Preclinical Pharmacokinetics and Acute Toxicity in Rats of 5-{[(2E)-3-Bromo-3-carboxyprop-2-enoyl]amino}-2-hydroxybenzoic Acid: A Novel 5-Aminosalicylic Acid Derivative with Potent Anti-Inflammatory Activity.

Compound 5-{[(2E)-3-bromo-3-carboxyprop-2-enoyl]amino}-2-hydroxybenzoic acid (C1), a new 5-aminosalicylic acid (5-ASA) derivative, has proven to be an antioxidant in vitro and an anti-inflammatory agent in mice. The in vivo inhibition of myeloperoxidase was comparable to that of indomethacin. The aim of this study was to take another step in the preclinical evaluation of C1 by examining acute toxicity with the up-and-down OECD method and pharmacokinetic profiles by administration of the compound to Wistar rats through intravenous (i.v.), oral (p.o.), and intraperitoneal (i.p.) routes. According to the Globally Harmonized System, C1 belongs to categories 4 and 5 for the i.p. and p.o. routes, respectively. An RP-HPLC method for C1 quantification in plasma was successfully validated. Regarding the pharmacokinetic profile, the elimination half-life was approximately 0.9 h with a clearance of 24 mL/min after i.v. administration of C1 (50 mg/kg). After p.o. administration (50 mg/kg), the maximum plasma concentration was reached at 33 min, the oral bioavailability was about 77%, and the compound was amply distributed to all tissues evaluated. Therefore, C1 administered p.o. in rats is suitable for reaching the colon where it can exert its effect, suggesting an important advantage over 5-ASA and indomethacin in treating ulcerative colitis and Crohn's disease.

Plant constituents and thyroid: A revision of the main phytochemicals that interfere with thyroid function.

In the past few decades, there has been a lot of interest in plant constituents for their antioxidant, anti-inflammatory, anti-microbial and anti-proliferative properties. However, concerns have been raised on their potential toxic effects particularly when consumed at high dose. The anti-thyroid effects of some plant constituents have been known for some time. Indeed, epidemiological observations have shown the causal association between staple food based on brassicaceae or soybeans and the development of goiter and/or hypothyroidism. Herein, we review the main plant constituents that interfere with normal thyroid function such as cyanogenic glucosides, polyphenols, phenolic acids, and alkaloids. In detail, we summarize the in vitro and in vivo studies present in the literature, focusing on the compounds that are more abundant in foods or that are available as dietary supplements. We highlight the mechanism of action of these compounds on thyroid cells by giving a particular emphasis to the experimental studies that can be significant for human health. Furthermore, we reveal that the anti-thyroid effects of these plant constituents are clinically evident only when they are consumed in very large amounts or when their ingestion is associated with other conditions that impair thyroid function.

Chondroprotective effects of purple corn anthocyanins on advanced glycation end products induction through suppression of NF-κB and MAPK signaling.

Formation of advanced glycation end products (AGEs), which are associated with diabetes mellitus, contributes to prominent features of osteoarthritis, i.e., inflammation-mediated destruction of articular cartilage. Among the phytochemicals which play a role in anti-inflammatory effects, anthocyanins have also been demonstrated to have anti-diabetic properties. Purple corn is a source of three major anthocyanins: cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside and peonidin-3-O-glucoside. Purple corn anthocyanins have been demonstrated to be involved in the reduction of diabetes-associated inflammation, suggesting that they may have a beneficial effect on diabetes-mediated inflammation of cartilage. This investigation of the chondroprotective effects of purple corn extract on cartilage degradation found a reduction in glycosaminoglycans released from AGEs induced cartilage explants, corresponding with diminishing of uronic acid loss of the cartilage matrix. Investigation of the molecular mechanisms in human articular chondrocytes showed the anti-inflammatory effect of purple corn anthocyanins and the metabolite, protocatechuic acid (PCA) on AGEs induced human articular chondrocytes via inactivation of the NFκb and MAPK signaling pathways. This finding suggests that purple corn anthocyanins and PCA may help ameliorate AGEs mediated inflammation and diabetes-mediated cartilage degradation.

