Simultaneous determination of seven phthalates and four parabens in cosmetic products using HPLC-DAD and GC-MS methods

Studies on the determination of seven kinds of phthalates, i.e. diethyl phthalate, dipropyl phthalate, dibutyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate, di-(2-ethylhexyl) phthalate, and dioctyl phthalate, and four parabens, i.e. methylparaben, ethylparaben, propylparaben, and butylparaben, in 15 kinds of cosmetic products, including hair sprays, perfumes, deodorants, cream, lotion, etc., by HPLC with diode array detection and GC-MS in electron impact ionization mode with selected-ion monitoring have been carried out. Methods have been developed for both qualitative and quantitative detection of phthalates and parabens. Extraction, clean-up, and analysis procedures have been optimized. HPLC and GC-MS determinations were performed after sonication-assisted extraction with methanol and clean-up with C18 SPE. These techniques permit detection of phthalates at a level of 10.0-100.0 microg/kg and of parabens at a level of 20.0-200.0 microg/kg. Overall recoveries were 85-108% with RSD values of 4.2-8.8%. Only one of the 15 examined samples was free from phthalates and parabens. The remaining 14 samples were found to contain at least three or more of these phthalates and/or parabens. The predominant phthalates and parabens detected in the studied samples were methylparaben, propylparaben, diethyl phthalate, dibutyl phthalate, dicyclohexyl phthalate, and di-(2-ethylhexyl) phthalate. The residue level is at 1.22-5289 mg/kg.

Studies on the lipophilicity of vehicles (or co-vehicles) and botanical oils used in cosmetic products

The lipophilic character of five vehicles (or co-vehicles): diethylhexylmaleate, dimethicone, light mineral oil, octyldodecanol and oleyl alcohol and eight botanical oils: Aloe vera oil, coconut oil, extra virgin olive oil, grape leaf oil, grape seed oil, hazelnut oil, jojoba oil and safflower oil was determined by partitioning esters of p-hydroxybenzoic acid (parabens) between them and phosphate buffer (pH 7.4). The results were compared to those obtained with 1-octanol. The most lipophilic effects were observed with octyldodecanol and oleyl alcohol for the vehicles (or co-vehicles), coconut oil, jojoba oil and safflower oil for botanical oils. Light mineral oil showed the least lipophilic effect. With butylparaben, it was observed that oleyl alcohol, octyldodecanol, coconut oil and jojoba oil were 0.94, 0.91, 0.74 and 0.68 times as lipophilic as 1-octanol respectively. The study indicates that octyldodecanol and oleyl alcohol could be good substitutes for 1-octanol in partition coefficient determination. The estimated permeability coefficients of the parabens suggest that octyldodecanol, oleyl alcohol, coconut oil and jojoba oil could be potential dermal permeation enhancers.

[Isolation and structure identification of chemical constituents from Polygala hongkongensis II]

OBJECTIVE

To isolate and elucidate the constituents of herbs of Polygala hongkongensis.

METHOD

The constituents were isolated and purify by chromatographic on silica gel, Sephadax LH-20 and semi-preparative HPLC. The structures were determined by NMR and MS spectral analysis.

RESULT

Six compounds were identified as euxanthone (1), 1, 3, 6-trihydroxyxanthone (2), 1, 4, 7-trihydroxy-3-methoxy-xanthone (3), p-hydroxybenzoic acid (4), 3, 4-dihydroxybenzoic acid (5), and methy 1 2, 5-dihydroxybenzoate (6).

CONCLUSION

The known compounds 1-6 were isolated from this plant for the first time.

