steve pannakal | Andhra University (original) (raw)

Papers by steve pannakal

RSC Advances

Reverse iontophoresis facilitated the extraction of phytochemicals from intact pomegranates in a ... more Reverse iontophoresis facilitated the extraction of phytochemicals from intact pomegranates in a non-destructive manner. These phytochemicals were subsequently identified using liquid chromatography coupled to untargeted mass spectrometry (LC-MS).

Biochemical Systematics and Ecology

A. Effect of polysaccharide on yeast chronological lifespan. Histogra... more A. Effect of polysaccharide on yeast chronological lifespan. Histogram showing area under the survival curve at different doses of polysaccharide extract (ng/ml), compared to the vehicle control (-ve) and a positive control 10 μg/ml Resveratrol (+ve) for S. cerevisiae. Error bars are standard deviation from the mean AUC of eight experiments. For statistical significance see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179813#pone.0179813.t001" target="_blank">Table 1</a>. B: The effect of polysaccharide on yeast Chronological Lifespan requires a functional TOR pathway. Histograms showing area under the survival curve at 10ng/ml of polysaccharide extract in BY4741 and BY4741 containing deletions of TOR1, SNF1, GCN5 and SIR2. Deletions represent replacement of the coding region with the KanMX selection casette. Error bars are standard deviations from the mean AUC of three measurements.</p

Natural Product Communications, 2014

Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, n... more Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, namely 2′,4′,5-trihydroxy-6,7-(2″,2″-dimethylchromene)-8-γ,γ-dimethylallylisoflavone (1a, auriculatin), 2′,5-dihydroxy-6,7-(2″,2″-dimethylchromene)-4′-γ,γ-dimethylallyloxyisoflavone (2a, isoauriculatin), 3′,4′,5-trihy-droxy-6,7-(2″,2″-dimethylchromene)-8-γ,γ-dimethylallylisoflavone (1b, auriculasin), and 3′,5-dihydroxy-6,7-(2″,2″-dimethylchromene)-4′-γ,γ-dimethylallyl-oxyisoflavone (2b, isoauriculasin). Auriculasin and isoauriculasin are reported for the first time with full NMR assignments. All metabolites were fully characterized by 1D and 2D NMR techniques including COSY, HSQC, HMBC experiments, mass spectra and in part on the basis of X-ray diffraction. Accurate ‘invariom’ refinements with aspherical scattering factors were carried out for 1a, 1b and 2a.

Natural Product Research, 2006

Three 2-naphthaldehydes, including the novel 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde, the simple... more Three 2-naphthaldehydes, including the novel 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde, the simple naphthoquinone plumbagin and the dimeric naphthoquinones diospyrin and 8&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-hydroxyisodiospyrin have been isolated from the roots of Diospyrosassimilis and their structures established by spectroscopic analysis.

INTRODUCTION The mulberry tree (Morus alba L.) is a prolific source of biologically active compou... more INTRODUCTION The mulberry tree (Morus alba L.) is a prolific source of biologically active compounds. There is considerable growing interest in probing M. alba twigs as a source of disruptive antioxidant lead candidates for cosmetic skin care product development. OBJECTIVE An integrated approach using high-performance liquid chromatography (HPLC) coupled with either chemical detection (CD) or high-resolution mass spectrometry (HRMS) was applied to the hydroalcoholic extract of M. alba to detect and identify lead antioxidant compounds, respectively. MATERIAL AND METHODS The twigs were weighed, powdered and homogenized using a mill and the extract was prepared using 70% aqueous ethanol. The antioxidant metabolites were detected with HPLC coupled with CD (based on the ORAC assay) and their structural identification was carried out using a Q-Exactive Orbitrap MS instrument. RESULTS Using this approach, 13 peaks were detected as overall contributors to the antioxidant activity of M. alba...

Phytochemistry, 2006

Chemical investigation of the roots of Diospyros assimilis had led to the isolation and character... more Chemical investigation of the roots of Diospyros assimilis had led to the isolation and characterization of six naphthalene derivatives, two 2-naphthaldehyes, namely 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde 1, 4-hydroxy-5-methoxy-2-naphthaldehye 2, its related isomer 5-hydroxy-4-methoxy-2-naphthaldehyde 3 and three commonly occurring naphthoquinones, diospyrin 4, 8'-hydroxyisodiospyrin 5 and the simple monomer, plumbagin 6. Their chemical structures were established by detailed NMR investigations including 1H and 13C NMR, HSQC, HMBC and NOESY experiments. In addition, the naphthalene derivatives 1-5 were evaluated for their in vitro antiprotozoal activity against protozoan parasites belonging to the genera Trypanosoma, Leishmania and Plasmodium. Among the tested compounds, naphthaldehyde 1 showed moderate inhibition of the growth of the parasites, T. brucei, T. cruzi, L. donovani with IC50 values of 19.82, 12.28 and 38.78 microM and displayed cytotoxicity towards rat skeletal my...

