Calotropis procera
(Family, Asclepiadeae) is implicated in a variety of ethno-medicinal therapies ranging form oral, skin, gastro-intestinal to respiratory problems. The effects of this plant on the sensitivity of micro-organisms need verification and its potential for cytotoxicity needs to be investigated. Thus, the anti-microbial and brine–shrimp lethality studies on the leaves and stem were carried out. The crude ethanolic extract of the stem and its ethylacetate fraction elicited good antibacterial activity against clinical strains of
Bacillus subtilis
, Staphylococcus aureus but gave minimal activity against
Escherichia coli
,
Klebsiella pneumoniae
and
Salmonella typhi
but none against the fungal isolate;
Candida albicans
. The brine-shrimp lethality assay analyzed using the Finney probit method showed that the crude ethanolic extracts of the leaves and stem displayed LD
50 values at 192 ppm and 182 ppm respectively. These findings indicate the potential of the plant as panacea for infectious diseases and also reveal a novel potential in the fight against tumors in man.