Superheated water as chromatographic eluent for parabens separation on octadecyl coated zirconia stationary phase

In this study, the use of pure water at superheated temperatures, between 100 and 200 degrees C, as a mobile phase for RP separation is explored. Instrumental parameters, such as temperature, flow rate, preheating and cooling, have shown significant effects on the quality of the chromatographic peaks. The properties of superheated water as an eluent were investigated by observing the chromatographic behaviour of four parabens on a carbon-clad zirconia (ZR) phase with covalently bonded octadecyl groups. Results were compared with those obtained at 30 degrees C on a silica-based phase with octadecyl groups, using water and ACN as mobile phase. The optimized method was finally applied to analyse parabens in a commercial body cream.

Variability in Human Skin Permeability In Vitro: Comparing Penetrants with Different Physicochemical Properties

Appreciating and compensating for the inherent variability associated with percutaneous absorption is essential in optimizing (trans)dermal therapy. In this study, the variability in human skin permeability associated with model penetrants of differing lipophilicity (caffeine (CF), methyl paraben (MP), and butyl paraben (BP)) was examined in a standardized intra-laboratory study (Franz cell experiments) using epidermal tissue from various donors. Experimentally derived permeability coefficients (K(P)) were also compared to that derived from two skin permeation models namely, Potts & Guy and Robinson (revised) models in order to further validate the Franz diffusion method employed and also elucidate the potential permeation pathway(s) employed by the model penetrants. Intra-subject variability associated with skin permeation of the model penetrants was generally found to be lower than inter-subject variability. Experimental K(P) values were found to be the same order of magnitude as predicted by the mathematical models. Calculated residual variance suggested the Potts and Guy's model to be relatively accurate in predicting skin permeability of the two parabens whilst the Robinson (revised) model was more effective for CF. The high variability in CF permeation compared to the parabens may suggest the in vitro skin permeation of solutes becomes more sensitive to intra- and/or inter-subject variation in skin lipid content, appendageal density, and imperfections (pores, cracks) as the hydrophilic nature of the solute increases. Such variability in skin permeability suggests a difference in CF permeation kinetics relative to the parabens. As such when performing in vitro drug permeation studies, it is essential that the variability in the absorption of the model permeants, according to their physicochemical properties, is considered when they are used to normalize or standardize any resulting data.

Antiandrogenic properties of parabens and other phenolic containing small molecules in personal care products

To identify the androgenic potency of commonly used antimicrobials, an in vitro androgen receptor-mediated transcriptional activity assay was employed to evaluate the androgenic/antiandrogenic activity of parabens and selected other antimicrobials containing a phenolic moiety. This cell-based assay utilizes a stably transfected cell line that lacks critical steroid metabolizing enzymes and is formatted in a 96-well format. At a concentration of 10 microM, methyl-, propyl- and butyl-4-hydroxybenzoate (parabens) inhibited testosterone (T)-induced transcriptional activity by 40%, 33% and 19%, respectively (P<0.05), while 4-hydroxybenzoic acid, the major metabolite of parabens, had no effect on T-induced transcriptional activity. Triclosan inhibited transcriptional activity induced by T by more than 92% at a concentration of 10 microM, and 38.8% at a concentration of 1.0 microM (P<0.05). Thirty-four percent of T-induced transcriptional activity was inhibited by thymol at 10 microM (P<0.05). Cell proliferation and/or cytotoxicity were not observed in any of the treatments. None of the compounds appeared to be androgenic when tested individually without T. The data presented in this report demonstrate that some widely used antimicrobial compounds have antiandrogenic properties and warrant further investigation to fully understand their potential impact on human reproductive health.

Investigating protein haptenation mechanisms of skin sensitisers using human serum albumin as a model protein

