Theses and Dissertations (Pharmaceutical Chemistry and Industrial Pharmacy)

Anti Microbial and Phytochemical Studies on Selected Nigerian Medicinal Plants: (1) Anti Microbial and Phytochemical Properties of Phyllanthus Discoideus (Euphorbiaceae).

2019-03-26T12:48:30Z

Anti Microbial and Phytochemical Studies on Selected Nigerian Medicinal Plants: (1) Anti Microbial and Phytochemical Properties of Phyllanthus Discoideus (Euphorbiaceae). Isah, Suleiman The aqueous methanolic extracts of 20 selected plant parts were screened for in-vitro antimicrobial activity against clinical strains of Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans at a test concentration of 10mg/ml using the agar well diffusion method and penicillin G, chloramphenicol and Nystatin as controls. The seeds of Parkia biglobosa, Glycine max, Voendzeia substerrana, Arachis hypogeal, Cajanus cajan, Samonea saman, Manihot esculenta (root bark) Uapaca esculenta (stem bark and root bark), exhibited no meaningful anti-microbial activity against all the tested organisms. Uapaca esculenta (leaf) exhibited significant activity against kleb. (IZD= 16mm), Samanea saman (stem bark and leaves) showed significant anti-staphylococcus aureus activities (IZD=17mm, 15mm respectively) which compared favourably to the controls penicillin G and chloramphenicol. Detarium microcarpum (seed), Phyllanthus mullerianus (leaf) and Phyllanthus discoideus (leaf) exhibited a broad spectrum anti-microbial activity against all the test micro-organisms with IZD’s ranging from (10mm – 20mm) an indication that they could be effective in severe bacterial infections. Interestingly to know is the anti-staphylococcus activity. (IZD=19mm) leaf extract higher than the control penicillin G (IZD=17mm). Crude 95% aqueous methanolic extract of Phyllanthus discoideus (yield = 29.75%) gave 14.315% of hexane solubles, 13.965% of ethylacetate solubles, 70.194% of absolute MeOH solubles and 1.624% of absolute MeOH insolubles. These solubility fractions were similarly screened in vitro for anti-microbial activity against the same micro-organisms. The absolute methanol soluble fraction displayed the widest spectrum of antimicrobial activity (IZD range 9mm-24mm). particularly noteworthy are the anti-E.coli activities of the absolute MeOH soluble fraction (IZD = 20mm), and its precipitate (IZD=18mm) and the anti-salmonella typhi activity (IZD=17mm), its precipitate (IZD=15mm), against chloramphenicol and penicillin G – resistant strains of E.coli and Salmonella typhi .These are accentuated compared to those of the crude extract. The most active absolute methanol soluble fraction was separated by PTLC in to fifteen bands on silica gel 60 GF254with solvent system acetone: chloroform:formic acid:water (6:6:1:05 v/v/v/v). The impure bands were further purified by using different elutants of increasing polarities into twelve additional fractions. The twenty seven fractions were similarly screened in-vitro for anti-microbial activity against the same micro-organism. Bands 1A, 2A, 3A,4A and 8A displayed significant anti-microbial activity particulary against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aureginosa & Klebsiella pneumonia which are comparable with that of controls. The glycosidic band 8A gave anti-Bacillus subtilis and anti-Staphylococcus aureus (IZD=18mm & 20mm respectively) which are comparable with that of the control penicillin G (IZD=20mm & 22mm respectively). The flavonoid glycosides 2A gave anti-Bacillus subtilis (IZD = 20mm, MIC 1.00mg/ml) which is the same as the control pencillin G (IZD = 20mm, MIC 1.037mg/ml). The phenolic fraction 1A and 9 gave anti-Candida albican activities which are comparable with that of Nystatin the control. Qualitative analysis of the bioactive bands/fractions using a combination of chemical and UV/visible spectrophotometric methods showed band 1A, 1B, 2A, 2B to contain tannins, flavonoids as glycosides while band 3 – 13 showed different form of glycosides and band 14 and 15 are phenolic compounds. The UV-spectra of the bands confirmed the phytochemical results for the presence of minor flavonoids of the isoflavonoid and flavones classes (λmax 207mm, 276mm) quinine glycosides (270nm – 275nm), flavan (λmax 207nm, 276nm) quinine glycosides (270nm – 275nm). This study reveals that a flavonoid glycosides, a minor flavonoid, alkaloids, Tannins are likely to be the active principles of Phyllanthus discoideus leaf with the possibility of synergistic action.

