Professor  Sami A Khalid, B.Pharm., M.Pharm., PhD - Faculty of Pharmacy, University of Science & Technology - Professor of Phytochemistry

Professor Sami A Khalid

B.Pharm., M.Pharm., PhD

Faculty of Pharmacy, University of Science & Technology

Professor of Phytochemistry

Khartoum, Khartoum | Sudan

Additional Specialties: Natural products chemistry

Professor  Sami A Khalid, B.Pharm., M.Pharm., PhD - Faculty of Pharmacy, University of Science & Technology - Professor of Phytochemistry

Professor Sami A Khalid

B.Pharm., M.Pharm., PhD

Introduction

Primary Affiliation: Faculty of Pharmacy, University of Science & Technology - Khartoum, Khartoum , Sudan

Additional Specialties:

Research Interests:

Publications

15Publications

113Reads

255Profile Views

48PubMed Central Citations

Azadirachta indica ethanolic extract protects neurons from apoptosis and mitigates brain swelling in experimental cerebral malaria.

Malar J 2013 Aug 29;12:298. Epub 2013 Aug 29.

Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, Buraydah 51452, Saudi Arabia.

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http://dx.doi.org/10.1186/1475-2875-12-298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3844317PMC
August 2013
20 Reads
1 Citation
3.110 Impact Factor

Encecalol angelate, an unstable chromene from Ageratum conyzoides L.: total synthesis and investigation of its antiprotozoal activity.

J Ethnopharmacol 2011 Sep 17;137(1):620-5. Epub 2011 Jun 17.

Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Münster, Germany.

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http://dx.doi.org/10.1016/j.jep.2011.06.015DOI Listing
September 2011
4 Reads
1 Citation
3.000 Impact Factor

The antiprotozoal activity of methylated flavonoids from Ageratum conyzoides L.

J Ethnopharmacol 2010 May 26;129(1):127-30. Epub 2010 Feb 26.

Institut für Pharmazeutische Biologie und Phytochemie IPBP, Westfälische Wilhelms-Universität Münster, Hittorfstrasse 56, D-48149, Münster, Germany.

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http://linkinghub.elsevier.com/retrieve/pii/S037887411000130
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http://dx.doi.org/10.1016/j.jep.2010.02.015DOI Listing
May 2010
4 Reads
11 Citations
3.000 Impact Factor

The antiprotozoal activity of sixteen asteraceae species native to Sudan and bioactivity-guided isolation of xanthanolides from Xanthium brasilicum.

Planta Med 2009 Oct 8;75(12):1363-8. Epub 2009 May 8.

Institut für Pharmazeutische Biologie und Phytochemie IPBP, Westfälische Wilhelms-Universität Münster, Münster, Germany.

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http://dx.doi.org/10.1055/s-0029-1185676DOI Listing
October 2009
15 Reads
10 Citations
2.152 Impact Factor

Decades of phytochemical research on African biodiversity.

Authors:
Sami A Khalid

Nat Prod Commun 2009 Oct;4(10):1431-46

Department of Pharmacognosy, Faculty of Pharmacy, University of Science and Technology, Omdurman, Sudan.

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October 2009
4 Reads

Quantitative structure--antiprotozoal activity relationships of sesquiterpene lactones.

Molecules 2009 Jun 8;14(6):2062-76. Epub 2009 Jun 8.

Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische Biologie und Phytochemie, Hittorfstrasse 56, D-48149 Münster, Germany.

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http://dx.doi.org/10.3390/molecules14062062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6254286PMC
June 2009
3 Reads
14 Citations
2.420 Impact Factor

Anti-trypanosomal activity of helenalin and some structurally related sesquiterpene lactones.

Planta Med 2002 Aug;68(8):750-1

Institut für Pharmazeutische Biologie der Heinrich-Heine-Universität, Düsseldorf, Germany.

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http://dx.doi.org/10.1055/s-2002-33799DOI Listing
August 2002
3 Reads
8 Citations
2.152 Impact Factor

limonoids from Khaya senegalensis.