Covalent modification of skin proteins by electrophiles is a key event in the induction of skin sensitisation but not skin irritation although the exact nature of the binding mechanisms has not been determined empirically for the vast majority of sensitisers. It is also unknown whether immunologically relevant protein targets exist in the skin contributing to effecting skin sensitisation. To determine the haptenation mechanism(s) and spectra of amino acid reactivity in an intact protein for two sensitisers expected to react by different mechanisms, human serum albumin (HSA) was chosen as a model protein. The aim of this work was also to verify for selected non-sensitisers and irritants that no protein haptenation occurs even under forcing conditions. HSA was incubated with chemicals and the resulting complexes were digested with trypsin and analysed deploying matrix-assisted laser desorption/ionization mass spectrometry, reverse phase high performance liquid chromatography and nano-electrospray tandem mass spectrometry. The data confirmed that different residues (lysine, cysteine, histidine and tyrosine) are covalently modified in a highly selective and differential manner by the sensitisers 2,4-dinitro-1-chlorobenzene and phenyl salicylate. Additionally, non-sensitisers 2,4-dichloro-1-nitrobenzene, butyl paraben and benzaldehyde and irritants benzalkonium chloride and sodium dodecyl sulphate did not covalently modify HSA under any conditions. The data indicate that covalent haptenation is a prerequisite of skin sensitisation but not irritation. The data also suggest that protein modifications are targeted to certain amino acids residing in chemical microenvironments conducive to reactivity within an intact protein. Deriving such information is relevant to our understanding of antigen formation in the immunobiology of skin sensitisation and in the development of in vitro protein haptenation assays.

Permeation of 4-cyanophenol and methyl paraben from powder and saturated aqueous solution through silicone rubber membranes and human skin

The objectives were to compare permeation from neat powder and saturated aqueous solution of two model compounds into homogeneous silicone rubber (polydimethylsiloxane) membranes (SRM) and human skin, which is heterogeneous, and to test the common assumption that solid chemicals do not absorb unless liquid is present. The steady-state flux of 4-cyanophenol (CP) through SRM from the powder (0.0684 +/- 0.0040 mg/cm2 x h) was almost the same as from a saturated solution (0.0789 +/- 0.0064 mg/cm2 x h, indicating that solid chemicals can absorb without the presence of liquids. The steady-state flux of CP through skin of a single subject was much smaller from the powder (0.0118 +/- 0.0064 mg/cm2 x h) than from the saturated solution (0.168 +/- 0.033 mg/cm2 x h). The average flux for powder relative to the saturated aqueous solution was 7.24% in skin compared with 87.2% in SRM for CP and 9.02% in skin compared with 99.9% in SRM for methyl paraben. It is evident that absorption into SRM and skin can occur from powdered chemicals and that surface oils or moisture are unnecessary. However, SRM proved to be a poor surrogate for dermal permeation from powders of CP and MP.

Controlled drug release from pellets containing water-insoluble drugs dissolved in a self-emulsifying system

The aim of the study was to provide a controlled release system, which could be used for the oral administration of highly water-insoluble drugs. Pellets have been prepared by extrusion/spheronization containing two model drugs (methyl and propyl parabens) of low water solubility. One type of pellets contained the drugs mixed with lactose and microcrystalline cellulose (MCC) and the other types of pellets contained the model drugs dissolved in a self-emulsifying system (4.8%) consisting of equal parts of mono-diglycerides and polysorbate 80 and MCC. Pellets of all types in the same size fraction (1.4-2.0 mm) were coated to different levels of weight gain, with ethylcellulose, talc and glycerol. A sample of pellets containing methyl parabens in the self-emulsifying system was pre-coated with a film of hydroxypropylmethyl cellulose from an aqueous solution and then coated as above. Dissolution experiments established that the presence of the self-emulsifying system enhanced the drug release of both model drugs and that the film coating considerably reduced the drug release from pellets made with just water, lactose and MCC. The coating reduced the drug release from the pellets containing the self-emulsifying system to a lesser extent but in relation to the quantity of coat applied to the pellets. The application of a sub-coating of hydroxypropylmethyl cellulose was able to reduce the release rate of methyl parabens self-emulsifying system ethyl cellulose coated pellets. Thus, the formulation approach offers the possibility of formulating and controlling the in vitro release of water-insoluble drugs from solid oral dosage forms.