Formulation and Optimization of Artemether and Lumefantrine Calcium Alginate Capsules Using Inverse Gelation Technique

2017-06-11T23:58:05Z

Formulation and Optimization of Artemether and Lumefantrine Calcium Alginate Capsules Using Inverse Gelation Technique Ezichi, Nnaji Lawrence Poorly water-soluble drug candidates are associated with dissolution, absorption and bioavailability challenges. Consequently, poor solubility and non-reproducible absorption from the gastrointestinal tract following oral administration constitute a biopharmaceutical concern to dosage form design and formulation. The use of lipid-based formulations to address this concern has been the choice of many scientists in the drug delivery domain. Artemether and Lumefantrine the drugs investigated in the work are poorly soluble with unpredictable absorption and bioavailability problems. In addition they may be prone to acid hydrolysis and precipitation respectively in gastric environment of the stomach. To date there is no published work on alginate capsules geared towards solving bioavailability problems and inactivation of Artemether and Lumefantrine in the stomach. In this work we aimed at employing optimized lipid-based formulation capable of solubilizing artemether and lumefantrine, and protecting artemether from possible stomach acid degradation using alginate capsules, for ultimate avoidance of resistance and improved antimalarial performance. A 33 full factorial experimental design was employed to optimize excipient compositions using JMP Discovery V10 Statistical Software. The software generated 27 formulae, which was transformed into formulations using inverse gelation technique and subsequently evaluated. The resulting responses were fed back to the software which was exclusively re-run. Five, out of the 125 formulae with the best predicted responses were chosen as the optimal batches. In vitro studies carried out on the optimized batches include quantity of oil encapsulated, percentage capsule yield, mean capsule diameter, percentage encapsulation, swelling index, mucoadhesivity, differential scanning calorimetry (DSC) and drug release / kinetic properties. In vivo antimalarial studies were carried out in mice against virulent rodent malaria parasite plasmodium berghei using Peter’s 4 days protocol. The percentages of drugs encapsulated were high for all the batches, 64.60 ±0.10% - 88.50 ±0.07%. The percentage of Artemether and Lumefantrine released in SGF pH 1.2 were in the range of 0.75± 0.01 to 23.86 ± 0.53% after 320 minutes while, in SIF pH 6.8 and pH 7.2, the percentage of Artemether and Lumenfantrine released were in the range of 13.79±0.75 to 99.43 ± 0.12%. The optimized batches exhibited higher antimalarial activities. DSC revealed that the oil-dissolved drugs did not crystallize out of the formulations. Optimized alginate capsules improved aqueous solubility of artemether and Lumenfantrine with increased in vivo antimalarial activity.

Phytochemical and Bioactivity-Guided Evaluation of the Antibacterial Constituents of Psidium Guajava (Linn.) and Loranthus Micranthus (Linn.) Leaves

