Silica Gel Chromatography Research Articles

Phytochemical Investigation and Determination of Antibacterial Activity of Solvent Leave Extracts of Carissa spinarum.

BackgroundAmong many traditionally used medicinal plants, Carissa spinarum (Agam) is a well-known indigenous plant in Ethiopia. It is used in its raw form to treat different diseases in different parts of the country. Therefore, the aim of this study is to investigate extraction, isolation, and determination of the antibacterial properties of the solvent leaf extract of Carissa spinarum.MethodsIn this study, 800 g of powdered leaves of Carissa spinarum were macerated with 2500 mL of methanol and yielded 58 g (7.25%, w/w) of gummy material. The extract was then further partitioned by using ethyl acetate and chloroform. The extracts were subjected to phytochemical screening test. The antibacterial activity of the three solvent leaf extracts of Carissa spinarum were evaluated using disc diffusion method. The methanol extract was subjected to column chromatography silica gel (60–200 mesh) by mixing methanol:petroleum ether (4:1). Then fractions were collected and investigated by TLC and finally identified using spectroscopy.ResultsThe three extracts (methanol, ethyl acetate, and chloroform) of Carissa spinarum were presented to antimicrobial activity by disc diffusion method against four bacterial species using gentamycin and ampicillin discs as positive controls and DMSO as a negative control. All extracts had a relatively antibacterial effect with different extent zones of inhibition. However, the methanol extract showed superior antibacterial activity compared with DMSO and ethyl acetate and chloroform extracts. These could due to variation of the phytoconstituents. The most probable structure of the compound isolated was 5-(2’,3’,4’,6’-tetrahydroxy-5’-methoxycyclohexyloxy)-2,3,4 trihydroxypentanoic acid.ConclusionData obtained from this study collectively indicated that the three solvent extracts of Carissa spinarum have a promising antimicrobial activity which supports the traditional claim of the plant for treatment of infection.

Preparation of the sphingolipid fraction from mycelia of Cordyceps sinensis and its immunosuppressive activity

Ethnopharmacological relevanceCordyceps sinensis (CS) is an herbal tonic in traditional Chinese medicine and is used to treat a wide range of disorders, including immune, kidney, respiratory, lung and cardiovascular diseases, in China. Most studies are focused mainly on nucleotides and polysaccharides from CS and consider them to be the main active ingredients, while other ingredients are often disregarded. Hundreds of sphingolipids have been identified from CS and showed inhibitory effects on mouse splenic lymphocytes. Aim of the studyThis study aimed to establish a method for preparing a fraction of sphingolipids from the mycelial powder of CS and evaluate its immunosuppressive activity. Materials and methodsFraction of sphingolipids (Fr-SPLs) were prepared by silica gel chromatography and reversed-phase chromatography. Its components were identified and quantified by Quadrupole-Orbitrap UHPLC–MS/MS. PBMCs were prepared from human blood, and splenic lymphocytes, B cells, and T cells were prepared from mouse spleens. The inhibitory effect of Fr-SPLs on cell viability was evaluated by CCK-8 assay. PBMC apoptosis and the ratio of CD4+ T cells and CD8+ T cells were quantified by flow cytometry analysis. The expression of IL-2, IL-10, and TNF-α in PBMCs was detected by ELISA kits. ResultsA fraction containing 84.83% of sphingolipids (SPLs) was prepared from the mycelia of CS and named Fr-SPLs. 15 SPLs were identified from the Fr-SPLs. Fr-SPLs significantly inhibited the viability of human peripheral blood mononuclear cells (PBMCs) with an IC50 value of 9.82 μg/mL and promoted PBMC apoptosis in a dose-dependent manner. Moreover, Fr-SPLs inhibited the viability of mouse splenocytes, as well as that of B cells and T cells derived from splenocytes. Furthermore, Fr-SPLs reduced the production of IL-2, IL-10, and TNF-α in PBMCs. ConclusionsFr-SPLs show immunosuppressive activity, and this study will be useful for preparing immunosuppressive components from CS and its mycelia for hyperimmune disease.