New progress in the pharmacology of protocatechuic acid: A compound ingested in daily foods and herbs frequently and heavily.

Protocatechuic acid is a natural phenolic acid, which widely exists in our daily diet and herbs. It is also one of the main metabolites of complex polyphenols, such as anthocyanins and proanthocyanins. In recent years, a large number of studies on the pharmacological activities of protocatechuic acid have emerged. Protocatechuic acid has a wide range of pharmacological activities including antioxidant, anti-inflammatory, neuroprotective, antibacterial, antiviral, anticancer, antiosteoporotic, analgesia, antiaging activties; protection from metabolic syndrome; and preservation of liver, kidneys, and reproductive functions. Pharmacokinetic studies showed that the absorption and elimination rate of protocatechuic acid are faster, with glucuronidation and sulfation being the major metabolic pathways. However, protocatechuic acid displays a dual-directional regulatory effect on some pharmacological activities. When the concentration is very high, it can inhibit cell proliferation and reduce survival rate. This review aims to comprehensively summarize the pharmacology, pharmacokinetics, and toxicity of protocatechuic acid with emphasis on its pharmacological activities discovered in recent 5 years, so as to provide more up-to-date and thorough information for the preclinical and clinical research of protocatechuic acid in the future. Moreover, it is hoped that the clinical application of protocatechuic acid can be broadened, giving full play to its characteristics of rich sources, low toxicity and wide pharmacological activites.

Evaluation of lipid nanoparticles for topical delivery of protocatechuic acid and ethyl protocatechuate as a new photoprotection strategy.

Excessive exposure to solar radiation induces injurious effects on human skin. Our previous study evidenced that protocatechuic acid (P0) and ethyl protocatechuate (P2) act against photodamage and photoaging. The present study aimed to develop solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for topical delivery of P0 or P2, as a strategy for photoprotection. Lipid nanoparticles exhibited mean particle size, polydispersity index, zeta potential and association efficiency between 200 and 400 nm, 0.160 to 0.460, -2.2 to -5.2 mV, and 60% to 80%, respectively. The formulations were stable for 3 months when stored at 4○C and 25○C/60% RH. SLNs/NLCs-P0 showed minor cytotoxicity effects compared with SLNs/NLCs-P2, in HaCat (keratinocytes) and HFF-1 (fibroblasts) cell lines. Additionally, bare NLCs exhibited less cytotoxicity effect, compared with bare SLNs. NLCs exhibited a controlled in vitro release of P0 and P2, and were able to protect the compounds against UVB degradation. Ex vivo permeability study showed that NLCs modulated P0 and P2 retention profiles on human skin layers. Furthermore, histological analysis of skin showed that NLCs-P0 did not cause morphological alterations, while NLCs-P2 showed a potential irritation effect in the skin structure. Based on these results, NLCs were considered a potential dermatological nanocarrier for P0 delivery.

Development, standardization, and validation of a biofilm efficacy test: The single tube method.

Methods validated by a standard setting organization enable public, industry and regulatory stakeholders to make decisions on the acceptability of products, devices and processes. This is because standard methods are demonstrably reproducible when performed in different laboratories by different researchers, responsive to different products, and rugged when small (usually inadvertent) variations from the standard procedure occur. The Single Tube Method (ASTM E2871) is a standard method that measures the efficacy of antimicrobials against biofilm bacteria that has been shown to be reproducible, responsive and rugged. In support of the reproducibility assessment, a six-laboratory study was performed using three antimicrobials: a sodium hypochlorite, a phenolic and a quaternary/alcohol blend, each tested at low and high efficacy levels. The mean log reduction in viable bacteria in this study ranged from 2.32 to 4.58 and the associated reproducibility standard deviations ranged from 0.89 to 1.67. Independent follow-up testing showed that the method was rugged with respect to deviations in sonication duration and sonication power but slightly sensitive to sonicator reservoir degassing and tube location within the sonicator bath. It was also demonstrated that when a coupon was dropped into a test tube, bacteria can splash out of reach of the applied antimicrobials, resulting in substantial bias when estimating log reductions for the products tested. Bias can also result when testing products that hinder the harvesting of microbes from test surfaces. The culmination of this work provided recommended changes to the early version of the standard method E2871-13 (ASTM, 2013b) including use of splashguards and microscopy checks. These changes have been incorporated into a revised ASTM method E2871-19 (ASTM 2019) that is the basis for the first regulatory method (ATMP-MB-20) to substantiate "kills biofilm" claims for antimicrobials registered and sold in the US.

