Browsing by Author "Orman, Emmanuel"

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    A comparative study of Ghanaian propolis extracts: Chemometric analysis of the chromatographic profile, antioxidant, and hypoglycemic potential and identification of active constituents
    (Scientific African, 2023-11) Amankwaah, Frederick; Addotey, John Nii; Orman, Emmanuel; Adosraku, Reimmel; Amponsah, Isaac Kingsley; 0000-0002-4372-3992
    Diabetes is a disease characterized by high post-prandial glucose levels, which lead to other complications such as peripheral end organ damage. The use of enzyme inhibitors in the management of Type-2 diabetes ensure the control of blood glucose levels via the control of carbohydrate metabolism. The use of standard agents such as acarbose is associated with unwanted side effects hence the need to investigate other sources of antihyperglycemic agents. Propolis, a natural substance from bees, possesses diverse biological activities including antioxidant, antimicrobial and antidiabetic properties. However, the phytochemical content of propolis and its extracts may vary depending on the geographical area, the solvent of extraction and type of bees. This study represents the first attempt to compare different extracts of propolis from the same source in sub-Saharan Africa. In this study, the effect of solvent and source of Ghanaian propolis on parameters such as the total phenolic and flavonoid contents, chromatographic profile, antioxidant and α-amylase inhibitory effects were investigated with the aim of identifying and characterizing the most promising extract, which could be of direct or indirect benefit in the management of Type-2 diabetes. Combinations of water, ethanol-water and ethanol extracts were prepared from propolis from three regions. Phytochemical screening was performed on the extracts after which the Folin Ciocalteu method and aluminum chloride colorimetric assay were used to estimate the total phenolic and flavonoid contents respectively. Antioxidant potential of extracts was estimated using DPPH and phosphomolybdenum assays. In-vitro α-amylase inhibition assay was used to investigate hypoglycemic effect of the extracts. Statistical tools such as ANOVA, principal component analysis, hierarchical cluster analysis employed to determine sources of variations within the data obtained, to classify the extracts based on activity and to predict the most effective extract. This extract was then subjected to UHPLC-Q-TOF MS/MS and GC–MS techniques to characterize the constituents. Chemometric analysis of the data obtained showed that the variations in the data could be explained by both propolis source and extraction solvent. Though ethanol extracts generally contained more constituents, the more notable activities were in the ethanol-water extracts. The ethanol-water extract of Bono East propolis (EWBE) was the most potent DPPH radical scavenger (IC50 of 149.37 ± 2.90 µg/mL as compared to 116.60 ± 0.93 µg/mL GAE standard). It was also one of the three extracts which were more potent than acarbose (369.89 µg/mL) in the α-amylase inhibition assay. The predominant constituents from the LC-MS dereplication of EWBE were caffeic acid and flavonoid derivatives whilst 5,5-dimethyl-1-oxa-5 silacyclononanone-9 was the most significant active constituent identified through the GC–MS analysis. The identified constituents are known to have strong antioxidant and antidiabetic properties. The effects of source and solvent of extraction on the biological and physicochemical properties of propolis in Ghana have been quantified using statistical tools. The combined biological effects of propolis suggest a possible role in their usage in the management of type-2-diabetes and its related complications. Ethanol-water extracts were the most promising with EWBE showing the strongest antihyperglycemic activity. Such extracts represent leads towards further research into toxicity and formulation in order to develop safe and useful products for the management of type-2 diabetes.
