Black Velvet Tamarind: Phytochemical Analysis, Antiradical and Antimicrobial Properties of the Seed Extract for Human Therapeutic and Health Benefits

Black Velvet Tamarind (BVT) is a famous edible fruit with multiple therapeutic properties. The aim of this study was to determine the secondary metabolites and evaluate the medicinal activities of the seed extract of the plant in order to scientifically report its possible medicinal applications in food and pharmaceutical industries. The pulverized seed was extracted with methanol/ethylacetate (2:1) and the concentrated extract was analyzed using gas chromatography-mass spectrometry (GC-MS), the antioxidant capacity was evaluated using galvinoxyl and 2,2ʹ-diphenyl-1-picryl-hydrazyl (DPPH) assays while the antibacterial activity was determined by agar-well diffusion method. From the GC-MS analysis, Twenty (20) organic compounds were identified in the seed extract, accounting for 99.3% of the identifiable components in the seed extract, and the main constituents were:4-O-methylmannose (40.46%), 9,9-dimethoxybicyclo[3.3.1]nona-2,4-dione (12.30%), palmitic acid (10.00%), nitroisobutylglycerol (8.60%), simiarenol (4.77%) and methyl-α-d-mannofuranoside (4.70%). The extract also contained some notable therapeutically active phenolic compounds such as dihydrochavicol (3.60%), p-chloro-m-cresol (0.67%) and p-vinylguaiacol (0.1%). The seed extract possesses significant free radical scavenging and antioxidant (IC50 and AAI) properties; for galvinoxyl assay (30.00-34.00%), 5.0 and 8.4 and DPPH assay (86.78-90.57%), 6.0 and AAI of 6.7, respectively. The result showed that the antioxidant properties of the seed extract of BVT increased in dose-concentration manner due to the synergetic activity of secondary metabolites present in the seed extract. This study showed that the seed of BVT possesses antioxidant and antimicrobial potential and it might be useful against ROS and RNS induced disorders. The seed of BVT can be used as an easily accessible source of natural antioxidant. The extract has high inhibitory effects at different concentrations (1000-250 µgml-1 ) on Enterococcus faecalis (30 mm) and Serratia marcescens (15 mm) isolated from clinical samples. The susceptibility of Gram positive and negative bacterial strains to the seed extract was due to the synergic activities of the secondary metabolites in the seed extract, most especially the phenolic compound and the terpenoids. This study showed that the seed extract of BVT has medicinally bioactive phytochemicals that may be useful in the formulation of food preservatives or drug supplements and treatment of bacterial infections.