Phytochemistry 1998 Nov;49(6):1769-1772

Department of Pharmacognosy, Faculty of Pharmacy, University of Khartoum, P.O. Box 1996, Khartoum, Sudan

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November 1998
14 Reads
3 Citations
2.550 Impact Factor

Experimental Azadirachta indica toxicosis in chicks.

PMID: 1609490

Vet Hum Toxicol.

Brown Hisex chicks were fed Azadirachta indica ripe fruit at 2, 5 or 10% of basic diet from their 7th to 35th d of age. Decreased body weight gain and efficiency of feed utilization and hepatonephropathy were most severe in chicks fed the 10% A indica diet. These changes were accompanied by anemia and increases in LDH, GOT and ALP activities and uric acid concentration and by decreased serum total protein. Hepatocytes and renal tubular cells did not completely revert to normal 2 w after removal from the test diets.

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Toxicological interactions of Abrus precatorius and Cassia senna in the diet of Lohmann broiler chicks.

Vet Hum Toxicol.

The combination of 0.5% Abrus precatorius seed and 2% Cassia senna fruit in the diet of Lohmann broiler chicks caused severe lesions, reduced weight gain, inefficient feed utilization and anemia. Organ lesions correlated with changes in clinical chemistry and hematology. Tissue recovery was not complete 2 w following withdrawal of the test diet. Feeding 0.5% Abrus or 2% Senna diets alone produced decreased growth and tissue lesions that did not return to normal 2 w following return to normal rations.

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Antiplasmodial activity of selected Sudanese medicinal plants with emphasis on Maytenus senegalensis (Lam.) Exell.

PMID: 10363837

J Ethnopharmacol.

The antiplasmodial activity of plant extracts related to four families was tested on chloroquine sensitive strain 3D7 and chloroquine resistant strain Dd2 of Plasmodium falciparum. The methanolic extract of Harrisonia abyssinica (Simaroubaceae) inhibited Dd2 with IC50 value of 4.7 microg/ml, while in 3D7, the IC50 value was 10 microg/ml. Most of the plants from the family Meliaceae showed highly potent antiplasmodial activity against the two tested strains. Khaya senegalensis, Azadirachta indica and Trichilia emetica showed IC50 values less than 5 microg/ml. The methanolic extract of Annona squamosa (Annonaceae) leaves showed high antiplasmodial activity with IC50 values of 2 and 30 microg/ml on 3D7 and Dd2, respectively. While stem bark showed moderate activity with IC50 values of 8.5 and 120 microg/ml on Dd2. Maytenus senegalensis (Celastraceae) possessed IC50 values of 3.9 on 3D7, 10 microg/ml on Dd2 and had no effect on lymphocyte proliferation even at the highest tested concentration; the IC50 was greater than 100 microg/ml. Liquid-liquid separation of the methanolic extract of M. senegalensis revealed that the dichloromethane extract possessed an IC50 value of only 2.1 microg/ml. Column fractionation of dichloromethane extract gave four fractions and fraction two showed an IC50 value of 0.5 microg/ml. Preliminary phytochemical analysis of dichloromethane fraction revealed terpenoids and traces of phenolic principles but no alkaloid, tannins or flavonoids were detected.

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Antiplasmodial activity of selected sudanese medicinal plants with emphasis on Acacia nilotica.

PMID: 10479756

Phytother Res.

Twenty-two plant organs from eleven plants comprising five families were extracted and screened for antiplasmodial activity in vitro against Plasmodium falciparum 3D7 (chloroquine sensitive) and Dd2 (chloroquine resistant and pyrimethamine sensitive). Fifty nine percent of plant extracts from 22 extracts exerted activity on P. falciparum strain 3D7 with an IC(50) less than 50 microg/mL, whereas 43% of plant extracts showed an IC(50) value within 50 microg/mL on Dd2 strains. Plant extracts from Gardenia lutea, Haplophyllum tuberculatum, Cassia tora, Acacia nilotica and Aristolochia bracteolata possessed IC(50) values less than 5 microg/mL on both tested strains. Bioassay guided fractionation of A. nilotica revealed that the ethyl acetate extract possessed the highest activity (IC(50) = 1.5 microg/mL). Fraction 2 (R(f) = 0.75) prepared by preparative chromatography showed the highest activity on P. falciparum (IC(50) = 1.7 microg/mL). Phytochemical analysis indicated that the most active phase contained terpenoids and tannins and was devoid of alkaloids and saponins. The effect of plant extracts on lymphocyte proliferation showed low toxicity to the human cells. This plant has been subjected to long term clinical trials in folk medicine and is a promising plant.