Saccharides in straw hydrolysate decrease cell membrane damage by phenolics by inducing the formation of extracellular matrix in yeast.

The bioconversion of rice straw into ethanol can alleviate the energy crisis and solve problems related to waste treatment. In this study, the effect of soluble polysaccharides (SPs) produced during rice straw saccharification on the formation of extracellular matrices (EMs) by the yeast Saccharomyces cerevisiae was investigated. SPs were characterized by high-performance liquid chromatography (HPLC) and fourier transform infrared spectroscopy (FT-IR). SPs reduced the inhibition of alcohol dehydrogenase activity by phenolic acids (PAs) and regulated the intracellular redox state, resulting in higher ethanol production. The results of flow cytometry, confocal laser scanning microscopy, and atomic force microscopy indicated that PAs changed microbial morphology and caused damage in microbial cell membranes. The protective effect of SPs against cell membrane damage could be attributed to the synthesis of polysaccharide-dependent extracellular matrix, which maintained cellular integrity even under phenolic acid stress. These findings provide new strategies to improve pretreatment and saccharification processes.

Toxicity of phenolic compounds to entomopathogenic nematodes: A case study with Heterorhabditis bacteriophora exposed to lentisk (Pistacia lentiscus) extracts and their chemical components.

Insects show adaptive plasticity by ingesting plant secondary compounds, such as phenolic compounds, that are noxious to parasites. This work examined whether exposure to phenolic compounds affects the development of insect parasitic nematodes. As a model system for parasitic life cycle, we used Heterorhabditis bacteriophora (Rhabditida; Heterorhabditiade) grown with Photorhabdita luminescens supplemented with different concentrations of plant phenolic extracts (0, 600, 1200, 2400 ppm): a crude ethanol extract of lentisk (Pistacia lentiscus) or lentisk extract fractionated along a scale of hydrophobicity with hexane, chloroform and ethyl acetate; and flavonoids (myricetin, catechin), flavanol-glycoside (rutin) or phenolic acids (chlorogenic and gallic acids). Resilience of the nematode to phenolic compounds was stage-dependent, with younger growth stages exhibiting less resilience than older growth stages (i.e., eggs < young juveniles < young hermaphrodites < infective juveniles < mature hermaphrodites). At high concentrations, all of the phenolic compounds studied were lethal to eggs and young juveniles. The nematodes were able to survive in the presence of medium and low concentrations of all studied compounds, but very few of those treatments allowed for reproduction beyond the infective juvenile stage and, at low concentrations, the crude 70% ethanol extract, chloroform and hexane extracts, and myricetin were associated with some impaired reproduction. The ethyl-acetate fraction and gallic acid were extremely lethal to the young stages and allowed almost no development beyond the infective juvenile stage. We conclude that exposure of infective juveniles to phenolics before they infect insects and post-infection exposure of other nematode developmental stages may affect the initiation of the infection, suggesting that the chemistry of dietary phenolics may limit H. bacteriophora's infection of insects.

Is cytotoxicity a determinant of the different in vitro and in vivo effects of bioactives?

