Phenotypic And Molecular Characterisation Of Some Amaranthus Accessions And Hepatoprotective Activity Of Their Ethanol Extract On Sodium Arsenite-Induced Toxicity In Male Rats

ABSTRACT

Amaranth is an underutilised crop with great potential as a source of essential nutrients. It also

contains bioactive compounds with potential health benefits. However, its characterisation for

agronomic and nutritional traits is limited. Likewise, information on its hepatoprotective

potential is scarce. In this study Amaranthus accessions were characterised using phenotypic and

molecular markers. The quality of its seed protein and hepatoprotective activity of its Ethanol

Seed Extract (ESE) on sodium arsenite (NaAS)-induced toxicity in male rats were also

investigated.

Twenty-nine accessions (27 from the United States Agricultural Research Station and 2 from

National Horticultural Research Institute, Ibadan) were characterised using 27 phenotypic traits

and 16 Random Amplified Polymorphic DNA (RAPD) primers. Protein quality was assessed

using Kjedahl method, amino acid analyzer and one-dimensional electrophoresis. The ESE of all

accessions were analysed for phytochemical contents and antioxidant activities. Two out of the

29 accessions with the highest nutritional contents were used for hepatoprotective study.

Experimental design consisted of two main groups (representing the two accessions), each

consisting of eight treatment groups of 5 rats each. Treatment groups comprised of control,

NaAS (2.5mg/kg body weight), amaranth seed extracts (100, 200, 300 mg/kg body weight) and

NaAS plus amaranth seed extracts (100, 200, 300 mg/kg). After 14 days of treatment, serum

Alanine Aminotransferase (ALT) and Gamma Glutamyl Transferase (GGT) activities were

assayed spectrophotometrically. Hepatic Superoxide Dismutase (SOD), Catalase and Glutathione

Peroxidase (GPx) activities were assayed likewise. Data were analysed using ANOVA and

Cluster at p=0.05.

For phenotypic traits, 57.5% variability was observed and accessions were grouped into five

clusters. The RAPD analysis yielded 193 loci. Genetic similarity coefficient ranged from 0.6 to

0.9 while dendogram grouped accessions into nine clusters. Total protein contents ranged from

11.8 to 19.0%. Total essential amino acids ranged from 31.2 to 44.9% and were limited in

tryptophan and leucine. Albumin, globulin and glutelin were the major protein fractions. Phytate,

total flavonoid, total polyphenol, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant and 2,

iii

2-azino-bis-3-ethylbenz-thiazoline-6-sulfonate (ABTS) values ranged from 0.8-1.9%; 7.8-11.0mg/100g; 23.9-35.4mg/100g; 82.8-95.4%; 111.3-271.6%; 157.6-208.8mM Trolox Equivalent (TE), respectively. Accessions A23 (Amaranthus hypochondriacus, AHC) and A28 (Amaranthus hybridus, AHB) had higher protein and phytochemical contents than the other accessions. The activities of ALT (16.7±1.0U/L) and GGT (3.5±0.9U/L) in NaAS-treated group were significantly higher than control (ALT - 9.4±1.3U/L, GGT - 1.7±0.7U/L) and lower in groups treated with AHC plus NaAS (100mg/kg - 14.1±0.8U/L, 3.2±0.6U/L), (200mg/kg - 12.6±0.3U/L, 2.6±1.1U/L) and (300mg/kg - 9.2±0.2U/L, 1.7±0.7U/L). Activities of ALT and GGT were also lower in AHB plus NaAS treated groups (100mg/kg - 12.5±1.4U/L, 2.9±0.7U/L), (200mg/kg - 11.8±0.8U/L, 2.3±0.9U/L), and (300mg/kg - 8.6±2.7U/L, 1.8±0.6U/L) when compared with NaAS-treated group. Hepatic SOD, Catalase and GPx activities were significantly lower in NaAS-treated group when compared with control and groups administered different doses of the amaranth extracts. Amaranth accessions A23 (Amaranthus hypochondriacus) and A28 (Amaranthus hybridus) contained a good balance of essential amino acids and the ethanol extract showed dose-dependent hepatoprotective activity. The diverse clusters can be used as parents in hybridization programmes.