Acid-base Method Research Articles

Two specific domains of the γ subunit of chloroplast FoF1 provide redox regulation of the ATP synthesis through conformational changes

Chloroplast FoF1-ATP synthase (CFoCF1) converts proton motive force into chemical energy during photosynthesis. Although many studies have been done to elucidate the catalytic reaction and its regulatory mechanisms, biochemical analyses using the CFoCF1 complex have been limited because of various technical barriers, such as the difficulty in generating mutants and a low purification efficiency from spinach chloroplasts. By taking advantage of the powerful genetics available in the unicellular green alga Chlamydomonas reinhardtii, we analyzed the ATP synthesis reaction and its regulation in CFoCF1. The domains in the γ subunit involved in the redox regulation of CFoCF1 were mutated based on the reported structure. An invivo analysis of strains harboring these mutations revealed the structural determinants of the redox response during the light/dark transitions. In addition, we established a half day purification method for the entire CFoCF1 complex from C. reinhardtii and subsequently examined ATP synthesis activity by the acid-base transition method. We found that truncation of the β-hairpin domain resulted in a loss of redox regulation of ATP synthesis (i.e., constitutively active state) despite retaining redox-sensitive Cys residues. In contrast, truncation of the redox loop domain containing the Cys residues resulted in a marked decrease in the activity. Based on this mutation analysis, we propose a model of redox regulation of the ATP synthesis reaction by the cooperative function of the β-hairpin and the redox loop domains specific to CFoCF1.

Effects of edible coatings of chitosan - fish skin gelatine containing black tea extract on quality of minimally processed papaya during refrigerated storage

Papaya fruit is a climacteric fruit that undergoes physical and chemical changes very quickly during storage. The edible coating is one method that can extend the shelf life of minimally processed fruit such as papaya. To improve the effect of edible the mechanical properties and functional value of edible coatings, black tea was added. The research aims to evaluate the application of edible coating from fish gelatin-chitosan enriched with black to the physicochemical characterization of the minimally processed papaya.The research was conducted through the extraction of tuna skin gelatin using the acid-base method. Furthermore, the preparation of edible coating solutions based on chitosan, gelatin, glycerol, and black tea with different concentrations of 0%, 5%, 10%, and 15%. The edible coating solution that has been obtained is then applied to minimally processed papaya fruit and stored for 1, 4, 7, and 10 days to determine the effect of edible coating on the physical, chemical and microbiological characteristics of papaya fruit.The results showed that the addition of black tea extract concentrations of 0%, 5%, 10%, and 15% had no significant effect on the color change of the resulting solution (p > 0.05), while the viscosity and pH occurred during the addition of the concentration to the coating solution which could eat (p < 0.05). Edible coating can suppress the decrease in weight loss and papaya texture. The chemical properties of minimally processed papaya such as pH, total dissolved solids, total titrated acid, antioxidant activity, and total carotenoids increased due to the ripening process and the effect of dissolved substances contained in the edible layer during storage. Total plate count (TPC) showed that edible coating treatment with the addition of black tea extract was able to suppress microbial growth during storage.

Extraction of chitin from white shrimp (Penaeus vannamei) shells using binary ionic liquid mixtures

Binary ionic liquid mixtures (IL) were used for the first time to extract chitin from shrimp shells. Two ionic liquids, 1-ethyl-3-methylimidazole acetate ([EMIM][Ac]) and 1-butyl-3-methylimidazole bromide salt ([BMIM][Br]), were mixed at ratios of 0:1, 1:1, 3:2, 4:1, and 1:0 and the properties of the IL and the characteristics of extracted chitin were investigated. With an increase in proportion of [EMIM][Ac], the viscosity, dielectric constant, and dielectric loss of IL gradually decreased (p < 0.05), whereas the conductivity, radius of gyration increased (p < 0.05). The best quality of chitin using IL (3:2) was achieved when the viscosity, conductivity, and radius of gyration were 0.16 ± 0.00 Pa‧s, 0.30 ± 0.01 S/m, and 0.10 ± 0.00 nm, respectively. The yield of chitin extraction using IL was 35.72 ± 0.31 %, and this was approximately 2.04 times higher than that using the acid-base method (17.50 ± 0.16 %). The Whiteness index (WI) of chitin extracted using IL (3:2) (94.93 ± 0.09) was better than commercial chitin (93.31 ± 0.11), and the secondary structure, surface morphology and thermal stability were similar to commercial chitin. Therefore, the binary ionic liquid mixture can be used as an effective green solvent to extract chitin from shrimp shells.