Steroids from Uncaria rhynchophylla

Thirteen steroids(1-13) were isolated from the non-alkaloid constituents of Uncaria rhynchophylla by column chromatography on silica gel, ODS, Sephadex LH-20, and preparative HPLC chromatography, and their structures were elucidated by analyses of the MS and NMR spectral data. All the compounds were isolated from the genus Uncaria for the first time, and 1 was a new compound. The ~1H-NMR and ~(13)C-NMR data of two compounds(12 and 13) in deuteron-chloroform were completely assigned. This study enriched the steroid constituents of U. rhynchophylla and provided scientific references for the elucidation of active constituents and further development and utilization of U. rhynchophylla.

Purification and characterization of antibacterial surfactin isoforms produced by Bacillus velezensis SK

Bacillus velezensis SK having broad-spectrum antimicrobial activity has been isolated from soil. The efficient extraction of antimicrobial compounds produced in various mediums has been done using Diaion HP-20 resin. Further, characterization of an antimicrobial compound by TLC, FTIR, in-situ bioautography analysis revealed the presence of cyclic lipopeptides, which is then purified by the combination of silica gel, size exclusion, dual gradient, and RP-HPLC chromatography techniques. Growth kinetic studies showed that Bacillus velezensis SK produces a mixture of lipopeptides (1.33 gL−1). The lipopeptide exhibits good pH (2–10) and temperature stability up to 80 °C. LC–ESI–MS analysis of partially purified lipopeptide identified variant of surfactin, further analysis of purified chromatographic fractions revealed the occurrence of most abundant C15-surfactin homologues (m/z 1036.72 Da). The isolated surfactin exhibits good antimicrobial activity (1600 AU/ml) against drug-resistant food-born B. cereus and human pathogen Staphylococcus aureus. Hence, identified strain B. velezensis SK and its potent antibacterial surfactin lipopeptide could be used in various food and biomedical applications.

Recovery and Seasonal Variation of Cinnamtannin B-1 from Laurel (Laurus nobilis L.) Pruning Wood Wastes.

Cinnamtannin B-1 (C-B1) is a commercially-available trimeric A-type procyanidin with remarkable cellular actions mainly derived from its high radical scavenging activity. C-B1 is the main phenolic compound of laurel wood, which has previously been isolated by a combination of conventional chromatographic techniques. The first aim of this work was to find laurel trees containing as much C-B1 as possible, and learn about the influence of variables, such as gender and harvest time, on the production of C-B1 by the tree. It was found that all studied trees tend to give higher C-B1 percentages in the May-July period, from 6 % to 18 %, and lower ones around March (spring) and November (fall), from 1 % to 8 %. In a general way, it also seems that the female trees tend to produce a bit more C-B1 (from 2.8 % to 17.3 %) than male ones (from 1.7 % to 13.4 %). In addition, eight minor phenolic compounds [(-)-ent-catechin (1), (-)-ent-epicatechin-(4α→8)-ent-epicatechin (2), (epi)catechin-(4→8)-(epi)afzelechin-(4→8)-(epi)catechin (3), (+)-epiafzelechin-(4β→8)-epicatechin (4), (-)-epicatechin (5), (-)-afzelechin-(4α→8)-epicatechin (6), (epi)afzelechin-(4→8)-(epi)afzelechin-(4→8)-(epi)catechin (7) and (+)-epicatechin-(4β→8,2β→O-7)-epicatechin-(4β→8)-catechin (C-D1)] were found and quantified in the ethyl acetate extract of the wood samples. The second aim of this work was to improve the recovery of C-B1 from laurel wood. The use of the fast centrifugal partition chromatography (FCPC) technique has allowed for a recovery of 96 % of a technical-grade C-B1 (64 % in a previous protocol using conventional column chromatography on silica gel and size-exclusion chromatography).

Determination of Wild Grape Phenolic Compounds in the Extracts of Winemaking Byproducts and Their Antioxidant Competency.

