Artificial Intestinal Juice Research Articles

Effects of Alginate Oligosaccharide Mixture on the Bioavailability of Lysozyme as an Antimicrobial Agent.

In this study, we report an oral drug delivery system without any additional process using pH-sensitive biopolymer, alginate, and alginate oligosaccharide with lysozyme as a model drug. These biopolymers exhibited pH-sensitive characteristics such as shrinking at acidic pH and eroding with dissolution at alkaline pH. The incorporation of lysozyme and biopolymers was performed an artificial intestinal juice (pH 6.8). The immobilization efficiency and lysozyme stability in gastric juice (pH 1.2) has been tested by E coil antimicrobial activity. The lysozyme without biopolymer immobilization lost approximately 80-90% of antimicrobial activity than that of pure lysozyme. However, the pH-sensitive biopolymer-controlled lysozyme maintained similar antimicrobial activity compared to that of pure lysozyme (50-90% of cell mortality). Therefore, this simple, easy, and rapid system can be effectively and practically applied for pathogen treatment for in vivo oral drug delivery.

Viability of Microencapsuls Containing Lactic Acid Bacteria under Stimulated Gastrointestinal Conditions while Incorporated in Steamed Rice Cake

The microencapsulation of Lactobacillus acidophilus NCIM2902 with alginate offers an effective means of delivery of viable bacterial cells in levels appropriate to the colon and helps in maintaining their survival during simulated gastric and intestinal juice. Non-encapsulated cells were completely destroyed when exposed to artificial gastric juice (AGJ) of pH 1.2 after 2h of incubation at 37°C, while the treatment declined the viable count of encapsulated samples only by 4 log. Encapsulated cells exhibited a significantly higher resistance to artificial intestinal juice (AIJ) than non encapsulated samples. Sensory properties of SRC were improved by the addition of encapsulated L. acidophilus.

Selected excipients and surfactants in oral solid dosage form with extract of Phaseoli pericarpium (Phaseolus vulgaris L.)

Summary Introduction: The common bean (Phaseolus vulgaris L.) is an annual plant grown in many countries all over the world including its different varieties in Poland. Herbal raw material are elongated pods – pericarp. Phaseoli pericarpium decreases the glucose blood level. Phaseoli pericarpium extracts manifest duretic properties, can be used in the treatment of edema, kidney diseases with decreased urinary excretion, nephrolithiasis. Objectives: To investigate the usefullness of selected excipients as carriers of dry extract from Phaseolus vulgaris pericarp. Methods: The method of direct tableting was used. In the further stage, the obtained tablets were subjected to appropriate tests. The first stage of the study evaluates Prosolv SMCC 50, PROSOLV EASYtab, EMDEX, Carmellose calcium and PRUV. These were used to manufacture 4 batches of tablets. In the second stage, an oral solid dosage was manufactured on the basis of the formulation composition of batch 1 tablets (Phaseoli pericarpium extract, Prosolv SMCC 50, PRUV). Then, different surfactants (cholesterol oxyethylate nTE = 30, cholesterol oxyethylate nTE = 40, Rofam nTE = 50), were successively added to this formulation, to obtain 3 batches of tablets. All 7 batches were manufactured in the Erweka tableting machine. Then, they were subjected to morphological tests and physicochemical evaluation. The release of active substances to 3 selected acceptor fluids (water, artificial gastric juice, artificial intestinal juice) was measured in accordance with the requirements of the general and specific monographs in European Pharmacopoeia 7. Results: The manufactured tablets had a smooth uniform surface with no stains, spalls or mechanical damage and yellow color originating from the extract. The obtained tablets, with surfactants in their composition, demonstrated pharmaceutical availability slightly higher than batch 1 tablets without surfactants. Conclusions: Excipients applied in appropriate proportions appear to be useful in the manufacturing of uncoated tablets containing extract of Phaseoli pericarpium.

Preparation and investigation of mefenamic acid - polyethylene glycol - sucrose ester solid dispersions.

