Neeraj Kumar

发表

A novel insight of Asp193His mutation on epigenetic methyltransferase activity of human EZH2 protein: An in-silico approach

N. Gautam, S. Kaur, Kamaljeet Kaur, 2019, Meta Gene.

Synthesis and anti-angiogenic activity of benzothiazole, benzimidazole containing phthalimide derivatives.

Neeraj Kumar, Bikram Singh, U. Sharma, 2013, Bioorganic & medicinal chemistry letters.

Antioxidant activity and ultra-performance LC-electrospray ionization-quadrupole time-of-flight mass spectrometry for phenolics-based fingerprinting of Rose species: Rosa damascena, Rosa bourboniana and Rosa brunonii.

Neeraj Kumar, Bikram Singh, S. S. Bari, 2009, Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association.

Ligand‐free Iron(II)‐Catalyzed N‐Alkylation of Hindered Secondary Arylamines with Non‐activated Secondary and Primary Alcohols via a Carbocationic Pathway

Neeraj Kumar, O. S. Nayal, M. S. Thakur, 2018 .

Chemical modification of L-glutamine to alpha-amino glutarimide on autoclaving facilitates Agrobacterium infection of host and non-host plants: A new use of a known compound

P. Das, P. Ahuja, Neeraj Kumar, 2011, BMC chemical biology.

Iron phthalocyanine as an efficient and versatile catalyst for N-alkylation of heterocyclic amines with alcohols: one-pot synthesis of 2-substituted benzimidazoles, benzothiazoles and benzoxazoles

P. Verma, Neeraj Kumar, Bikram Singh, 2013 .

In-silico studies on Myo inositol-1-phosphate synthase of Leishmania donovani in search of anti-leishmaniasis

G. Kothandan, Neeraj Kumar, Satabdi Saha, 2020, Journal of biomolecular structure & dynamics.

Designing Vasicine‐Derived Ligands and Their Application for Ruthenium‐Catalyzed Transfer Hydrogenation Reactions in Water: Synthesis of Amines and Alcohols

Neeraj Kumar, Bikram Singh, U. Sharma, 2016 .

Metal-free transfer hydrogenation of nitroarenes in water with vasicine: revelation of organocatalytic facet of an abundant alkaloid.

Neeraj Kumar, S. Sharma, Manoranjan Kumar, 2014, The Journal of organic chemistry.

Antioxidant activity of Potentilla fulgens: An alpine plant of western Himalaya

V. Kaul, V. Jaitak, Neeraj Kumar, 2010 .

Immunomodulatory active compounds from Tinospora cordifolia.

Neeraj Kumar, Bikram Singh, S. Bhalerao, 2012, Journal of ethnopharmacology.

Online antioxidant activity and ultra-performance LC-electrospray ionisation-quadrupole time-of-fight mass spectrometry for chemical fingerprinting of Indian polyherbal formulations

Neeraj Kumar, P. Bhandari, K. Bhutani, 2016, Natural product research.

Reversed phase-HPLC for rapid determination of polyphenols in flowers of rose species.

V. Kaul, Neeraj Kumar, Bikram Singh, 2008, Journal of separation science.

Isolation and characterization of flavanols from Anthocephalus cadamba and evaluation of their antioxidant, antigenotoxic, cytotoxic and COX-2 inhibitory activities

Neeraj Kumar, Bikram Singh, U. Sharma, 2016 .

Investigation of ethyl acetate extract/fractions of Acacia nilotica willd.Ex Del as potent antioxidant.

Neeraj Kumar, Rajbir Singh, Bikram Singh, 2009 .

Highly Chemo‐ and Regioselective Reduction of Aromatic Nitro Compounds Catalyzed by Recyclable Copper(II) as well as Cobalt(II) Phthalocyanines

Praveen Kumar, Neeraj Kumar, Bikram Singh, 2010 .

Copper(II) trans-bis-(glycinato): an efficient heterogeneous catalyst for cross coupling of phenols with aryl halides

Neeraj Kumar, Sanny Verma, S. Jain, 2012 .

Synthesis of substituted amines and isoindolinones: catalytic reductive amination using abundantly available AlCl3/PMHS

Neeraj Kumar, Bikram Singh, U. Sharma, 2012 .

