Investigation of Total Phenolic, Flavonoids and Antioxidant Activity of Miyana-Dalu (Duplazum esculentum) Under Different Extraction Conditions and Cooking Methods

Abstract

Miyana-dalu (Duplazum esculentum) is one of the nutritious edible ferns. Nevertheless, the nutritional value of these greens can be altered during preparation and processing. Availability of literature on the phytochemical profile of this plant is limited and such investigation will depend on extractions. In this study, six different cooking treatments by adding salt, coconut oil, coconut milk and spices individually or as a combination, were compared with the raw extract. At the same time the raw extract was obtained with three different solvents (ethanol, chloroform, distilled water) and two different extraction methods (blending and ultra-sonication) to compare the effect of extraction conditions on phytochemical content and antioxidant activity. The initial screening tests showed, positive results for carbohydrates, flavonoids, saponin and steroids. Highest TPC (8.23±0.35 GAE mg/100g), TFC (1.91 ±0.13m g QU /ml), FRAP (11.41 ± 0.08 mg TE/ 100g) and the lowest IC50 for DPPH (0.025 ±0.00 g/ml) values were observed of the cooked samples with coconut milk, salt and spices. The raw extract gave significantly higher values for all the parameters than all the cooking methods compared (TPC=36.16±0.23 GAE mg/100g, 1.08± 0.04 QU mg/ml). Among the extraction solvents, ethanol extract gave the highest TPC, TFC, FRAP and the lowest IC50 values. Ultra-sonication resulted higher TPC values than pulverizing. Both TPC and TFC showed positive correlation with the DPPH radical scavenging activity. It is rich with fiber (4.64±0.84%) and protein (2.34±0.26%). This study concludes that ethanol is the most efficient solvent for phytochemical extraction among the three solvents tested for investigation of bioactive compound profile for further studies while ultra-sonication being the best extraction technique. The raw form is rich with bioactive compounds cooking with coconut milk which is the most used preparation method, revealed to be the best in preserving the potential health benefits.