including the heart, kidney and so on. This study was designed to evaluate the modulatory effects of protocatechuic acid (PCA) against DOX-induced nephrotoxicity in rats. Animals were randomly grouped into five groups. Methods Group 1 served as the normal control (CTR). A single dose of DOX at 20 mg/kg was administered intraperitoneally (i.p.) to animals in Group 2. Groups 3 and 4 were pretreated with PCA for 5 days (doses of 10 and 20 mg/kg body weight, respectively) after which DOX was injected (PCA-10 + DOX and PCA-20 + DOX). Group 5 received PCA only at a dose of 20 mg/kg body weight (PCA-20). Results The results revealed significant elevations (p < 0.05) in malondialdehyde content, expressions of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX2) in the kidney. Likewise, increased serum levels of creatinine and urea of DOX group were observed. A significant decrease (p < 0.05) in glutathione (GSH) level and antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione s- transferase (GST) activities in the kidney were observed compared with the control. Pretreatment with PCA (10 and 20 mg/kg, p.o.) for 5 days prior to the i.p. injection of DOX reduced MDA levels, modulated iNOS and COX2 activities and improved kidney function markers as well as oxidative stress parameters. Findings from the histopathology studies confirms the protective effects of PCA on DOX-induced damage on the kidney cells. Conclusions This study has demonstrated the anti-inflammatory and antioxidative properties of PCA, which could be part of its possible protective mechanisms against nephrotoxicity induced by DOX.

Effect of protocatechuic acid-layered double hydroxide nanoparticles on diethylnitrosamine/phenobarbital-induced hepatocellular carcinoma in mice

Researchers investigating cancer chemotherapy and management continue to search for agents that selectively kill malignant cells and leave healthy neighboring cells intact. Natural products provide relevant resources for anti-cancer drug discovery. However, the physicochemical properties of these compounds limit their efficient uptake and bioavailability. We introduced a nanocarrier system, namely, zinc-aluminum-layered double hydroxide (ZnAl-LDH) intercalated with protocatechuic acid. In this study, the efficacy and toxicity of protocatechuic acid intercalated in zinc aluminum-layered double hydroxide nanoparticles (PCA-ZnAl) against diethylnitrosamine/phenobarbital (DEN/PB)-induced hepatocellular carcinoma (HCC) in BALB/c mice was evaluated. HCC in male mice was induced by a single-dose intraperitoneal administration of DEN and was promoted by the introduction of PB via drinking water for 12 weeks. HCC induction was confirmed after the DEN/PB introduction period by measurement of the elevated level of serum α-feto protein (AFP). The results showed that the level of α-fetoprotein was significantly reduced in PCA-ZnAl (350±43.90 ng/mL), doxorubicin (DOX) (290±20.52 ng/mL) and ZnAl-LDH (390±19.65 ng/mL) treated animals compared to HCC mice treated with normal saline (580.4± 52.04 ng/mL). Superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels were significantly increased, whereas the level of lipid peroxidation was significantly decreased in HCC mice treated with DOX, PCA-ZnAl and ZnAl-LDH compared with those in HCC mice treated with saline. Restoration of hepatocyte morphology was observed following treatment that was comparable to that in the normal control group. Deterioration of hepatic cells and a significant increase of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) were observed in the cancer-induced untreated group compared with that in the groups treated with nanoparticles. The histopathological features of the liver obtained from PCA-ZnAl-treated mice showed a uniform size with a similar distribution of the nuclear-cytoplasmic ratio and nucleus centrally located in the cytoplasm, similar to the normal liver cells. The results underscored the potential of PCA-ZnAl for the treatment of hepatocellular carcinoma.