Iron(III) Chloride‐Catalyzed Decarboxylative–Deaminative Functionalization of Phenylglycine: A Tandem Synthesis of Quinazolinones and Benzimidazoles

Richa, Neeraj Kumar, S. Sharma, 2015 .

Tin‐Catalyzed Selective Reductive Hydroamination of Alkynes for the Synthesis of Tertiary Amines

Neeraj Kumar, S. Sharma, O. S. Nayal, 2016 .

Antimutagenic extract from Tinospora cordifolia and its chemical composition.

Praveen Kumar, Neeraj Kumar, Bikram Singh, 2010 .

In vitro Antioxidant Activity from Leaves of Oroxylum

N. Sharma, Neeraj Kumar, Bikram Singh, 2008 .

In vitro Antioxidant Activity from Leaves of Oroxylum indicum (L.) Vent. -A North Indian Highly Threatened and Vulnerable Medicinal Plant

N. Sharma, Neeraj Kumar, Bikram Singh, 2008 .

Sensitive and fluorescent Schiff base chemosensor for pico molar level fluoride detection: In vitro study and mimic of logic gate function

P. Ghosh, P. Banerjee, Neeraj Kumar, 2016 .

A rapid RP-HPTLC densitometry method for simultaneous determination of major flavonoids in important medicinal plants.

V. Kaul, Neeraj Kumar, Bikram Singh, 2007, Journal of separation science.

Inhibition of H2O2-induced DNA damage in single cell gel electrophoresis assay (comet assay) by castasterone isolated from leaves of centella asiatica

Neeraj Kumar, Bikram Singh, R. Bhardwaj, 2010 .

Modulatory role of alizarin from Rubia cordifolia L. against genotoxicity of mutagens.

Neeraj Kumar, Bikram Singh, Prabhjit Kaur, 2010, Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association.

Evaluation of antigenotoxic activity of isoliquiritin apioside from Glycyrrhiza glabra L.

Neeraj Kumar, Bikram Singh, Prabhjit Kaur, 2009, Toxicology in vitro : an international journal published in association with BIBRA.

Ultrafast UPLC-ESI-MS and HPLC with monolithic column for determination of principal flavor compounds in vanilla pods.

Neeraj Kumar, A. Sinha, U. Sharma, 2009, Journal of separation science.

Anti-free radical activities of kaempferol isolated from Acacia nilotica (L.) Willd. Ex. Del.

Neeraj Kumar, Rajbir Singh, Bikram Singh, 2008, Toxicology in vitro : an international journal published in association with BIBRA.

Biflavonoids from Lonicera japonica.

V. Kaul, Neeraj Kumar, Bikram Singh, 2005, Phytochemistry.

Amides From Plants: Structures and Biological Importance

Neeraj Kumar, Vishal Kumar, V. Bhatt, 2018 .

Solvent‐free, l‐Leucine‐Catalyzed Direct Dehydrative Esterification of Carboxylic Acids with Alcohols: Direct Synthesis of 3‐Alkoxy 1(3 H)‐isobenzofuranone

Neeraj Kumar, Bikram Singh, U. Sharma, 2018 .

CuI nanoparticles as recyclable heterogeneous catalysts for C–N bond formation reactions

R. Bal, Neeraj Kumar, Bikram Singh, 2017 .

Chemical Prospection of Important Ayurvedic Plant Tinospora cordifolia by UPLC-DAD-ESI-QTOF-MS/MS and NMR

P. Verma, Neeraj Kumar, Bikram Singh, 2015, Natural product communications.

Simultaneous Determination of Ten Sugars in Tinospora cordifolia by Ultrasonic Assisted Extraction and LC-ELSD

Neeraj Kumar, Bikram Singh, U. Sharma, 2010 .

Silica-based monolithic column with evaporative light scattering detector for HPLC analysis of bacosides and apigenin in Bacopa monnieri.

Neeraj Kumar, Bikram Singh, Inderjeet Kaur, 2009, Journal of separation science.

Iron and Palladium(II) Phthalocyanines as Recyclable Catalysts for Reduction of Nitroarenes

P. Verma, Neeraj Kumar, Bikram Singh, 2014, Catalysis Letters.

Direct One-Pot Cobalt(ii) Phthalocyanine Catalyzed Synthesis of N-Substituted Isoindolinones

Neeraj Kumar, Bikram Singh, U. Sharma, 2012 .

