MPhil Thesis

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A study of arsenic pollution in ground water of Bangladesh and finding a method for its removal from drinking water
(© University of Dhaka, 2025-03-12) Siddique, Mohd. Noor-e-Alam
Analytical chemistry of the separation of some metal ions with benzimidazole from mixed solutions
(© University of Dhaka, 2025-03-12) Begum, Rozina
Assessment of pesticide residues and nutrient levels in some vegetable samples
(©University of Dhaka, 2023-09-10) Sobnom, Farhana
The human diet relies heavily on vegetables as a source of nutrients. Vegetable consumption has increased due to changing lifestyles and the need to maintain health. Pesticide residues in vegetables are now a major global concern. Consumers might be at risk for health problems if they consume vegetables that have residual pesticide levels exceeding their individual maximum residue limits (MRL). Thus, to know the extent of residual contamination, there is a need to explore pesticide remainders in vegetables. However, pesticides are harmful to human health and the environment. It is essential to predict the level of pesticides in different vegetables to secure the human health and save the environment. The current research was designed based on four market samples such as: Potol or pointed gourd (Trichosanthes dioica), Korola or bitter gourd (Momordica charantia), Tomato (Solanum lycopersicum), Kacha morich or Green chili (Capsicum frutescens) and Phulcopi or cauliflower (Brassica oleracea var. botrytis) collected from two districts of Bangladesh to determine the level of residual pesticides.
Chemical and biological studies of leaves and twigs of anogeissus rivularis and some hypoglycemic herbal formulations
(University of Dhaka, 2019-04-25) Hosen, Md. Anowar
Hexane and Ethyl acetate extracts of leaves and twigs of Anogeissusrivularis and their sub-fractions were tested for anticancer activities on the six common human cancer cell lines; P-388, KB, HT-29, MCF-7, A549and two normal human kidney cell lines ASK and Hek293. Sub-fractions, 1F-3, 1F-5, Et-1F-2, Et-1F-3, and Et-1F-4 were found to possess significant anticancer activities (ED50 <4, 3.40, 4.50, 4.60 and 6.37 µg/mL respectively) on P-388 cell lines. The same extracts and their sub-fractions were also tested for anti-HIV-1 RT. The two extracts showed moderate activity but the two sub-fractions, 1F-5& Et-1F-7 were found to be very active (growth inhibition 97% & 92%, respectively). From the active extracts four new compounds namely, 2-(3՜,4՜-Dimethoxy-phenyl)-3-methyl-5-propenyl-2,3-dihydro-benzofuran (20), Dimer of 4,6-Dihydroxy-2-(4՜-hydroxy-benzyl)-benzofuran-3-one (21), 2-[(3՜,4՜-Dihydroxy-phenyl)-hydroxy-methyl]-4,6-dihydroxy-benzofuran-3-one (22), 2,5-Bis-[(4՜-hydroxy-phenyl)(4՜՜-hydroxy-phenyl)]-3,4-dimethyl-tetrahydro-furan-3-ol (23), together with thirteen known compounds namely, betulinic acid (3β-Hydroxy-19β-hydrogen-lup-20-(29)-en-28-oic acid)(3), 3β-Hydroxy-20(29)-en-lupan-30-al (6),29-Nor-20-oxolupeol (7), 3β,6β-Dihydroxylup-20(29)-ene(8),3,3՜,4՜-Tri-O-methylellagic acid (9),3,3՜-Di-O-methylellagic acid(12), (S)-naringenin(4՜,5,7-Trihydroxyflavanone) (13),p-Cumaric acid ((E)-3-(4՜-Hydroxyphenyl)-2-propenoic acid)(14),2,3-dihydro-p-cumaric acid(3-(4՜-Hydroxyphenyl)-propanoic acid)(15), protocatechuic acid (3,4-Dihydroxybenzoic acid)(16), Stigmast-5-en-3-O-β-glucoside(17),loliolide (6-Hydroxy-4,4,7a-trimethyl-5,6,7,7a-tetrahydro-4H-benzofuran-2-one) (18),vanillic acid (3-Methoxy 4-hydroxybenzoic acid) (19) were isolated by chromatographic techniques. The structure of this compounds were elucidated by spectroscopic methods using UV, FTIR, high resolution 1H &13C NMR and Mass spectrometry (HRMS-ESI-TOP) and Single Crystal X-ray Diffraction.