Six phenolic compounds namely, quercetin-3-O-rutinoside (1), 3-O-caffeoylquinic acid (2), luteoli... more Six phenolic compounds namely, quercetin-3-O-rutinoside (1), 3-O-caffeoylquinic acid (2), luteolin-7-O-glucoside (3), apigenin-7-O-rutinoside (4), apigenin-7-O-b-D-glucopyranoside (5) and quercetin (6) were isolated from the whole plant of Pilea microphylla using conventional opensilica gel column chromatography and preparative HPLC. Further, these compounds were characterized by 1D, 2D NMR techniques and high-resolution LC-MS. Compounds 1-3 and 6 exhibited significant antioxidant potential in scavenging free radicals such as DPPH, ABTS and SOD with IC 50 of 3.3-20.4 mmol/L. The same compounds also prevented lipid peroxidation with IC 50 of 10.4-32.2 mmol/L. The compounds also significantly prevented the Fenton reagent-induced calf thymus DNA damage. Pre-treatment with compounds 1-3 and 6 in V79 cells attenuated radiation-induced formation of reactive oxygen species, lipid peroxidation, cytotoxicity and DNA damage, correlating the antioxidant activity of polyphenols with their radioprotective effects. Compounds 1, 3 and 6 significantly inhibited lipid peroxidation, presumably due to 3 0 ,4 0-catechol ortho-dihydroxy moiety in the Bring , which has a strong affinity for phospholipid membranes. Oxidation of flavonoids, with catechol structure on Bring , yields a fairly stable ortho-semiquinone

A new 2',6'-dimethoxy-4',5'-(2",2"-dimethyl)-pyranochalcone (1) and three known flavanones, namel... more A new 2',6'-dimethoxy-4',5'-(2",2"-dimethyl)-pyranochalcone (1) and three known flavanones, namely 5-hydroxy-7methoxy-8-(3,3-dimethylallyl)-flavanone (methyl glabranin) (2), 5,7-dimethoxy-8-(3,3-dimethylallyl)-flavanone (candinone) (3) and 5-O-methyl obovatin (pongachin) (4), have been isolated from the chloroform extract of the roots of Tephrosia pulcherrima. The flavonoids were fully characterized by detailed 1D-and 2D-NMR spectroscopic investigations. The pyranochalcone 1 showed significant antimicrobial activity when tested against a series of microorganisms .

$Research paper thumbnail of Polyphenolic fraction of Pilea microphylla (L.) protects Chinese hamster lung fibroblasts against γ-radiation-induced cytotoxicity and genotoxicity$

Environmental Toxicology and Pharmacology, 2012

Present study was designed to compare cytoprotective and antigenotoxic activity of the polyphenol... more Present study was designed to compare cytoprotective and antigenotoxic activity of the polyphenolic fraction of Pilea microphylla (PM1) with that of its active polyphenolic constituents against ␥-radiation in V79 cells. PM1 was standardized with respect to the polyphenols present by RP-HPLC. It was evaluated for its free radical scavenging potential using Fenton reaction-induced DNA damage and lipid peroxidation. Further, PM1 was subjected against ␥-radiation-induced cytotoxicity and genotoxicity in V79 cells. PM1 significantly reduced free radical-mediated calf thymus DNA damage and lipid peroxidation. Among the concentrations tested (12.5, 25 and 50 g/ml) for radioprotection, PM1 at 25 g/ml exhibited maximum protection. Further, when compared with constituent polyphenols viz., rutin, quercetin and chlorogenic acid (concentrations equivalent to that present in PM1-25 g/ml), a combination of polyphenols was found most effective in preventing ␥-radiation-induced cytotoxicity and genotoxicity. To conclude, radioprotection is possibly a synergistic effect of the phytochemicals present in the herbal extract, rather than any single component.