Twelve-Week Protocatechuic Acid Administration Improves Insulin-Induced and Insulin-Like Growth Factor-1-Induced Vasorelaxation and Antioxidant Activities in Aging Spontaneously Hypertensive Rats

Protocatechuic acid (PCA), a strong antioxidant, has been reported for its cardiovascular-protective effects. This study aimed to investigate the effects of PCA administration on vascular endothelial function, mediated by insulin and insulin-like growth factor-1 (IGF-1), and antioxidant activities in aging hypertension. Thirty-six-week-old male aging spontaneously hypertensive rats were randomly divided into vehicle control (SHR) and PCA (SHR+PCA) groups, while age-matched Wistar–Kyoto rats (WKY) served as the normotensive vehicle control group. The oral PCA (200 mg/kg/day) was administered daily for a total of 12 weeks. When the rats reached the age of 48 weeks, the rat aortas were isolated for the evaluation of vascular reactivity and Western blotting. Also, nitric oxide (NO) production and antioxidant activities were examined among the three groups. The results showed that, when compared with the SHR group, the insulin-induced and IGF-1-induced vasorelaxation were significantly improved in the SHR+PCA group. There was no significant difference in the endothelium-denuded vessels among the three groups. After the pre-incubation of phosphatidylinositol 3-kinase (PI3K) or NO synthase (NOS) inhibitors, the vasorelaxation was abolished and comparable among the three groups. The protein levels of insulin receptors, IGF-1 receptors, phospho-protein kinase B (p-Akt)/Akt, and phospho-endothelial NOS (p-eNOS)/eNOS in aortic tissues were significantly enhanced in the SHR+PCA group when compared with the SHR group. Moreover, significant improvements of nitrate/nitrite concentration and antioxidant activities, including superoxide dismutase, catalase, and total antioxidants, were also found in the SHR+PCA group. In conclusion, the 12 weeks of PCA administration remarkably improved the endothelium-dependent vasorelaxation induced by insulin and IGF-1 in aging hypertension through enhancing the PI3K–NOS–NO pathway. Furthermore, the enhanced antioxidant activities partly contributed to the improved vasorelaxation.

Cocrystal of 5-Fluorouracil: Characterization and Evaluation of Biopharmaceutical Parameters

To prepare the cocrystals of 5-fluorouracil (5-FU) with GRAS status coformers via a cocrystallization technique with an aim to improve physicochemical properties as well as bioavailability for colon cancer, breast cancer, and prostate cancer. The mechanochemical method was used in the preparations of three crystals of 5-FU with gentisic acid (5-FUGA), 3,4-dihydroxybenzoic acid (5-FUBA), and 4-aminopyridine (5-FUPN). A thermoanalytical and spectroscopic technique was used for their characterization. Their biological evaluation was done in different cancer cell lines. The new solid pure crystal forms were characterized by DSC, FTIR, and PXRD. The crystal structure was determined from single crystal and PXRD that exposed the existence of the monoclinic and triclinic crystal system with P21/n and P-1 space groups. The dermatokinetic studies on the rat skin revealed two- to threefold improvement in relative bioavailability as compared to pure 5-FU. "MTT assay was performed by varying the concentrations of the drug from 1 to 50 μg mL^-1. After 24 h, the cell viability dropped to 70.67%, 74.05%, and 76.37% in MCF-7, Hela, and Caco-2 cell lines when the concentration of 5-FU was 50 μg mL^-1", while it dropped dramatically in cocrystals 5-FUGA (22.06%, 24.63%, and 25.61%), 5-FUBA (31.22%, 29.46%, and 32.81%), and 5-FUPN (21.65%, 32.64%, and 21.46%). All the results indicated that 5-FU cocrystals possess better antitumor efficacy than free drug. Thus, cocrystallization expands the extent of the existing pre-formulation options ahead of pure API form to ameliorate the bioavailability and permeability.

The Contribution of Complementary and Alternative Medicine to Reduce Antibiotic Use: A Narrative Review of Health Concepts, Prevention, and Treatment Strategies

AIM

The aim of this narrative review was to explore the potential contributions of CAM to reduce antibiotic use.

METHODS

We searched PubMed, Embase, and Cochrane Database of Systematic Reviews with a specific, limited set of search terms and collected input from a group of expert CAM researchers to answer the question: What is known about the contribution of CAM health and health promotion concepts, infection prevention, and infection treatment strategies to reduce antibiotic use? Results. The worldview-related CAM health concepts enable health promotion oriented infection prevention and treatment aimed at strengthening or supporting the self-regulating ability of the human organism to cope with diseases. There is some evidence that the CAM concepts of health (promotion) are in agreement with current conceptualization of health and that doctors who practice both CAM and conventional medicine prescribe less antibiotics, although selection bias of the presented studies cannot be ruled out. There is some evidence that prevention and some treatment strategies are effective and safe. Many CAM treatment strategies are promising but overall lack high quality evidence.