Chemical and biological studies on the pigments of tomato (lycopersicon esculentum Mill.) and litchi (litchi Chinensis Sonn.) of Bangladesh
(University of Dhaka, 2019-10-16) Mostofa, Md. Golam
Tomato (Lycopersicon esculentum Mill.) is one of the most important widely consumed vegetables of the Solanaceae family, of Bangladesh whereas Litchi (Litchi chinensis Sonn.) is one of the most beautiful as well as uncommon sub-tropical evergreen tree belonging to the Sapindaceae family and sub-family Nepheleae, native to Southeast Asia, is fast becoming popular throughout the world because of its attractive appearance and delicious taste. Tomatoes and their products such as tomato pulp, ketchup, juice and sauce are important source of micronutrients; these contain certain minerals (notably potassium) and carboxylic acids, including ascorbic, citric, malic, fumaric and oxalic acids. All of these are essential for health because of their antioxidant and antimicrobial activities in plants as well as in animals and humans. Among vegetables, Lycopersicon esculentum are rich sources of carotenoids – principally lycopene, followed by β-carotene, lutein, phytofluene, phytoene and tocophrols are also present. Lycopene the most abundant pigment (60-64 %) is mainly responsible for the characteristic deep-red colour of ripe tomato fruits and tomato products. Because of the presence of long-chain conjugated double bonds, lycopene has been reported to possess antioxidant and antimicrobial activity and is superior to lutein or β - carotene. Numerous epidemiological studies have suggested that a large consumption of raw tomato and tomato based products may experience a decreased risk for developing certain cancers such as prostate cancer, lung and stomach cancer, and cardiovascular diseases. The antioxidant and antimicrobial capacity, together with provitaminic properties typical of other tomato carotenoids has drawn attention towards widely consumed fruits over years. The second most important carotenoid is β-carotene, which represents about 7% of the total carotenoid content. Preliminary trials were carried out before to proceed for Soxhlet extraction these involve use of ethyl acetate (EtOAc) as solvent for extraction. Moreover different solvents i.e. ethyl acetate (100%), di-mixture (acetone: pet ether, 1:1, v/v) and tri-mixture (n-hexane: acetone: ethanol, 2:1:1, v/v/v) were employed. Ethyl acetate was the best solvent for extracting of trans- and cis-isomers of lycopene and β-carotene. The consumption of tomato would exert nutritional, biological and health benefits by virtue of their antioxidant, antimicrobial and anti-inflammatory activity. Attempts were taken into account to explain the scientific basis for the medicinal and nutritional benefits of these fruits. The phytochemical contents, antioxidant and antimicrobial activity were also assessed. The in-vitro antimicrobial activity of the test microorganism was performed by agar disc diffusion method by measuring the diameter of zone of inhibition in terms of millimeter with a calibrated scale. The isolation, purification and identification of chemical structure of the isolated lycopene and β - carotene involve the use of thin layer chromatography (TLC), vacuum liquid chromatography (VLC), column chromatography and spectroscopic methods. The tomato extract described in this application is the ethyl acetate (100%), acetone: pet ether (1:1, v/v) and n-hexane: acetone: ethanol (2:1:1, v/v/v) extracts of ripe tomato fruits with lycopene content ranging from 17 to 29 mg/100 g. The lycopene content in tomato differs with the variety, geographic location, technique of cultivation, soil condition and degree of ripeness of tomato fruits. The significant antimicrobial activity of active extracts was evaluated using bacterial cultures of Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Streptococcus pneumonia (S. pneumonia), and fungal cultures of Aspergillus niger (A. niger), Aspergillus flavus (A. flavus), Candida albicans (C. albicans) was compared with the Ciprofloxacin and Ketoconazole as standard antimicrobes. Chloroform extract showed more antibacterial and antifungal activities and most of the extracts executed moderate to good antimicrobial activity against the tested micro-organisms. The various extracts of tomato were active against the entire tested microorganisms for anti-bacterial activity with the range of Minimum Inhibitory Concentration (MIC) values for S. aureus (MIC: 17-33 μg /ml), E. coli (MIC: 16-32 μg /ml) S. pneumonia (MIC: 1733 μg /ml) and P.aeruginosa (MIC: 15-39 μg /ml) and for anti-fungal activity with the range of MIC values for A. niger (MIC: 17-34 μg/ml), A. flavus (18-37 μg/ml) and C. albicans (16-35 μg/ml). Fruits and vegetables are known to contain a variety of different antioxidant compounds such as ascorbic acid, tocopherol, glutathione and carotenoids, which may all contribute to protection against oxidative damage. General phytochemical screening of the Litchi chinensis revealed the presence of alkaloids, steroids, phenolic compounds, tannins, saponins and fatty acids. These phenolic compounds belong to the class of anthocyanins, flavanol or flavonoids and are antioxidant compounds remains in the pericarp, seeds and flowers of litchi fruits. In general, phenolic acids and flavonoids exhibit powerful antioxidant activities that inhibit key enzymes in mitochondrial respiration, offer protection against coronary heart diseases, and have anti-inflammatory, antitumor and antimicrobial activities. That’s why Litchi chinensis has wide folk medicinal uses. The extraction was carried out using dried powder of litchi fruits pericarp (LFP) with distilled methanol (MeOH) in a soxhlet apparatus. The MeOH extract was concentrated in vacuo. These