The analysis of methylxanthine fractions obtained from Camellia sinensis cultivated in Turkey and effects on the in vitro inhibition of CYP2D6 enzyme.

Tea is a worldwide consumed herbal beverage and it was aimed in this study to reveal the major fractions of green and black tea in order to enlighten the in vitro inhibition potency on the well-known drug metabolizing enzyme CYP2D6 activity. Methylxanthine fractions were extracted from green and black tea and a yield of 0.265 g (1.06%) for 25 g of dried black tea and 0.302 g (1.2%) for 25 g of green tea was calculated. High-performance liquid chromatography analysis represented that the major components of the methylxanthine fractions were caffeine, theobromine, and theophylline. Methylxanthine content of black tea was 368.25 ± 4.6 µg/ml caffeine, 89.30 ± 2.3 µg/ml theobromine, and 3.40 ± 0.5 µg/ml theophylline, whereas that of green tea was 176.50 ± 3.7 µg/ml caffeine, 53.85 ± 1.4 µg/ml theobromine, and 2.06 ± 0.7 µg/ml theophylline. The results of concentration-dependent inhibition studies were 76% green tea, 75% black tea, and 55% caffeine at concentration of 10 mg/ml. The inhibition rates of green and black tea on CYP2D6 activity were 76% and 75%, respectively, where that of quinidine, the well-known inhibitor of CYP2D6, was 82%. Our results indicate that green and black tea is very likely to modify the CYP2D6 enzyme activity.

Finger sweat analysis enables short interval metabolic biomonitoring in humans.

Metabolic biomonitoring in humans is typically based on the sampling of blood, plasma or urine. Although established in the clinical routine, these sampling procedures are often associated with a variety of compliance issues, which are impeding time-course studies. Here, we show that the metabolic profiling of the minute amounts of sweat sampled from fingertips addresses this challenge. Sweat sampling from fingertips is non-invasive, robust and can be accomplished repeatedly by untrained personnel. The sweat matrix represents a rich source for metabolic phenotyping. We confirm the feasibility of short interval sampling of sweat from the fingertips in time-course studies involving the consumption of coffee or the ingestion of a caffeine capsule after a fasting interval, in which we successfully monitor all known caffeine metabolites as well as endogenous metabolic responses. Fluctuations in the rate of sweat production are accounted for by mathematical modelling to reveal individual rates of caffeine uptake, metabolism and clearance. To conclude, metabotyping using sweat from fingertips combined with mathematical network modelling shows promise for broad applications in precision medicine by enabling the assessment of dynamic metabolic patterns, which may overcome the limitations of purely compositional biomarkers.

Electrochemical sensing platform based on covalent organic framework materials and gold nanoparticles for high sensitivity determination of theophylline and caffeine.

A new covalent organic framework (COF) has been prepared with 1,3,6,8-tetra(4-formyl phenyl) pyrene (TFPPy) and 2,6-diaminopyridine (DP) as building units through a Schiff base reaction by a simple tube oven heating procedure and the structure of the COF has been characterized in detail. The obtained DP-Py COF is employed to fabricate a novel electrochemical sensing platform for sensitive and selective determination of theophylline (TP) and caffeine (CAF) simultaneously through compounding with AuNPs; the peak positions of TP and CAF are 0.95 V and 1.28 V, respectively. The synergistic effect between DP-Py COF and AuNPs effectively enhances the analytical sensitivity for the target analytes. Under the optimized experimental conditions, the electrochemical sensing platform shows a sensitive voltammetric response and wide linear range to both TP and CAF, and the detection limits are 0.19 µM and 0.076 µM (S/N = 3), respectively. This method has been successfully used for the determination of TP and CAF in compound paracetamol capsules and black tea samples. The recovery and relative standard deviations (RSD) of TP are 99.3~101% and 97.6~101% and 1.3~2.0% and 1.3~2.1%, respectively, and the recovery and RSD of CAF are 96.1~102% and 99.4~104% and 2.8~3.9% and 1.7~3.2%, respectively. Compared with traditional detection methods, the constructed sensing platform has better performance and is expected to be widely used also in other real sample analyses.