BACKGROUND: Foodstuffs of both plant and animal origin contain a wide range of bioactive compounds. Although human intervention studies are mandatory to assess the health effects of bioactives, the in vitro approach is often used to select the most promising molecules to be studied in vivo. To avoid misleading results, concentration and chemical form, exposure time, and potential cytotoxicity of the tested bioactives should be carefully set prior to any other experiments. METHODS: In this study the possible cytotoxicity of different bioactives (docosahexaenoic acid, propionate, cyanidin-3-O-glucoside, protocatechuic acid), was investigated in HepG2 cells using different methods. Bioactives were supplemented to cells at different concentrations within the physiological range in human blood, alone or in combination, considering two different exposure times. RESULTS: Reported data clearly evidence that in vitro cytotoxicity is tightly related to the exposure time, and it varies among bioactives, which could exert a cytotoxic effect even at a concentration within the in vivo physiological blood concentration range. Furthermore, co-supplementation of different bioactives can increase the cytotoxic effect. CONCLUSIONS: Our results underline the importance of in vitro cytotoxicity screening that should be considered mandatory before performing studies aimed to evaluate the effect of bioactives on other cellular parameters. Although this study is far from the demonstration of a toxic effect of the tested bioactives when administered to humans, it represents a starting point for future research aimed at verifying the existence of a potential hazard due to the wide use of high doses of multiple bioactives.

Therapeutic Application of Natural Medicine Monomers in Cancer Treatment.

BACKGROUND: Natural medicine monomers (NMMs) isolated from plants have been recognized for their roles in treating different human diseases including cancers. Many NMMs exhibit effective anti-cancer activities and can be used as drugs or adjuvant agents to enhance the efficacy of chemotherapy and radiotherapy. Some NMMs, such as paclitaxel and camptothecin, have been extensively studied for decades and are now used as anti-cancer medicines due to their remarkable curative effects, such as inhibiting cancer cell proliferation and metastasis, and inducing cell death and differentiation. METHODS: After extensively reviewing papers related to NMM studies in cancers, we grouped NMMs into six categories based on their chemical structures. We summarized the anti-cancer activities of these NMMs and current knowledge of molecular mechanisms for them to exert their functions. RESULTS AND CONCLUSION: Many NMMs from plants can effectively inhibit cancer cells with low or tolerable toxicity to patients. Some NMMs have been well-characterized for their anti-cancer activities and have already been used as clinical drugs or adjuvant agents; however, the mechanisms underlying the cancer suppressive activities of most NMMs remain poorly understood. Many NMMs can be used as initial structural scaffolds to design and develop novel therapeutics against cancers. This review summarizes reports related to signaling pathways mediated by different NMMs and can provide a theoretical basis for clinical application and new drug development of NMMs.

Toxicity of phenolipids: Protocatechuic acid alkyl esters trigger disruption of mitochondrial membrane potential and caspase activation in macrophages.

Phenolipids are a class of phenolic compounds with a lipidic moiety that have been receiving increasing attention due to their promising biological activities; however data regarding their toxicity and mechanism of action are scarce. A series of 11 phenolipids consisting of alkyl esters derivatives of the natural molecule protocatechuic acid was synthesized and evaluated against a panel of cancer and non-cancer cell lines. The macrophage cell line RAW 264.7, widely used as a tool for screening anti-inflammatory drugs, was more susceptible to the toxicity of these molecules than human cancer cells, reason for which mechanist studies were conducted. The parent molecule was not toxic up to 100µM, however structural modifications by inclusion of carbon side chains resulted in increased toxicity, compounds bearing 8-14 carbons being the most toxic and displaying IC50 in the nanomolar range. Mechanistic studies showed that phenolipids elicit chromatin condensation, loss of cell viability and disruption of mitochondrial membrane potential (ΔΨm), increased reactive oxygen species (ROS) and activation of caspase-9/3, thus pointing to the involvement of mitochondria in the programmed cell death process taking place. This is the first study addressing the toxicity and mechanism of action of protocatechuic acid derivatives, which is relevant in light of the recent interest in these molecules.