PLOS ONE, Jul 20, 2017

The traditional Indian medicine, Ayurveda, provides insights and practical solutions towards a he... more The traditional Indian medicine, Ayurveda, provides insights and practical solutions towards a healthy life style. Rasayana is a branch of Ayurveda known for preserving and promoting health, enhancing the quality of life and delaying the aging process. In the traditional knowledge, the Rasayana herb, Chlorophytum borivilianum (C. borivilanum) is regarded as a general health promoting tonic that delays aging and increases lifespan, cognitive function and physical strength. Aging is a complex and multifactorial physiological phenomenon that manifests itself over a wide range of biological systems, tissues, and functions. Longevity is an obvious marker of physiological aging. Simple model systems such as the single-cell budding yeast Saccharomyces cerevisiae (S. cerevisiae) and the nematode, Caenorhabditis elegans (C. elegans) are widely used to study the aging process and longevity. Here, we show that a polysaccharide fraction obtained from C. borivilianum increases the lifespan of S. cerevisiae and C. elegans, using an automated screening platform (Chronoscreen TM). Chemical analysis of this extract revealed a low molecular weight polysaccharide of 1000 Da, predominantly comprising Glu1!6Glu linkage. This polysaccharide showed significant dose-dependent extension of the median lifespan of S. cerevisiae by up to 41% and of the median lifespan of C. elegans by up to 10%. Taking cue from these results and the traditionally described benefits of Rasayanas on skin rejuvenation, we tested in vitro the polysaccharide for potential skin benefits. In a keratinocyte culture, we observed that this polysaccharide increased cell proliferation significantly, and induced synthesis of hyaluronic acid (HA), a well-known extracellular matrix component. Furthermore, when added to culture medium of human reconstructed epidermis, we observed an enhanced production of epidermal markers, e.g. CD44 and HA that are otherwise diminished in aged skin. Together, these results suggest that in addition to lifespan extension of S. cerevisiae and C. elegans, a polysaccharide from the Rasayana herb, C. borivilianum may have beneficial effects on skin aging parameters.

PloS one, 2017

A new compound, (2S)-p-hydroxyphenethyl 2-bromo-2-methyldodeconate (1) and 7,3′-dimethoxy-5,4′-di... more A new compound, (2S)-p-hydroxyphenethyl 2-bromo-2-methyldodeconate (1) and 7,3′-dimethoxy-5,4′-dihydroxy flavone, together with lupeol and stigmasterol were isolated from the stem bark of Citharexylum fruticosum (Verbenaceae). The structures of the compounds were established on the basis of the interpretation of NMR (1 H, 13 C, COSY and HMBC) spectra, as well as low and high-resolution mass spectrometric data. In this paper, we report on the structure elucidation of 1.

Natural Product Communications

A new 2′,6′-dimethoxy-4′,5′-(2″,2″-dimethyl)-pyranochalcone (1) and three known flavanones, namel... more A new 2′,6′-dimethoxy-4′,5′-(2″,2″-dimethyl)-pyranochalcone (1) and three known flavanones, namely 5-hydroxy-7-methoxy-8-(3,3-dimethylallyl)-flavanone (methyl glabranin) (2), 5,7-dimethoxy-8-(3,3-dimethylallyl)-flavanone (candinone) (3) and 5- O-methyl obovatin (pongachin) (4), have been isolated from the chloroform extract of the roots of Tephrosia pulcherrima. The flavonoids were fully characterized by detailed 1D- and 2D-NMR spectroscopic investigations. The pyranochalcone 1 showed significant antimicrobial activity when tested against a series of micro-organisms.

Natural Product Communications

A new phenolic glucoside, (rel)-2-(4',6'-dibenzoyl-β-glucopyranosyloxy)-7-(1α-hydroxy-2α-ethoxy-6... more A new phenolic glucoside, (rel)-2-(4',6'-dibenzoyl-β-glucopyranosyloxy)-7-(1α-hydroxy-2α-ethoxy-6α-acetyloxy-3oxocyclohex-4-enoyl)-benzyl alcohol (Flacourticin) (1) and the known, 2-(4',6'-dibenzoyl-β-glucopyranosyl)-5-hydroxy benzyl alcohol (4'-benzoylpoliothrysoside) (2) together with the new, (2E)-heptyl-3-(3,4-dihydroxyphenyl) acrylate (3), (+)-catechin (4) and sitosterol-β-D-glucoside were isolated from Flacourtia indica. Their structures were assigned on the basis of 1D, 2D-NMR and as well by analysis of the LC-ESIMS data. The isolated compounds (1-4) were evaluated for α,αdiphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, and 3 was found to be twofold less potent, with an IC 50 =12.01 μg/mL, compared to the positive control, Rutin, (IC 50 = 5.83 μg/mL).