Solvent and temperature effect of accelerated solvent extraction (ASE) coupled with ultra-high-pressure liquid chromatography (UHPLC-PDA) for the determination of methyl xanthines in commercial tea and coffee.

BACKGROUND: Methyl xanthines (MX), known for its psychostimulant effect, occurs mostly in tea and coffee samples. However most of the market available products does not mention the proper amount and quality of MX present where, its consumption in high amount may pose health risks. AIM OF THE STUDY: To develop and validate a fast, efficient and reliable method of MX extraction along with a sensitive, rapid and precise method for simultaneous analysis of MX i.e. Theobromine (TB), Theophylline (TH) and Caffeine (C), with application in commercial tea and coffee samples. MATERIALS AND METHODS: Accelerated Solvent Extraction (ASE) was utilized for the first time to extract MX, whereas UHPLC-DAD was applied in order to quantify MX. RESULTS: ASE resulted a high extract yield (940.22 ± 192.28 mg/g) with optimized conditions of temperature (100 °C) and solvent (MeOH). UHPLC-DAD showed retention time (min) of 1.51 (TB), 1.81 (TH), 2.30 (C) with r2 values (0.980-0.988). Average MX (µg/mL) was as; TB (14.73 ± 20.9), TH (32.05 ± 55.5), C (121.87 ± 32.3). The method application in commercial samples showed a high extract yield with MX concentration (mg/g) as; TB (0.13-0.38), TH (0-0.55), C (7.14-11.20). Temperature and solvent variation showed important correlation with samples in terms of extraction yield. CONCLUSION: ASE-UHPLC/DAD revealed a fast and sensitive method of MX extraction, quantification and quality determination in market available tea and coffee samples.

Preparation of porous aromatic framework modified graphene oxide for pipette-tip solid-phase extraction of theophylline in tea.

A new material called as porous aromatic frameworks modified graphene oxide (PAFs-GO) was synthesized, and it was used as an adsorbent in pipette-tip SPE for the effective purification and enrichment of theophylline in tea sample by HPLC. The properties of PAFs-GO were characterized by field emission SEM, FTIR, thermogravimetry analysis and Brunauer Emmett Teller N2 adsorption-desorption analysis. The results of static adsorption and dynamic adsorption test showed PAFs-GO had higher adsorption ability (93.25 mg/g) than graphene oxide. The LOD and LOQ of the method were 0.0141 and 0.0471 µg/mL, respectively. The acceptable method reproducibility was found as intra- and inter-day precisions, yielding the RSDs <4.62%. By introducing PAFs as support skeleton, the specific surface area of GO was effectively increased, and the penetrability was improved. Studies showed that the proposed method had been successfully applied for purification and enrichment of theophylline in complex tea matrix.

A Rapid and Accurate Method for the Determination of Methylxanthines in Different Nervous System Stimulant Beverages.

Background: Caffeine, theophylline, and theobromine are methylxanthines commonly found in coffee, tea, cola, and cocoa. Other sources may be soft drinks or energy drinks. All of them are stimulants of the nervous system and can be used for the treatment of some diseases. The three xanthines produce addiction with typical abstinence symptoms. Among young people, the consumption of energy beverages is increasing, and the growing market causes concern about the caffeine intake. To evaluate intake of methylxanthines, their accurate determination can be helpful. Methods: A simple method for their determination without sample pretreatment was applied to beverages, including coffee, tea, cola, and energy drinks. The separation was achieved by LC with UV detection. The method was validated in terms of linearity, LOD and LOQ, accuracy, and reproducibility. Results: The drinks were directly injected after a filtration, and no matrix effect was demonstrated. The procedure proved to be simple, time saving, accurate, and reproducible and may be recommended for reliable assays in routine work. The investigated samples showed a range of caffeine concentration from 100 to 3050 mg/L. Possible intake of methylxanthines from miscellaneous types of drinks was assessed considering the European Food Safety Authority Opinion on the safety of caffeine consumption. Our results were in good agreement with other authors. Conclusions: A fast and accurate method for the simultaneous determination of three xanthynes in beverages was validated. The selected strategy has proved to be fit-for-purpose by applying it to different nervous system stimulant drinks. Highlights: A simple and time saving procedure was proposed for the separation, detection, and quantitation of three methylxantynes in nervous system stimulant drinks. No sample preparation was needed, and speculation could be made about the possible intake of them from beverages.