Mefenamic acid (MA) is a widely used non-steroidal antiinflammatory (NSAID) drug. The adverse effects typical of NSAIDs are also present in the case of MA, partly due to its low water solubility. The aim of this study was to increase the water solubility of MA in order to influence its absorption and bioavailability. Solid dispersions of MA were prepared by the melting method using polyethylene glycol 6000 and different types (laurate, D-1216; palmitate, P-1670; stearate, S-1670) and amounts of sucrose esters as carriers. The X-ray diffraction results show that MA crystals were not present in the products. Dissolution tests carried out in artificial intestinal juice showed that the product containing 10 % D-1216 increased water solubility about 3 times. The apparent permeability coefficient of MA across human Caco-2 intestinal epithelial cell layers was high and, despite the difference in solubility, there was no further increase in drug penetration in the presence of the applied additives.

The Gastrointestinal Tract Metabolism and Pharmacological Activities of Grosvenorine, a Major and Characteristic Flavonoid in the Fruits of Siraitia grosvenorii.

Grosvenorine is the major flavonoid compound of the fruits of Siraitia grosvenorii (Swingle) C. Jeffrey, a medical plant endemic to China. In the present study, for the first time, the grosvenorine metabolism in an in vitro simulated human gastrointestinal tract (including artificial gastric juice, artificial intestinal juice and intestinal flora), as well as its pharmacological activities (including anti-complement, antibacterial and antioxidant activities), was investigated. The results showed that grosvenorine was metabolized by human intestinal flora; its four metabolites were isolated by semi-preparative HPLC and identified by NMR as kaempferitrin, afzelin, α-rhamnoisorobin, and kaempferol. Further pharmacological evaluation showed that grosvenorine exhibited good antibacterial and antioxidant activities, with its metabolites possessing more potent activities. Although grosvenorine did not present obvious anticomplement activity, its metabolites showed interesting activities. This study revealed that intestinal bacteria play an important role in the gastrointestinal metabolism of grosvenorine and significantly affect its pharmacological activities.

Determination of borneol in Fufang Danshen intestinal adhesion pellets and study its in vitro dissolution in different dosage form

The borneol was included with β-CD and prepared Fufang Danshen intestinal adhesion pellets. GC method for determination of borneol in Fufang Danshen intestinal adhesion pellets was established to study its in vitro dissolution and make a comparison with the Fufang Danshen tablet, in this way, the rationality of dosage form was evaluated. The first method of dissolution determination was used for determining the in vitro dissolution of borneol in Fufang Danshen intestinal adhesion pellets in artificial intestinal juice, and Fufang Danshen tablet in artificial gastric juice and intestinal juice, respectively. Result shows: the concentration of borneol in Fufang Danshen intestinal adhesion pellets and Fufang Danshen tablet was 0.79% and 0.80%, respectively. Its in vitro dissolution was nearly 70% within 12 h in Fufang Danshen intestinal adhesion pellets, and in Fufang Danshen tablet, the dissolution was about 60% within 20 min and more than 90% within 40 min, and in artificial gastric juice, was less than 20% within 40 min but more than 80% till 150 min. Research suggests that in comparison with Fufang Danshen tablet, in vitro dissolution of borneol in the Fufang Danshen intestinal adhesion pellets showed an obvious sustained release behavior. The borneol in Fufang Danshen intestinal adhesion pellets was included with β-CD and prepared enteric preparations. To some extent, the stimulation on stomach and intestinal mucosa can be reduced and safety can be improved.

Microencapsulation of new probiotic formulations for gastrointestinal delivery: in vitro study to assess viability and biological properties.

The paper describes the preparation of new probiotic formulations based on chitosan-coated alginate microcapsules containing three different probiotic strains, Lactobacillus plantarum PBS067, Lactobacillus rhamnosus PBS070, and Bifidobacterium animalis subsp. lactis PBS075 taken individually and as a mixture of them. The effects of microencapsulation on the viability of the strains in conditions simulating the gastrointestinal tract and under industrial processes conditions were studied. In addition, an evaluation of their probiotic properties was also investigated by in vitro tests on the human intestinal cell line HT-29 to explore the effect of microencapsulation on health beneficial effect of the considered strains. Non-encapsulated cells were completely destroyed when exposed to simulated gastric juice and other stress conditions, while encapsulated cells exhibited a significantly higher resistance to artificial intestinal juice and heat and osmotic treatment. Moreover, in this study, the effect of the various microencapsulated probiotic strain formulations was compared with analogous formulations also containing the β-glucan Pleuran. The microencapsulation effectively protected the selected bacteria, as single strain and as a mixture of the three strains in both the formulations with and without Pleuran, from simulating gastrointestinal tract and industrial process conditions in delivering the viable cells without any significant adverse effect on their functionalities. The comparative study of the immunomodulatory properties of each single strain and the mixture of the three strains revealed a synergistic effect of the probiotic mixture, but no appreciable difference between the two kinds of formulations could be detected, as the effect of Pleuran is covered by the higher potential of the probiotic strains.