A Bio-Chemosynthetic Approach to Superparamagnetic Iron Oxide-Ansamitocin Conjugates for Use in Magnetic Drug Targeting.

A combination of mutasynthesis using a mutant strain of A. pretiosum blocked in the biosynthesis of amino-hydroxybenzoic acid (AHBA) and semisynthesis relying on a Stille cross-coupling step provided access to new ansamitocin derivatives of which one was attached by a thermolabile linker to nanostructured iron oxide particles. When exposed to an oscillating electromagnetic field the resulting iron oxide/ansamitocin conjugate 19 heats up in an aqueous suspension and the ansamitocin derivative 16 is released by means of a retro-Diels-Alder reaction. It exerts strong antiproliferative activity (IC50 =4.8 ng mg-1 ) in mouse fibroblasts. These new types of conjugates have the potential for combating cancer through hyperthermia and chemotherapy using an electromagnetic external trigger.

Potential anticancer activity of lichen secondary metabolite physodic acid.

Secondary metabolites present in lichens, which comprise aliphatic, cycloaliphatic, aromatic and terpenic compounds, are unique with respect to those of higher plants and show interesting biological and pharmacological activities. However, only a few of these compounds, have been assessed for their effectiveness against various in vitro cancer models. In the present study, we investigated the cytotoxicity of three lichen secondary metabolites (atranorin, gyrophoric acid and physodic acid) on A375 melanoma cancer cell line. The tested compounds arise from different lichen species collected in different areas of Continental and Antarctic Chile. The obtained results confirm the major efficiency of depsidones. In fact, depsides atranorin and gyrophoric acid, showed a lower activity inhibiting the melanoma cancer cells only at more high concentrations. Whereas the depsidone physodic acid, showed a dose-response relationship in the range of 6.25-50 µM concentrations in A375 cells, activating an apoptotic process, that probably involves the reduction of Hsp70 expression. Although the molecular mechanism, by which apoptosis is induced by physodic acid remains unclear, and of course further studies are needed, the results here reported confirm the promising biological properties of depsidone compounds, and may offer a further impulse to the development of analogues with more powerful efficiency against melanoma cells.

Detoxification of hydroxylated polychlorobiphenyls by Sphingomonas sp. strain N-9 isolated from forest soil.

To examine the biodegradation of hydroxylated polychlorobiphenyls (OH-PCBs), we isolated Sphingomonas sp. strain N-9 from forest soil using mineral salt medium containing 4-hydroxy-3-chlorobiphenyl (4OH-3CB) at the concentration of 10 mg/L. Following incubation with strain N-9, the concentration of 4OH-3CB decreased in inverse proportion to strain N-9 proliferation, and it was converted to 3-chloro-4-hydroxybenzoic acid (4OH-3CBA) after 1 day. We observed that strain N-9 efficiently degraded lowly chlorinated OH-PCBs (1-4 Cl), while highly chlorinated OH-PCBs (5-6 Cl) were less efficiently transformed. Additionally, strain N-9 degraded PCBs and OH-PCBs with similar efficiencies, and the efficiency of OH-PCB degradation was dependent upon the positional relationships between OH-PCB hydroxyl groups and chlorinated rings. OH-PCB biodegradation may result in highly toxic products, therefore, we evaluated the cytotoxicity of two OH-PCBs [4OH-3CB and 4-hydroxy-3,5-dichlorobiphenyl (4OH-3,5CB)] and their metabolites [4OH-3CBA and 3,5-chloro-4-hydroxybenzoic acid (4OH-3,5CBA)] using PC12 rat pheochromocytoma cells. Our results revealed that both OH-PCBs induced cell membrane damage and caused neuron-like elongations in a dose-dependent manner, while similar results were not observed for their metabolites. These results indicated that strain N-9 can convert OH-PCBs into chloro-hydroxybenzoic acids having lower toxicity.

Effects of long-term continuous cropping on soil nematode community and soil condition associated with replant problem in strawberry habitat.