Development and Validation of New Methods for Quality Control of the Antiviral Substance FAVIPIRAVIR

The introduction into the production of medicinal substances involves the creation of a pharmaceutical dossier, an important component of which is data on pharmaceutical development and quality control methods. The physico-chemical properties of the antiviral substance of favipiravir were investigated, and some basic sections of the analytical documentation were developed. With the help of a complex of physical, chemical, and physico-chemical methods of analysis, the "Identification" test was developed, and the structure of favipiravir was proven. Methods for the determination of related substances by the HPLC with UV detection and the assay of favipiravir by the acid-base titration method, suitable for substance quality control, have been developed. Relative retention times and correction factors for calculating their content are established for all impurities. The methods were validated on the parameters of specificity, accuracy, correctness, and linearity in the studied range of concentrations.

Chitosan electrospun nanofibers derived from Periplaneta americana residue for promoting infected wound healing

Periplaneta americana has been used medicinally for years to treat a wide variety of skin lesions or ulcers. However, a sizable portion of the drug residues that are retained after extraction are routinely thrown away, thus posing a hazard to the environment and depleting resources. In this study, low molecular weight Periplaneta americana chitosan (LPCS) and high molecular weight Periplaneta americana chitosan (HPCS) were extracted from Periplaneta americana residue (PAR) based on the conventional acid-base method and two deacetylation methods. Moreover, the physicochemical properties and structural differences between the above two chitosan and commercial chitosan (CS) were compared using different methods. Next, two nanofibers comprising different ratios of Periplaneta americana chitosan (LPCS or HPCS), polyvinyl alcohol (PVA), and polyethylene oxide (PEO) were prepared and optimized. The above nanofibers exhibited excellent mechanical properties, antibacterial properties, and biocompatibility while facilitating wound healing in an infected rat whole-layer wound model by promoting wound closure, epithelialization, collagen deposition, and inflammation reduction. In brief, this study produced an effective and affordable wound dressing and offered a suggestion for the comprehensive utilization of Periplaneta americana residue.

Self-extracted corn-stalk cellulose/epoxy resin composites

In order to make full use of crop waste stalk, corn-stalk cellulose (CSC) was extracted by acid–base method and used as modifier of epoxy resin (E51) to prepare the self-extracted corn-stalk cellulose/epoxy resin composites (CSCEC). Differential scanning calorimeter (DSC), thermogravimetry (TG) analysis, dynamic mechanical analysis (DMA), morphology analysis by scanning electron microscope (SEM), the mechanical properties by electronic universal testing machine and impact testing machine were used for characterization and analysis. The experimental results showed that when the CSC content was 20 wt%, the impact strength of the composite was 2.50 kJ/m2, which was 127.2% higher than that of pure epoxy resin. When the CSC content was 20 wt%, the Tg of epoxy resin obtained by DMA was the lowest, 167.4 °C, which decreased by 11.3 °C compared with that of pure epoxy resin. The SEM result showed that the fracture surface of the composite became obviously rough and had of obvious folds, which was a ductile fracture. These results indicated that the addition of CSC could toughen the epoxy resin.