In-vivo and In-vitro Metabolism Study of Timosaponin B-II Using HPLC-ESI-MS n

Timosaponin B-II (TB-II), a representative furostanol saponin in Rhizoma anemarrhenae, has been used as an emperor herb in many Chinese herbal formulas to treat diabetes and senile dementia. However, its metabolism and tissue distribution had not been investigated so far. In this work, a sensitive and specific high-performance liquid chromatography-electrospray ionization tandem mass spectrometry method was applied for the identification of TB-II and its major metabolites in in-vivo and in-vitro samples. Rat urine, feces, plasma and tissues were collected after oral administration of TB-II at a single dose of 300 mg kg−1. Furthermore, TB-II was incubated in artificial gastric juice (AGJ) and artificial intestinal juice (AIJ). As a result, 19 metabolites were detected and identified by comparing their HPLC behavior and MS n spectra profile with those of the parent drug. Moreover, the structures of its five metabolites were identified by using the standards prepared by the acid hydrolysis of TB-II. In addition to the parent drug, 14, 12, 6, 1, 1 and 7 metabolites were detected in rat urine, feces, plasma, heart, kidney and liver, respectively, while no metabolites or the parent drug were found in rat brain, spleen and lung. Seven metabolites appeared in AIJ incubation samples, but the parent drug was absent. Nine metabolites along with the parent drug were observed in AGJ incubation samples. The biotransformation pathways of TB-II mainly included dehydration, deglycosylation, hydroxylation, oxidation and E-ring cleavage. This is the first comprehensive investigation of the in-vivo and in-vitro metabolism of TB-II. The result provided important information for further pharmacological research on TB-II.

Esterification of the Free Carboxylic Group in 3,4-di-O-caffeoylquinic Acid Enhances the Inhibition Activity against Respiratory Syncytial Virus (RSV)

Based on molecular docking analysis, nine alkyl 3,4-di-O-caffeoyl- quinates have been designed. Started from 3,4-di- O-caffeoylquinic acid (3,4-DCQA), all the compounds have been synthesized using thionylchloride as coupling reagent with yields of 56%-72%. By applying plaque reduction assay, the anti-respiratory syncytial virus (RSV) activities of all the compounds were evaluated. The IC50 values of all the derivatives were 2.9 to 7.8 times less than that of 3,4-DCQA itself. Isopropyl 3,4-Di-O-caffeoyl quinate (LS-4) was confirmed as the most active compound with IC50 value of 0.3 μM. It was indicated that hydrophobic groups with 2 to 4 carbon chain length were optimal for the enhancement of anti-RSV activity. Interestingly, all the derivatives showed greater cytotoxicity than 3,4-DCQA. Except LS-5, LS-6 and LS-9, all the derivatives have less toxicity than ribavirin. Furthermore, the stabilities of LS-4 in water, artificial gastric juice (AGJ), and artificial intestinal juice were evaluated, respectively. It was shown that LS-4 is stable in AGJ with the hydrolysis rate of 24.9% after 6 hours incubation at 37°C.

Liquid Chromatography-Tandem Mass Spectrometry for Determination of Aflatoxin B1, Deoxynivalenol and Zearalenone in Artificial Porcine Gastrointestinal Digestive Juice

A rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of aflatoxin B1 (AFB1), deoxynivalenol (DON) and zearalenone (ZEA) in artificial porcine gastrointestinal digestive juices, and successfully applied to the in vitro evaluation of adsorption efficiency of mycotoxin adsorbent. The formula feed was digested by artificial gastric and small intestinal juices in vitro, and then the mycotoxins and adsorbent were added in specific ratios. After incubation and centrifugation, the supernatant was diluted 10-fold and then analyzed by LC-MS/MS. The three mycotoxins were separated on a reversed-phase C18 column using a gradient elution program with 0.2 mM ammonium acetate aqueous solution and 0.1% formic acid in methanol as mobile phases. Qualitative analyses were performed under multiple-reaction monitoring mode, and quantitative analyses were carried out by using isotope internal standard method. Under the optimum conditions, the limit of quantification for AFB1, DON and ZEA was 1, 50 and 40 μg L−1 in gastric digested juice and 0.3, 50 and 20 μg L−1 in intestinal digested juice respectively, and the relative standard deviations (RSDs) were less than 5.0%. Then the thermal stability was investigated by incubating the analytes at 39.0 °C ± 0.5 °C for 1, 2, 5 and 10 h, and the experiment results showed that the three mycotoxins were stable under these conditions. Furthermore, the method was used to evaluate the binding efficacies of eight mineral adsorbents and five organic adsorbents. The mineral binders demonstrated binding efficacies of 85.13%–96.50%, 8.11%–14.71% and 13.67%–29.97% for AFB1, DON and ZEA in gastric digestive juice, and 76.15%–92.96%, 12.29%–31.31%, 0%–23.16% in intestinal digestive juice, respectively. The organic adsorbents exhibited binding efficacies of 7.42%–16.65%, 6.68%–16.24% and 18.56%–38.96% for AFB1, DON and ZEA in gastric digestive juice, and 8.65%–13.42%, 3.83%–23.49%, 24.88%–4.76% in intestinal digestive juice, respectively.

Stability study in biological samples and metabolites analysis of astragaloside Ⅳ in rat intestinal bacteria in vitro

To figure out the stability and intestinal bacteria metabolites of rats in vitro of astragaloside IV ( AST), this research was done to explore the stability of AST in the artificial gastric juice. artificial intestinal juice and rat liver homogenate and the metabolism in rat intestinal in vitro. HPLC was used to calculate the remaining rate of AST in biological samples by measuring the content of AST, while metabolites were determined by combining the methods of TLC, HPLC and LC-MS/MS. It turned out that AST was difficult to metabolize in the artificial gastric juice, artificial intestinal juice and rat liver. Also, the metabolic pathway of AST was stepped by deglycosylation. Firstly, AST was converted to its secondary etabolites (6-O-β-D-glucopyranosyl- cycloastragenol, CMG) by removal of xylose moiety at C-3, then transformed into cycloastragenol (CAG) after hydrolytic removal of the glucose moiety at C-6. All the results suggested that the metabolism of AST in vivo occurs mainly in the intestinal by hydrolysis of glycosyl. In conclusion, hydrolysis of intestinal flora is the main reason that AST metabolizes.

The Effect of in Vitro Digestion on the Structural, Morphologic Characteristics and Fermentability of Raw Banana Starch

This study aimed to observe the effect of in vitro digestion on the structural and morphologic characteristics, and find the relationship between in vitro digestion and colonic fermentation of raw banana starch. After digested by artificial gastric juice and artificial intestinal juice, the starch granules were damaged, but not drastic. X-ray diffractograms showed that the crystal polymorph (C-type) was not changed and the degree of crystallinity was increased after digestion. There were no significant differences in chemical structure according to the infrared spectrum analysis. The swelling power and solubility of the digested starches were greater than that of raw banana starch at all temperatures. Banana starches digested by gastric and intestinal juice presented high fermentability, expressed by total short chain fatty acids. The results may be due to the slight changes on structural and morphologic characteristics. To conclude, passage through the stomach and small intestine increased susceptibility of raw banana starch to further fermentation, to increase the production of metabolically active short chain fatty acids.

Study on Degradation of Radix Isatidis Polypeptide in Artificial Gastrointestinal Environment

Radix Isatidis is a traditional Chinese medicine for treatment of influenza and inflammation in China. In this paper, in order to study the degradation situation of Radix Isatidis polypeptide in artificial gastrointestinal environment, the SDS-PAGE (Sodium dodecyl sulfate-polyacrylamide gel electrophoresis) method was used to detect the degradation of Radix Isatidis polypeptide in artificial intestinal juice and gastric juice, and it showed that Radix Isatidis peptides could be degradated to different degrees. HPLC (High Performance Liquid Chromatography) was used to determine the change of peptides degradation, and it indicated that free amino acid levels did not change significantly. The result after degradation was also detected by BCA method, and it showed that there were still a large number of polypeptides in the liquid. From this experiment we can come to this conclusion that Radix Isatidis polypeptides in artificial gastrointestinal juice mostly degraded into a series of different molecular weight peptides.