CONCLUSIONS

CAM prevention and treatment strategies may contribute to reducing antibiotic use, but more rigorous research is necessary to provide high quality evidence of (cost-)effectiveness.

Phenolic Compounds of Catalpa speciosa, Taxus cuspidate, and Magnolia acuminata have Antioxidant and Anticancer Activity

Tree bark represents an important source of medicinal compounds that may be useful for cancer therapy. In the current study, high-performance liquid chromatography with diode-array detection (HPLC-DAD) was used to determine the profile of the phenolic compounds of Catalpa speciosa, Taxus cuspidata, and Magnolia acuminata bark extracts. The antioxidant and anticancer bioactivities against different cancer cell lines were investigated. M. acuminata exerted significantly higher antioxidant activities in the diphenyl picrylhydrazine and β-carotene-linoleic acid assays than the other species. In C. speciosa, novel profiles of phenolic acids (ferulic acid was the predominant compound) and catechin were detected. In T. cuspidata, six phenolic acids were detected; the predominant compounds were hydroxycaffeic acid and protocatechuic acid. In M. acuminata, two phenolic acids and three catechins were detected; catechin was the predominant compound. The three species exerted clear anticancer activity against MCF-7, HeLa, Jurkat, T24, and HT-29 cells, with the strongest activity found in the extracts from M. acuminata. No antiproliferative activity against normal cells was found. Flow cytometry revealed greater accumulation of necrotic and early/late apoptotic cells in various treated cancer cells than in untreated control cells, and protocatechuic acid induced a similar accumulation of necrotic cells to that of the bark extracts. Caspase-3 and -7 activity was increased in cancer cells treated with different bark extracts; the highest activity was found in the M. acuminata treatment. Our results suggested that the treatment of cancer cells with bark extracts of M. acuminata, C. speciosa, and T. cuspidata, and protocatechuic acid induced apoptosis, suggesting an association between anticancer activities and individual phenolic compounds.

Investigation of Chitosan Nanoparticles Loaded with Protocatechuic Acid (PCA) for the Resistance of Pyricularia oryzae Fungus against Rice Blast

In this study, chitosan nanoparticles were used as a carrier for Protocatechuic acid (PCA) to resist Pyricularia oryzae against rice blast. The final compound was characterized using zeta potentials for its surface electricity, Fourier transform infrared (FT-IR) analysis and transmission electron microscopy (TEM) were conducted for functional groups and for particle sizes and shape, respectively. The zeta potential results showed that loading PCA causes chitosan nanoparticle (CSNP) to decrease in surface electrons. The TEM images revealed that the particle size of chitosan (CS), although increasing in size when carrying PCA molecules, showed sufficient size for reasonable penetration into fungal cells. The FT-IR analysis showed that all functional group in CSNP carried PCA matched with previous studies. The antifungal test showed that diameters of inhibition zone of CS increases significantly after loading PCA, exhibiting the strongest antimicrobial effect on the Pyricularia oryzae fungus compared with weaker effects exhibited by CSNP alone or PCA. Our results suggested that CSNP loaded with PCA could be a potential compound for eradication of Pyricularia oryzae and that further testing on in vitro rice plants is recommended to reaffirm this possibility.

The Pharmacological Potential of Oil Palm Phenolics (OPP) Individual Components

The oil palm tree (Elaeis guineensis) from the family Arecaceae is a high oil-producing agricultural crop. A significant amount of vegetation liquor is discarded during the palm oil milling process amounting to 90 million tons per year around the world. This water-soluble extract is rich in phenolic compounds known as Oil Palm Phenolics (OPP). Several phenolic acids including the three isomers of caffeoylshikimic acid (CFA), p-hydroxybenzoic acid (PHBA), protocatechuic acid (PCA) and hydroxytyrosol are among the primary active ingredients in the OPP. Previous investigations have reported several positive pharmacological potentials by OPP such as neuroprotective and atheroprotective effects, anti-tumor and reduction in Aβ deposition in Alzheimer's disease model. In the current review, the pharmacological potential for CFA, PHBA, PCA and hydroxytyrosol is carefully reviewed and evaluated.