Reactivation of the spent Ni/ZnO-based adsorbent with enhanced initial activity for gasoline desulfurization

The widespread application of the S-Zorb technique generates a large quantity of spent Ni/ZnO-based adsorbents which are hazardous wastes. Reactivation and recycling of the spent adsorbents generate huge environmental benefits, which unfortunately has not gained deserved attention. Herein, a modified acid-base coupling method was developed for reactivation of the spent adsorbents. Extra active sites of nickel are introduced into the reactivated adsorbents to improve the initial desulfurization activity. It was carried out by introducing nickel salt into the acid reactivation system followed by the precipitation process during the alkali treatment step. The obtained adsorbents were characterized systematically and the possible reactivation mechanism was disclosed. The newly formed nickel oxides are well dispersed over the reactivated adsorbents and exhibit a strong interaction with support. It favors the increase of hydrogenolysis centers for CS bonds breakage, improving the desulfurization activity. The newly reactivated adsorbent with extra 10 wt% nickel loading shows significantly improved initial desulfurization activity compared with the reactivated adsorbent without extra nickel loading. It even exhibits comparable desulfurization performance to the fresh adsorbent in gasoline desulfurization and the sulfur content in outlet meets the Euro V standard (below 10 μg g−1).

SINTESIS DAN KARAKTERISASI SIFAT FISIK DAN KIMIA KATALIS BENTONIT-ZnO

The use of bentonite clay as a catalyst has been reported by many studies. The catalytic activity of clays is generally not very high. Therefore, the clay must be modified before use. Synthesis and characterization of ZnO (Bentonite-ZnO) modified clay was carried out. This study aimed to determine the physical and chemical properties of modified Bentonite with ZnO. Bentonite was dipped first and then intercalated with ZnO which was expected to form pillars. The synthesized Bentonite-ZnO was characterized according to the benefits of Bentonite-ZnO as a catalyst using X-Ray Diffraction, SEM-EDS, FTIR, surface area using Methylene Blue adsorption method, and surface acid sites using an acid-base titration method. The characterization results showed that the intercalation of ZnO into bentonite did not increase the distance between layers, the catalyst became more homogeneous and there was an increase in the number of Zn elements, the appearance of absorption bands in the 3600; 1600 – 1650; 2900-2850 and 450 cm-1 regions which identified the functional group characteristics of Bentonite-ZnO and surface area and acid sites of 46.357 m2/g and 5.887 x 1022 sites/g, respectively.&#x0D; Keywords: bentonite, catalyst, characterization, pillared, ZnO.

A facile approach for the determination of degree of deacetylation of chitosan using acid-base titration

Several spectroscopic techniques such as nuclear magnetic resonance (NMR), UV-visible, Fourier transform infrared (FT-IR), etc. have been already used for the determination of degree of deacetylation (DD) of chitosan. These techniques involve the interpretation of spectral data apart from sample preparation for obtaining DD of chitosan. In addition, inaccurate interpretation of data sometimes misleads researchers to get an exact value of DD of chitosan. Among them, NMR is an excellent technique for the estimation of DD of chitosan but expensive and not found easily in every research laboratory. On the other hand, titrimetric methods have been employed by many researchers for determining the DD of chitosan but these existing methods involve many complex calculations, which do not always give accurate results. Moreover, few of the acid-base titration methods are little complicated for execution. Therefore, in this present study, we adopted a very handy and simple acid-base titration method with a new approach and proposed a new equation facilitating the ease of calculation that is not reported elsewhere for the determination of DD value by observing the net volume of NaOH consumed for the complete neutralization of protonated amino groups (-NH3+) of chitosan describing the novelty of the work. All the DD values (77.04 ± 1.36; 81.71 ± 1.73; 91.68 ± 1.42 for CS1, CS2, and CS3 respectively) obtained for various chitosan samples were in good agreement with the reported DD values (>75%, >80%, and >85% for CS1, CS2, and CS3 respectively) mentioned in the specifications of chitosan samples supplied by the manufacturer. Finally, the experimental DD values were further validated with the DD values (77.39%, 81.64%, and 90.5% for CS1, CS2, and CS3 respectively) obtained from the interpretation of 13C-NMR spectral data and all the experimental DD values were consistent with the DD values as calculated based on NMR spectra.

