Tag Archives: Antimicrobial

Antimicrobial Activity of Methanol Extracts and Fractions of the Leaf and Stem Bark of Vitex Doniana Sweet (Lamiaceae) (Published)

The objective of this study was to investigate the antimicrobial activity of leaves and stem bark of Vitex doniana Sweet (Lamiaceae) in vitro on clinical isolates of Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Fresh dried leaves and stem bark of Vitex doniana were extracted by cold maceration which yielded a mucilaginous methanol extract. Fractionation of the crude extract was done with hexane, ethyl acetate, butanol and water in that order. Phytochemical analysis and lethality tests (LD50) were carried out using standard procedures. Antimicrobial activity of the extracts and fractions at 50, 100, 200 and 400 mg/ml were evaluated using the agar well diffusion method. Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, flavonoids, carbohydrates, steroids, cardiac glycosides. Lethality was not observed in the mice even at 5000 mg/kg. Results showed significant (P < 0.05) antimicrobial activity as well as a broad spectrum activity. This study therefore supports claims by traditional health practitioners.   

Keywords: Acute Toxicity, Antimicrobial, Bacteriostatic, Phytochemical, Vitex Doniana

Chemical Active Ingredients in Superiv® (Liquid Herbal Supplement) and Its Antimicrobial In-Vitro Assay (Published)

An experiment was carried out to evaluate the chemical active ingredients present in Superliv®, a liquid herbal mixture produced by Ayurvet India and marketed in Nigeria by Animal Care Konsult, using the essential oil method involving the extraction process, the gas chromatography and the mass selective detector (MSD) technique. Results from this study shows that the major active ingredient in the herbal supplement is Pyrimidine (83.33%) which has been considered as an effective antioxidant. The other part of the experiment assessed the In-vitro antimicrobial effect of Superliv®. Theherbal supplement (Superliv®) was incorporated into MacConkey agar medium which was prepared by suspending 47g in 1 litre of distilled water. Dissolved completely and then sterilized by autoclaving at 121oC for 15minutes. After cooling to about 55oC, it was poured into Petri-dish and sensitive Escherichia coli and Staphylococcus aureus were inoculated into the medium and incubated. The herbal supplement had no significant antimicrobial in-vitro effect on the gram positive and gram negative bacteria at the manufacturers recommended dosage. However at an increased concentration of 60 -100% it had inhibitory growth effect on the gram positive and while at 90-100% on negative bacteria.

Keywords: Antimicrobial, Antioxidant, Bacterial, Chemical., Herbal

Antimicrobial Activity of Medicinal Plants and the Biological Effects of Selected Plants on Staphylococcus Aureus (Published)

Several natural products especially secondary metabolites have formed the basis of medicines, although it’s been often difficult to justify the presence of these compounds in the biochemistry of plant; this as posited by Cragg et al., in their presentation on Ethnobotany and the Search for New Drugs, Ciba Foundation Symposium draws a challenge to scientists. It has been suggested that these compounds may have been synthesized by the plants as part of the defense system of the plant; a good example is that plants are known to produce phytoalexins as a response to attack by bacteria and fungi. Cragg and Newmann in Biodiversity: A continuing source or novel drug leads, support this though stating that the compound produced provides an invaluable resource that has been used to find new drug molecules This paper is set to identify the antimicrobial activity of these medicinal plants and their biological effects. The sampled out plant extracts include Thymus vulgaris, Berberis vulgaris and Calluna vulgaris with which inhibition or activation by different chemical catalysts is performed to establish their effects in the tested natural extracts. Experimental design is used where the reagents are determined and chemical reactions performed in the procedures as outlined in the methodology section. The results of the microbial activity based on the level of concentration is then recorded for every crude extracts and the effects of each with different antibiotics against Staphylococcus aureus. This study reflects that berberine showed excellent synergistic activity against Staphylococcus aureus at relatively low concentration and thus can be used against staphylococcus infections

Keywords: Antimicrobial, Berberis Vulgaris, Calluna Vulgaris, Metabolites, Staphylococcus Aureus, Thymus Vulgaris


The increasing rate of resistance to antibiotics and insecticides by microorganisms and various insect pests have become an issue of Public Health concern. In this research, various concentrations of extracts were tried against three Gram negative isolates, zones of inhibitions were recorded in (mm) after 24hrs. Fourth (4th) instar larvae of A. gambiae were tested against various extract concentrations, and mortality recorded over 72hours. Results obtained showed that both methanolic and aqueous extract of seed samples showed excellent antimicrobial activity against the isolates tested. The aqueous extract showed more activity against both E. coli and E. aerogenes, however Klebsiella spp were more susceptible to the methanolic extract. The Minimum Inhibitory Concentration (MIC) values of isolates determined usingbroth dilution method reveals that the MIC of the methanolic Extracts were 20mg/ml, 30mg/ml and 10mg/ml for E. coli, E. aerogenes and K. pneumonia respectively. MIC values of the aqueous extracts were found to be 30mg/ml, 20mg/ml and 30mg/ml for E. coli, E. aerogenes and K. pneumonia respectively. Result of larvicidal assay revealed that the methanolic seed extract of P. nitida showed a remarkable activity against the insect larva with a mean mortality of 18.7 ± 1.5, 19.3 ± 1.2 and 19.7 ± 0.6 for extract concentrations of 0.5mg/ml, 1.0mg/ml and 2.0mg/ml respectively after 24hours exposure. However, aqueous extract had mean mortalities of 4.7 ± 1.2 and 6.3 ± 1.2 at concentrations of 4.0mg/ml and 5.0 mg/ml after 72hours exposure time. LT95 values of methanolic seed extract at (P ≤ 0.05) was found to be 29 hrs and 16 hrs at concentrations of 0.5mg/ml and 1.0mg/ml, while LT95 value for aqueous extract at (P ≤ 0.05) was 489 hrs at 1.0mg/ml. This research shows that seed extracts of P. nitida are both efficient antimicrobials and larvicidal agents and its potential can be harnessed for future use.