Preliminary ecological risk assessment of butylparaben and benzylparaben -2. Fate and partitioning in aquatic environments

Butylparaben and benzylparaben, used as preservatives mainly in cosmetic products, have recently been shown to be weakly estrogenic. Batch sunlight photolysis and river water biodegradation experiments were conducted to determine the persistence of these compounds in aquatic environments. As a result, benzylparaben was found to be moderately photodegradable whereas both n-butylparaben and i-butylparaben were highly stable against sunlight. Both benzylparaben and butylparabens were relatively biodegradable in the river water but the degradability was dependent on the sampling site and time. Batch sorption experiments were also conducted to determine the coefficients of sorption into river sediments and a model soil sample. The determined coefficients were slightly higher for benzylparaben than the two butylparabens and comparable to that of the natural estrogen 17beta-estradiol. The coefficients were also higher for sediment/soil with a higher organic content and the organic-carbon-based sorption coefficient (log K oc) shows a moderate linear correlation with the octanol-water partition coefficient (log K ow). These results suggest that hydrophobic interaction plays a predominant role in sorption at neutral pH.

Estrogenic personal care products in a greywater reuse system

The occurrence and fate of parabens in a greywater system was assessed. The potential for removal of residual paraben concentrations in effluent greywater with chlorine dioxide was also investigated. The influent to the greywater plant was characterised by considerable variation, with concentrations from below the detection limit to 40 microg/L and the five commonly used parabens in consumer products were frequently detected. After the biological treatment only two paraben were detected with concentration from 65-120 ng/L. Chlorine dioxide treatment of the biologically treated effluent with dosages down to 0.75 mg/L resulted in more than 97% reduction of all parabens. Formation of the by-product chloroform was insignificant from the chlorine dioxide treatment.

Assay of artemether, methylparaben and propylparaben in a formulated paediatric antimalarial dry suspension

Two HPLC-UV methods are described for the separate determination of artemether (AM) and the combined preservatives, methylparaben and propylparaben in a pharmaceutical dosage form. These analytes are contained in a dry suspension with a high amount of non-soluble excipients, some of which can interfere with the analysis. This makes their separation and analysis of the actives complex. Moreover, due to the wide difference in concentrations, the three analytes could not be quantitated simultaneously. Artemether was analysed using a reversed-phase Nucleosil C(18) column [5 microm, 125 mm x 4 mm (i.d.)] with a mixture of acetonitrile: potassium phosphate buffer pH 5.0 (0.05 M): water [48:32:10 (v/v/v)] as mobile phase. Due to the low solubility of the hydroxy benzoic acid esters in water, their sodium salts were used in the formulation. Complete separation of these preservatives was achieved on the same type of column as artemether using as eluent acetonitrile: potassium phosphate buffer pH 5.0 (0.05 M) (30:70, v/v). Quantitation was achieved with UV detection at 215 nm for artemether and 254 nm for the parabens, respectively. And in both methods, pump flow rate was 1.0 ml/min, sample injection volume 20 microl, ambient temperature maintained and no prior sample extraction methods were necessary throughout the experiments. Calibration curves were linear at concentration ranges of 4-16 microg/ml, 1-4 microg/ml and 1-10 mg/ml for methylparaben, propylparaben and artemether respectively. The excipient powder interference could be eliminated by diluting the sample and the analytes eluted at relatively short times using these systems. Both methods were further validated in terms of specificity, linearity, precision and accuracy. The procedures prescribed here are simple, selective and can be used for routine quality control and stability indicating tests involving the analysed compounds formulated in complex matrices.