Continuous cropping changes soil physiochemical parameters, enzymes and microorganism communities, causing "replant problem" in strawberry cultivation. We hypothesized that soil nematode community would reflect the changes in soil conditions caused by long-term continuous cropping, in ways that are consistent and predictable. To test this hypothesis, we studied the soil nematode communities and several soil parameters, including the concentration of soil phenolic acids, organic matter and nitrogen levels, in strawberry greenhouse under continuous-cropping for five different durations. Soil pH significantly decreased, and four phenolic acids, i.e., p-hydroxybenzoic acid, ferulic acid, cinnamic acid and p-coumaric acid, accumulated with time under continuous cropping. The four phenolic acids were highly toxic to Acrobeloides spp., the eudominant genus in non-continuous cropping, causing it to reduce to a resident genus after seven-years of continuous cropping. Decreased nematode diversity indicated loss of ecosystem stability and sustainability because of continuous-cropping practice. Moreover, the dominant decomposition pathway was altered from bacterial to fungal under continuous cropping. Our results suggest that along with the continuous-cropping time in strawberry habitat, the soil food web is disturbed, and the available plant nutrition as well as the general health of the soil deteriorates; these changes can be indicated by soil nematode community.

Synthesis of mono Mannich bases of 2-(4-hydroxybenzylidene)-2,3-dihydroinden-1-one and evaluation of their cytotoxicities.

Chalcones and Mannich bases are a group of compounds known for their cytotoxicities. In this study restricted chalcone analogue, compound 2-(4-hydroxybenzylidene)-2,3-dihydroinden-1-one MT1, was used as a starting compound to synthesize new mono Mannich bases since Mannich bases may induce more cytotoxicity than chalcone analogue that they are derived from by producing additional alkylating center for cellular thiols. In this study, cyclic and acyclic amines were used to synthesize Mannich bases. All compounds were tested against Ca9-22 (gingival carcinoma), HSC-2, HSC-3 and HSC-4 (oral squamous cell carcinoma) as tumour cell lines and HGF (gingival fibroblasts), HPC (pulp cells) and HPLF (periodontal ligament fibroblasts) human normal oral cells as non tumour cell lines. Cytotoxicity, selectivity index (SI) values and potency selectivity expression (PSE) values expressed as a percentage were determined for the compounds. According to data obtained, the compound MT8 with the highest PSE value bearing N-methylpiperazine moiety seems to be a good candidate to develop new cytotoxic compounds and is suited for further investigation.

Toxin profile of Gymnodinium catenatum (Dinophyceae) from the Portuguese coast, as determined by liquid chromatography tandem mass spectrometry.

The marine dinoflagellate Gymnodinium catenatum has been associated with paralytic shellfish poisoning (PSP) outbreaks in Portuguese waters for many years. PSP syndrome is caused by consumption of seafood contaminated with paralytic shellfish toxins (PSTs), a suite of potent neurotoxins. Gymnodinium catenatum was frequently reported along the Portuguese coast throughout the late 1980s and early 1990s, but was absent between 1995 and 2005. Since this time, G. catenatum blooms have been recurrent, causing contamination of fishery resources along the Atlantic coast of Portugal. The aim of this study was to evaluate the toxin profile of G. catenatum isolated from the Portuguese coast before and after the 10-year hiatus to determine changes and potential impacts for the region. Hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) was utilized to determine the presence of any known and emerging PSTs in sample extracts. Several PST derivatives were identified, including the N-sulfocarbamoyl analogues (C1-4), gonyautoxin 5 (GTX5), gonyautoxin 6 (GTX6), and decarbamoyl derivatives, decarbamoyl saxitoxin (dcSTX), decarbamoyl neosaxitoxin (dcNeo) and decarbamoyl gonyautoxin 3 (dcGTX3). In addition, three known hydroxy benzoate derivatives, G. catenatum toxin 1 (GC1), GC2 and GC3, were confirmed in cultured and wild strains of G. catenatum. Moreover, two presumed N-hydroxylated analogues of GC2 and GC3, designated GC5 and GC6, are reported. This work contributes to our understanding of the toxigenicity of G. catenatum in the coastal waters of Portugal and provides valuable information on emerging PST classes that may be relevant for routine monitoring programs tasked with the prevention and control of marine toxins in fish and shellfish.