Antifilarial activity of diterpenoids from Taxodium distichum

Neeraj Kumar, Bikram Singh, S. Verma, 2016, Parasites & Vectors.

Highly selective direct reductive amidation of nitroarenes with carboxylic acids using cobalt(II) phthalocyanine/PMHS

Neeraj Kumar, S. Sharma, Manoranjan Kumar, 2014 .

Zinc phthalocyanine with PEG-400 as a recyclable catalytic system for selective reduction of aromatic nitro compounds

P. Verma, Neeraj Kumar, Bikram Singh, 2012 .

Chemical composition and larvicidal activity of Zanthoxylum armatum against diamondback moth, Plutella xylostella

Neeraj Kumar, Bikram Singh, Vishal Kumar, 2016, Natural product research.

SHORT COMMUNICATION Chemical composition and larvicidal activity of Zanthoxylum armatum against diamondback moth, Plutella xylostella

Neeraj Kumar, Bikram Singh, Vishal Kumar, 2016 .

Highly efficient water-mediated approach to access benzazoles: metal catalyst and base-free synthesis of 2-substituted benzimidazoles, benzoxazoles, and benzothiazoles

P. Verma, Neeraj Kumar, Bikram Singh, 2015, Molecular Diversity.

Immunomodulatory active steroidal saponins from Asparagus racemosus

Neeraj Kumar, Bikram Singh, S. Bhalerao, 2013, Medicinal Chemistry Research.

Antifilarial activity of diterpenoids from Taxodium distichum

Neeraj Kumar, Bikram Singh, S. Verma, 2016, Parasites & Vectors.

Catalyst-free water mediated reduction of nitroarenes using glucose as a hydrogen source

Neeraj Kumar, Bikram Singh, U. Sharma, 2013 .

Transition Metal–Free Sodium Borohydride Promoted Controlled Hydration of Nitriles to Amides

P. Verma, Neeraj Kumar, Bikram Singh, 2013 .

Rapid and Efficient Cascade Synthesis of 2‐Amino‐4(3 H)‐quinazolinones over an In Situ‐Generated Heterogeneous CuCO3–K2CO3 Nanocomposite

Neeraj Kumar, S. Sharma, O. S. Nayal, 2016 .

Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes.

Neeraj Kumar, Shivani Choudhary, Neeraj Kumar, 2011, Chemical communications.

Unravelling 2-aminoquinazolin-4(3H)-one as an organocatalyst for the chemoselective reduction of nitroarenes

R. Rana, Neeraj Kumar, S. Sharma, 2018 .

Microwave assisted synthesis of phenanthridinones and dihydrophenanthridines by vasicine/KOtBu promoted intramolecular C-H arylation.

Neeraj Kumar, Bikram Singh, U. Sharma, 2016, Organic & biomolecular chemistry.

Phosphane-free green protocol for selective nitro reduction with an iron-based catalyst.

P. Verma, Neeraj Kumar, Bikram Singh, 2011, Chemistry.

Vasicine from Adhatoda vasica as an organocatalyst for metal-free Henry reaction and reductive heterocyclization of o-nitroacylbenzenes

Neeraj Kumar, Bikram Singh, U. Sharma, 2016 .

Substrate‐Controlled Diastereoselective Synthesis of Sugar‐Based Chlorinated Perhydrofuro[2,3‐b]pyrans via Copper(I)‐Catalyzed Radical Cyclization

D. Gupta, Neeraj Kumar, R. Ram, 2017 .

Rapid and Efficient Cascade Synthesis of 2-Amino-4(3H)-quinazolinones over an in situ-Generated Heterogeneous CuCO3-K2CO3 Nanocomposite.

Neeraj Kumar, S. Sharma, O. S. Nayal, 2016 .

Combined Thiourea Dioxide-Water : An Effective Reusable Catalyst for the Synthesis of Polyhydroquinolines via Hantzsch Multicomponent Coupling

Neeraj Kumar, Sanny Verma, S. Jain, 2012 .

Transition Metal-Free Sodium Borohydride Promoted Controlled Hydration of Nitriles to Amides.