Study of hydroxy propyl guar derivative for its gelling property and it's use in the formulation of tenoxicam gels

Gels of tenoxicam 1% w/w were formulated using 2% w/w hydroxy propyl guar derivative and 3% w/w sodium carboxy methyl cellulose as gelling agents. A detailed rheological investigation was carried out to study the influence of preservative, drug and preservative, solvent system and the preservative, drug, solvent system and the preservative on the pseudoplastic behaviour of polymers. Hydroxy propyl guar derivative in 2% w/w strength resulted in gels with a higher pseudoplastic index value of 3.383 in contrast to an index value of 1.797 for a 3% w/w sodium carboxy methyl cellulose gels of a similar composition. The gels were stored at different temperatures and variations in pH values were recorded. Hydroxy propyl guar derivative based gels revealed variations in pH values over a narrow range in contrast to sodium carboxy methyl cellulose gels. The gels were subjected to short term stability studies by storing gels at refrigerated temperature, lab temperature, at 37 degrees C and at 45 degrees C. Gels based on hydroxy propyl guar derivative revealed better drug keeping qualities in contrast to sodium carboxy methyl cellulose stabilized gels. Release studies of tenoxicam from formulations across hairless albino mice skin revealed a zero order drug release pattern from both the formulations.

[Chemical constitutents of Bauhinia aurea]

OBJECTIVE

To study the chemical constituents of Bauhinia aurea.

METHOD

The compounds were isolated with column chromatography. The structures were determined by MS and NMR spectroscopic techniques.

RESULT

Nine aromatic acid derivatives, two triterpenes and three steroids were isolated from the 90% ethanolic extract and their structures were identified as 3,4-di-hydroxybenzoic acid (1), 4-hydroxybenzoic acid (2), 3-hydroxy-4-methoxy-benzoic acid (3), 4-hydroxy-3-methoxybenzoic acid (4) , gallic acid (5) , methyl gallate (6) , ethyl gallate (7) , lupeol (8) , lupenone (9) , stigmast4-en-3-one (10) beta-sitosterol (11) and daucosterol (12).

CONCLUSION

This is the first report of chemical constituents from B. aurea. Compounds were isolated from this genus for the first time, except 5,8,11 and 12.

Paraben Transport and Metabolism in the Biomimetic Artificial Membrane Permeability Assay (BAMPA) and 3-Day and 21-Day Caco-2 Cell Systems

Noncellular and cellular in vitro models for predicting intestinal absorption were used to investigate the transport and metabolism of parabens. The biomimetic artificial membrane permeability assay (BAMPA) membrane was constructed by impregnating a lipid solution on a hydrophobic filter. Caco-2 cells at passage numbers 65 to 80 were cultured in either the accelerated 3-day Biocoat™ system or the standard 21-day Transwell™ cell culture system. Paraben transport across the BAMPA system showed a parabolic relationship. The lowest log P (p-hydroxybenzoic acid) and highest log P compounds (heptyl and octyl parabens) had apparent permeabilities (Papp) less than 1.0 × 10-6 cm/s and Papp was maximal at approximately 8.5 × 10-6cm/s for the intermediate log P (ethylparaben) compound. With the Biocoat™, a similar parabolic relationship was found. In the 21-day Caco-2 cells, the parabens were metabolized by esterases at to p-hydroxybenzoic acid. In conclusion, the in vitro models added complementary insight into the absorption process, such as the transport route, intrinsic permeability, and extent of metabolism of the parabens. This study indicated that presystemic metabolism of orally ingested parabens to the p-hydroxybenzoic acid in the intestine may limit systemic exposure to alkyl-paraben esters in vivo.

Long-lived nuclear spin states in the solution NMR of four-spin systems

The existence of long-lived nuclear spin states in four-spin systems is explored by solution-state NMR experiments. Long-lived states are proved to exist in three different natural product molecules, each containing either a AA'BB' or a AA'XX' proton spin system. The measured state lifetimes are between four and eight times the spin-lattice relaxation time constants.

[Chemical constituents in root of Zanthoxylum nitidum]

OBJECTIVE

To study the chemical constituents of Zanthoxylum nitidum.

METHOD

Column chromatography on Silica gel and Sephadex LH - 20, and recrystallization were applied for the isolation and purification of the constituents. The structures were elucidated on the basis of spectral analysis, chemical evidences and by comparison with the data reported in literature.