Phytochemical profiling, polyphenol composition, and antioxidant activity of the leaf extract from the medicinal halophyte Thespesia populnea reveal a potential source of bioactive compounds and nutraceuticals

The present study evaluated the phytochemical constituents, nutritional attributes, and the antioxidant capacity of the medicinal halophyte Thespesia populnea. The metabolite profiling by GC-QTOF-MS analysis identified 37 metabolites among which sucrose, malic acid, and turanose were the most abundant. A total of 18 polyphenols and 17 amino acids were identified by the HPLC-DAD analysis. The most abundant polyphenols in T. populnea were gallic acid, catechin, and myricetin. Other polyphenols like protocatechuic acid, epigallocatechin gallate, rosmarinic acid, ellagic acid, rutin, and naringenine were also detected in ample amounts. The leaf extract demonstrated higher antioxidant as well as lipid peroxidation inhibition activities. A correlation analysis revealed a positive correlation between the antioxidant capacity and the phenolic compounds viz. gallic acid, catechin, myricetin, quercetin, apigenin, cinnamic acid, and coumarin which indicates that these phenolic compounds are the main contributors of the antioxidant potential of T. populnea. The results of this study establish T. populnea as a potential source of nonconventional functional food. PRACTICAL APPLICATIONS: The data presented here indicate that T. populnea can be considered as a nonconventional functional food and potential source of energy, antioxidants, minerals, essential amino acids, and bioactive compounds in herbal formulations, food supplements, or nutraceuticals. The metabolites identified from this halophyte have pharmacological and nutraceutical potentials, suggesting T. populnea as an ideal candidate for application in the food and phytopharmaceutical industries to produce health-promoting products, functional foods, and herbal medicines.

Two flavonoid metabolites, 3,4-dihydroxyphenylacetic acid and 4-methylcatechol, relax arteries ex vivo and decrease blood pressure in vivo

SCOPE

The flavonoid quercetin reduces arterial blood pressure in animals and humans but the mechanisms remains elusive. The aim of this study was to test the activity of flavonoid microbial metabolites, which can participate on the final vasorelaxant effect.

METHODS AND RESULTS

Both ex vivo (isolated rat thoracic aorta and mesenteric artery) and in vivo (normotensive and spontaneously hypertensive rats) approaches were used in this study. 4-methylcatechol and 3,4-dihydroxyphenylacetic acid (DHPA) had greater vasorelaxant effects on mesenteric artery than 3-(3-hydroxyphenyl)propionic acid, the previously reported metabolite with vasorelaxant effect. In vivo testing confirmed their blood pressure decreasing effect given both as bolus and slow infusion. Their mechanism at molecular level was different.

CONCLUSIONS

This study is the first to show that flavonoid metabolites DHPA and 4-methylcatechol decrease arterial blood pressure and hence a mixture of microbial metabolites formed in the gastrointestinal tract may be responsible for or contribute to the effect of orally ingested quercetin.

Protocatechuic Acid Attenuates Trabecular Bone Loss in Ovariectomized Mice

Primary osteoporosis is a disease related to excessive bone resorption due to estrogen insufficiency that occurs postmenopause. Protocatechuic acid (PCA), or 3,4-dihydroxybenzoic acid, is a common compound present in numerous plants. Although numerous biological activities of PCA have been identified, its antiosteoporotic function has not been well established. In this study, the antiosteoporotic activity of PCA supplementation was determined in ovariectomized (OVX) female ICR mice at 12 weeks after OVX. The biomechanical properties of a bone were evaluated by microcomputed tomography. The signaling molecules associated with osteoclast differentiation were determined in bone marrow cells through immunoblot or RT-PCR. Oral supplementation with PCA (20 mg/kg/day) significantly ameliorated the OVX-mediated stimulation of osteoclast activity based on decreases in serum levels of receptor activator of nuclear factor κB ligand (RANKL), osteocalcin, and bone alkaline phosphatase and increase in serum osteoprotegerin (each group, n = 6; p < 0.05). In addition, the OVX-induced decreases in mRNA expression levels of cathepsin K, calcitonin receptor, nuclear factor of activated T cell cytoplasmic 1 (NFATc1), and tumor necrosis factor (TNF) receptor-associated factor-6 (TRAF6) in bone marrow cells were significantly attenuated (each group, n = 6; p < 0.05). Finally, the loss of trabecular bone and changes in biomechanical properties of a bone were significantly improved by supplementation with 20 mg/kg PCA (each group, n = 6; p < 0.05). Collectively, our results show that PCA supplement suppressed trabecular bone loss in OVX mice and therefore might be an effective alternative approach for preventing the progression of postmenopausal osteoporosis.