P. Verma, Neeraj Kumar, Bikram Singh, 2013 .

Transition metal-free 1,3-dimethylimidazolium hydrogen carbonate catalyzed hydration of organonitriles to amides

P. Verma, Neeraj Kumar, Bikram Singh, 2013 .

Synthesis of tertiary arylamines: Lewis acid-catalyzed direct reductive N-alkylation of secondary amines with ketones through an alternative pathway.

Neeraj Kumar, Bikram Singh, U. Sharma, 2016, Chemical communications.

Cobalt(II) Phthalocyanine‐Catalyzed Highly Chemoselective Reductive Amination of Carbonyl Compounds in a Green Solvent

P. Verma, Neeraj Kumar, Bikram Singh, 2012 .

Synthesis of chlorinated bicyclic C-fused tetrahydrofuro[3,2-c]azetidin-2-ones.

Neeraj Kumar, Nem Singh, R. Ram, 2010, The Journal of organic chemistry.

Synthesis of 2,4-disubstituted 3-chlorofurans and the effect of the chlorine substituent in furan Diels-Alder reactions

Neeraj Kumar, R. Ram, 2008 .

Synthesis, Antibacterial and Antifungal Activity of 2-Amino-1,4-naphthoquinones Using Silica-Supported Perchloric Acid (HClO4—SiO2) as a Mild, Recyclable and Highly Efficient Heterogeneous Catalyst.

Neeraj Kumar, Bikram Singh, A. Gulati, 2013 .

Vasicine catalyzed direct C–H arylation of unactivated arenes: organocatalytic application of an abundant alkaloid

Neeraj Kumar, S. Sharma, Vishal Kumar, 2013 .

Silica-supported boric acid with ionic liquid: a novel recyclable catalytic system for one-pot three-component Mannich reaction.

P. Verma, Neeraj Kumar, Bikram Singh, 2011, Chemical & pharmaceutical bulletin.

Montmorillonite‐K10‐Catalyzed Microwave‐Assisted Direct Amidation of Unactivated Carboxylic Acids with Amines: Maintaining Chiral Integrity of Substrates

Neeraj Kumar, Bikram Singh, U. Sharma, 2017 .

Grafting of oxo-vanadium Schiff base on graphene nanosheets and its catalytic activity for the oxidation of alcohols

Neeraj Kumar, Harshal P. Mungse, O. P. Khatri, 2012 .

Silica-Supported Boric Acid Catalyzed Synthesis of Dihydropyrimidin-2-ones, Bis(indolyl)methanes, Esters and Amides.

P. Verma, Neeraj Kumar, Bikram Singh, 2014 .

Nickel Phthalocyanine Assisted Highly Efficient and Selective Carbonyl Reduction in Polyethylene Glycol-400

P. Verma, Neeraj Kumar, Bikram Singh, 2012, Catalysis Letters.

An Efficient Metal-Free Mono N-Alkylation of Anilines via Reductive Amination Using Hydrosilanes

R. Rana, Neeraj Kumar, O. S. Nayal, 2018, European Journal of Organic Chemistry.

Emerging Catalytic Methods for Amide Synthesis

Neeraj Kumar, Bikram Singh, U. Sharma, 2013 .

Ni(II) and Cu(II) complexes of bidentate thiosemicarbazone ligand: Synthesis, structural, theoretical, biological studies and molecular modeling

Neeraj Kumar, P. Jain, N. Misra, 2020, Applied Organometallic Chemistry.

Synthesis of highly substituted m-chlorophenolic biaryls by chlorine substituent-promoted Diels–Alder reaction of 2-aryl-3-chlorofurans

Neeraj Kumar, R. Ram, 2008 .

Chemoselective Reductive Amination of Carbonyl Compounds for the Synthesis of Tertiary Amines Using SnCl2·2H2O/PMHS/MeOH.

Neeraj Kumar, S. Sharma, O. S. Nayal, 2015, The Journal of organic chemistry.

Phosphane‐Free Green Protocol for Selective Nitro Reduction with an Iron‐Based Catalyst.

P. Verma, Neeraj Kumar, Bikram Singh, 2011 .

2-Aminoquinazolin-4(3H)-one as an Organocatalyst for the Synthesis of Tertiary Amines.

Neeraj Kumar, O. S. Nayal, S. Maurya, 2018, Organic letters.