Effects of hydroalcoholic and enzyme-assisted extraction processes on the recovery of catechins and methylxanthines from crude and waste seeds of guarana (Paullinia cupana).

Catechins and methylxanthines are natural molecules in guarana (Paullinia cupana) that are associated with antioxidant and stimulatory effects in the human body. There are few natural sources of these antioxidants. The most popular molecule used in foods and beverages is caffeine, which, most of the time, is derived from synthetic sources. In this work, cold hydroalcoholic (CHM), hot hydroalcoholic (HHM), and aqueous enzymatic maceration (AEM) were applied to crude (CG) and waste guarana seeds (WG) to process these materials into natural added-value products with enhanced levels of catechin, epicatechin, epicatechin gallate, caffeine, theobromine and theophylline. The highest level of catechins and methylxanthines was extracted with HHM. Nevertheless, AEM enhanced the global yield in the extract, probably due to the solubilization of other substances. The maceration procedures applied to guarana contributed to the valorization of this plant crop by providing antioxidant sources with clear applications in food and nonfood industries.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers for the dispersive magnetic solid-phase microextraction of green tea.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers grafted on silica were developed for the selective recognition and separation of theophylline, theobromine, (+)-catechin hydrate, and caffeic acid from green tea through dispersive magnetic solid-phase microextraction. A new ternary deep eutectic solvent was adopted as a functional monomer. The materials obtained were characterized by FTIR spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, NMR spectroscopy, and powder X-ray diffraction. The practical recovery of the theophylline, theobromine, (+)-catechin hydrate, and caffeic acid isolated with ternary deep eutectic solvent magnetic molecularly imprinted polymers in green tea were 91.82, 92.13, 89.96, and 90.73%, respectively, and the actual amounts extracted were 5.82, 4.32, 18.36, and 3.69 mg/g, respectively. The new method involving the novel material coupled with dispersive magnetic solid-phase microextraction showed outstanding recognition, selectivity and excellent magnetism, providing a new perspective for the separation of bioactive compounds.

Simultaneous determination of theophylline and caffeine on novel [Tetra-(5-chloroquinolin-8-yloxy) phthalocyanato] manganese(III)-Carbon nanotubes composite electrode.

This work reports the synthesis of new symmetrically substituted manganese(III) phthalocyanine (2eOHMnPc) (2) containing tetra 5-chloroquinolin-8-yloxy group at the peripheral position for the first time. Manganese(III) phthalocyanine (2) was synthesized by cyclotetramerization of 4-(5-chloroquinolin-8-yloxy)phthalonitrile (1) in the presence of corresponding metal salt (manganese(II) chloride). This peripherally substituted phthalocyanine complex (2) was purified by column chromatography and characterized by several techniques such as IR, mass and UV-Visible spectral data. This novel synthesized phthalocyanine was mixed with multiwalled carbon nanotubes in order to prepare the novel catalytic surface on glassy carbon electrode for theophylline and caffeine detection in acidic medium. The novel composite electrode surfaces were characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Individual and simultaneous determination of theophylline and caffeine were studied by differential pulse voltammetry. The detection limits were individually calculated for theophylline and caffeine as 6.6 × 10-9 M and 5.0 × 10-8 M, respectively. In simultaneous determination, LODs were calculated for theophylline and caffeine as 8.1 × 10-9 M and 3.0 × 10-7 M, respectively. The practical applicability of the proposed modified electrode was tested for the determination of theophylline and caffeine in green tea, cola and theophylline serum.

Application of HRAM screening and LC-MS/MS confirmation of active pharmaceutical ingredient in "natural" herbal supplements.