2017-06-11T23:58:07Z

Phytochemical and Bioactivity-Guided Evaluation of the Antibacterial Constituents of Psidium Guajava (Linn.) and Loranthus Micranthus (Linn.) Leaves Ukwueze, Stanley Ejike Antibiotics have remained the mainstay of drug therapy of infectious diseases worldwide. Their use is, however, limited by their numerous adverse effects and rapid development of microbial resistance. Identification of natural products from plants that may serve as valuable sources of antimicrobial agents for medicinal or agricultural uses seems to be a viable alternative to the conventional antibiotics. To achieve this goal, biological assays should be carried out in order to identify promising plant extracts, guide the separation and isolation, and to evaluate "lead" compounds. Psidium guajava Linn. and Loranthus micranthus Linn. have been employed traditionally in Nigeria and other parts of the globe for the treatment of various human ailments such as wounds, gastrointestinal tract disorders and other forms of infective and non-infective disorders. The main objective of this study was to identify and isolate the antibacterial compounds from the leaves of Psidium guajava and Loranthus micranthus L. The specific objectives were to: (i) carry out phytochemical evaluation and isolation of antibacterial constituents of the plants using standard methods, (ii) elucidate the structures of the isolated secondary metabolites, and (iii) carry out antibacterial assay of the isolated compounds. Fresh leaves of Loranthus micranthus (Linn.) parasitic on the stem of Persea americana were collected at Nsukka while those of Psidium guajava were collected from the bio-resource area of the University of Port Harcourt in June 2010. The leaves were then cleaned, air-dried for 14 days and milled to coarse powder. The powdered materials (800 g each) were defatted with n-hexane (5 L) and extracted in a soxhlet extractor with 90.0 % methanol. The methanol extract was further fractionated to yield the chloroform, ethyl acetate, acetone and methanol soluble fractions. Each of the fractions was screened for antibacterial activity using Agar-well diffusion method. Phytochemical tests were carried out using standard procedures. The fractions that had the best antibacterial activity were subjected to column chromatographic separation and monitored by analytical thin layer chromatography (TLC). The ethyl acetate fraction (PsG-EF) from P. guajava that gave satisfactory bioassay result was subjected to further Sephadex-LH 20 chromatographic fractionation and purification to afford ten fractions (PsG-EF1 to PsG-EF10) which were pooled. Fractions PsG-EF4, PsG-EF5 and PsG-EF7 that had good antibacterial activity were subjected to semi-preparative reverse phase high pressure liquid chromatography (HPLC) purification to isolate the phenolic compounds; I-V. The structures of these compounds were elucidated by analytical and spectral techniques which included: ultra violet (UV), proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), distortionless enhancement by polarization transfer (DEPT), proton-proton correlation spectroscopy (1H-1HCOSY), heteronuclear multiple quantum correlation (HMQC), heteronuclear multiple bond correlation (HMBC) and electron spray ionization-mass spectroscopy (ESI-MS) analyses. The isolated compounds were screened against standard strains of Staphylococus aureus (ATCC 25923) and Escherichia coli (ATCC 35219) using broth dilution assay method, and the MIC values determined and compared with ceftriaxone. All data obtained were analyzed by GraphPad Prism® 5 using differences in mean by two-way ANOVA and further subjected to Bonferroni post-tests to compare replicate means. The results were presented as mean ± SEM. Differences between means were considered significant at P<0.05. The results showed that the ethyl acetate fraction (PsG-EF) from P. guajava yielded one known compound (IV) and four novel phenolic compounds (I, II, III & V). The isolated compounds were elucidated as : 2,4-dihydroxy-6-O-βD-glucopyranosyl benzophenone (I); 2,4-dihydroxy-3-methyl-6-O-βD-glucopyranosylbenzophenone (II); 2,4-dihydro xy-3-methyl-6-O-βD-glucopyranosylbenzophenone (4→5", 6'→1") benzene-2",3",4",5"-tetraol (III); quercertin-3-O-αL-arabinofuranoside (IV) and 2,4-dihydroxy-6-O-βD-glucopyranosylbenzophenone (4→5", 6'→1") benzene-2",3",4",5"-tetraol (V). Compounds I, II, III, and V are new natural products which have not been previously reported in literature for this plant, guava, and the trivial names Guajaphenone A, B, C and D were proposed, while Compound IV has been previously reported as Guaijaverin. The various fractions of Psidium guajava L. exhibited significant (p < 0.05) antibacterial activities while for Loranthus micranthus L., its various fractions showed significantly lower values (p > 0.001) when compared with the control (ceftriaxone) suggestive of a generally weak or negligible antibacterial action. All the isolated compounds from P. guajava were also found to have moderate antibacterial activities against E. coli and S. aureus in comparison with ceftriaxone whlie I and IV showed lower MICs than those of the other isolates against the test organisms.

