The Bioactive Potential of Culturable Fungal Endophytes Isolated From the Leaf of Catharanthus roseus (L.) G. Don.

INTRODUCTION: Endophyte is considered a source of natural bioactive secondary metabolites that provides an array of bioactive lead compounds. The present study was aimed to determine the antimicrobial and anti-inflammatory potential of fungal endophytes isolated from Catharanthus roseus. METHODS: A total of seven fungal endophytes crude extract were screened against bacterial pathogens. Of these, Curvularia geniculata CATDLF7 crude extract exhibited the most potent inhibitory activity against bacterial pathogens. Hence, CATDLF7 crude extract was subjected to chromatographic separation. This purification leads to the isolation of six pure compounds (1PS - 6PS). Of these, 3PS was found to be a major constituent and most effective against clinical isolates of methicillin- resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 100 to 200 µg/ml. Based on the spectroscopic data, 3PS was characterized as α,ß- dehydrocurvularin. This compound also showed synergistic interaction with norfloxacin and reduced its MIC up to 32-folds with a fractional inhibitory concentration index (FICI) of 0.09. RESULTS: To understand the possible antibacterial mechanism of action, α,ß-dehydrocurvularin alone (100 µg/ml) exhibited efflux pump inhibitory potential by 0.84 fold decreasing in ethidium bromide (EtBr) fluorescence. In addition, α,ß-dehydrocurvularin inhibited inflammatory cytokines TNF-α and IL-6 production, which is further validated by molecular docking scores -4.921 and -5.641, respectively, for understanding orientation and binding affinity. CONCLUSION: Overall, the results highlighted identifying bioactive compound α,ß-dehydrocurvularin, which could be used as an antimicrobial and anti-inflammatory agent.

In-silico Studies and Wet-Lab Validation of Camptothecin Derivatives for Anti-Cancer Activity Against Liver (HepG2) and Lung (A549) Cancer Cell Lines.

BACKGROUND: In the present study, we have explored the utility of QSAR modelling, in silico ADMET, docking, chemical semi-synthesis, and in vitro evaluation studies for the identification of active camptothecin (CPT) derivatives against cancer-targeting human liver (HepG2) and lung (A549) cancer cell lines. METHODS: Two QSAR models were developed as screenings tools using the multiple linear regression (MLR) method followed by ADMET and docking studies. The regression coefficient (r2) and cross-validation regression coefficients (rCV2T) of the QSAR model for the HepG2 cell line was 0.95 and 0.90, respectively, and for the A549 cell line, it was 0.93 and 0.81, respectively. RESULTS: In silico studies show that CPT derivatives (CPT-1 and CPT-6) possess drug-like properties. Docking performed on DNA Topoisomerase-I showed significant binding affinity. Finally, predicted active derivatives were chemically semi synthesized, spectroscopically characterized, and evaluated in-vitro for cytotoxic/anticancer activity against HepG2 and A549 cell lines. CONCLUSION: The experimental results are consistent with the predicted results. These findings may be of immense importance in the anticancer drug development from an inexpensive and widely available natural product, camptothecin.

Antiplasmodial potential of extracts from two species of genus Blumea.

CONTEXT: A number of Blumea (Asteraceae) species are being used in traditional Chinese and Indian folklore medicines to cure various diseases including cancer, fungal and bacterial infections. OBJECTIVE: To evaluate the in vitro antiplasmodial potential and cytotoxicity of various extracts and fractions of B. membranacea DC and B. eriantha DC and high performance liquid chromatography (HPLC) chemical fingerprinting of their crude extracts. MATERIALS AND METHODS: The aerial parts and roots of B. membranacea and B. eriantha were extracted with ethanol and the extracts were successively partitioned with n-hexane, ethyl acetate and n-butanol, which were later evaluated for their in vitro antiplasmodial activity against Plasmodium falciparum NF-54 and in vitro cytotoxicities against non-cancerous Vero cell line. HPLC chemical fingerprinting was performed on extracts of B. membranacea and B. eriantha. RESULTS: The n-hexane (MA1), ethyl acetate (MA2) fractions of aerial parts and n-butanol (MR3) fraction of roots of B. membranacea showed IC50 values of 17.4, 19.0 and 3.3 µg/mL respectively, while the n-hexane (EA1), ethyl acetate (EA2) fractions of aerial parts and ethyl acetate (ER2) fraction of roots of B. eriantha showed IC50 values of 25.0, 26.5 and 15.6 µg/mL, respectively, against P. falciparum NF-54. All these fractions were non-toxic to Vero cells. DISCUSSION AND CONCLUSION: Both B. membranacea and B. eriantha possesses a high degree of selective antiplasmodial activity (selectivity index up to >60) and hence, may find their use in antimalarial phytopharmaceuticals as well as in discovery of a safer and novel antimalarial lead.