Phenolphthalein Indicator in Titrimetric Estimation of Benzoic Acid Solubility and Distribution in Water and Benzene-Buffer Solutions

In solubility and partitioning process of benzoic acid, the various factors are involved such as temperature, solute-solvent interaction and dissociation of acid into ionic state in taking solvents. Here, we reported the benzoic acid (solute) solubility in gram/100gram of solvent in different pH benzene-buffer solutions which are analyzed by using of titration method and partition study of these acid into solvents like water and benzene layer by shake-flask acid-base titration method, at room temperature (25°C) for 24 hours. In titrimetric estimation the solute benzoic acid solubility and their partition in between of water and in different pH buffer solutions as in medium of acidic, neutral and basic, a phenolphthalein indicator have been used well. The solvents and benzene-buffer solutions having different pH 4.0, 7.0 and 9.0 is titrated against as 0.01, 0.05 and 0.1N NaOH solutions by using phenolphthalein as indicator, where the end point show a pink color for each reading. Concentration of benzoic acid into water and solvent benzene layers is being calculated as by applying the equation of normality determination and distribution coefficient as from Nernst distribution law equation.

Overcharge to Remove Cathode Passivation Layer for Reviving Failed Li–O 2 Batteries

Overcharge to Remove Cathode Passivation Layer for Reviving Failed Li–O ₂ Batteries

Design and evaluation of in vivo bioavailability in beagle dogs of bilayer tablet consisting of immediate release nanosuspension and sustained release layers of rebamipide

The purpose of this study was to develop a once-daily, bilayer matrix tablet with immediate (IR) and sustained release (SR) layers of poorly water-soluble and absorption site dependent rebamipide (RBM) to substitute three times a day IR tablet. Owing to the pH-dependent poor water solubility of RBM in low pH condition, salt-caged nanosuspensions (NSPs) consisting of RBM and poloxamer 407 (POX 407) or poloxamer 188 (POX 188) were prepared using an acid-base neutralization method to increase the dissolution rate, which was subsequently applied to the immediate-release (IR) layer. Polyethylene oxide (PEO) with different molecular weights (PEO 100,000 and PEO 5,000,000) and hydroxypropyl methylcellulose 4000 (HPMC 4000) were then investigated as SR agents to incorporate into the SR layer with pure RBM via wet granulation method. The dissolution profile of the optimized bilayer tablet having 50% IR and 50% SR layer of 300 mg RBM showed that the IR layer could rapidly disintegrate in pH 1.2 buffer solution within 2 h, reaching 50% of drug release from the tablet, followed by an extended drug release from the SR layer in pH 6.8 buffer over 24 h. An in vivo pharmacokinetic study was carried out in beagle dogs to compare the optimal formulation (300 mg RBM bilayer tablet) and the commercial tablet (Mucosta® 100 mg) as a reference. Unexpectedly, despite enhanced dissolution rate in a controlled manner, a designed bilayer tablet had no dose- and dosage form dependent in vivo bioavailability in beagle dogs as compared with IR 100 mg RBM reference tablet. It was evident that solubility in low pH condition, gastric residence time and absorption site of RBM should be carefully considered for designing specific SR or gastroretentive dosage form to improve therapeutic outcomes.

The Potential of Corncobs in Producing Reduced Graphene Oxide as a Semiconductor Material

A simple chemical approach was developed to synthesize reduced graphene oxide (RGO) from corncob waste through the acid-base method with the addition of PEG-2000 at specific concentrations. The morphology and structure of RGO were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The process of reduction and quality of RGO were examined carefully with UV-Vis spectroscopy, infrared spectroscopy, and X-ray diffractometry. Based on the treatment and characterization, the diffraction data showed a prominent peak of RGO at a 2-theta position of 24.01°. The existence of C=C functional groups was detected in aromatic compound groups and alkene functional groups in aliphatic hydrocarbon compounds by infrared spectroscopy. The use of corncobs as the main raw material synthesized by an environmentally friendly route has tremendous potential in producing RGO that can be used as an efficient semiconductor material.