Salvia miltiorrhizaBurge (Danshen): a golden herbal medicine in cardiovascular therapeutics

Salvia miltiorrhiza Burge (Danshen) is an eminent medicinal herb that possesses broad cardiovascular and cerebrovascular protective actions and has been used in Asian countries for many centuries. Accumulating evidence suggests that Danshen and its components prevent vascular diseases, in particular, atherosclerosis and cardiac diseases, including myocardial infarction, myocardial ischemia/reperfusion injury, arrhythmia, cardiac hypertrophy and cardiac fibrosis. The published literature indicates that lipophilic constituents (tanshinone I, tanshinone IIa, tanshinone IIb, cryptotanshinone, dihydrotanshinone, etc) as well as hydrophilic constituents (danshensu, salvianolic acid A and B, protocatechuic aldehyde, etc) contribute to the cardiovascular protective actions of Danshen, suggesting a potential synergism among these constituents. Herein, we provide a systematic up-to-date review on the cardiovascular actions and therapeutic potential of major pharmacologically active constituents of Danshen. These bioactive compounds will serve as excellent drug candidates in small-molecule cardiovascular drug discovery. This article also provides a scientific rationale for understanding the traditional use of Danshen in cardiovascular therapeutics.

The possible mechanisms of protocatechuic acid-induced central analgesia

It is aimed to investigate the central antinociceptive effect of protocatechuic acid and the involvement of stimulation of opioidergic, serotonin 5-HT_2A/2C, α2-adrenergic and muscarinic receptors in protocatechuic acid-induced central analgesia in mice. Time-dependent antinociceptive effects of protocatechuic acid at the oral doses of 75, 150 and 300 mg/kg were tested in hot-plate (integrated supraspinal response) and tail-immersion (spinal reflex) tests in mice. To investigate the mechanisms of action; the mice administered 300 mg/kg protocatechuic acid (p.o.) were pre-treated with non-specific opioid antagonist naloxone (5 mg/kg, i.p.), serotonin 5-HT_2A/2C receptor antagonist ketanserin (1 mg/kg, i.p.), α2-adrenoceptor antagonist yohimbine (1 mg/kg, i.p.) and non-specific muscarinic antagonist atropine (5 mg/kg, i.p.), respectively. The antinociceptive effect of protocatechuic acid was observed at the doses of 75, 150 and 300 mg/kg in tail-immersion test, at the doses of 150 and 300 mg/kg in hot-plate test at different time interval. The enhancement in the latency of protocatechuic acid-induced response to thermal stimuli was antagonized by yohimbine, naloxone and atropine in tail-immersion test, while it was antagonized only by yohimbine and naloxone pretreatments in hot-plate test. These results indicated that protocatechuic acid has the central antinociceptive action that is probably organized by spinal mediated cholinergic and opiodiergic, also spinal and supraspinal mediated noradrenergic modulation. However, further studies are required to understand how protocatechuic acid organizes the interactions of these modulatory systems. As a whole, these findings reinforce that protocatechuic acid is a potential agent that might be used for pain relief. Additionally, the clarification of the effect and mechanisms of action of protocatechuic acid will contribute to new therapeutic approaches and provide guidance for new drug development studies.

A Review on Ethnopharmacological Applications, Pharmacological Activities, and Bioactive Compounds of Mangifera indica (Mango)

Mangifera indica (family Anacardiaceae), commonly known as mango, is a pharmacologically, ethnomedically, and phytochemically diverse plant. Various parts of M. indica tree have been used in traditional medicine for the treatment of different ailments, and a number of bioactive phytochemical constituents of M. indica have been reported, namely, polyphenols, terpenes, sterols, carotenoids, vitamins, and amino acids, and so forth. Several studies have proven the pharmacological potential of different parts of mango trees such as leaves, bark, fruit peel and flesh, roots, and flowers as anticancer, anti-inflammatory, antidiabetic, antioxidant, antibacterial, antifungal, anthelmintic, gastroprotective, hepatoprotective, immunomodulatory, antiplasmodial, and antihyperlipemic. In the present review, a comprehensive study on ethnopharmacological applications, pharmacological activities, and bioactive compounds of M. indica has been described.