Large-scale separation of antipsychotic alkaloids from Rauwolfia tetraphylla L. by pH-zone-refining fast centrifugal partition chromatography.

pH-zone-refining centrifugal partition chromatography was successively applied in the large-scale separation of close R(f) antipsychotic indole alkaloids directly from CHCl(3) fraction of Rauwolfia tetraphylla leaves. Two experiments with increasing mass from 500 mg to 3 g of crude alkaloid extracts (1C) of R. tetraphylla were carried out in normal-displacement mode using a two-phase solvent system composed of methyl tert-butyl ether/ACN/water (4:1:5, v/v/v) where HCl (12 mM) was added to the lower aqueous stationary phase as a retainer and triethylamine (5 mM) to the organic mobile phase as an eluter. The two centrifugal partition chromatography separations afforded a total of 162.6 mg of 10-methoxytetrahydroalstonine (1) and 296.5 mg of isoreserpiline (2) in 97% and 95.5% purity, respectively, along with a 400.9 mg mixture of α-yohimbine and reserpiline (3 and 4). Further, this mixture was resolved over medium pressure LC using TLC grade silica gel H (average particle size 10 µm), which afforded 160.4 mg of α-yohimbine (3) and 150.2 mg of reserpiline (4) in >95% purities. The purity of the isolated antipsychotic alkaloids was analyzed by high-performance LC and their structures were characterized on the basis of their 1D, 2D NMR and electrospray ionization-mass spectroscopic data.

Novel antiplasmodial agents from Christia vespertilionis.

The roots, leaves and stems of Christia vespertilionis were separately and successively extracted with methanol and aqueous-methanol (1:4, v/v) and were evaluated in vitro for their antiplasmodial potential against Plasmodium falciparum NF-54. The aqueous-methanolic stem (AS) extract was the most active (IC50 7.5 microg/mL) followed by the methanolic leaf (ML) extract (IC50 32.0 microg/mL). The in vivo antimalarial activity of the combined plant extract of C. vespertilionis was also assessed in P. berghei infected mice, which showed 87.8% suppression of parasitaemia as compared with complete suppression by chloroquine on day 8. Finally, detailed chemical investigation of C. vespertilionis resulted in the isolation and characterization of fifteen compounds (1-15), of which two (1 and 4) are being reported for the first time from nature. The novel compound 1 possesses potent antiplasmodial activity (IC50 = 9.0 microg/mL).

Quantitative determination of bioactive 4-hydroxy-α-tetralone, tetralone-4-O-ß-D-glucopyranoside and ellagic acid in Ammannia baccifera (Linn.) by reversed-phase high-performance liquid chromatography.

Ammannia baccifera is an important component of various Chinese herbal formulations for which a rapid, simple, sensitive, gradient and reproducible reversed-phase high-performance liquid chromatographic method has been developed for the quantitative estimation of its bioactive constituents, 4-hydroxy-α-tetralone (4H), tetralone-4-O-ß-D-glucopyranoside (T4) and ellagic acid (EA). The chromatographic separation of samples was performed on a Chromatopak Peerless C18 (250 × 4.6 mm i.d., 5 µm) column by gradient elution with 0.1% trifluoroacetic acid in water and methanol at a flow rate of 0.6 mL/min, a column temperature at 25°C and ultraviolet detection at λ 254 nm. The limit of detection (LOD) and limit of quantification (LOQ) were 1.51 and 5.06 µg/mL for EA, 0.70 and 2.33 µg/mL for T4 and 0.22 and 0.73 µg/mL for 4H, respectively. Good results were achieved with respect to linearity (r(2) > 0.999), repeatability (relative standard deviation ≤ 1.73%) and recovery (99.06-100.76%). The method was validated for linearity, accuracy, repeatability, LOQ and LOD. The method is simple, accurate and precise and was successfully applied to the analysis of these three analytes in five different leaf and root samples of A. baccifera; the method may be recommended for routine quality control analysis of various Chinese herbal formulations containing A. baccifera.