<b>Background and Objective:</b> Various medicinal herbs and fruits in Thailand composed of many bioactive phytochemicals, which are support health and reduce the harmful of many diseases. The main objectives of this study were to extract wild grape residues obtained from wine production and fractionate them by silica column chromatography and investigate the chemical substances and antioxidant competency. <b>Materials and Methods:</b> Methanolic crude extract of wild grape pomace was fractionated by silica gel chromatography using the mixture methanol/ethyl acetate as eluting solvents. The chemical substances including total phenolic, flavonoid, saponin and condensed-tannin were investigated by colorimetric spectrophotometer. The antioxidant activities with free radical scavenging (DPPH and ABTS) and reducing power antioxidants (FRAP and CUPRAC) were tested. Finally, High Performance Liquid Chromatography (HPLC) was applied for the analysis of the individual phenolic compounds. <b>Results:</b> The fractionated extracts had higher chemical substances than crude extract, except total phenolic. Among the substances, condensed-tannins showed the highest content in the fractionated extracts. The active substances showed higher ABTS free radical scavenging activity than DPPH and metal-reducing power antioxidant by CUPRAC than FRAP assays. The dominant phenolic substances in the fractionated extracts were gallic acid, resveratrol, quercetin, epicatechin and caffeic acid. <b>Conclusion:</b> The pomace of immature wild grape fruits from wine production contained various types of chemical substances and antioxidant competency. The obtained results provide more information on the wild grape fruits in terms of phytochemical source and their activity.

MRNA Purification: Technology Aspects and Impurities TFF, Chromatography, UF/DF (Resins, Magnetic Beads, Monoliths)

m RNA VACCINE production like other biopharmaceutical need various purification stages in the manifacturing process. In this process are used techniques like: (TFF) tangential flow filtration followed by different chromatographic procedure (affinity and ion exchange separation) with various kinds of resin and then UF/DF technique (Ultrafiltration-diafiltration). So it is of interest to verify that the materials used for this kind of procedure is solid phases or for the membrane and if released impurity in the final product. For Silica-based Reversed-Phase packing’s, a carbon load percentage indicates the amount of functional bonded phase attached to the Silica-base material. Aim of this work is to investigate the role played by these characteristics in the separation process of mRNA. Because this parameter influence the retention time it is interesting to evaluate the use in separation technique of biopharmaceuticals and this also is for the carbon coated silica columns. Silica gel for chromatography can be produced by systemic process but also form Rice treated at high temperature. What kind of effect can be played using an high level of carbon coated silica material on the final purified product? The graphitic particle can be found as impurity during the manufacturing process of these resins? And what is the role played by carbon (graphene-quantum dots) membrane as reported in various research application?

Stereoselective synthesis of C3-tetrasubstituted oxindoles via copper catalyzed asymmetric propargylation.

Herein, a copper catalyzed asymmetric propargylation of 2-oxindole-3-carboxylate esters with terminal propargylic esters is described. This strategy successfully provides a direct approach to constructing a broad range of chiral C3-tetrasubstituted oxindoles with contiguous tertiary and quaternary carbon stereocenters in high yields and excellent enantioselectivities (16 examples, up to 99% yield and 98% ee). Moreover, the diastereoisomers of the two newly formed stereocenters can be separated by silica gel chromatography, thereby providing a valuable stereoselective access to all four possible stereoisomers of C3-tetrasubstituted oxindoles.

Novel chemical- and protein-mediated methods for glucosamine detection

We describe to novel approaches for the determination of glucosamine (GlcN). The first approach is based on the chemical derivatization of GlcN with the non-fluorophor 1,3-diphenyl-1,3-propanedione (DPPD), which results in a condensation product with interesting fluorescent properties. The obtained compound was isolated by silica-gel chromatography and its structure elucidated by NMR and mass spectrometry. The second approach is based on a previously undescribed sensitivity of the enzyme glucosamine-6-phosphate deaminase (GPDA) towards GlcN, which resulted in the precipitation of the enzyme. Using a rational enzyme engineering approach and both liquid-based and plate-based screening methods, mutational GPDA variants with significantly improved precipitation properties were identified and characterized. These novel glucosamine detection methods may be a useful addition to the repertoire of currently available glucosamine detection sensors.

