Browsing by Author "Idowu, D. O."

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Antimicrobial, phytochemical and cytotoxicity activities of extracts of Lannea welwitschii (Hiern) Engl. (Annacardiaceae)
(Science Association of Nigeria, 2012) Idowu, P. A.; Idowu, D. O.
Towards-discovering new agents to treat microbial infections, methanolic extracts of leaves, stem and roots of Lannea welwitschii were screened for antibacterial and antifungal activity against Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Pseudomonas aeruginosa (ATCC 27853), Salmonella typhimurium (ATCC 14028), Proteus vulgaris (ATCC 6380), Escherichia coli (ATCC 25922), Rhizopus spp. (Lab Stock) and Candida albicans (ATCC 18804). Agar cup diffusion method was used to determine zone of inhibition while Minimum Inhibitory Concentration (MIC) on Staph, aureus and E. coli were determined by agar dilution method. Phytochemical screening was done to determine the type of secondary metabolite while cytotoxicity was determined by Brine-Shrimps Lethality (BSL) assay. All the plant parts showed antimicrobial activity against all the test organisms with zone of inhibition of 11.0-20.0 mm, and MIC of 0.31 and 0.62mg/ml on Staph, aureus (ATCC 25923) and E. coli (ATCC 25922) respectively. The LC50 from the cytotoxicity test (BSL) were 196.49 and 100.00 µg/mL for the leaves and stem extracts respectively. Saponins, tannins, cardiac glycosides (steroids) and flavonoids were detected. Therefore L. welwitschii as a medicinal plant contains metabolites having broad spectrum antimicrobial activity, and the methanolic extracts were relatively non-toxic..
Antimicrobial, phytochemical and cytoxicity activities of exxtracts of Lannea welwitschii (Hiern) Engl. (Annacardiaceae
(Ibadan University Press for the Science Association of Nigeria, 2012) Idowu, P. A.; Idowu, D. O.
Towards discovering new agents to treat microbial infections, methanolic extracts of leaves, stem and roots of Lannea welwitschii were screened for antibacterial and antifungal activity against Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Pseudomonas aeruginosa (ATCC 27853), Salmonella typhimurium (ATCC 14028), Proteus vulgaris (ATCC 6380), Escherichia coli (ATCC 25922), Rhizopus spp. (Lab Stock) and Candida albicans (ATCC 18804). Agar cup diffusion method was used to determine zone of inhibition while Minimum Inhibitory Concentration (MIC) on Staph. aureus and E. coli were determined by agar dilution method. Phytochemical screening was done to determine the type of secondary metabolite while cytotoxicity was determined by Brine- Shrimps Lethality (BSL) assay. All the plant parts showed antimicrobial activity against all the test organisms with zone of inhibition of 11.0-20.0 mm, and MIC of 0.31 and 0.62mg/ml on Staph. aureus (ATCC 25923) and E. coli (ATCC 25922) respectively. The LC,, from the cytotoxicity test (BSL) were 196.49 and 100.00 μg/mL for the leaves and stem extracts respectively. Saponins, tannins, cardiac glycosides (steroids) and flavonoids were detected. Therefore L. welwitschii as a medicinal plant contains metabolites having broad spectrum antimicrobial activity, and the methanolic extracts were relatively non-toxic.
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.
Chemical constituents, antimicrobial and antioxidant activities of the essential oil of leaves of Dombeya buettneri K. Schum
(National Institute for Pharmaceutical Research and Development (NIPRD), 2021) Idowu, D. O.; Idowu, P. A.; Aiyelaagbe, O. O.
The essential oil of the leaves of Dombeya buettneri was investigated for chemical composition, antioxidant and antimicrobial activities. The oil was separated by Gas Chromatography (GC) and analysed by Gas Chromatography/Mass Spectrometry (GC-MS) methods. Antimicrobial activity was evaluated by broth dilution method to determine the minimum inhibitory concentration (MIC) on Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 18804 while antioxidant activity was determined by three methods (DPPH, FRAP and ABTS). The GC-MS detected a total of 23 compounds (93.9% identification) which were dominated by Apocarotenes (64.9%) and Non-terpene derivatives (20.2%), the main compounds identified being hexahydrofarnesylacetone (32.5%), dihydroedulan IIA (9.6%), (E) –geranylacetone (7.8%), β-selinene (5.4%) and 2-pentyl furan (4.6%). The oil showed a good antimicrobial activity with respective MIC and MBC of 6.25 and 12.50%v/v on Staph. aureus, 12.5 and 25.0 %v/v on E. coli; MIC and MFC on Candida albicans were 12.5 and 25.0%v/v respectively. The free radical antioxidant activity (DPPH expressed as % inhibition) at 25, 50 and 100 mg/mL were 8.0993±0.827, 14.7657±0.8151 and 19.449±0.6678 respectively. The antioxidant potential (FRAP) was 0.076713±0.012275 mg/FeSO4.eq/g. The result of 2, 2-azobis-3- ethylbenzothiazoline-6-sulfonate radical scavenging ability (ABTS) showed the oil to possess free radical scavenging ability of 0.37759±0.0025 mg/AA Equiv./g. The leaves of Dombeya buetnneri possess essential oils that are rich in phytochemicals with good antimicrobial and antioxidant activities; which can be of significant application in food, drug and cosmetic industries.
