Scholarly works in Pharmaceutical Microbiology

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Author: search.filters.author.Idowu, P. A.Subject: search.filters.subject.Antimicrobial activity

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    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.
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    Extracts of Trichilia heudelotii (Meliaceae) Planch, a Nigerian medicinal plant have antibacterial and antifungal activity.
    (West Bengal, India, 2024) Adeniyi, B. A.; Adagbasa, O. O.; Idowu, P. A.; Igbokwe, C. O.; Moody, J. O. B.; Aiyelaagbe, O. O.
    There is no overemphasizing the need for novel phytotherapeutic agents to combat the menace of drug resistance in microbial pathogens. Many plant species so far, have yielded some bioactive compounds with great promise for such drugs. Trichilia heudelotii (Meliaceae) is commonly used in traditional medicine in Nigeria for the treatment of many microbial infections ranging from gastrointestinal infections to gonorrhea. This study is thus designed to determine the phytochemicals present in T. heudeloti and evaluate the plant’s extracts' antimicrobial activity on some bacterial and fungal isolates. The phytochemical screening was done using standard procedures. Soxhlet extracts using n-hexane and methanol were drying in vacuo. The methanol extract was partitioned into petroleum ether, chloroform, and aqueous fractions. The antibacterial and antifungal activity of the extracts determined using the agar-well diffusion method. The MICs were determined for the extracts using the agar dilution method. The qualitative phytochemical screening revealed the presence of tannins, saponins, alkaloids, cardenolides, and anthraquinones in the leaf, stem bark, and root bark of T. heudelotii. The extracts showed considerable activity against Gram-positive and Gram-negative organisms, and fungi with dermatophytes including Klebsiella spp, Escherichia coli, Proteus spp, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Neisseria gonorrhoeae, Mycobacterium smegmatis, Candida albicans, Aspergillus niger, Rhizopus stolonifer, Penicillium spp, Microsporium canis, and Trichophyton mentagrophytes. The mean diameter of zones of inhibition exhibited by the extracts ranged between 10mm+ 0.5 and 32+ 0.33mm. The methanol extracts compared favourably with the gentamycin (standard control). The minimum inhibitory concentration (MIC) ranged between 0.157mg/mL and 20mg/mL. The crude methanol extracts and methanol residue showed the highest activity of all the extracts while the hexane extract showed the lowest activity and the Petroleum ether fraction was inactive. These results showed the potential of T. heudelotii as a possible candidate for bioactive compounds for the discovery and development of new drugs for the treatment of diseases caused by test pathogens.
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    Antimicrobial Activity of Crude Extract of Grewia mollis Smith (Malvaceae) on Clinical Isolates of Escherichia coli from Cases of Diarrhoea
    (College of Medicine and Allied Health Sciences, University of Sierra Leone, 2021) Okunye, O. L.; Idowu, P. A.; Ike, W. E.; Ojieabu, W. A.; Fasuyi, O. C.
    Background: Escherichia coli is one of the leading causes of primary intestinal infections, particularly diarrhoea and other types of opportunistic infections of humans. The antimicrobial, phytochemical contents and minimum inhibitory concentration of Grewia mollis Smith (Malvaceae) were determined in a quest to evaluate their potentials as sources of alternative medicine for the treatment of diarrhoea. Methods: The bacteriological investigation was carried out on 25 clinical isolates of Escherichia coli from cases of diarrhoea which includes; sub-culturing onto eosin methylene blue agar and incubated at 370C for 24 hours. Gram staining, lactose fermentation, indole formation from tryptophan, gelatin liquefaction and Voges–Proskauer test were carried out on the isolates. The antimicrobial, phytochemical analysis and minimum inhibitory concentration (MIC) of Grewia mollis extract were determined using Evans and Trease method. Results: Grewia mollisleave methanol, ethyl acetate and N- hexane extracts gave extraction yield 8.40, 3.86 and 2.55 respectively. Tannins, saponins, flavonoids and alkaloids were detected as bioactive compounds from the leave of Grewia mollis investigated. The minimum inhibitory and minimum bactericidal concentration of the extract elicited remarkable antimicrobial activity in correlation to the polarity of each solvent. Conclusion: Therefore, Grewia mollis leave extracts hold the potential for clinical application.
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    Antibacterial activity of crude extract Nauclea latifolia Smith (Rubiaceae) and some selected antibiotics on clinical isolates of Salmonella typhi
    (Dental Consultants Association of Nigeria, OOUTH, Sagamu, Nigeria, 2020) Okunye, O. L.; Idowu, P. A.; Kolade, T. T.
    Background: Nauclea latifolia Smith (Rubiaceae) is a valuable medicinal plant used in folkloric medicine in the treatment of Typhoid fever. The public health significance of Salmonella typhi, the aetiologic agent in typhoid fever lies in the increasing resistance to antimicrobial agents. Objectives: To determine the antimicrobial potentials of the crude extracts of the leaves of Nauclea latifolia on clinical isolates of Salmonella typhi compared with some conventional antibiotics. Methods: Antibiogram was carried out on 25 biochemically confirmed clinical isolates of Salmonella typhi using disc diffusion method of Kirby Bauer. Nauclea latifolia leaves extracted with ethyl acetate and methanol in a Soxhlet apparatus were screened for secondary metabolites. The minimum inhibitory concentrations (MICs) of the extracts were determined by agar dilution method on the isolates. Results: The antibiogram of Samonella typhi showed the following resistance patterns: Augmentin (24.0%), amoxicillin (44.0%), chloramphenicol (32.0%), gentamicin (20.0%), cloxacillin (96.0%), ciprofloxacin (8.0%), erythromycin (60.0%), tetracycline (32.0%) and cotrimoxazole (60.0%). The extracts showed good antibacterial activity on the clinical isolates including those resistant to antibiotics. The MIC of methanol extract ranged from 1.56mg/ml to 6.25mg/ml and 3.13mg/ml to 25.0 mg/ml for ethyl acetate extract with the exception of isolates 11, 12, 19 and 20 with high MIC values as 50mg/ml. The methanol and ethyl acetate extracts gave a yield of 11.7% and 3.5% respectively. Bioactive secondary metabolites were detected from the extracts. Conclusion: The crude extracts of the leaves of Nauclea latifolia contained antimicrobial agents that were active on Salmonella typhi which could be used alone and in supportive with conventional antibiotics for therapeutic management of typhoid fever.
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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..
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    Antimicrobial activity of the crude extracts and isolated fractions of Garcinia kola Heckel stem bark
    (Science Association of Nigeria, 2006) Idowu, P. A.; Moody, J. O.; Odelola, H. A.
    The stem bark of Garcinia kola, commonly used for various ailments in traditional medicine in Nigeria was examined for antimicrobial activity. Crude chloroform and methanolic extracts and fractions isolated from the chloroform extract using column chromatography were screened for in-vitro antibacterial and antifungal activities. As tested using agar cup diffusion method on Staphylococcus aureus (NCTC 6571), Escherichia coli (NCTC 9001), Pseudomonas aeruginosa (NCTC 6750), Bacillus cereus (Lab. Stock), Candida albicans .(NCTC 7534) and Aspergillus niger (Lab. Stock), the crude extracts showed good activity at 10 and 20mg/ml respectively. The 14 fractions isolated from the column chromatography also showed varying but significant degree of activity on most of the tested organisms at lOOpg/ml. The study has shown that G. Kola bark has antimicrobial activities that justify its uses in traditional medicine in Nigeria as anti-infective agent. Also, the fact that most fractions showed antimicrobial activity is an indication that G. Kola bark has many antimicrobial constituents which are different but closely related.