RESULT

From the CHCl3 fraction and n-butanol fraction of the EtOH extract of the roots of Z. nitidum, 10 compounds were isolated and identified as 2, 4-dihydroxypyrimidine (1), syringic acid (2) , 2, 6-dimethoxy-1, 4-benzoquinone (3) , 4-hydroxybenzoic acid (4), ethylparaben (5), (Z)-3-(2, 3, 4-trimethoxyphenyl) acrylic acid (6), 5, 6, 7-trimethoxycoumarin (7), stigmast-9 (11) -en-3-ol (8), daucosterol (9), beta-sitosterol (10).

CONCLUSION

Compounds 1-9 were isolated and identified from the roots of Z. nitidum for the first time. Furthermore, we note here the first isolation of compound 6 as a natural product.

Phenolic components and antioxidant activity of Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos

Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos, used as raw material for topical and oral photoprotective formulations, was fractioned by HPLC and the main components with antioxidant capability were identified by means of UV spectra, electrochemical detection, and MSn. Phenolic compounds were identified as 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, caffeic acid, 4-hydroxycinnamic acid, 4-hydroxycinnamoyl-quinic acid, ferulic acid, and five chlorogenic acid isomers. Total ferric antioxidant capacity (FRAP) of HPLC eluted fractions was measured. The results suggest that the herein identified compounds support, at least partially, the antioxidant and radical scavenging capacities of Fernblock.

Fast and high-resolution ion chromatography at high pH on short columns packed with 1.8μm surfactant coated silica reverse-phase particles

Rapid ion chromatographic separations of small inorganic anions are performed on columns packed with high-pH resistant Zorbax Extend-C18 1.8 microm silica particles. Seven anions (iodate, chloride, nitrite, bromide, nitrate, phosphate, sulphate) are separated with 1.3 and 2 cm long x 0.46 cm I.D. C18 columns coated with the surfactant didodecyldimethylammonium bromide (DDAB). A 40 s separation is achieved at 2 mL/min with a 2.5 mM 4-hydroxybenzoic acid eluent at pH 10. Finally, the DDAB removal procedure is improved to eliminate the pressure build-up caused by precipitation of the surfactant in the column upon uncoating.

Relationship between chlorine consumption and chlorination by-products formation for model compounds

The objective of this research is to investigate the relationship between chlorine decay and the formations of disinfection by-products (DBP), including trichloromethane (TCM) and chloroacetic acid (CAA) in the presence of four model compounds, i.e., resorcinol, phloroglucinol, p-hydroxybenzoic acid, and m-hydroxybenzoic acid. The chlorine degradation in model compounds with OH and/or COOH functional groups were rapid after chlorination. The TCM yields of carboxylic group substituted compounds (3-hydroxybenzoic acid [3-HBA], 4-hydroxybenzoic acid [4-HBA]) were found to be lower than that of the m-dihydroxy substituted compounds. Phloroglucinol, with one more OH substitution group than resorcinol, tends to form significant amounts of CAA after chlorination. However, it was observed that with the COOH substitution of 3-HBA and 4-HBA tend to exhibit more CAA formation potential than resorcinol. The developed parallel second and first-order reaction model for chlorine demand has been successfully utilized for TCM, CAA and DBP formation modeling. A high correlation between CAA and TCM was observed for the model compounds.

A model for the drug release from a polymer matrix tablet—effects of swelling and dissolution

A model for simulating the drug release from a swelling and dissolving polymer tablet is presented and verified to data. The model is based on a mechanistic approach, and it can therefore be employed to study the sensitivity of true physical constants, for instance the drug diffusion coefficient or the drug solubility. The model generates the drug and polymer release profiles and the front positions of the total tablet, the solid core, and of the solid-drug-solubilized-drug interface. The convective contribution to mass transfer is shown to be of great importance. This is most markedly noticed for slowly diffusing drugs. In a simulation with a low value of the drug diffusion coefficient, it is shown that the initial drug release rate is faster than the polymer dissolution rate, followed by a second stage with a slower drug release rate. Furthermore, it is shown that polymer dissolution influences the drug release profile significantly, but not the front position of saturated drug in the gel layer. The model is verified against drug release and polymer dissolution data for the slightly soluble drug Methyl paraben and the soluble drug Saligenin in a poly (ethylene oxide) tablet, resulting in good agreement between model and experiments.

