The Antibacterial Activity of Leaf Extracts of Eucalyptus camaldulensis (Myrtaceae)

The antibacterial activity of the leaf extracts of Eucalyptus camaldulensis was studied against Klebsiella spp, Salmonella typhi, Yersinia enterocolitica, Pseudomonas aeruginosa (Gram-negative), Staphylococcus aureus and Bacillus subtilis by the agar diffusion method. The methanol extract, dichloromethane fraction and methanol residue at 10mg mL-1 displayed broad spectrum activity against all the test organisms but the petroleum ether fraction showed no activity. The antibacterial activity of the extracts was compared to the drug gentamycin. The minimum inhibitory concentrations of the methanol extract and dichloromethane fraction determined by the agar dilution method ranged between 0.04 and 10mg mL-1 with that of Bacillus subtilis being the least. Phytochemical screening of the plant revealed the presence of tannins, saponins and cardiac glycosides. The results of this study support the traditional use of Eucalyptus camaldulensis leaves as an antibacterial agent. Key words: Eucalyptus camaldulensis, antibacterial activity, minimum inhibitory concentration, methanol extract, dichloromethane fractio

Evaluation of the Antimicrobial Activity of Root and Leaf Extracts of Terminalia Glaucescens

An assessment of the antimicrobial activity of the leaf and root extracts of Terminalia glaucescens against certain bacterial isolates were carried out. The organisms tested included Pseudomonas aeruginosa, Bacillus anthracis, Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Candida albicans and Proteus spp, using the agar dilution method. The root and leaf extracts showed appreciable activity against all the tested organisms. However the root extract was found to have a higher activity at 100mg mL-1 than the leaf extract at the same concentration especially on the two Gram positive bacteria tested. The mean diameter of the zones of inhibition exhibited by the extracts was between 15mm and 33mm. Minimum inhibitory concentrations (MIC) of the extracts against the bacterial isolates were also determined. The lowest MIC observed for both the root and leaf extracts was 6.25 on Pseudomonas aeruginosa. The antimicrobial activity of the extracts was compared with ampicillin used as a positive control

Evaluation of Antimicrobial Activity of Anacardium occidentale (Linn.)

The extracts of the leaves and stem bark of anacardium occidentale were screened for phytochemically for the presence of secondary metabolites and for in vitro antibacterial activity. The phytochemical screening revealed the presence of alkaloids and tannins. The methanol and aqueous leaf extracts and the methanol extract of the stem bark were tested against Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Candida albicans and Escherichia coli using the agar dilution method. The leaf methanol extracts presented a higher activity than the aqueous extracts. The antibacterial activity was greatest against K. pneumoniae, Bacillus anthracis and Candida albicans. Also the leaf extracts showed greater activity than the stem bark extracts. Of the six organisms tested, the stem bark extracts had activity against three. The mean diameter of the zones of inhibition exhibited by the extracts was between 13mm and 22mm. Bacillus subtilis showed the highest zone of inhibition (22mm) to the leaf methanol extract. The extracts compared favourably with ampicillin used as a standard control

Evaluation of Antimicrobial Activity of Anacardium occidentale (Linn.)

The extracts of the leaves and stem bark of anacardium occidentale were screened for phytochemically for the presence of secondary metabolites and for in vitro antibacterial activity. The phytochemical screening revealed the presence of alkaloids and tannins. The methanol and aqueous leaf extracts and the methanol extract of the stem bark were tested against Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Candida albicans and Escherichia coli using the agar dilution method. The leaf methanol extracts presented a higher activity than the aqueous extracts. The antibacterial activity was greatest against K. pneumoniae, Bacillus anthracis and Candida albicans. Also the leaf extracts showed greater activity than the stem bark extracts. Of the six organisms tested, the stem bark extracts had activity against three. The mean diameter of the zones of inhibition exhibited by the extracts was between 13mm and 22mm. Bacillus subtilis showed the highest zone of inhibition (22mm) to the leaf methanol extract. The extracts compared favourably with ampicillin used as a standard control

The Phytochemical Screening and Antimicrobial Activity of Leaf Extracts of Eucalyptus camaldulensis and Eucalyptus torelliana (Myrtaceae)

Extracts of leaves of Eucalyptus camaldulensis and Eucalyptus torelliana were screened phytochemically for the presence of secondary metabolites and for in vitro antibacterial properties. Methanol and dichloromethane extracts of leaves of Eucalyptus camaldulensis and Eucalyptus torelliana were studied for their antibacterial activity against 8 clinically isolated organisms of gastrointestinal origin viz., Klebsiella species UCH 2101, Proteus mirabilis UCH 2102, Proteus mirabilis UCH 2204, Salmonella typhi UCH 2201, Escherichia coli CHO 3101, Escherichia coli UCH 2103, Pseudomonas aeruginosa CHO 3102 and Pseudomonas aeruginosa UCH 2203. The result of the phytochemical screening showed that both extracts contained tannins, saponins, cardiac glycosides but in addition to these, E. torelliana was found to contain anthraquinones. Both extracts were also found to inhibit all the isolates at 10mg mL-1 concentration. The diameter of zones of inhibition exhibited by the extracts was between 10mm and 22mm. The methanol extracts compared favorably with gentamycin used as a standard control. The minimum inhibitory concentrations determined by the agar dilution method were between 0.04mg mL-1 and 10mg mL-1. The results obtained from this study reveals that extracts of Eucalyptus camaldulensis and Eucalyptus torelliana possess antibacterial activities against enteric pathogens and the extracts may be a potential source of new antimicrobials against enteric organisms

The antiviral activity of leaves of Eucalyptus camaldulensis (Dehn) and Eucalyptus torelliana (R. Muell)

Human enteroviruses are the major cause of aseptic meningitis and are resistant to all known antibiotics and chemotherapeutic agents. Methanolic extracts of Eucalyptus camaldulensis and Eucalyptus torelliana were tested on human enteroviruses: Poliovirus type I, Coxsackievirus B and Echovirus 6. The virucidal tests showed that the crude extracts were active on the test viruses: poliovirus type 1, coxsackievirus B and echovirus 6 giving a neutralization index of one log and above. The cytotoxicity assay of the crude extracts to L20B (a genetically engineered mouse cell line) and human rhabdomyo sarcoma (RD) cells showed that the extract of E. torelliana was more toxic than the extract of E. camaldulensis. The antiviral study showed that the extract of E. torelliana was more active than that of E. camaldulensis