Heterobimetallic μ2-halocarbyne complexes.

The halocarbyne complexes [M(CX)(CO)2(Tp*)] (M = Mo, W; X = Cl, Br; Tp* = hydrotris(dimethylpyrazolyl)borate) react with [AuCl(SMe2)], [Pt(η2-H2CCH2)(PPh3)2] or [Pt(η2-nbe)3] (nbe = norbornene) to furnish rare examples of μ2-halocarbyne complexes [MAu(μ2-CX)Cl(CO)2(Tp*)], [MPt(μ2-CCl)(CO)2(PPh3)2(Tp*)] and [W2Pt(μ2-CCl)2(CO)4(Tp*)2]. The complex [WPt(μ2-CCl)(CO)2(PPh3)2(Tp*)] spontaneously rearranges to the μ2-carbido complex [WPt(μ2-C)Cl(CO)2(PPh3)2(Tp*)] during silica-gel chromatography. One phosphine ligand of [WPt(μ2-CCl)(CO)2(PPh3)2(Tp*)] is readily substituted by CO to afford [WPt(μ2-CCl)(CO)3(PPh3)(Tp*)]. These μ2-halocarbyne complexes have been interrogated by spectroscopic, crystallographic and computational methods, the latter by reference to data for terminal halocarbyne precursors [M(CX)(CO)2(Tp*)].

New eudesmane sesquiterpenoids from Atractylodis Macrocephalae Rhizoma and their inhibitory activities against SREBPs

Three sesquiterpenoids were isolated and purified from the 95% ethanol extract of Atractylodis Macrocephalae Rhizoma by column chromatography on silica gel, Sephadex LH-20, ODS, and high-performance liquid chromatography(HPLC). Their chemical structures were identified on the basis of spectroscopic analysis and physiochemical properties as(7Z)-8β,13-diacetoxy-eudesma-4(15),7(11)-diene(1), 7-oxo-7,8-secoeudesma-4(15),11-dien-8-oic acid(2), and guai-10(14)-en-11-ol(3). Compounds 1 and 2 are new compounds and compound 3 was obtained from Compositae family for the first time. Compounds 1, 2, and 3 showed weak inhibitory activities against sterol regulatory element-binding proteins(SREBPs).

Isolation and characterization of anti-tumor compounds from ethyl acetate extract of Rumex japonicus houtt roots and their cytotoxic effects

To isolate and characterize anti-tumor compounds through nuclear magnetic resonance (NMR) spectroscopy of ethyl acetate extract of R. japonicus Houtt root and their cytotoxic effects were evaluated in terms of measuring inhibition of growth of three cancer cell lines: human hepatoma cells (HepG2), cerebral glioma cells (U251) and ovarian carcinoma cells (SK-OV-3/DDP). The roots of R. japonicus Houtt were extracted with ethanol, and partitioned with petroleum ether, dichloromethane and ethyl acetate, respectively. The ethyl acetate extract was separated chromatographically using macroporous resin, positive and negative phase silica gel and high performance liquid chromatography. The structures of isolated compounds were elucidated by nuclear magnetic resonance (NMR) spectral data. Ten compounds were isolated form the ethyl acetate extract of R. japonicus roots. Their structures were determined as emodin (1), chrysophanol (2), aloe emodin (3), physcion (4), quercetin (5), resveratrol (6), β-sitosterol (7), 3β-acetoxy-28-hydroxyurs-12-ene (8), sucrose (9) and dibutyl phthalate (10). Among of them, compounds 1, 3, 4, 6 and 8 exhibited highly significant (p<0.05) cytotoxicities against HepG2 to a certain extent. Compounds 3-6 exhibited moderate cytotoxicities against U251 with IC50 values of 19.8, 23.5, 23.8 and 17.8 µM, respectively. Compounds 1, 2 and 7 also exhibited cytotoxicities against U251 to a certain extent with IC50 values of 48.3, 50.1 and 85.3 µM, respectively. Compounds 1-6 exhibited moderate cytotoxicities against (SK-OV-3/DDP) with IC50 values of 62.8, 64.2, 31.3, 61.0, 47.4 and 42.0 µM, respectively.