Antihyperglycemic agents from Ammannia multiflora.

The serial chromatographic separation of chloroform and n-butanol fractions of Ammannia multiflora resulted in the isolation and characterization of 4-hydroxy-alpha-tetralone (1) and 3,3'-(2R,5R)-tetrahydrofuran-2,5-diyldiphenol (ammaniol, 2). Compound 1 was chemically modified into six semi-synthetic acyl and aryl derivatives (1A - 1F). The isolated compounds 1 and 2 along with semi-synthetic derivatives 1A - 1F were evaluated for in vitro antihyperglycemic activity employing 2-deoxyglucose uptake by L-6 rat muscle cell lines. The results indicated that both the isolates, as well as derivatives (1A - 1F), have the property to stimulate glucose uptake. Ammaniol (2) increased glucose uptake significantly (64.8%), while one of the aryl derivatives of 1, 4-O-(3,4,5-trimethoxybenzoyl)-alpha-tetralone (1D), showed potent antihyperglycemic activity and increased glucose uptake by 94.6%, even more than rosiglitazone (88.8%). Further, since 1D possesses better antihyperglycemic activity than rosiglitazone (standard), this might be a new safer antidiabetic drug of herbal origin.

Bioenhancing and antimycobacterial agents from Ammannia multiflora.

The methanolic extract of Ammannia multiflora (Lythraceae) showed significant bioenhancing activity with the antibiotic nalidixic acid. Bioassay-guided fractionation of MeOH extract resulted in the isolation of a novel compound, 2,5-bis-(3,3'-hydroxyaryl)tetrahydrofuran, named as ammaniol (5), along with 9 other known compounds (1-4, 6-10). Furthermore, compound 4-hydroxy- α-tetralone (1) was converted into five semisynthetic acyl derivatives, 1A-1E, which were evaluated along with compounds 1, 5, 6, 9, and 10 for their bioenhancing activity in combination with nalidixic acid against the two strains, CA8000 and DH5 α, of Escherichia coli. The results showed that the methanolic extract of A. multiflora and compounds 1 and 9 possessed significant bioenhancing activity and reduced the dose of nalidixic acid fourfold while compounds 5, 6, 10 and semisynthetic derivatives 1A- 1E reduced the dose of nalidixic acid twofold. Compound 5 was also tested for antimycobacterial activity against Mycobacterium H37Rv and was found to show moderate activity (MIC 25 µg/mL) against this pathogen.

Simultaneous determination of three steroidal glycoalkaloids in Solanum xanthocarpum by high performance thin layer chromatography.

A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitation of three bioactive steroidal glycoalkaloid (SGA) markers, solasonine (SN), solamargine (SM) and khasianine (KN) in the plant Solanum xanthocarpum. Extraction efficiency of targeted SGAs from plant matrix using methanol and acidified methanol were studied using percolation, ultrasonication and microwave techniques. The separation was achieved on silica gel 60F(254) TLC plates using chloroform-methanol-water as mobile phase. The quantitation of SGAs was carried out using the densitometric reflection/absorption mode at 520 nm after post chromatographic derivatization using Dragendorff's reagent. The method was validated for peak purity, precision, accuracy, robustness, limit of detection (LOD) and quantitation (LOQ). Method specificity was confirmed using retention factor (R(f)), Vis spectral correlation and electrospray ionization mass spectra (ESI-MS) of marker compounds in the sample track.

Cytotoxic evaluation of semisynthetic ester and amide derivatives of oleanolic acid.

Although a number of chemicals have been isolated from Lantana camara, only a few have been evaluated for their biological significance. As part of our drug discovery program for cytotoxic agents from Indian medicinal plants, roots of L. camara L. were chemically investigated, which resulted in the isolation and identification of a cytotoxic agent, oleanolic acid (1b) as a major constituent. Oleanolic acid was converted into six semi-synthetic ester (2-7) and seven amide (8-14) derivatives. The ester derivatives (2-7) showed 3-6 times more selective activity than 1b against the human ovarian cancer cell line (IGR-OV-1), while amide derivatives 8-14 showed 16-53 times more selective activity against the human lung cancer cell line (HOP-62). Structure activity relationship within the ester (2-7) and amide (8-14) derivatives are discussed.