Monitoring Cu(II)-insulin and Mn(II)-insulin complexes using potentiometric, chromatographic, UV–vis absorption and fluorescence emission spectroscopic techniques

In the present work, Cu(II)-insulin and Mn(II)-insulin complexes were investigated using potentiometric acid-base titration, UV–vis absorption and fluorescence (FL) emission spectroscopy, and liquid chromatography (UFLC). Cu(II) and Mn(II) ions are essential nutritional trace elements. They have important activities with enzymes and proteins in the human body. Insulin is a peptide hormone that regulates glucose level in the body. Cu(II) and Mn(II) metal ions are bound to insulin molecules, and their protein complexes form. The binding behaviors of the essential nutritional metal ions to insulin molecules have physiological importance in a human body or drug formulations. The binding properties of Cu(II) and Mn(II) ions to insulin molecule were examined using different methods and compared with each other. It was shown that the Cu(II)-insulin complex formation could be monitored by potentiometric acid-base titration, UV–vis absorption, UFLC and FL methods. However, UV–vis absorption, UFLC and FL methods are not suitable for the monitoring Mn(II)-insulin complexes. The binding mechanism of Cu(II) ions is different than the binding mechanism of Mn(II) ions. The Cu(II) binding is governed by the chelating mechanism, while the Mn(II) binding is by ionic interaction. The acid-base potentiometric titration method is a cheap practical method to check whether the binding of metal ions to protein is or not as well as Cu(II) and Mn(II) metal ions. UV–vis absorption spectroscopy can be used for protein-metal ion interactions via a chelating mechanism.

Spasmolytic Effect of Papaya (Carica papaya L.) Leave Alkaloid on Isolated Rat Myometrial Contraction in vitro

This study aimed to investigate the action of crude alkaloid extract from papaya leaves (PA) on the isolated rat myometrium in vitro. The alkaloids were extracted from papaya leaves using conventional acid-base method. The myometrium strips were taken from female Wistar rats pretreated with diethylstilbestrol (100 mg) for 24 h before the experiment. A preliminary experiment has shown that PA had no effect on myometrial contraction. However, PA (10-6 - 10-3 gm/mL) significantly inhibited myometrium contraction pre-contracted with a depolarizing solution in a concentration-dependent fashion. PA (10-5, 3×10-5 or 10-4 gm/mL) or verapamil (10-9, 10-8 and 10-7 M) were able to inhibit the myometrial contractile response to CaCl2 (10-5 - 3×10-2 M) in Ca2+-free solution and cause a rightward shift of log concentration-response curve. PA also significantly inhibited myometrium contraction produced by oxytocin (1 mU/mL), ACh (3×10-5 M) and PGF2a (10-5 M). Furthermore, propranolol (10-7 M) caused no effect on uterine relaxation induced by PA (10-6 - 10-3 gm/mL), although it inhibited uterine relaxation induced by isoproterenol (10-10 - 10-5 M). These results indicated that PA was a uterine relaxant. Its mechanism of action may be unrelated to stimulation of b2-adrenergic receptors of the uterus. This action may be contributed to mainly the Ca2+ influx, possibly through voltage-operated Ca2+ channel on the plasma membrane, and to a lesser extent by a rise in Ca2+ release from internal storage. However, the action of PA at intracellular sites, downstream of Ca2+ influx such as the contractile machinery of the myometrium, cannot be excluded.&#x0D; HIGHLIGHTS&#x0D; &#x0D; Alkaloid extract from Carica papayaleaves has shown to be a uterine relaxant on isolated rat uterus in vitro&#x0D; The alkaloid extract was able to inhibit uterine contraction stimulated by various uterine stimulants such as acetylcholine, oxytocinand prostaglandin F2alpha&#x0D; The inhibition on uterine contraction may be due to the inhibition on calcium influx into the uterine muscle cells&#x0D; &#x0D; GRAPHICAL ABSTRACT

Comparison on chemical features and antioxidant activity of polysaccharides from Auricularia auricula by three different enzymes.