Formulation and Evaluation of Some in Vitro and in Vivo Properties of Artemether-Loaded Self Emulsifying Drug Delivery System

2017-06-11T23:58:11Z

Formulation and Evaluation of Some in Vitro and in Vivo Properties of Artemether-Loaded Self Emulsifying Drug Delivery System Ugwu, Calister Elochukwu The aims of this research work were to formulate artemether-loaded self emulsifying drug delivery system (SEDDS), evaluate some of its in vitro and in vivo properties, and prevent drug precipitation through supersaturation approach. The solubility of artemether (ARM) in various oils, surfactants and cosurfactants was determined using the equilibrium solubility method. Vehicles such as Triacetin®, Labrasol® and Transcutol P® were selected as components of the formulation due to their high solubilising capacities. Pseudoternary phase diagrams were constructed in order to select the optimized batches. SEDDS containing 40 mg, 50 mg and 55 mg of ARM respectively were formulated and called non-hydroxypropylmethylcellulose batches (non-HPMC batches) while those containing 5 % hydroxypropylmethylcellulose (HPMC), a precipitation inhibitor, were called HPMC batches. The melting point of artemether was determined. The following evaluation tests: droplet size, preformulation and postformulation visual isotropicity, emulsification time, refrigeration cycle, centrifugation, aqueous dilution, viscosity, pH, drug content, and crystallization/precipitation studies were carried out. In vitro release studies of the formulations were carried out in simulated gastric fluid (SGF) without pepsin (pH, 1.2) and stimulated intestinal fluid (SIF) without pancreatin (pH, 6.8) respectively. Finally, the antimalarial activity of the ARM was evaluated using 25 mice grouped into five groups: SEDDS-treated group, chloroquine-treated group, placebo-treated group, untreated group (negative control) and aqueous ARM dispersion-treated group (positive control). The melting point range was obtained as 86-88 oC. Results showed that ARM has high solubility in Triacetin® (136.00 ± 0.09 mg/ml), Labrasol® (156.00 ± 0.01 mg/ml), and Transcutol P® (166.00 ± 0.02 mg/ml). From the pseudoternary phase diagrams, the optimized batches of Smix (1:0.5, and 3:1) were selected. The preformulation visual isotropicity test carried out on the optimized batches showed that the oil: Smix ratios; 1:2.0, 1:2.5, 1:3.5 and 1:4 were isotropically stable, while the postformulation visual isotropicity test showed that the SEDDS remained thermodynamically stable after 72 h. There was no significant difference in the emulsification times of the HPMC and non-HPMC batches. The result of refrigeration cycle and centrifugation test showed no variation in the physical properties such as colour, odour change or phase separation. Phase separation was not noticed after dilution of the SEDDS to 1 L with 0.1N HCl. There was no significant difference in the loading efficiency (%) between HPMC and non-HPMC batches. Also, there was no significant change in the pH of the HPMC and non-HPMC batches. There was, however, significant difference (p < 0.05) in the viscosity of the HPMC and non-HPMC batches. After three hours of the SEDDS formulation in aqueous phase, the photomicrographs revealed the presence of some drug crystals in the non-HPMC batches, while no crystal was observed in the HPMC batches. The drug release profiles of non-HPMC batches showed T50 (time to release 50 % of the drug) and T85 (time to release 85 % of the drug) values that ranged between 3-8 min and 14-22 min respectively in SIF, and 3-4 min and 5-18 min respectively in SGF. On the other hand, the drug release profiles of HPMC batches showed T50 and T85 values that ranged between 8-35 min, and 53-153 min in SGF and T50 and T85 values that ranged between 4-13 min and 92-213 min respectively in SIF. Results of antimalarial studies showed the following percent activities: SEDDS-treated group (94.00 ± 0.57 %), chloroquine-treated group (59.00 ± 0.85 %), placebo-treated group (16.0 ± 4.1 %), and aqueous ARM-treated group (47.0 ± 1.8 %). The SEDDS-treated group had a significantly (p < 0.05) higher antimalarial activity than the rest.