Chemical Composition of the Essential Oil of Centella asiatica (L.) Urb. from Western Himalaya †

Neeraj Kumar, Bikram Singh, V. P. Joshi, 2007 .

Flavonoids from Rosa Damascena Mill. †

V. Kaul, Neeraj Kumar, Bikram Singh, 2006 .

Umbelliferone – An antioxidant isolated from Acacia nilotica (L.) Willd. Ex. Del.

Neeraj Kumar, Rajbir Singh, Bikram Singh, 2010 .

Steroidal saponins from Asparagus racemosus.

Neeraj Kumar, Bikram Singh, U. Sharma, 2009, Chemical & pharmaceutical bulletin.

An improved method for thin layer chromatographic analysis of saponins.

Neeraj Kumar, Bikram Singh, T. K. Bhat, 2012, Food chemistry.

Furostanol Saponin and Diphenylpentendiol from the Roots of Asparagus racemosus

Neeraj Kumar, Bikram Singh, U. Sharma, 2012, Natural product communications.

New Hopane Triterpenes and Antioxidant Constituents from Potentilla Fulgens

V. Kaul, V. Jaitak, Neeraj Kumar, 2010, Natural Product Communications.

Chemical and biological aspects of iridoid bearing plants of temperate region

V. Kaul, P. Ahuja, Neeraj Kumar, 2005 .

Simultaneous determination of sugars and picrosides in Picrorhiza species using ultrasonic extraction and high-performance liquid chromatography with evaporative light scattering detection.

V. Kaul, Neeraj Kumar, Bikram Singh, 2008, Journal of chromatography. A.

Comprehensive metabolic profiling of Zanthoxylum armatum and Zanthoxylum acanthopodium leaves, bark, flowers and fruits using ultra high performance liquid chromatography

Neeraj Kumar, Bikram Singh, U. Sharma, 2018 .

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC‐DAD‐ESI‐QTOF–MS/MS

Neeraj Kumar, Bikram Singh, U. Sharma, 2017, Journal of pharmaceutical and biomedical analysis.

A New Lignan from the Leaves of Zanthoxylum armatum

Neeraj Kumar, Bikram Singh, S. Sharma, 2017, Natural product communications.

Quantitative and structural analysis of amides and lignans in Zanthoxylum armatum by UPLC-DAD-ESI-QTOF-MS/MS.

Neeraj Kumar, Bikram Singh, Vishal Kumar, 2014, Journal of pharmaceutical and biomedical analysis.

Steroidal alkaloids from Holarrhena antidysenterica (L.) WALL.

V. Kaul, Neeraj Kumar, Bikram Singh, 2007, Chemical & pharmaceutical bulletin.

Insecticidal Toxicity of Spilanthol from Spilanthes acmella Murr. against Plutella xylostella L.

Neeraj Kumar, Bikram Singh, Anuradha Sharma, 2012 .

Cucurbitacins from Bacopa monnieri.

V. Kaul, Neeraj Kumar, Bikram Singh, 2007, Phytochemistry.

Polysaccharide enriched immunomodulatory fractions from Tinospora cordifolia (Willd) miers ax hook. f. & Thoms.

P. Verma, Neeraj Kumar, Bikram Singh, 2012, Indian journal of experimental biology.

Zephgrabetaine: A New Betaine-type Amaryllidaceae Alkaloid from Zephyranthes grandiflora

Neeraj Kumar, Bikram Singh, U. Sharma, 2013, Natural product communications.

Isolation of 24-epibrassinolide from leaves of Aegle marmelos and evaluation of its antigenotoxicity employing Allium cepa chromosomal aberration assay

Neeraj Kumar, Bikram Singh, R. Bhardwaj, 2008, Plant Growth Regulation.

Antioxidant activity and identification of bioactive compounds from leaves of Anthocephalus cadamba by ultra-performance liquid chromatography/electrospray ionization quadrupole time of flight mass spectrometry.

Neeraj Kumar, Bikram Singh, U. Sharma, 2012, Asian Pacific journal of tropical medicine.

Online HPLC-DPPH method for antioxidant activity of Picrorhiza kurroa Royle ex Benth. and characterization of kutkoside by ultra-performance LC-electrospray ionization quadrupole time-of-flight mass spectrometry.