Ethyl acetate extract of Smilax glabra Roxb roots and its major active compound astilbin promote osteoblastogenesis in vitro by upregulating bone cell differentiation- associated genes

Objective: To investigate the osteoblastogenic activity of the ethyl acetate (EtOAc) extract of Smilax glabra Roxb roots and its major active compound astilbin. Methods: Astilbin was isolated from EtOAc extract using silica gel chromatography combined with fraction crystallization. Chemical structure of astilbin was determined by analysis of the spectroscopic data in comparison with the literature. MTT method was used to detect the toxicity. Alkaline phosphatase (ALP) activity was determined by the spectrophotometric method at 405 nm using p-nitrophenyl phosphate as a substrate. Calcium deposition was stained with alizarin red-S, distained with cetylpyridium chloride, and quantified at 562 nm. In silico model for astilbin-ALP interaction was analyzed using AutoDock 4.2.6. The changes in expression of osteoblast differentiation related genes were determined using quantitative real-time PCR. Results: Both the EtOAc extract and astilbin had no toxicity toward osteoblast MC3T3-E1 cells at 5.0, 10, 25, and 50 μg/mL. At 25 μg/ mL, they enhanced ALP activity and mineralization of osteoblasts up to 30% and 55% for the EtOAc extract and 22% and 41% for astilbin, respectively. Molecular docking analysis of astilbin-ALP interaction revealed Arg167, Asp320, His324, and His437 were key residues participating in hydrophobic interaction; meanwhile, His434 and Thr436 residues were involved in hydrogen bond formation in the active site of human tissue-nonspecific ALP. Moreover, the expression level of genes opn, col1, osx, and runx2 were up-regulated in astilbin treated samples with the fold changes as 2.2; 3.7; 4.1; 2.3, respectively at 10 μg/mL (P&lt;0.05). Conclusions: The EtOAc extract and its major compound astilbin exhibit osteoblastogenic activity by up-regulating important markers for bone cell differentiation. It could be a new and promising osteogenic agent with dual actions for therapeutic applications.

Isolation and Identification of Antibacterial and Antifungal Compounds from Praxelis clematidea R. M. King &amp; H. Robinson as an Effective Potential Treatment against Rice Pathogens

Bacterial leaf blight and blast diseases caused by the bacterium Xanthomonas oryzae pv. oryzae and the fungus Pyricularia oryzae, respectively, are among the most important infectious diseases affecting rice. We evaluated the antimicrobial effects of compounds derived from Praxelis clematidea on Xanthomonas oryzae and Pyricularia oryzae. The dried aerial parts of Praxelis clematidea were subjected to ethanol extraction, separated by solvent partitioning using hexane, chloroform, ethyl acetate, and water. In vitro assays demonstrated that the main antibacterial and antifungal activities were distributed in the ethyl acetate and chloroform fractions, respectively. These fractions were further separated using silica gel chromatography and reversed-phase chromatography. Finally, we isolated five compounds, 1–5, that inhibited the growth of Xanthomonas oryzae in vitro and four compounds, 6–9, that exhibited in vitro antifungal activity against Pyricularia oryzae. We evaluated their antimicrobial activities and identified their chemical structures by NMR and mass spectrometry analyses. This is the first study to isolate compound 2 (4,4′,4″-nitrilotriphenol) as an alternative microbial from natural resources and evaluate its physiological activity. Moreover, this is the first report to demonstrate antibacterial activity in comparison with flavonoids. Praxelis clematidea extracts plausibly exert both antibacterial and antifungal effects, which should be further validated in field trials.