The clinical heterogeneity of coenzyme Q10 deficiency results from genotypic differences in the Coq9 gene.

Primary coenzyme Q10 (CoQ10) deficiency is due to mutations in genes involved in CoQ biosynthesis. The disease has been associated with five major phenotypes, but a genotype-phenotype correlation is unclear. Here, we compare two mouse models with a genetic modification in Coq9 gene (Coq9(Q95X) and Coq9(R239X)), and their responses to 2,4-dihydroxybenzoic acid (2,4-diHB). Coq9(R239X) mice manifest severe widespread CoQ deficiency associated with fatal encephalomyopathy and respond to 2,4-diHB increasing CoQ levels. In contrast, Coq9(Q95X) mice exhibit mild CoQ deficiency manifesting with reduction in CI+III activity and mitochondrial respiration in skeletal muscle, and late-onset mild mitochondrial myopathy, which does not respond to 2,4-diHB. We show that these differences are due to the levels of COQ biosynthetic proteins, suggesting that the presence of a truncated version of COQ9 protein in Coq9(R239X) mice destabilizes the CoQ multiprotein complex. Our study points out the importance of the multiprotein complex for CoQ biosynthesis in mammals, which may provide new insights to understand the genotype-phenotype heterogeneity associated with human CoQ deficiency and may have a potential impact on the treatment of this mitochondrial disorder.

Recent advances in toxicological testing of the stratum corneum.

α-Hydroxy acid (AHA) formulations are commonly used for skin chemical peelings. The primary target is the stratum corneum (SC). The aim of this study was to assess the effects of various glycolic acid concentrations and commercial phenolic acid formulations on the SC. Quantitative colorimetry of a corneoxenometry bioassay was used. The test procedure involved glycolic acid concentrations ranging from 3% to 70% in alcoholic solution. Exposure times were set for 1 min and 3 min. The bioassay showed consistent reactivity with a dose-effect relationship when using the selected low exposure times. In a similar procedure the aggressiveness of commercially available phenolic acid formulations was identified not using hazardous in vivo testing. Corneoxenometry appears useful for in vitro testing of AHA peeling agents during short exposure times.

Anticancer nanodelivery system with controlled release property based on protocatechuate-zinc layered hydroxide nanohybrid.

BACKGROUND: We characterize a novel nanocomposite that acts as an efficient anticancer agent. METHODS: This nanocomposite consists of zinc layered hydroxide intercalated with protocatechuate (an anionic form of protocatechuic acid), that has been synthesized using a direct method with zinc oxide and protocatechuic acid as precursors. RESULTS: The resulting protocatechuic acid nanocomposite (PAN) showed a basal spacing of 12.7 Å, indicating that protocatechuate was intercalated in a monolayer arrangement, with an angle of 54° from the Z-axis between the interlayers of the zinc layered hydroxide, and an estimated drug loading of about 35.7%. PAN exhibited the properties of a mesoporous type material, with greatly enhanced thermal stability of protocatechuate as compared to its free counterpart. The presence of protocatechuate in the interlayers of the zinc layered hydroxide was further supported by Fourier transform infrared spectroscopy. Protocatechuate was released from PAN in a slow and sustained manner. This mechanism of release was well represented by a pseudo-second order kinetics model. PAN has shown increased cytotoxicity compared to the free form of protocatechuic acid in all cancer cell lines tested. Tumor growth suppression was extensive, particularly in HepG2 and HT29 cell lines. CONCLUSION: PAN is suitable for use as a controlled release formulation, and our in vitro evidence indicates that PAN is an effective anticancer agent. PAN may have potential as a chemotherapeutic drug for human cancer.