P. Ahuja, Neeraj Kumar, Bikram Singh, 2010, Indian journal of experimental biology.

Highly Efficient Iron Phthalocyanine Catalyzed Oxidative Synthesis of Imines from Alcohols and Amines.

P. Verma, Neeraj Kumar, Bikram Singh, 2014 .

Iron Phthalocyanine as an Efficient and Versatile Catalyst for N‐Alkylation of Heterocyclic Amines with Alcohols: One‐Pot Synthesis of 2‐Substituted Benzimidazoles, Benzothiazoles and Benzoxazoles.

P. Verma, Neeraj Kumar, Bikram Singh, 2013 .

WITHDRAWN: A novel insight of Asp193His mutation on epigenetic methyltransferase activity of human EZH2 protein: An in-silico approach

N. Gautam, S. Kaur, Kamaljeet Kaur, 2019, Informatics in Medicine Unlocked.

Immunomodulatory active steroidal saponins from Asparagus racemosus

Neeraj Kumar, Bikram Singh, S. Bhalerao, 2013, Medicinal Chemistry Research.

Chemical Composition of Essential Oil among Seven Populations of Zanthoxylum armatum from Himachal Pradesh: Chemotypic and Seasonal Variation

Neeraj Kumar, Bikram Singh, U. Sharma, 2017 .

In Vitro Studies on the Antioxidant/Antigenotoxic Potential of Aqueous Fraction from Anthocephalus cadamba Bark

Neeraj Kumar, Bikram Singh, U. Sharma, 2014 .

Hepatoprotective effect of Ginkgo biloba leaf extract on lantadenes-induced hepatotoxicity in guinea pigs.

Neeraj Kumar, O. Sharma, Pawan Kumar, 2014, Toxicon : official journal of the International Society on Toxinology.

Simultaneous quantification of Amaryllidaceae alkaloids from Zephyranthes grandiflora by UPLC-DAD/ESI-MS/MS.

Neeraj Kumar, Bikram Singh, Shiv Kumar, 2012, Journal of pharmaceutical and biomedical analysis.

Dammarane triterpenoid saponins from Bacopa monnieri

Neeraj Kumar, Bikram Singh, P. Bhandari, 2009 .

Highly efficient water-mediated approach to access benzazoles: metal catalyst and base-free synthesis of 2-substituted benzimidazoles, benzoxazoles, and benzothiazoles

P. Verma, Neeraj Kumar, Bikram Singh, 2015, Molecular Diversity.

Lonijaposides, Novel Cerebrosides from Lonicera japonica

V. Kaul, Neeraj Kumar, Bikram Singh, 2006 .

Direct Waste-Free Synthesis of Amides from Nonactivated Carboxylic Acids and Amines: Application to the Synthesis of Tetrahydroisoquinolines

P. Verma, Neeraj Kumar, Bikram Singh, 2015 .

Direct Waste-Free Synthesis of Amides from Nonactivated Carboxylic Acids and Amines: Application to the Synthesis of Tetrahydroisoquinolines.

P. Verma, Neeraj Kumar, Bikram Singh, 2015 .

Micro-LC Determination of Swertiamarin in Swertia species and Bacoside-A in Bacopa monnieri

V. Kaul, Neeraj Kumar, Bikram Singh, 2006 .

Bacosterol glycoside, a new 13,14-seco-steroid glycoside from Bacopa monnieri.

V. Kaul, Neeraj Kumar, Bikram Singh, 2006, Chemical & pharmaceutical bulletin.

Therapeutic potential of natural products from terrestrial plants as TNF-α antagonist.

P. Verma, Neeraj Kumar, Bikram Singh, 2012, Current topics in medicinal chemistry.

Chemical Fingerprint Analysis of Phenolics of Albizia chinensis Based on Ultra-Performance LC-Electrospray Ionization-Quadrupole Time-of-Flight Mass Spectrometry and Antioxidant Activity

Neeraj Kumar, Bikram Singh, A. Chaudhary, 2011, Natural product communications.

Recent advances in the chemistry of phthalimide analogues and their therapeutic potential.

Neeraj Kumar, Bikram Singh, U. Sharma, 2010, Mini reviews in medicinal chemistry.