Antioxidant properties and nutritive values of native figs consumed in northern Thailand

Abstract

The antioxidant properties of five native figs in northern Thailand that have been used as food and medicinal plants including Ficus auriculata, F. fistulosa, F. hispida, F. racemosa and F. semicordata were examined by DPPH and ABTS radical scavenging assays as well as total phenolic content. The parts of plant being investigated included tips, leaves, inflorescence (syconium), immature fruits and mature fruits. The DPPH radical scavenging assay results showed that the highest antioxidant activity was found in the tips of F. hispida, the tips, leaves, inflorescence and immature fruits of F. fistulosa and F. semicordata and the leaves of F. auriculata with IC50 values in the range of 12.47±0.04-33.43±1.09 µg mL-1. This was comparable to the standard antioxidant compounds, Trolox and α-Tocopherol that have IC50 values at 12.67±0.06 and 24.51±0.28 µg mL-1, respectively. These extracts also showed quantitative antioxidation activities according to the ABTS radical scavenging assay (100.36-383.29 mg TEAC g extract-1) and the total phenolic content (128.27-954.80 mg GAE g extract-1). The nutritive values were evaluated in the inflorescence and mature fruits of F. auriculata and F. semicordata, the native figs that have preference consumption by local people. Their nutritive properties were as follows; moisture contents (76.99-89.04%), crude proteins (0.57-1.23%), fat (0.52-1.44%), ash (0.61-1.26%), total carbohydrates (8.37-19.41%), dietary fibers (5.61-9.89%), total sugar (0.10-2.08%), food energy (42.63-94.52 kcal 100 g-1) and energy from fat (4.68-12.96 kcal 100 g-1). The mineral elements contents were exceptionally high with calcium content ranging from 51.65-157.90 mg 100 g-1, iron 0.34-0.54 mg 100 g-1, magnesium 20.10-25.50 mg 100 g-1, potassium 211.30-436.00 mg 100 g-1, phosphorus 28.02-45.11 mg 100 g-1 and sodium content ranging from less than 0.01-1.38 mg 100 g-1. The results indicated that these northern Thai figs have potential as good source of native antioxidants and nutritional value which could be further applied in healthy food or pharmaceutical industries.