Chemical Constituents, Antimicrobial and Antioxidant Activities of the Essential Oil of Leaves of Dombeya buettneri K. Schum. (Sterculiaceae)
(National Institute for Pharmaceutical Research and Development (NIPRD), 2021) Idowu, D. O.; Idowu, P. A.; Aiyelaagbe, O. O.
The essential oil of the leaves of Dombeya buettneri was investigated for chemical composition, antioxidant and antimicrobial activities. The oil was separated by Gas Chromatography (GC) and analysed by Gas Chromatography/Mass Spectrometry (GC-MS) methods. Antimicrobial activity was evaluated by broth dilution method to determine the minimum inhibitory concentration (MIC) on Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 18804 while antioxidant activity was determined by three methods (DPPH, FRAP and ABTS). The GC-MS detected a total of 23 compounds (93.9% identification) which were dominated by Apocarotenes (64.9%) and Non-terpene derivatives (20.2%), the main compounds identified being hexahydrofarnesylacetone (32.5%), dihydroedulan IIA (9.6%), (E) –geranylacetone (7.8%), β-selinene (5.4%) and 2-pentyl furan (4.6%). The oil showed a good antimicrobial activity with respective MIC and MBC of 6.25 and 12.50%v/v on Staph. aureus, 12.5 and 25.0 %v/v on E. coli; MIC and MFC on Candida albicans were 12.5 and 25.0%v/v respectively. The free radical antioxidant activity (DPPH expressed as % inhibition) at 25, 50 and 100 mg/mL were 8.0993±0.827, 14.7657±0.8151 and 19.449±0.6678 respectively. The antioxidant potential (FRAP) was 0.076713±0.012275 mg/FeSO4.eq/g. The result of 2, 2-azobis-3-ethylbenzothiazoline-6-sulfonate radical scavenging ability (ABTS) showed the oil to possess free radical scavenging ability of 0.37759±0.0025 mg/AA Equiv./g. The leaves of Dombeya buetnneri possess essential oils that are rich in phytochemicals with good antimicrobial and antioxidant activities; which can be of significant application in food, drug and cosmetic industries.
Isolation and characterization of a novel xanthone with broad-spectrum antibacterial activity from the roots of Allanblackia floribunda Oliver (Guttiferae).
(Nigerian Society of Pharmacognosy, 2024) Idowu, P. A.; Idowu, D. O.; Aladedunye, O. O.; Okorie, D. O.
The increasing antimicrobial resistance of pathogens to existing therapeutic agents is currently a global health challenge, which led us to a bioassay-guided investigation of Allanblackia floribunda Oliver (Guttiferae) roots for new antimicrobial constituents. The roots were extracted successively in Soxhlet with hexane, ethyl acetate and methanol. Isolation from the ethyl acetate extract was done using an open Column Chromatography, and Preparative Thin Layer Chromatography for purification. Structural elucidation was done using extensive 1-D and 2-D NMR, IR, MS data and physico-chemical properties. Antimicrobial activity and Minimum Inhibitory Concentration (MIC) were determined using agar-well diffusion and broth dilution methods, respectively. The root extracts, pooled fractions and isolated compound were tested on bacteria including Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Bacillus subtilis ATCC 6633 and clinical isolates of Salmonella typhi. The root extracts and pooled fractions (Al , Al A, F , A and A ) were active on the test bacteria with zones of 1 2 19 18 100 inhibition ranging from 12 to 20 mm. Fraction Al A showed highest consistent activity comparable to gentamycin standard and 2 yielded compound Al , a novel xanthone: 1, 2, 3, 4, 5, 8-hexahydroxy-9H-xanthen-9-one. The MICs in mg/mL of Al on the test 2 2 organisms are: S. aureus (0.75), E. coli (1.25), P. aeruginosa (1.13), B. subtilis (0.15) and S. typhi (0.08). These results justify the ethnomedicinal use of the root bark of Allanblackia floribunda in the treatment of diseases and the isolated xanthone has a high potential to become a chemotherapeutic agent for bacterial infections.
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.