Efficacy of Cyanotis tuberosa (Roxb.) Schult. &Schult. f. root tubers' active fraction as anti-diabetic, antihyperlipidemic and antioxidant in Streptozotocin-induced diabetic rats

Ethnopharmacological relevanceCyanotis tuberosa (Roxb.) Schult. &Schult.f. is traditionally used as ethnomedicine for curing several ailments like diabetes, liver problems, ulcers, etc. ObjectiveThe present study was designed to evaluate the anti-diabetic potential of Cyanotis tuberosa root tubers (CTRT)in Streptozotocin (STZ) induced diabetic rats. Materials and methodsAnti-hyperglycemic activity of hexane extract of CTRT was investigated in diabetic rats. Silica gel chromatography was used to fractionate the hexane extract and the fraction's antihyperglycemic activity was checked in diabetic rats. Effects of long-term (30 days) treatment with an active fraction (CTAF) were evaluated in diabetic rats for 30 days by measurement of body weights, glycemic control, insulin levels, HbA1c, and serum and tissue lipid profiles. Lipid peroxide levels and antioxidant status were measured in the liver and kidney. Hepatic and Renal functional markers were also measured. Phytochemical characterization of CTAF was carried out by LC-ESI-MS/MS analysis. ResultsHexane extract of CTRT at a dose of 750 mg/kg b.w produced significant antihyperglycemic activity in diabetic rats whereas CTAF has produced maximum antihyperglycemic activity at the dose of 75 mg/kg b.w. Following long-term treatment with CTAF in diabetic rats, significant improvement in glycemic control, (HbA1c) along with decreased insulin resistance (HOMA-IR), increase in body weights, and plasma insulin were observed. Also, CTAF ameliorated the serum and tissue lipid profiles. In addition, CTAF suppressed lipid peroxidation and restored the activities of antioxidant enzymes in the liver and kidney to normal levels. Further, CTAF reversed the liver and kidney functional markers to normalcy. LC-ESI-MS/MS analysis revealed the presence of 7 different phytoconstituents. ConclusionThis study confirmed that CTAF exerts antidiabetic effects in diabetic rats by improving insulin secretion, glycemic control, and restoring functional activities of the liver and kidney. Our results suggest that root tubers of Cyanotis tuberosa can be used as a complementary or alternative agent for the treatment of diabetes mellitus.

Stachybotrys Chartarum Secondary Metabolots of Poisonic Microzoquary

Filtered culture fluids of the Stachybotrys chartarum strain were exhaustively extracted with ethyl acetate. The iso lated red residue was subjected to column chro matography (silica gel) with gradient elution, resulting in 2 different fractions. Fraction 1-2 consisted of a crystalline material that showed the same parameters of 1H and 13C as the parameters of staxibotrilaktam and staxibotrilaktam А, a derivative of driman's sesquiterpenoid. The structure proposed for this compound was based on spectroscopic data and no indication of the configuration of stereogenic carbon atoms was obtained. The fungus was produced mainly stachybotrys fully characterized derived sesquiterpenoid of drimana.

Precise Detection and Visualization of Cyclooxygenase-2 for Golgi Imaging by a Light-Up Aggregation-Induced Emission-Based Probe

Precise Detection and Visualization of Cyclooxygenase-2 for Golgi Imaging by a Light-Up Aggregation-Induced Emission-Based Probe

