Toxicity and Antimicrobial Activities of Amaranthus caudatus L. (Amaranthaceae) Harvested From Formulated Soils at Different Growth Stages

Abstract

This study examined the toxicity and antimicrobial effects of ethanol and aqueous extracts from Amaranthus caudatus grown on soils formulated from parent particles of silt, sand and clay in a glasshouse. Four different soils namely; sandy clay loam, loam, clayey loam and silty clay loam from were formulated were used for cultivation with the unfractionated soil which was the control. Crude extracts obtained from the plant shoots harvested at different growth stages were tested on some certain gram-negative and gram-positive bacteria and some fungi via agar dilution assay. The toxicity of the water and ethanol extracts was also examined via Artemia salina assay and the level of lethality was measured against Clarkson’s lethality scale. All aqueous samples, as well as ethanol extracts of flowering and pre-flowering harvests of control soil tested, were non-toxic (LC50 > 1 mg/mL). At post flowering, the ethanolic extracts were highly toxic mostly in clayey loam, control, sandy-clayey loam soils (LC50 < 0.5 mg/mL). Also, antifungal effects of the plant revealed that extracts inhibited the growth of Candida albicans significantly with mild effect on Candida glabrata, Penicillium chrysogenum and Penicillium aurantiogriseum suggesting that the plant is a promising pharmacological candidate in the treatment of candidiasis. For an optimal yield of non-toxic supplement for household consumption which may also serve as pharmacological precursors, clayey loam soil is recommended for cultivation and harvesting may occur at pre-flowering or flowering stage using ethanol and water as solvents of extraction.

The Dual Nature of Amaranth—Functional Food and Potential Medicine

“…This peptide was selected after analysis of the protein fraction from A. tricolor and characterized as being highly antimicrobial [ 38 ]. The antimicrobial activity of ethanolic and aqueous extracts of Amaranthus caudatus was also examined in a study by Jimoh and colleagues [ 39 ]. Streptococcus pyogenes, Staphylococcus aureus, Bacillus subtilis, Streptococcus pneumoniae, Escherichia coli, and Pseudomonas aeruginosa were tested in this study.…”

“…The ethanolic extract of amaranth showed stronger antimicrobial activity than the aqueous extract. The extracts also showed antifungal activity with an MIC in the range of 0.675 to 10 mg/mL [ 39 ]. A new application of amaranth seed oil (apolar fraction from Amaranthus cruentus L. seeds extract) as an agent against Candida albicans was examined by De Vita and colleagues.…”

The Importance ofSceletium tortuosum(L.) N.E. Brown and Its Viability as a Traditional African Medicinal Plant

“…Examples of familiar natural plant products that are used as drugs and/or dietary supplements are: artemisinin, paclitaxel, ginsenoside, lycopene, and resveratrol [22]. Secondary metabolites play a major role in plants' adaptation to their environment and are thought to be responsible for antimicrobial and anti-viral activities exhibited by plants [23,24]. Apart from protecting plants against leaf damage instigated by the incident light intensity via ultra-violet trapping mechanisms, they cause allelopathy, antipathogens and antifeeding mechanisms in plants [25][26][27].…”

Suitability of Roselle-Hibiscus sabdariffa L. as Raw Material for Soft Drink Production

“…Incorporation of antioxidant-rich foods in our daily diet boosts our immune system and it is safer and cheaper than commercially available antioxidants. Accumulation of free radicals in the body leads to oxidative stress, which is linked to several diseases in the body and can even cause death [26,27]. Antioxidants are compounds, which inhibit the rate of oxidation of molecules in the body through the obstruction of the multiplication of the chain reaction of free radicals.…”