To investigate and compare the chemical features and antioxidant activities of Auricularia auricula polysaccharides (AAPs), three different AAPs (AAP-M, AAP-D, and AAP-C) were prepared by mannanase, β-dextranase, and cellulase. Their chemical features were determined using high-performance liquid chromatography and infrared spectroscopy. The antioxidant properties were performed both in vitro and in vivo. Results showed that the surface morphology of the A. auricula cell wall treated with three enzymes was slightly different under scanning electron microscopy. The extraction yields of AAP-M, AAP-D, and AAP-C were 18.33% ± 1.93%, 26.42% ± 0.87%, and 17.17% ± 0.08% under optimal conditions, respectively. The monosaccharide composition, molecular weight (AAP-M, AAP-D, and AAP-C were 1.03E+03kDa, 1.76E+03kDa, and 1.15E+03kDa, respectively), and antioxidant activities of the three AAPs were different. AAP-C composed of mannose, glucuronic acid, glucose, and galactose, exhibiting the remarkable ability of scavenging ABTS+ , DPPH, and H2 O2 (IC50 was 0.065, 0.081, and 0.293mg/ml, respectively). Moreover, AAP-C could significantly prolonged the lifespan of Caenorhabditis elegans under oxidative stress (p<.05). The results showed that cellulase could be served as an efficient enzyme to prepare AAPs with higher antioxidant capacity. PRACTICAL APPLICATIONS: According to the statistics of China Edible Fungi Association in 2019, the output of Auricularia auricula was accounting for 17.54% of the total output of edible fungi. AAPs account for more than 60% of the fruiting bodies and have various biological activities. Cell wall breaking is an important process of extracting AAPs which has always been the bottleneck restricting the production of AAPs. The traditional chemical acid-base method will pollute the environment, and the yield of hot water extraction is low. In contrast, the bioenzyme method widely used because of its mild conditions and environmental friendly. In this paper, three common bioenzymes which have been widely used in food industry were used to extract AAPs, and Box-Behnken design to improve the yield of AAPs. The results show that AAP-C had high yield and strong antioxidant activity. This study could provide a reference for the industrial production of AAPs.

Synthesis and spectrometric study of some nucleophilic reactions of the antiepileptic molecule; 5,5-diphenyl imidazolidine-2,4-dione.

New reaction routs were performed for the compound 5,5-diphenyl 2,4-imidazolidinedione (I) to give derivatives (II – VII). These reactions include acylation, halogenation, reduction, and nucleophilic substitutions. Most of the derivatives showed variable chemical reactivities and thermal stability, and the N1 and N3 disubstituted analogue were found much less stable, and hydrolyzes easily in the reaction medium. According to 1H and 13C NMR measurement's, 1,3-Dichloro-5,5-diphenyl imidazolidine-2,4-dione (V) was found to chlorinate the methyl group of the solvent DMSO-d6. Sodium hydroxide consumption analysis was established to reveal the molecularity against NaOH, by following acid-base volumetric method.