Determination of Folic Acid in Multivitamin Preparations by Reversed Phase HPLC

A great variety of components in multivitamin preparations containing folic acid, and a variety of test methods and conditions of folic acid determination proposed by manufacturers, require alignment of test procedures for products with similar composition.The aim of the study was to compare the results of experimental verification of folic acid determination procedures which use reversed phase high-performance liquid chromatography (RP HPLC) with isocratic elution mode. Materials and methods: The Agilent 1260 Infinity II LC system with a diode array detector (280 nm), isocratic elution mode, C8- and C18-bonded silica gel chromatographic columns, model mixtures containing folic acid, cyanocobalamin, ferrous sulfate, and potassium iodide, were used in the study.Results: The lowest relative standard deviation of the folic acid peak area (RSD=0.09%), and the lowest asymmetry factor (As=1.04) for folic acid were observed for the model mixture “ferrous sulfate+folic acid+cyanocobalamin” and the following test conditions. Column: 250×4.0 mm, silica gel for chromatography, octylsilyl (C8), endcapped; mobile phase: methanol‒phosphate buffer (12:88), pH 6.6; column temperature: 25ºС. The study demonstrated the feasibility of using these conditions for determination of pteroic acid impurity with simultaneous precipitation of interfering ferrous ions, using ethylenediaminetetraacetic acid solution, pH 9.5, as a solvent.Conclusions: RP HPLC can be recommended as an optimal aligned test procedure for determination of folic acid in combination products. It is recommended to use a solution containing folic and pteroic acids for system suitability testing.

Using HPLC-DAD and GC-MS Analysis Isolation and Identification of Anticandida Compounds from Gui Zhen Cao Herbs (Genus Bidens): An Important Chinese Medicinal Formulation.

Gui Zhen Cao is an herbal formulation that has been documented in Chinese traditional medicine as a remedy for diarrhea, dysentery, inflammation, and toxicity. The sources of this formulation (Bidens pilosa L., Bidens biternata (Lour.) Merr. & Sherff, Bidens bipinnata L.) are also listed in ethnomedicinal reports all over the world. In this study, all these plants are tested for in vitro anticandida activity. A quantitative evaluation of the phytochemicals in all these plants indicated that their vegetative parts are rich in tannins, saponins, oxalates, cyanogenic glycoside and lipids; moreover, the roots have high percentages of alkaloids, flavonoids, and phenols. The results indicated significant anticandida activity, especially for the hexane extract of B. bipinnata leaves which inhibited C. albicans (42.54%), C. glabrata (46.98%), C. tropicalis (50.89%), C. krusei (40.56%), and C. orthopsilosis (50.24%). The extract was subjected to silica gel chromatography and 220 fractions were obtained. Purification by High Performance Liquid Chromatography with Diode-Array Detection (HPLC–DAD) and Gas Chromatography tandem Mass Spectrometry (GC-MS/MS) analysis led to the identification of two anticandida compounds: dehydroabietic and linoleic acid having an inhibition of 85 and 92%, respectively.

Chloropyridinyl Esters of Nonsteroidal Anti-Inflammatory Agents and Related Derivatives as Potent SARS-CoV-2 3CL Protease Inhibitors.

We report the design and synthesis of a series of new 5-chloropyridinyl esters of salicylic acid, ibuprofen, indomethacin, and related aromatic carboxylic acids for evaluation against SARS-CoV-2 3CL protease enzyme. These ester derivatives were synthesized using EDC in the presence of DMAP to provide various esters in good to excellent yields. Compounds are stable and purified by silica gel chromatography and characterized using 1H-NMR, 13C-NMR, and mass spectral analysis. These synthetic derivatives were evaluated in our in vitro SARS-CoV-2 3CLpro inhibition assay using authentic SARS-CoV-2 3CLpro enzyme. Compounds were also evaluated in our in vitro antiviral assay using quantitative VeroE6 cell-based assay with RNAqPCR. A number of compounds exhibited potent SARS-CoV-2 3CLpro inhibitory activity and antiviral activity. Compound 9a was the most potent inhibitor, with an enzyme IC50 value of 160 nM. Compound 13b exhibited an enzyme IC50 value of 4.9 µM. However, it exhibited a potent antiviral EC50 value of 24 µM in VeroE6 cells. Remdesivir, an RdRp inhibitor, exhibited an antiviral EC50 value of 2.4 µM in the same assay. We assessed the mode of inhibition using mass spectral analysis which suggested the formation of a covalent bond with the enzyme. To obtain molecular insight, we have created a model of compound 9a bound to SARS-CoV-2 3CLpro in the active site.