Biotransformation of ferulic acid to protocatechuic acid by Corynebacterium glutamicum ATCC 21420 engineered to express vanillate O-demethylase

Ferulic acid (4-hydroxy-3-methoxycinnamic acid, FA) is a lignin-derived phenolic compound abundant in plant biomass. The utilization of FA and its conversion to valuable compounds is desired. Protocatechuic acid (3,4-dihydroxybenzoic acid, PCA) is a precursor of polymers and plastics and a constituent of food. A microbial conversion system to produce PCA from FA was developed in this study using a PCA-producing strain of Corynebacterium glutamicum F (ATCC 21420). C. glutamicum strain F grown at 30 °C for 48 h utilized 2 mM each of FA and vanillic acid (4-hydroxy-3-methoxybenzoic acid, VA) to produce PCA, which was secreted into the medium. FA may be catabolized by C. glutamicum through proposed (I) non-β-oxidative, CoA-dependent or (II) β-oxidative, CoA-dependent phenylpropanoid pathways. The conversion of VA to PCA is the last step in each pathway. Therefore, the vanillate O-demethylase gene (vanAB) from Corynebacterium efficiens NBRC 100395 was expressed in C. glutamicum F (designated strain FVan) cultured at 30 °C in AF medium containing FA. Strain C. glutamicum FVan converted 4.57 ± 0.07 mM of FA into 2.87 ± 0.01 mM PCA after 48 h with yields of 62.8% (mol/mol), and 6.91 mM (1064 mg/L) of PCA was produced from 16.0 mM of FA after 12 h of fed-batch biotransformation. Genomic analysis of C. glutamicum ATCC 21420 revealed that the PCA-utilization genes (pca cluster) were conserved in strain ATCC 21420 and that mutations were present in the PCA importer gene pcaK.

Biological Evaluation and Molecular Docking of Protocatechuic Acid from Hibiscus sabdariffa L. as a Potent Urease Inhibitor by an ESI-MS Based Method

Studies on enzyme inhibition remain a crucial area in drug discovery since these studies have led to the discoveries of new lead compounds useful in the treatment of several diseases. In this study, protocatechuic acid (PCA), an active compound from Hibiscus sabdariffa L. has been evaluated for its inhibitory properties against jack bean urease (JBU) as well as its possible toxic effect on human gastric epithelial cells (GES-1). Anti-urease activity was evaluated by an Electrospray Ionization-Mass Spectrometry (ESI-MS) based method, while cytotoxicity was assayed by the MTT method. PCA exerted notable anti-JBU activity compared with that of acetohydroxamic acid (AHA), with IC50 values of 1.7 and 3.2 µM, respectively. PCA did not show any significant cytotoxic effect on (GES-1) cells at concentrations ranging from 1.12 to 3.12 µM. Molecular docking study revealed high spontaneous binding ability of PCA to the active site of urease. Additionally, the anti-urease activity was found to be related to the presence of hydroxyl moieties of PCA. This study presents PCA as a natural urease inhibitor, which could be used safely in the treatment of diseases caused by urease-producing bacteria.

Pharmacological effects of protocatechuic acid and its therapeutic potential in neurodegenerative diseases: Review on the basis of in vitro and in vivo studies in rodents and humans

Protocatechuic acid has very promising properties potentially useful in the inhibition of neurodegenerative diseases progression. It is the main metabolite of the complex polyphenolic compounds and is believed to be responsible for beneficial effects associated with consumption of the food products rich in polyphenols. Protocatechuic acid is present in the circulation significantly longer and at higher concentrations than parent compounds and easily crosses the blood brain barrier. The aim of the following paper is to provide an extensive and actual report on protocatechuic acid and its pharmacological potential in prevention and/or treatment of neurodegenerative diseases in humans based on existing data from both in vitro and in vivo studies. Experimental studies strongly support the role of protocatechuic acid in the prevention of neurodegenerative processes, including Alzheimer's and Parkinson's diseases, due to its favorable influence on processes underlying cognitive and behavioral impairment, namely accumulation of the β-amyloid plaques in brain tissues, hyperphosphorylation of tau protein in neurons, excessive formation of reactive oxygen species and neuroinflammation. There is a growing evidence that protocatechuic acid may become in the future efficacious and safe substance that protects against neurodegenerative disorders.