Fire-Prevention Characteristics of an Active Colloid Prepared from Stimulated Fly Ash Component

In this paper, an active colloid (AC) with a three-dimensional network framework, prepared from stimulated fly ash (FA) component by an acid–base compound chemical method, was proposed for prevention of coal mine fire. During the stimulation process, the active substance in fly ash can be released and transformed into effective components for fire prevention. Research results show that Al3+, Fe3+, and Ti4+ from FA can serve as metal cross-linking agents to graft-copolymerize with sodium carboxymethyl cellulose. Mg2+ and Ca2+ can be formed into halogenated salts that are encapsulated by composite colloids and cooperate with them to participate in fire prevention. The remaining fly ash solid particles served as an inert component can be fixed in the framework to encapsulate more water, improving the colloid’s strength and water retention. The content of the active component was measured by inductively coupled plasma (ICP) emission spectroscopy to evaluate the stimulation effect of fly ash. The gel time, viscosity, water retention, and other performance parameters were determined for evaluation of physical characteristics. The fire-prevention performances of AC were also determined by the inhibition performance test, thermogravimetric analysis, and infrared spectroscopy. Moreover, the fire-prevention mechanism of AC was also explored. These results showed that the AC prepared from the stimulated fly ash component can greatly inhibit the spontaneous combustion of coal and can be chosen as a potential material for prevention of coal mine fire caused by spontaneous combustion of coal.

The extraction mechanism research for the separation of indole through the formation of deep eutectic solvents with quaternary ammonium salts

Indole is an important industrial substance that can be derived from coal tar. However, traditional acid-base separation method causes serious environmental problems. In this research, the indole separation abilities of different quaternary ammonium salts (QASs) from nitrogen-containing compounds and azeotrope systems were explored. Series of QASs with different substituent groups were investigated through examining the extraction efficiency, including tetraethylammonium chloride (TEAC), betaine hydrochloride (BHC), tetramethylammonium chloride (TMAC), tetraethylammonium bromide (TEAB), and benzyl trimethylammonium chloride (BTMAC). Among them, TEAC was found to be able to form deep eutectic solvents (DES) with indole. The effects of different experimental conditions such as extraction time, extraction temperature, and mole ratio were studied and optimum extraction conditions were obtained. Quantum calculation was employed to explore the extraction mechanism. σ-profiles and σ-surfaces of QASs ions and related compounds were derived from COSMO database and analyzed to explore their interaction forces. The interaction energies between QASs ions and related compounds composed by misfit, van der Waals (VDW) and hydrogen bond (HB) were calculated based on COSMO-RS theory. Using these methods, the separation possibilities of indole through DES formation by QASs can be speculated. Ultimately, the bond lengths and interaction energies between QASs and indole were calculated concretely using Material Studio. The above quantum calculation proved the existence of hydrogen bonds between indole and QASs and the deductions obtained from quantum calculation were consistent with the experimental results. According to the above analysis, the separation method through DES formation was proved to have a relatively high requirement for extractant. The mechanism research in this article provided essential reference for the selection of applicable extractant, and the prediction of the separation efficiency.

Uji Sitotoksik Ekstrak Alkaloid Daun Belimbing Wuluh (Averrhoa bilimbi L.) terhadap Larva Udang (Artemia salina)

Research on cytotoxic test of alkaloids extract of belimbing wuluh leaves has been conducted. The objective of this research are to determine the yield, toxicity, TLC chromatogram pattern, and compounds in alkaloids extract of belimbing wuluh leaves with GC-MS. Alkaloid extraction process uses acid base method, the phytochemical tests was carried out with reagents Dragendorff, Wagner and Meyer. Toxicity test of alkaloids extract of belimbing wuluh leaves with BSLT method on A. salina larvae to determine LC50 value. Alkaloids extract of belimbing wuluh leaves were analyzed by TLC and GC-MS. The yield of alkaloids extract of belimbing wuluh leaves obtained was 10, 13 %. The results of phytochemical tests were carried out which showed positive containing alkaloids. LC50 value of the alkaloids extract of belimbing wuluh leaves indicated that is very toxic. The LC50value obtained is 9.170 ppm. Analysis using TLC with eluent of n-hexane: ethyl acetate (8:2) showed 5 stains. GC-MS analysis showed are alkaloid compound with an odd molecular weight.