In vitro antimicrobial, anthelmintic and cyclooxygenase-inhibitory activities and phytochemical analysis of Leucosidea sericea.
BACKGROUND
Leucosidea sericea is used as a vermifuge and in the treatment of ophthalmia by various tribes in southern African countries.


OBJECTIVE
The study aimed at screening leaves and stems of Leucosidea sericea for pharmacological activity and validating the plant's traditional use. A general phytochemical screening was also carried out.


METHODS
Petroleum ether (PE), dichloromethane (DCM), ethanol (EtOH) and water extracts of the plant parts were investigated for antimicrobial, anthelmintic and cyclooxygenase (COX) inhibitory activities. Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and Candida albicans were used for the antimicrobial evaluation. Caenorhabditis elegans was used for the anthelmintic assay using the microdilution technique. Cyclooxygenase-1 and -2 (COX-1 and -2) were used to evaluate the anti-inflammatory potential of the plant extracts. Phytochemical analysis for phenolic compounds, including gallotannins, condensed tannins and flavonoids was done using 50% methanol extracts of the leaves and stems employing spectrophotometric methods.


RESULTS
The leaf extracts exhibited broad spectrum antibacterial activity ranging from 0.025 to 6.25mg/ml. The most noteworthy minimum inhibitory concentration (MIC) of 0.025 mg/ml was exhibited by PE and DCM leaf extracts against Bacillus subtilis and Staphylococcus aureus, respectively. In the anthelmintic assay, the best minimum lethal concentration (MLC) value of 0.26 mg/ml was observed for the DCM and EtOH leaf extracts. Both leaf and stem organic solvent extracts exhibited high to moderate inhibition against COX-1 and -2 at a screening concentration of 250 microg/ml. At lower concentrations, the extracts displayed a dose-dependent inhibition, with the lowest IC(50) values of 0.06 microg/ml (COX-1) and 12.66 microg/ml (COX-2) exhibited by the PE extract of the leaves. Generally, the leaf extracts exhibited better pharmacological activities and contained higher amounts of phenolic compounds than the stem extracts. Alkaloids and saponins were only detected in the leaf and stem extracts, respectively.


CONCLUSIONS
The reported results support the local use of Leucosidea sericea against eye infections and as a vermifuge. The pharmacological activities exhibited by the leaf extracts are probably due to their higher phenolic levels.
Aremu
A O
AO
Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa.
Fawole
O A
OA
Chukwujekwu
J C
JC
Light
M E
ME
Finnie
J F
JF
Van Staden
J
J
D000818:Animals; D000871:Anthelmintics / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D001412:Bacillus subtilis / Q000187:drug effects / Q000502:physiology; D017173:Caenorhabditis elegans; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D015817:Eye Infections / Q000188:drug therapy / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000502:physiology; D008826:Microbial Sensitivity Tests / Q000379:methods; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D018515:Plant Leaves; D018547:Plant Stems; D012393:Rosacea; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology
D000871:Anthelmintics; D000900:Anti-Bacterial Agents; D016861:Cyclooxygenase Inhibitors; D010936:Plant Extracts