Effects of anthocyanins on the prevention and treatment of cancer

Anthocyanins are a class of water-soluble flavonoids, which show a range of pharmacological effects, such as prevention of cardiovascular disease, obesity control and antitumour activity. Their potential antitumour effects are reported to be based on a wide variety of biological activities including antioxidant; anti-inflammation; anti-mutagenesis; induction of differentiation; inhibiting proliferation by modulating signal transduction pathways, inducing cell cycle arrest and stimulating apoptosis or autophagy of cancer cells; anti-invasion; anti-metastasis; reversing drug resistance of cancer cells and increasing their sensitivity to chemotherapy. In this review, the latest progress on the anticancer activities of anthocyanins and the underlying molecular mechanisms is summarized using data from basic research in vitro and in vivo, from clinical trials and taking into account theory and practice.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Alpinia oxyphylla Miq. fruit extract activates IGFR-PI3K/Akt signaling to induce Schwann cell proliferation and sciatic nerve regeneration

BACKGROUND

It is known that the medicinal herb Alpinia oxyphylla Miq. is widely used as a remedy for diarrhea as well as the symptoms accompanying hypertension and cerebrovascular disorders. Moreover, it has also been reported that Alpinia oxyphylla Miq. has beneficial effects on anti-senescence and neuro-protection. This study focuses on the molecular mechanisms by which the Alpinia oxyphylla Miq. fruits promote neuron regeneration.

METHODS

A piece of silicone rubber was guided across a 15 mm gap in the sciatic nerve of a rat. This nerve gap was then filled with various doses of Alpinia oxyphylla Miq. fruits to assess their regenerative effect on damaged nerves. Further, we investigated the role of Alpinia oxyphylla Miq. fruits in RSC96 Schwann cell proliferation.

RESULTS

Our current results showed that treatment with the extract of Alpinia oxyphylla Miq. fruits triggers the phosphorylated insulin-like growth factor-1 receptor- phosphatidylinositol 3-kinase/serine-threonine kinase pathway, and up-regulated the proliferating cell nuclear antigen in a dose-dependent manner. Cell cycle analysis on RSC96 Schwann cells showed that, after exposure to Alpinia oxyphylla Miq. fruit extract, the transition from the first gap phase to the synthesis phase occurs in 12-18 h. The expression of the cell cycle regulatory proteins cyclin D1, cyclin E and cyclin A increased in a dose-dependent manner. Transfection with a small interfering RNA blocked the expression of phosphatidylinositol 3-kinase and induced down-regulation both on the mRNA and protein levels, which resulted in a reduction of the expression of the survival factor B-cell lymphoma 2.

CONCLUSION

We provide positive results that demonstrate that Alpinia oxyphylla Miq. fruits facilitate the survival and proliferation of RSC96 cells via insulin-like growth factor-1 signaling.

Flavonoid metabolite 3-(3-hydroxyphenyl)propionic acid formed by human microflora decreases arterial blood pressure in rats

There are reports of positive effects of quercetin on cardiovascular pathologies, however, mainly due to its low biovailability, the mechanism remains elusive. Here, we report that one metabolite formed by human microflora (3-(3-hydroxyphenyl)propionic acid)relaxed isolated rat aorta and decreased arterial blood pressure in rats.

Allium hookeri root protects oxidative stress-induced inflammatory responses and β-cell damage in pancreas of streptozotocin-induced diabetic rats

Background

Water extract from the root of Allium hookeri (AH) shows anti-inflammatory, antioxidant, and free radical scavenging effects. In this study, the ameliorating effects of AH on oxidative stress-induced inflammatory response and β-cell damage in the pancreas of streptozotocin (STZ)-induced type 1 diabetic rats were investigated.

