Toxicity and Antimicrobial Activities of Amaranthuscaudatus L. (Amaranthaceae) Harvested From Formulated Soils atDifferent Growth Stages

摘要

This study examined the toxicity and antimicrobial effects of ethanol and aqueousextracts from Amaranthus caudatus grown on soils formulatedfrom parent particles of silt, sand and clay in a glasshouse. Four differentsoils namely; sandy clay loam, loam, clayey loam and silty clay loam from wereformulated were used for cultivation with the unfractionated soil which was thecontrol. Crude extracts obtained from the plant shoots harvested at differentgrowth stages were tested on some certain gram-negative and gram-positivebacteria and some fungi via agar dilution assay. The toxicity of the water andethanol extracts was also examined via Artemia salina assay andthe level of lethality was measured against Clarkson’s lethality scale. Allaqueous samples, as well as ethanol extracts of flowering and pre-floweringharvests of control soil tested, were non-toxic (LC50 > 1 mg/mL).At post flowering, the ethanolic extracts were highly toxic mostly in clayeyloam, control, sandy-clayey loam soils (LC50 < 0.5 mg/mL). Also,antifungal effects of the plant revealed that extracts inhibited the growth ofCandida albicans significantly with mild effect onCandida glabrata, Penicillium chrysogenumand Penicillium aurantiogriseum suggesting that the plant is apromising pharmacological candidate in the treatment of candidiasis. For anoptimal yield of non-toxic supplement for household consumption which may alsoserve as pharmacological precursors, clayey loam soil is recommended forcultivation and harvesting may occur at pre-flowering or flowering stage usingethanol and water as solvents of extraction.