Functional evaluations of a new type formula that features a state change from liquid to semi-solidified state depending upon pH

Summary Background & aims Some problems such as gastroesophageal reflux, vomiting and diarrhea are cited complications associated with enteral nutrition. Half-solidified formulas can reduce these problems; however, such formulas cannot be administered through nasogastric tubes, and are, therefore, not as convenient as liquid formulas. To solve these problems, we have developed a new type formula which includes the alginate. It has the functions of both liquid and half-solidified type. In this study, we performed functional evaluations of this new type formula. Methods The state changes of three type formulas in artificial gastric/intestinal juice were compared by evaluating the “solidification rate”. Moreover, in rat stomach, state changes of each formula were evaluated by studying the “intragastric holding rate” and the “intragastric solidification rate”. Results The new type formula could be administered through nasogastric tubes. It changed into a semi-solidified state in artificial gastric juice and liquefied in artificial intestinal juice. In rats, the intragastric solidification rate of the new type formula was 79 ± 3%, and the intragastric holding rate was 80 ± 6%. These results were similar to those observed for the half-solidified formula. Conclusion The new type formula (A) can be administered through nasogastric tubes, (B) changes into the “semi-solidified state” from the liquid state in rat stomach, and (C) changes back to the “liquid state” in intestinal juice. The new type formula changed its state depending on pH. These results suggest that the new type formula has the advantages of both liquid and half-solidified formulas.

Stability of akebia saponin D in gastrointestinal contents of rats

In order to study the stability of akebia saponin D (ASD) in biological fluids in vitro, the determination methods of ASD were established in this study. Akebia saponin D was dissolved in artificial gastric juice, intestinal juice and gastrointestinal contents of rats, respectively, then thermostatically maintained at 37 degrees C. At time intervals after degradation, samples were withdrawn and the concentrations of ASD were determined by HPLC, from which stability of it at different biological specimen was evaluated. As a result, ASD was totally degraded in large intestinal contents of rats in 8 hours. ASD was very stable in artificial gastric juice, intestinal juice and gastric contents of rats. All of the above data proved that ASD was easily degraded by coliform bacteria but stable in acid environment and with the presence of digestive enzyme.

Thymoquinone-loaded PLGA nanoparticles: antioxidant and anti-microbial properties

The aim of the present study was to synthesize and characterize the Thymoquinone (TQ) encapsulated PLGA (poly (dl-lactide-co-glycolide) nanoparticles, and further evaluate for its antioxidant and anti-bacterial activities. TQ is a potential active ingredient of Nigella sativa seed and possess a spectrum of therapeutic properties. Nanoparticles were prepared according to solid-in-oil-in-water (s/o/w) solvent evaporation method. Dynamic laser light scattering (DLS) and SEM studies indicated a mean particle size of < 200 nm. The success of encapsulation was confirmed by FTIR technique, and the encapsulation efficiency (EE) of TQ was determined to be 62%. In vitro drug release study showed a maximum release of TQ at 75% and 54 % respectively for artificial intestinal and gastric juices over the period of 7 days. DPPH radical scavenging activity of the nanoparticles was found to be 71% at 1 mg/ml concentration. It also exhibited antibacterial property against E. coli, Staphylococcus aureus and Salmonella typhi strains, tested using well diffusion method. In conclusion, our study shows that PLGA encapsulated TQ nanoparticle with sustained release property has preserved antioxidant as well as anti-microbial activity, and therefore suggesting its therapeutic applications in various food samples.DOI: http://dx.doi.org/10.3329/icpj.v2i12.17017 International Current Pharmaceutical Journal, November 2013, 2(12): 202-207

Novel Controlled Release Solid Dispersion for the Delivery of Diclofenac Sodium

This study presents development and evaluation of novel sustained release system of diclofenac sodium (DS) prepared by solid dispersion (SD) technique using Eudragit E 100 (EE 100) and/or Eudragit S 100 (ES 100) as carriers. Compatibility of the drug and its crystalline nature in the SD were examined using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The drug was relatively stable, amorphous in the SD. The greater amount of EE100 or ES 100 in the SD slowed down the release rates with smaller dissolution efficiency and hence the mean dissolution time was enhanced. Moreover, combined carriers of EE 100-ES 100 exhibited more dissolution retarding effect than any of the carriers. The release of drug followed anomalous transport in artificial intestinal juice (pH 6.8).