The growing market of herbal remedies worldwide could pose severe problems to consumers' health due to the possible presence of potentially harmful, undeclared synthetic substances or analogues of prescription drugs. The present work shows a simple but effective approach to unequivocally identify synthetic anorectic compounds in allegedly 'natural' herbal extracts, by exploiting liquid chromatography/time of flight (Q-TOF LC/MS) technology coupled to liquid chromatography/triple quadrupole (LC-MS/MS) confirmation and quantitation. The procedure was applied to five tea herbal extracts and pills sold as coadjutant for weigh loss. The method exploited liquid-liquid sample extraction (LLE) and separation in a C18 (2.1mm×150mm, 1.8µm) column. QTOF acquisitions were carried out both in scan mode and all ion MS/MS mode and results were obtained after search against ad hoc prepared library. Sibutramine, 4-hydroxyamphetamine, caffeine and theophylline were preliminary identified samples. Confirmation and quantitation of the preliminary identified compounds were obtained in LC-MS/MS after preparation of appropriated standards. Sibutramine, caffeine and theophylline were finally confirmed and quantitate.

An aptamer nanopore-enabled microsensor for detection of theophylline.

This paper reports an aptamer-based nanopore thin film sensor for detecting theophylline in the buffer solution and complex fluids including plant extracts and serum samples. Compared to antibody-based detection, aptamer-based detection offers many advantages such as low cost and high stability at elevated temperatures. Experiments found that this type of sensor can readily detect theophylline at a concentration as low as 0.05µM, which is much lower than the detection limit of current lab-based equipment such as liquid chromatography (LC). Experiments also found that the aptamer-based sensor has good specificity, selectivity, and reasonable reusability with a significantly improved dynamic detection range. By using the same nanopore thin film sensors as the reference sensors to further mitigate the non-specific binding effect, the theophylline in plant extracts and serum has been detected. Only a small amount (~1µL) of plant extracts or serum samples is required to measure theophylline. Its low cost and ease-of-operation make this type of sensor suitable for point-of-care application to monitor the theophylline level of patients in real time.

Poly(para-phenyleneethynylene)-Sensor Arrays Discriminate 22 Different Teas.

Two nine-element sensor arrays, consisting of either three cationic poly(para-phenyleneethynylene)s (PPE) or the same PPEs complexed by cucurbituril[8] (CB[8]) at pH 3, 7, and 13 in water, discriminate 22 different teas and some of their small molecule components, including caffeine, theobromine and theophylline. Both arrays distinguish all of the black, green and oolong teas. The discrimination occurs by differential fluorescence modulation of the components of the sensor array and the treatment of the collected data by linear discriminant analysis. The signal is generated by either simple quenching (PPE only array) or the disruption of the PPE/CB[8] complex and quenching of the complex's or the PPEs' fluorescence through the polyphenolic colorants of the teas. Added amino acids, theobromine, theophylline, and caffeine give a fluorescence turn on of the PPE-CB[8] array, due to the disruption of the self-assembled complex, while for the PPE-alone tongue only caffeine, theobromine, and theophylline elicited useful fluorescence response. Both tongues discriminate different teas without any problem.

Rapid assessment of bioactive phenolics and methylxanthines in spent coffee grounds by FT-NIR spectroscopy.

Spent coffee grounds (SCGs) are a great source of bioactive compounds with interest to pharmaceutical and cosmetic industries. Phenolics and methylxanthines are the main health related compounds present in SCG samples. Content estimation of these compounds in SCGs is of upmost importance in what concerns their profitable use by waste recovery industries. In the present work, near-infrared spectroscopy (NIRS) was proposed as a rapid and non-destructive technique to assess the content of three main phenolics (caffeic acid, (+)-catechin and chlorogenic acid) and three methylxanthines (caffeine, theobromine and theophylline) in SCG samples obtained from different coffee brands and diverse coffee machines. The content of these compounds was determined for 61 SCG samples by HPLC coupled with diode-array detection. Partial least squares (PLS) regression based models were calibrated to correlate diffuse reflectance NIR spectra against the reference data for the six parameters obtained by HPLC. Spectral wavelength selection and number of latent variables were optimized by minimizing the cross-validation error. PLS models showed good linearity with a coefficient of determination for the prediction set (Rp(2)) of 0.95, 0.92, 0.88, 071 and 0.84 for caffeine, caffeic acid, (+)-catechin, chlorogenic acid and theophylline, respectively. The range error ratio (RER) was higher for caffeine (17.8) when compared to other compounds (12.0, 10.1, 7.6 and 9.2, respectively for caffeic acid, (+)-catechin, chlorogenic acid and theophylline). Moreover, the content of caffeine could be used to predict the antioxidant properties of SCG samples (R=0.808, n=61), despite not presenting this property itself. The results obtained confirmed that NIRS is a suitable technique to screen SCG samples unveiling those with high content of bioactive compounds, which are interesting for subsequent extraction procedures.