Keywords: Antimicrobial, Larvicidal, Picralima Nitida, Seed Extracts


Water and methanolic extracts of the leaves, stems, and pulp of Lebanese Cedar (Cedrus libani), were assayed for antibacterial and antifungal properties against human and food spoilage pathogens namely: Klebsiella pneumonia, MRSA, ESBL E. coli, Listeria monocytogenes, and Candida albicans using disk diffusion method. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were evaluated. The bacterial and fungal strains tested showed a various degree of sensitivity represented by inhibition zone diameter: Klebsiella pneumonia (27mm), MRSA (27mm), ESBL Escherichia coli (20mm), and Candida albicans (21mm). Listeria monocytogenes showed the strongest inhibition zone 70 and 37mm with methanolic and water leaves extracts respectively. The MIC, MBC, and MFC were between 5- 200 µl/ml, and 300 µl/ml respectively. Time-kill curve showed a fast and sharp antimicrobial activity. The efficacy of killing by Lebanese cedar extract was essentially the same in light and dark. Phytochemical analysis of Lebanese cedar extract explored the presence of terpenoids, flavenoids, glycosides, phenols, saponins and traces of tannins. Electron microscopy examination of cells treated with Lebanese cedar extracts showed a great variation in the cell structure.



Keywords: Antimicrobial, Food Spoilage Microorganisms, Human Pathogens, Lebanese Cedar

Comparative Studies of the Antimicrobial Activities of Different Chewing Sticks on Some Selected Pathogenic Microorganisms (Review Completed - Accepted)

The crude aqueous and methanol extract of the chewing sticks were assessed for antimicrobial activity and the active principles present in them. The antimicrobial activities of the methanol and aqueous extract of ten (10) different types of chewing sticks were determined against a wide variety of pathogenic bacteria and fungi. The extract was tested against bacteria likeStapylococcusaureus, Escherichia coli, Bacillus cereus, βeta. haemolytic streptococcus, Bacillus subtilisATCC 6633, ShigellaflexneriATCC 12022, SerratiamarscenceATCC 39006, EnterobacteraerogensATCC 13045, Proteus mirabilisATCC 2598, and fungi such as Candida albicans, Aspergillusflavus, Aspergillusniger, and Aspergillusfumigatus. The methanol crude extract of the chewing sticks have greater zone of inhibition compare with the aqueous extracts. All plants tested displayed antimicrobial activityes against one or more of the tested organisms but Fagarazanthoxyloidesshows greater antibacterial against Escherichia coli 40mm, Stapylococcusaureus34mm, while Disthemonanthusbenthamianusdisplayed the highest antifungal activity against Candida albican with 11mm. Minimum inhibitory concentration (MIC) of each active values were as well determined using agar well diffusion method. The chewing sticks contain antimicrobial agents though the concentration and composition of the bioactive substances may differ amongst the plants.The result showed that the extract of the plants also possessed some active principles such as tannin, phenol, steroid, saponin, alkaloid, anthraquinones. Thus, the chewing sticks extract may serve as sources for chemotherapeutic agents for the management of Orofacial infections caused by broad spectrum pathogenic organisms and could also be suitable for better dental care. It is concluded that methanol extract and aqueous extract of the chewing sticks exhibited significant amount of antimicrobial and trace amount of antifungal.

Keywords: Antimicrobial, Phytochemical, agar well diffusion, chewing stick extracts, dental caries, disc plate method, sensitivity

Hepatoprotective and Antidiarrhogenic Property of Aqueous Extract of Anacardium Occidentale (Linn.) (Review Completed - Accepted)

The aqueous extract from leaves of Anacardium occidentale was evaluated for inhibitory activity against Bacillus cereus and also the extent of damage to internal organs if consumed orally was investigated. The percentage yield of the extract was found to be 8% of the total mass. Phytochemical screening of the extract reveals the presence of bioactive molecules like alkaloids, tannin, saponin, anthraquinone, phenol and cardiac glycoside. The extract was found to inhibit the growth of the B. cereus in vivo. The extract was tested in-vivo against Bacillus cereus after determining the Infectivity dose 50 (ID50) of the organism on albino rats. The weights of the animals were found to be treatment dependent. The control group has constant weight increase throughout the days of the experiment while group infected with Bacillus has constant decrease in weight from the onset of infection. Haematological analysis of the blood revealed that an increase in the packed cell volume (PCV) of the infected animals but treated with the extract while there was reduction in the PCV of the untreated group. The total white blood cell (WBC) was also determined which was found to be higher in the group inoculated with the bacterium. The plasma alanine aminotransferase (ALT) and aspartate aminotransferase activity (AST) was also measured to liver disease in the infected group and also the group that were administered with drug. Histopathological analysis was also carried out on the major organs like the liver and intestine which showed the extent of damage on the organs pictorially. The extract was found to be toxic as indicated by the observed necrotic lesion in the organs of treated group coupled with the increase in the level of the enzyme markers. The study justifies the use of leaf of Anacardium in traditional medicine.

Keywords: Antimicrobial, Hepatoprotective, Phytochemical, histopathological