FACULTY OF PHARMACY
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Item Phytochemical, antioxidant and antibacterial studies of extracts and chromatographic fractions of Gmelina arborea Roxb (Lamiaceae).(Faculty of Pharmaceutical Sciences, University of Jos, Nigeria, 2024) Idowu, P. A.; Ashiru, A. O.; Idowu, D. O.; Olaiya, C. O.; Karigidi, K.Antimicrobial resistance and oxidative stress are increasing and researchers are being encouraged to search the natural plant products, due to their popular usage in ethno-medicine, for alternative source of antimicrobial and antioxidant compounds. Gmelina arborea used in West-Africa and Ayurveda folkloric medicine to cure several diseases was therefore investigated for phytochemical, antioxidant and antimicrobial activities. Extracts and chromatographic fractions of the root-bark tested for antibacterial activity with the MIC determined on seven selected bacteria using agar dilution method. The antioxidant capacity of the crude extracts was determined by six (6) methods: total flavonoid content, total phenolic content, ferric reducing power, total antioxidant capacity, Trolox equivalent antioxidant capacity and DPPH (2,2-diphenyl-1-picryhydrazyl) properties. Phytochemical screening indicated the presence of saponins, tannins, flavonoids, terpenoids anthraquinones, phenols and alkaloids. The methanol and ethyl acetate extracts of the plant showed good antibacterial activities (18 mm inhibitory zones and MIC and MBC 12.5–100 mg/mL) against P. aeruginosa ATCC 27853 and S. aureus ATCC 6571. Antioxidant study of the extracts revealed that both ethyl acetate and methanol extracts have good antioxidant capacity comparable to that of ascorbic acid standard. Therefore, Gmelina arborea could prove a valuable source of developing new antimicrobial and antioxidant compounds for therapeutic uses.Item Chemical composition and biological activities of volatile oil of the stem of Dombeya buettneri K. Schum. (Sterculiaceae).(Elsevier B.V., 2023) Idowu, D. O.; Aiyelaagbe, O. O.; Idowu, P. A.Essential oil, obtained from the stem of Dombeya buettneri and characterized by high resolution GC–MS was tested for antimicrobial (using broth dilution method) and antioxidant (using spectrophotometric methods: DPPH, FRAP and ABTS) properties. Forty-three (43) essential oil components were detected which account for 96.8% of the total oil content comprising mainly: Non-terpene derivatives (31.8%), Apocarotenes (24.3%), Sesquiterpenoids (15.3%), Sesquiterpene hydrocarbons (14.4%), Monoterpenoids (10.1%) and Monoterpene hydrocarbons (0.9%). The major identified compounds in the oil were (E)- geranylacetone (14.8%), δ-cadinene (8.9%), n-hexadecane (7.8%), Tetradecanal (6.2%), β-ionone (4.9%), Borneol (4.2%), Viridiflorol (3.5%), Guaiol (3.4%), caryophyllene oxide (3.4%), Palustrol (2.5%) and Spathulenol (2.5%). The oil displayed antibacterial and antifungal activities on Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 18804 with respective Minimum Inhibitory Concentration (MIC) of 6.25, 12.5 and 12.5%v/v. The Minimum Bactericidal/Fungicidal Concentrations on the test organisms ranged from 12.5 to 25.0%v/v. The antioxidant assay by DPPH showed a concentration dependent values of 8.0993±0.827 at 25 mg/mL, 14.7657±0.8151 and 19.449±0.6678 at 100 mg/mL with good IC50 value of 1098 μg/mL as compared with reference ascorbic acid standard with IC50 of 23.52 μg/mL. The Ferric reducing antioxidant assay (FRAP) showed activity at concentration of 0.076713±0.001227mg/FeSO4Equiv./g, while ABTS showed an activity at 0.3776±0.0025 mg AA Equiv./g with respect to the standards. The current study showed that the volatile oil of Dombeya buettneri stem possess good antioxidant and antimicrobial properties that could be utilized for cosmetic and pharmaceutical health benefits.