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The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part II.

PMID: 22414104

Curr Med Chem.

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined by the WHO. Furthermore, malaria (caused by various Plasmodium species) can be considered a neglected disease in certain countries and with regard to availability and affordability of the antimalarials. Living organisms, especially plants, provide an innumerable number of molecules with potential for the treatment of many serious diseases. The current review attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs. In part I, a general description of the diseases, the current state of therapy and need for new therapeuticals, assay methods and strategies applied in the search for new plant derived natural products against these diseases and an overview on natural products of terpenoid origin with antiprotozoal potential were given. The present part II compiles the current knowledge on natural products with antiprotozoal activity that are derived from the shikimate pathway (lignans, coumarins, caffeic acid derivatives), quinones of various structural classes, compounds formed via the polyketide pathways (flavonoids and related compounds, chromenes and related benzopyrans and benzofurans, xanthones, acetogenins from Annonaceae and polyacetylenes) as well as the diverse classes of alkaloids. In total, both parts compile the literature on almost 900 different plant-derived natural products and their activity data, taken from over 800 references. These data, as the result of enormous efforts of numerous research groups world-wide, illustrate that plant secondary metabolites represent an immensely rich source of chemical diversity with an extremely high potential to yield a wealth of lead structures towards new therapies for NTDs. Only a small percentage, however, of the roughly 200,000 plant species on earth have been studied chemically and only a small percentage of these plants or their constituents has been investigated for antiprotozoal activity. The repository of plant-derived natural products hence deserves to be investigated even more intensely than it has been up to present.

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The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part I.

PMID: 22414103

Curr Med Chem. 2012;19(14):2128-75.

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined as such by WHO due to the neglect of financial investment into research and development of new drugs by a large part of pharmaceutical industry and neglect of public awareness in high income countries. Another major tropical protozoan disease is malaria (caused by various Plasmodium species), which -although not mentioned currently by the WHO as a neglected disease- still represents a major problem, especially to people living under poor circumstances in tropical countries. Malaria causes by far the highest number of deaths of all protozoan infections and is often (as in this review) included in the NTDs. The mentioned diseases threaten many millions of lives world-wide and they are mostly associated with poor socioeconomic and hygienic environment. Existing therapies suffer from various shortcomings, namely, a high degree of toxicity and unwanted effects, lack of availability and/or problematic application under the life conditions of affected populations. Development of new, safe and affordable drugs is therefore an urgent need. Nature has provided an innumerable number of drugs for the treatment of many serious diseases. Among the natural sources for new bioactive chemicals, plants are still predominant. Their secondary metabolism yields an immeasurable wealth of chemical structures which has been and will continue to be a source of new drugs, directly in their native form and after optimization by synthetic medicinal chemistry. The current review, published in two parts, attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs.

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Top co-authors

Reto Brun
Reto Brun

Swiss Tropical and Public Health Institute

5
Thomas J Schmidt
Thomas J Schmidt

Westfälische Wilhelms-Universität Münster

5
Marcel Kaiser
Marcel Kaiser

Swiss Tropical and Public Health Institute

4
Selma Bedri
Selma Bedri

College of Applied Medical Sciences

1
Eltahir A Khalil
Eltahir A Khalil

University of Khartoum

1
Mohammad A Alzohairy
Mohammad A Alzohairy

College of Applied Medical Sciences

1
Ligia Salgueiro
Ligia Salgueiro

Università degli Studi di Cagliari

1