Acceleration of paraben sorption to polyethylene terephthalate: a freeze-thaw phenomenon

The evaluation of preservative stability in a formulation throughout its life cycle (production, shipping, and storage) is an important part of product development and essential to ensuring that potential microbial contamination is satisfactorily controlled. This work investigates the unexpected losses of propyl and butylparaben in oral solutions packaged in polyethylene terephthalate (PET) bottles. The samples endured a temperature-cycling study that was designed to simulate extreme temperature fluctuations that could be encountered during product shipping and handling. An investigation into the preservative-package interaction indicated that the paraben preservatives precipitate as a result of the freezing process. The precipitated parabens at the bottom of the bottle dissolve as the solution warms. Without agitation of the solution, the local concentration of the parabens in the vicinity of the dissolving solids increases and is higher than in the oral solution at large. It appears that the combination of the localized high paraben concentration and increased temperature (50 degrees C) increases the kinetics of paraben sorption.

Influence of Crystal Structure on the Compaction Properties of n-Alkyl 4-Hydroxybenzoate Esters (Parabens)

PURPOSE

The aim of the study is to examine the influence of slip planes on the nanoindentation hardness and compaction properties of methyl, ethyl, n-propyl, and n-butyl 4-hydroxybenzoate (parabens).

METHODS

Molecular modeling calculations, embodying the attachment energy concept, were performed to predict the slip planes in the crystal lattices, whereas the nanoindentation hardness of the crystals and the tensile strength of directly compressed compacts were measured.

RESULTS

Unlike the other three parabens, methyl paraben has no slip planes in its crystal lattice, and its crystals showed greater nanoindentation hardness, corresponding to lower plasticity, whereas its tablets exhibited substantially lower tensile strength than those of ethyl, propyl, or butyl paraben.

CONCLUSIONS

The nanoindentation hardness of the crystals and the tensile strength of directly compressed tablets were each found to correlate directly with the absence or presence of slip planes in the crystal structures of the parabens because slip planes confer greater plasticity. This work presents a molecular insight into the influence of crystal structural features on the tableting performance of molecular crystals in general and of crystalline pharmaceuticals in particular.

Antioxidant flavonol glycosides from Schinus molle

Chromatographic separation of aqueous MeOH extract of the leaves of Schinus molle L. has yielded two new acylated quercetin glycosides, named isoquercitrin 6''-O-p-hydroxybenzoate (12) and 2''-O-alpha-L-rhamnopyranosyl-hyperin 6''-O-gallate (13), together with 12 known polyphenolic metabolites for the first time from this species, namely gallic acid (1), methyl gallate (2), chlorogenic acid (3), 2''-alpha-L-rhamnopyranosyl-hyperin (4), quercetin 3-O-beta-D-neohesperidoside (5), miquelianin (6), quercetin 3-O-beta-D-galacturonopyranoside (7), isoquercitrin (8), hyperin (9), isoquercitrin 6''-gallate (10), hyperin 6''-O-gallate (11) and (+)-catechin (14). Their structures were established on the basis of chromatographic properties, chemical, spectroscopic (UV, 1H, 13C NMR) and ESI-MS (positive and negative modes) analyses. Compounds 4-9 and 11 exhibited moderate to strong radical scavenging properties on lipid peroxidation, hydroxyl radical and superoxide anion generations with the highest activities shown by 6 and 7 in comparison with that of quercetin as a positive control in vitro.