concentrated mass was treated with pet ether. The pet ether fraction was examined by TLC (silica gel: pet ether, 90:10) showed the presence of five spots of which two were violet, two pink and one green. The presence of pink colour spot was thought to be an indication of the presence of either steroid or fatty acid material or both. However its Salkowski and Liberman-Burchard reaction gave positive results confirming the presence of steroids. Upon VLC and crystallization of the fraction T-7 and purified it to mini column chromatography and the light yellowish fraction TS-2 was left undisturbed at room temperature gave white sharp needle crystals. The crystals were dissolved in chloroform and transferred to a vial marked SS-I. Its TLC study showed a single spot with the R value of 0.38. After recrystallization isolated compound was characterized by UV, IR, f 1 H‐NMR, 13 C‐NMR, DEPT-135 spectrum and it was identified Stigmasterol. This is the first report so far of occurrence and details spectroscopic description of this compound from litchi fruit pericarp (LFP). The antibacterial activities of litchi fruit parts both pulp and waste (peel and seeds) extracted using two different solvents (ethanol and acetone), were evaluated against medically important bacteria i.e. E. coli, P. aeruginosa, S. aureus, and B. subtilis. The antibacterial activity of litchi pulp and waste were compared with Bacitracin as standard antibiotic. The results revealed that litchi waste ethanolic extract exerted the strongest inhibition against all tested bacterial strains compared to other extracts while pulp acetonic extract showed no effect against most of tested bacteria. Extracted Stigmasterol was further used to determine its antimicrobial activity. The antimicrobial activity ranged from 12 mm to 23.5 mm for the Stigmasterol and 19.5 mm to 27.5 for Gentamicin against E. coli, P.aeruginosa, S. aureus and K. pneumoniae. In comparison with standard antibacterial compound Gentamicin (20 μg /mL) it was found that purified Stigmasterol (20 μg /mL) has antimicrobial activity almost equivalent to the standard. The antioxidant activities were found in the Litchi Fruits Pericarp (LFP) approximately 15% of total fruits. Possibly these are due to the presence of phenolics, flavonoids and ascorbic acids. To achieve the antioxidant activity LFP was treated with preheated Charcoal to make them free from oily and colouring materials. This cleaned mixture contains powerful antioxidant compounds, such as ascorbic acid, phenolic acids and flavonoids which are capable of blocking the harmful effects of free radicals in the body. Antioxidant activities of phenolic and flavonoid compounds of LFP of litchi extracts were evaluated using Ferric (Fe 3+ ) reducing antioxidant power (FRAP) assay activity.
Chemical studies of hypoglycemic and anti-HIV extract of lagerstroemia speciosa linn. (Lythraceae)
(© University of Dhaka, 2025-03-12) Al Faruk, Md. Josim
Determination of radionuclides in tap water of Dhaka city and their biological effects on human of different ages
(© University of Dhaka, 2025-03-12) Ferdous, Jannatul
ISOLATION AND CHARACTERIZATION OF ANTIOXIDANT AND ANTIMICROBIAL COMPOUNDS FROM GARUGA PINNATA
(©University of Dhaka, 2023-09-19) Pulak, Abdullah Nasir
Phytochemical analysis was carried out in this study to isolate and characterize antibacterial and antioxidant chemicals found in the stem and bark of Garuga pinnata Roxburgh. Garuga pinnata belongs to the Burseraceae family has been investigated for evaluation of their biological activities. The powder of dried stem and bark of Garuga pinnata was extracted with Hexane, dichloromethane, ethyl acetate, and methanol. Different chromatographic techniques have attempted to isolate secondary metabolites from dichloromethane and ethylacetate extract of the stem and bark. It has been possible to isolate four compounds from the dichloromethane extracts of the stem and bark of Garuga pinnata. Different spectroscopic techniques have established the structures of the compounds. The isolated compounds were Stigmasterol, ß-sitosterol, Isofouequrone, and Lupeol. The isolated compounds were identified by extensive analyses of their high-resolution 1 H-NMR (400 MHz) and 13 C-NMR(100MHz). The extracts of stem and bark of Garuga pinnata, i.e., Methanol Soluble Fraction (MSF), Hexane Soluble Fraction (HSF), Dichloromethane Soluble Fraction (DCMSF), were subjected to assay for various biological screening such as Antioxidant activity screening and Antimicrobial screening. The crude plant extract and its different soluble fractions were investigated to evaluate biological activities in vitro. In the analysis of free radical scavenging, the EASF of bark and stem of Garuga pinnata with an IC value of 21.588 µg/mL had excellent free radical scavenging activity. 50 Test antimicrobial activity against a number of Gram-positive and Gram-negative bacteria and fungi were done for ethyl acetate extract, methanol extract, Dichloromethane extract, and a mixture of compound-1 and Compound-2 (mixture of Stigmasterol and β-sitosterol). The ethyl acetate and dichloromethane extracts exhibited antimicrobial activity against all of the test micro-organisms and fungi. The methanol extract does not show good antimicrobial activity against the Grampositive micro-organisms. The mixture of compound-1 and compound-2(GPE-1 & 2, as a mixture of Stigmasterol and β-sitosterol) showed almost similar activity as ethyl acetate crude extract (9-12 mm inhibition zone) against nearly all the microorganisms and fungi. In Brine shrimp lethality bioassay, among all extractives of leaves of Garuga pinnata, the highest brine shrimp lethality was given by HSF (110.15 µg/mL) followed by EASF (55.48 µg/mL), and MSF (80.99 µg/mL).