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    The search for new anti-plasmodial agents: fate of mitragyna inermis, pseudocedrela kotschyi and moringa oleifera
    (2015-04-21) Orman, Emmanuel
    Malaria treatment keeps failing because of resistance. With recent speculations about genes likely to be coding for Artemisinin resistance, it has become pertinent to extend the search for new agents. This study was undertaken to evaluate the In-vivo antiplasmodial effects of traditionally used medicinal plants for malaria treatment. It also sought to evaluate them for possible future compound (s) isolation and drug development. Leaves and stem bark of Moringa oleifera (Moringaceae), twigs of Mitragyna inermis (Rubiaceae) and leaves of Pseudocedrela kotschyi (Meliaceae), were selected based on ethnopharmacological studies, collected and authenticated in the Department of Herbal Medicine, KNUST, Kumasi. The samples were dried at room temperature for a month and then pulverized. Aqueous and methanolic extracts were prepared and stored under refrigeration (-18 oC) until use. Samples of the powdered plant materials were also kept for investigation. Phytochemical screening was carried out on both powdered plant materials and the extracts. The extracts were also evaluated for their In-vivo antiplasmodial activity. Initial screening was carried out on the aqueous extracts of Moringa oleifera leaves (ML) and stem bark (MSB) at 500 and 750mg/kg respectively, and Pseudocedrela kotschyi leaves (PK) and Mitragyna inermis twigs (MT), both at 500 mg/kg for 7 days. Extracts were administered orally to Plasmodium berghei infected ICR mice (25-30 g). The most effective aqueous extract, ML, was then evaluated at 250, 500, 750 and 1000 mg/kg using Artemether-Lumefantrine (A/L) at 4 mg/kg as reference drug. Both Four-Day Suppressive Test and seven days of Curative Test were conducted. The weights of the animals, physical signs showing either clinical deterioration or wellness and survival of the animals were also monitored. The methanolic extracts of Moringa oleifera leaves (MOR), Pseudocedrela kotschyi leaves (PSD) and Mitragyna inermis twigs (MIT), each at 500 mg/kg, were also evaluated on P. berghei infected BALB/c mice (20-25 g) using A/L at 4 mg/kg as reference drug. The weights of the experimental animals were also monitored. Chromatographic fingerprints for the extracts were developed using reversed high performance liquid chromatography. The aqueous extracts obtained were MT (16.736 g; 1.67%), PK (16.6736 g; 3.33%), MSB (23.3355 g; 1.17%) and ML (24.1123 g; 2.41%). The methanolic extracts were MOR (16.4624 g; 11.65%), MIT (33.9513 g; 2.26%) and PSD (60.019 g; 5.91%). Phytochemical screening showed presence of alkaloids, tannins, coumarins, phytosterols, flavonoids and glycosides, with some variations in the compositions in the aqueous and methanolic extracts. The suppressions from the initial screening were as follows; ML (84% - 99.15%; AUC = 521.3), MSB (65% - 96.88%; AUC = 491.6), MT (47.67% – 84.49%; AUC = 340.8) and PK (22.47% - 82.91%; AUC = 275.0). ML extracts (250-1000 mg/kg) exhibited significant reduction in parasitemia in the four-day suppressive test (F6,49 = 4.309; p =0.0014). However, 250 mg/kg (69.31%; p < 0.001) and 500 mg/kg (77.26%; p < 0.001) extracts exhibited relatively higher activities compared to 750 mg/kg (25.28%; p < 0.001) and 1000 mg/kg (07.12%; p > 0.05). In the curative test, similar results were obtained with significant parasitemia reduction for 250 mg/kg (AUC = 52.52 ± 6.732; p < 0.01) and 500 mg/kg (AUC = 49.62 ± 3.804; p < 0.01) compared to the positive control group (AUC = 101.3 ± 14.32). In addition, physical signs such as piloerection, lethargy and decreased locomotor activity were observed to be progressive in all experimental groups except A/L. Finally, survival analysis showed that although 750 mg/kg and 1000 mg/kg groups recorded relatively higher mortalities, statistical analysis didn’t show any significant difference. In evaluating the methanolic extracts, percentage suppressions by day-3 post infection were as follow; MOR (67.08%), MIT (44.37%) and PSD (25.79%). Parasite reduction ratio (PRR), an indication of extract potency, was observed to be declining with day for the extracts whereas that of A/L kept increasing exponentially. The chromatograms developed gave indication of the complexity of the extracts and also showed feasibility of optimizing the experimental conditions for preparative HPLC fractionation of the extracts.