Predictive evaluation of pharmaceutical properties of direct compression tablets containing theophylline anhydrate during storage at high humidity by near-infrared spectroscopy.

BACKGROUND: Theophylline anhydrate (TA) in tablet formulation is transformed into monohydrate (TH) at high humidity and the phase transformation affected dissolution behavior. OBJECTIVE: Near-infrared spectroscopic (NIR) method is applied to predict the change of pharmaceutical properties of TA tablets during storage at high humidity. METHODS: The tablet formulation containing TA, lactose, crystalline cellulose and magnesium stearate was compressed at 4.8 kN. Pharmaceutical properties of TA tables were measured by NIR, X-ray diffraction analysis, dissolution test and tablet hardness. RESULTS: TA tablet was almost 100% transformed into TH after 24 hours at RH 96%. The pharmaceutical properties of TA tablets, such as tablet hardness, 20 min dissolution amount (D20) and increase of tablet weight (TW), changed with the degree of hydration. Calibration models for TW, tablet hardness and D20 to predict the pharmaceutical properties at high-humidity conditions were developed on the basis of the NIR spectra by partial least squares regression analysis. The relationships between predicted and actual measured values for TW, tablet hardness and D20 had straight lines, respectively. CONCLUSIONS: From the results of NIR-chemometrics, it was confirmed that these predicted models had high accuracy to monitor the tablet properties during storage at high humidity.

Biofunction-assisted aptasensors based on ligand-dependent 3' processing of a suppressor tRNA in a wheat germ extract.

We have developed a novel type of biofunction-assisted aptasensor that harnesses ligand-dependent 3' processing of a premature amber suppressor tRNA and the subsequent amber suppression of a reporter gene in a wheat germ extract.

Alkaloids and athlete immune function: caffeine, theophylline, gingerol, ephedrine, and their congeners.

Plant alkaloids are found in foods, beverages, and supplements consumed by athletes for daily nutrition, performance enhancement, and immune function improvement. This paper examined possible immunomodulatory roles of alkaloids in exercise contexts, with a focus on human studies. Four representative groups were scrutinized: (a) caffeine (guaranine, mateine); (b) theophylline and its isomers, theobromine and paraxanthine; (c) ginger alkaloids including gingerols and shogaol; and (d) ephedra alkaloids such as ephedrine and pseudoephedrine. Emerging or prospective alkaloid sources (Goji berry, Noni berry, and bloodroot) were also considered. Human in vitro and in vivo studies on alkaloids and immune function were often conflicting. Caffeine may be immunomodulatory in vivo depending on subject characteristics, exercise characteristics, and immune parameters measured. Caffeine may exhibit antioxidant capacities. Ginger may exert in vivo anti-inflammatory effects in certain populations, but it is unclear whether these effects are due to alkaloids or other biochemicals. Evidence for an immunomodulatory role of alkaloids in energy drinks, cocoa, or ephedra products in vivo is weak to nonexistent. For alkaloid sources derived from plants, variability in the reviewed studies may be due to the presence of unrecognized alkaloids or non-alkaloid compounds (which may themselves be immunomodulatory), and pre-experimental factors such as agricultural or manufacturing differences. Athletes should not look to alkaloids or alkaloid-rich sources as a means of improving immune function given their inconsistent activities, safety concerns, and lack of commercial regulation.

