Abstract:
The purpose of this study was to establish the quantities and antioxidant activity in fruits and leaves of Tamarindus indica L. collected from three agro-ecological zones of Tanzania represented by Morogoro, Tanga and Dodoma regions. Samples were studied for their total phenolic and flavonoid contents as well as their antioxidant activity. The total phenolic content in all extracts of the fruits and leaves were significantly different (p<0.05) and ranged from 1994.4±530.77 to 17874.67±5234 mg GAE/100g. Similarly the total flavonoid content in tamarind leaf and fruit extracts ranged from 880±609.45 to 11483.11±2559.67 mg CE /100 g dry weight. There was a significant difference (p<0.05) between the antioxidant activity in the leaf (54.39±0.13%) and fruit extracts (40.11±0.03%). Tamarind leaf extracts exhibited significantly higher (p<0.05) radical scavenging activity than fruit extracts. The antioxidant activity in fruit extracts expressed in percentage ranged between 29.27±0.06% and 40.11±0.03% while in leaf extracts the activity ranged from 22.33±0.08% to 54.39±0.13%. In a decreasing order the radical scavenging activity from Coastal leaf extracts had the highest activity followed by Eastern leaf extracts and lastly Central leaf extracts. In fruit samples, Coastal fruit extracts had the highest activity followed by Central fruit extracts and Eastern fruit extract being the least active. Ferric reducing power (FRAP) for leaves and fruits ranged between 6968±3655.91 μM Fe (II)/g and 76822.67±23259.9 μM Fe (II)/g dry mass respectively. The values in FRAP assay expressed the corresponding concentration and electron donating antioxidants. Antioxidant activity positively correlated with the total phenolic and flavonoid contents (R2=0.923). Geographical location and climatic conditions have shown to have profound effects on the amount and activity of antioxidants available in both tamarind fruits and leaves. Findings from the study have indicated that tamarind can be used as a cheap source for antioxidants. However further agronomic studies should be considered to justify the effects of agro-ecological differences on antioxidant activity.