Isolation and structure elucidation of biologically active secondary metabolites from endophytic fungi
(© University of Dhaka, 2025-03-12)
Isolation of secondary metabolites from herbal medicine and myristica fragrans Houtt
(© University of Dhaka, 2025-03-12) Haque, Mohammad Ziaul
Mitigation of arsenic from groundwater by air exposure and flocculation
(© University of Dhaka, 2025-03-12) Khalil, Md. Ibrahim
Physico-chemical Properties of Imidazolium-Based Ionic Liquids in Pure and Mixed Polar Solvents
(University of Dhaka, 2019-10-17) Afrosre, Momana
Ionic liquids comprise entirely ions and are fluid at temperatures around 100 °C or below. The physico-chemical properties of IL change dramatically upon addition of one or more molecular solvent/s and therefore, binary and ternary mixtures of ILs with molecular solvents have received significant attention in recent years. They provide the means of accumulation of knowledge regarding the types of interaction and may exhibit the appearance of a new phenomenon, which is absent in the pure state of ILs. With a view to a proper understanding molecular level interactions of IL based systems, in this work, binary liquid mixtures of N, N-dimethylformamide (DMF) with acetonitrile (ACN), 1-ethyl 3-methylimidazolium bis(triflouromethanesulfonylimide)([emim][TFSI]) with ACN and DMF in the whole composition range and 1-ethyl 3-methylimidazolium hexaflourophosphate([emim][PF6]) with ACN and DMF have been prepared. The different interactions in these binary mixtures have been investigated by measuring physico-chemical properties with varying the compositions of different components. Effects of temperature and composition on some fundamental physico-chemical properties- density, viscosity, refractive index and conductivity of these binary mixtures also have been investigated. The excess molar volume (VE), excess viscosity (∆η) and excess refractive index (∆n) were calculated and the results were fitted to Redlich-Kister polynomials. The values of VE and ∆η were negative and ∆n were positive over the whole composition range for these binary mixtures. The minima in VE and ∆η were observed at mole fraction of IL, XIL ~ 0.2 and 0.5 respectively for [emim][TFSI] and DMF mixtures, for [emim][TFSI]-ACN the minima in VE and ∆η were observed at mole fraction of IL, XIL ~ 0.2 and 0.6, respectively . With increasing XIL, the refractive index of these binary mixtures gradually increased. The conductivity of the binary mixtures have been measured by the impedance spectroscopy method and the data have been used to infer about the ionic characteristics of the binary systems. Finally, from the understanding of these three binary mixtures, ternary mixtures of [emim][TFSI] , DMF and ACN have been prepared and physico-chemical properties of these ternary mixtures have been studied in the temperature range from 20 to 50 oC with change in the composition of different components. The changes in density, viscosity and refractive index as a function of compositions have been correlated with the variation of these properties with temperature. The excess molar volume, excess viscosity and excess refractive index of these ternary mixtures have been deduced from the results of physico-chemical properties. The values of VE and ∆η were negative over the whole composition range. Thus, the ultimate goal of this work has been to unveil inter-molecular interactions of different binary and ternary mixtures of ILs with different polar molecular solvents.
Phytochemical investigation on oyster mushroom (Pleurotus ostreatus)
(© University of Dhaka, 2025-03-12) Bina, Hasina Begom
Phytochemical Studies on some species of the Amaranthaceae Family
(© University of Dhaka, 2025-03-12) begum, Mirza jesmine
Preparation, characterization and voltammetric studies of metal complexes of sulphur containing essential amino acids
(© University of Dhaka, 2025-03-12) mamun, Mohammad al