Natural product communications, 2014

Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, n... more Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, namely 2',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1a, auriculatin), 2',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyloxyisoflavone (2a, isoauriculatin), 3',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1b, auriculasin), and 3',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyl-oxyisoflavone (2b, isoauriculasin). Auriculasin and isoauriculasin are reported for the first time with full NMR assignments. All metabolites were fully characterized by 1D and 2D NMR techniques including COSY, HSQC, HMBC experiments, mass spectra and in part on the basis of X-ray diffraction. Accurate 'invariom' refinements with aspherical scattering factors were carried out for 1a, 1b and 2a.

Natural product communications

Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, n... more Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, namely 2',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1a, auriculatin), 2',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyloxyisoflavone (2a, isoauriculatin), 3',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1b, auriculasin), and 3',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyl-oxyisoflavone (2b, isoauriculasin). Auriculasin and isoauriculasin are reported for the first time with full NMR assignments. All metabolites were fully characterized by 1D and 2D NMR techniques including COSY, HSQC, HMBC experiments, mass spectra and in part on the basis of X-ray diffraction. Accurate 'invariom' refinements with aspherical scattering factors were carried out for 1a, 1b and 2a.

Phytochemistry Letters, 2008

Phytochemistry, 2004

Six quinones were isolated from the chloroform extract of the roots of Diospyros sylvatica and id... more Six quinones were isolated from the chloroform extract of the roots of Diospyros sylvatica and identified as 2-methyl-anthraquinone, plumbagin, diosindigo, diospyrin, isodiospyrin and microphyllone. The effect of the root extract on the orientation and survival of the subterranean termite, Odontotermes obesus was tested. In addition, four of these quinones were tested on the survival of the subterranean termite. In a direct-choice experiment, exposure to an extract-treated filter disc had a significantly repellent effect over the solvent-treated filter disc. The no-choice experiment revealed the toxic property of the extract as well as the tested quinones and showed high mortality of the O. obesus workers after 48 h on forced exposure. The major termiticidal components identified were plumbagin, isodiospyrin and microphyllone while diospyrin was not toxic to termites at the concentration tested. All the quinones are reported for the first time from D. sylvatica.

RSC Advances

Biochemical Systematics and Ecology

Natural Product Communications, 2014

Natural Product Research, 2006

Phytochemistry, 2006

$Research paper thumbnail of Polyphenolic fraction of Pilea microphylla (L.) protects Chinese hamster lung fibroblasts against γ-radiation-induced cytotoxicity and genotoxicity$

Environmental Toxicology and Pharmacology, 2012

PLOS ONE, Jul 20, 2017

PloS one, 2017

Natural Product Communications

Natural product communications, 2014

Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, n... more Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, namely 2',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1a, auriculatin), 2',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyloxyisoflavone (2a, isoauriculatin), 3',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1b, auriculasin), and 3',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyl-oxyisoflavone (2b, isoauriculasin). Auriculasin and isoauriculasin are reported for the first time with full NMR assignments. All metabolites were fully characterized by 1D and 2D NMR techniques including COSY, HSQC, HMBC experiments, mass spectra and in part on the basis of X-ray diffraction. Accurate 'invariom' refinements with aspherical scattering factors were carried out for 1a, 1b and 2a.

Natural product communications

Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, n... more Chemical re-examination of the roots of T. calophylla led to the isolation of four isoflavones, namely 2',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1a, auriculatin), 2',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyloxyisoflavone (2a, isoauriculatin), 3',4',5-trihydroxy-6,7-(2",2"-dimethylchromene)-8-gamma,gamma-dimethylallylisoflavone (1b, auriculasin), and 3',5-dihydroxy-6,7-(2",2"-dimethylchromene)-4'-gamma,gamma-dimethylallyl-oxyisoflavone (2b, isoauriculasin). Auriculasin and isoauriculasin are reported for the first time with full NMR assignments. All metabolites were fully characterized by 1D and 2D NMR techniques including COSY, HSQC, HMBC experiments, mass spectra and in part on the basis of X-ray diffraction. Accurate 'invariom' refinements with aspherical scattering factors were carried out for 1a, 1b and 2a.

Phytochemistry Letters, 2008

Phytochemistry, 2004