Molecular and biochemical characterization of caffeine synthase and purine alkaloid concentration in guarana fruit.

Guarana seeds have the highest caffeine concentration among plants accumulating purine alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of purine alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein.

Electrochemical determination of theophylline in foodstuff, tea and soft drinks based on urchin-like CdSe microparticles modified glassy carbon electrode.

A simply electrochemical method based on CdSe microparticles modified glassy carbon electrode (GCE) was developed to determine theophylline using cyclic voltammetry and differential pulse voltammetry. Theophylline showed a well-defined oxidation peak at the fabricated electrode in phosphate buffer solution and the oxidation peak current is much higher than that at the bare GCE, indicating that CdSe can effectively improve the oxidation of theophylline. Several effect factors on theophylline determination were optimised, such as CdSe amount, solution pH, scan rate and accumulation time. Under the optimal conditions, the oxidation peak current of theophylline was proportional to its concentration in the range of 1.0-40 and 40-700 µM with a correlation coefficient of 0.9974 and 0.9956, respectively. The limit of detection was estimated to be 0.4 µM (S/N=3). The developed method showed good reproducibility and excellent selectivity. The fabricated electrode was successfully used to determine theophylline in tea, carbonated cola drink, fruit juice drink, fermented milk drink and preserved fruit with acceptable recovery.

Development of a chromatographic low pressure flow injection system: application to the analysis of methylxanthines in coffee.

In this work, the coupling of a commercial monolithic column to a traditional low pressure FIA system is proposed for the analysis of theobromine, theophylline and caffeine in coffee brewed samples using UV detection. The parameters mobile phase composition, flow rate and loop volume were evaluated and discussed considering the various chromatographic parameters in order to enable resolution of the methylxanthines studied within the coffee brewed sample matrix. The analyses of methylxanthines in coffee brewed samples by the proposed methodology were in good agreement with those obtained by the reference procedure based on HPLC. Relative errors were below 6% for all samples analyzed. Detection limits in the selected experimental conditions were within 10(-6)M range for theobromine and theophylline, and 10(-5) M for caffeine. The determination rate of the three methylxanthines for coffee brewed samples was ca of 10 h(-1). The main advantage of the proposed flow system was the possibility to perform chromatographic separations in low pressure flow systems. This substantial improvement was achieved due to the compatibility of monolithic columns within the flow injection system surpassing in this way one of the main handicaps of traditional flow analysis systems. Additional features of the strategy presented were low cost, efficiency, high versatility and low reagent consumption comparing to HPLC methodologies usually followed in the case study herein presented.

Zinc-pectinate beads as an in vivo self-assembling system for pulsatile drug delivery.

Zinc-pectinate beads are interesting drug carriers for oral delivery. In order to investigate their in vitro and in vivo release behaviour, ionotropic gelation was used to entrap theophylline into calcium- or zinc-pectinate beads. Beads were investigated in vitro for their particle properties, especially the release kinetic in different media, and their in vivo pharmacokinetic parameters were tested in rats. Particle size varied between 1.8 and 2.8mm and encapsulation rates between 27 and 30% for Ca- and Zn-pectinate beads, respectively. While Ca-pectinate beads revealed a relative fast disintegration, drug release profiles from Zn-pectinate beads were very much release medium-dependent. Especially, in the presence of phosphate ions, the release from Zn-pectinate beads was blocked at 20% and 40% of the total drug load when tested in phosphate buffer or simulated colonic medium. In vivo Zn-pectinate beads (t(max): 12.0 ± 0.1h) led to a significant lag time for the theophylline absorption compared to Ca-pectinate (t(max): 6.0 ± 2.8h) or free theophylline (t(max): 2.5 ± 2.1h). This delayed release was attributed to the formation of a zinc phosphate coating in vitro and in vivo inducing the retention of theophylline release. Zn-pectinate beads exhibit interesting properties due to its potential as pulsatile delivery system induced by the in situ formation of Zn phosphate, while Ca-pectinate was found to be of limited suitability for controlled release of theophylline.