Methods

AH (100 mg/kg body weight/day) was orally administered every day for 2 weeks to STZ-induced diabetic rats. After the final administration of AH, biochemical parameters including glucose, insulin, reactive oxygen species levels, and protein expressions related to antioxidant defense system in the pancreas of STZ-induced diabetic rats.

Results

The diabetic rats showed loss of body weight and increased pancreatic weight, while the oral administration of AH attenuated body and pancreatic weight changes. Moreover, the administration of AH caused a slightly decrease in the serum glucose level and a significant increase in the serum and pancreatic insulin levels in the diabetic rats. AH also significantly reduced the enhanced levels of reactive oxygen species, oxidative stress biomarker, in the serum and pancreas. The diabetic rats exhibited a down-regulation of the protein expression related to antioxidant defense system in the pancreas, but AH administration significantly up-regulated the expression of the heme oxygenase-1 (HO-1). Furthermore, AH treatment was reduced the overexpression of nuclear factor-kappa B (NF-кB)p65 and NF-кBp65-induced inflammatory cytokines such as tumor necrosis factor-α and interleukin-6. In addition, AH treatment was less pancreatic β-cell damaged compared with those of the diabetic rats.

Conclusion

These results provide important evidence that AH has a HO-1 activity on the oxidative stress conditions showing pancreato-protective effects against the development of inflammation in the diabetic rats. This study provides scientific evidence that AH protects the inflammatory responses by modulated NF-кBp65 signaling pathway through activation of HO-1 in the pancreas of STZ-induced diabetic rats.

Bioactive Phenylpropanoids, Phenolic Acid and Phytosterol from Landolphia owariensis P. Beauv Stringy Seed Pulp

Landolphia owariensis P. Beauv is economically important for latex/rubber and folklore medicine. Its stringy seed pulp is freely eaten by humans and animals. Thus, L. owariensis stringy seed pulp was extracted serially with hexane and acetone to isolate and characterize its active pharmaceutical ingredients. Solvent/solvent partition and chromatographic separations afforded four bioactive compounds, (E)-3-(3,4-Dihydroxylcinnamoyl)quinic acid [(E)-Chlorogenic acid], I; (E)-3-(3,4-Dihydroxylcinnamoyl)quinic acid methyl ester [(E)-Chlorogenic acid methyl ester], II; 3,4-Dihydroxylbenzoic acid, (Protocatechuic acid), III; and 22,23-Dihydrostigmaster-3β-ol (3β-Sitosterol) (IV). Structures of I, II and III were assigned by combinations of high-performance liquid chromatography-ultraviolet-visible spectroscopy, 1D and 2D nuclear magnetic resonance spectroscopy, high-performance liquid chromatography-mass spectrometry and reference to published literatures, while compound IV was identified by chemical methods and gas chromatography-mass spectrometry. The phenylpropanoids and phenolic acid (compounds I, II and III) are notable standard antioxidants with confirmed hepatic-protective activity and other exciting biological activities. Compound IV has been reported to possess anti-inflammatory activity, anti-colon cancer action and a cholesterol-lowering effect. The described compounds are important medicinal constituents of L. owariensis stringy seed pulp, and this is the first major report on the phytochemistry of L. owariensis P. Beauv.

Pharmacokinetic Profile of Eight Phenolic Compounds and Their Conjugated Metabolites after Oral Administration of Rhus verniciflua Extracts in Rats

Rhus verniciflua (Toxicodendron vernicifluum) is a medicinal tree popularly used in Asian countries such as China, Japan, and Korea as a food additive or herbal medicine because of its beneficial effects. R. verniciflua extract (RVE) contains diverse phenolic compounds, such as flavonoids, as its major biological active constituents. In this study, the pharmacokinetic profiles of eight phenolic compounds were investigated following oral administration of RVE to rats. The eight phenolic compounds were 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, fisetin, fustin, butin, sulfuretin, taxifolin, and garbanzol. The plasma concentrations of the eight compounds were determined by using a liquid chromatography-triple-quadrupole mass spectrometer before and after treatment with β-glucuronidase. When 1.5 g/kg RVE was administered, the eight compounds were all detected in plasma, mainly as conjugated forms. These pharmacokinetic data would be useful for understanding the pharmacological effects of RVE.