Encapsulation in alginate and alginate coated-chitosan improved the survival of newly probiotic in oxgall and gastric juice

This study was undertaken to develop an optimum composition model for the microencapsulation of a newly probiotic on sodium alginate using response surface methodology. The individual and interactive effects of three independent variables, namely sodium alginate concentration, biomass concentration, and hardening time, were investigated using Box–Behnken design experiments. A second ordered polynomial model was fitted and optimum conditions were estimated. The optimal conditions identified were 2% for sodium alginate, 1010UFC/ml for biomass, and 30min for hardening time. The experimental value obtained for immobilized cells under these conditions was about 80.98%, which was in close agreement with the predicted value of 82.6%. Viability of microspheres (96%) was enhanced with chitosan as coating materials. The survival rates of free and microencapsulated Lactobacillus plantarum TN8 during exposure to artificial gastrointestinal conditions were compared. The results revealed that the encapsulated cells exhibited significantly higher resistances to artificial intestinal juice (AIJ) and artificial gastric juice (AGJ). Microencapsulation was also noted to effectively protect the strain from heating at 65°C and refrigerating at 4°C. Taken together, the findings indicated that microencapsulation conferred important protective effects to L. plantarum against the gastrointestinal conditions encountered during the transit of food.

High-Performance Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometry for Metabolism Study of Timosaponin AIII

A sensitive method based on high-performance liquid chromatography-electrospray ionization tandem mass spectrometry was developed for the determination of timosaponin AIII (TA3) and its in vivo and in vitro metabolites. The rat plasma, urine, feces and tissue samples were collected after oral administration of TA3 at a single dose of 300 mg/kg. TA3 was incubated into artificial gastric juice and artificial intestinal juice. The in vivo and in vitro samples were purified by using liquid-liquid extraction. The structures of metabolites were elucidated by comparing their molecular weights, retention times and tandem mass spectrometric spectra with those of the parent drug. As a result, four metabolites (deglycosylated TA3, two hydroxylated TA3 and timosaponin BII) and the parent drug were found in in vivo and in vitro samples. In addition to the parent drug, one, one and two metabolites were identified in heart, urine and feces, respectively. Only the parent drug was detected in plasma, liver and kidney. One hydroxylation metabolite and TA3 were identified from incubation samples with AGJ, whereas two hydroxylation metabolites and TA3 were detected from the incubation with AIJ. This is the first systematic metabolism study of TA3. The biotransformation pathways of TA3 primarily included deglycosylation, hydroxylation and glycosylation.

Adsorption of indole on KOH-activated mesoporous carbon

Ordered mesoporous carbons with a 3D wormhole-like structure were synthesized by a soft-templating method. The resorcinol-formaldehyde (RF) was used as a carbon source and a triblock copolymer Pluronic F127 was used as a soft templating agent. The molar ratios of Pluronic F127/Resorcinol were changed 0.0027 (RF-F127(1)), 0.0040 (RF-F127(2)) and 0.0053 (RF-F127(3)). The mesoporous carbons were activated using KOH to improve their porosity. After the KOH activation, the micropore volume and surface area of ultramicropore were largely increased for all the mesoporous carbons. The adsorption of indole from a buffer solution and an artificial intestinal juice solution was measured. The KOH-activated carbons showed high adsorption rate for indole in the buffer solution. This result suggests that the existence of mesopores and 3D-interconnected pore structures reduced the diffusion resistance. On the other hand, in the case of the adsorption of indole from the artificial intestinal juice solution, after a certain period, the desorption of indole was observed for K-RF-F127(2) and K-RF-F127(3). Other bulky compounds would diffuse slowly and be adsorbed in place of indole due to a strong interaction. However, the desorption of indole was not observed for K-RF-F127(1), whose mesopore is smaller than the other KOH-activated carbons. These results suggest that both an appropriate mesopore size tuning and an increase in the micropore surface area are essential for developing a high-performance adsorbent for indole.