EFFECT OF COOKING METHODS ON TOTAL PHENOLICS AND ANTIOXIDANT ACTIVITY OF SELECTED WILD EDIBLE PLANTS

Objective: The target of this appraisal was to explore the impacts of various cooking techniques, for example, boiling and microwave cooking on total phenolics and antioxidant activity of Zanthoxylum acanthopodium, Viburnum foetidum, Houttuynia cordata, Sonchus arvensis and Oenanthe linearis, widely consumed by the common individuals of the North-Eastern area of India.Methods: The antioxidant activities of the plants were determined by using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, ABTS radical scavenging ability, reducing power capacity, estimation of total phenolic content, flavonoid content and flavonol content.Results: Total phenolics content (TPC) of fresh vegetables ranged from 108.28 to 253.99 mg/100 g (as gallic acid equivalent) on a dry weight basis. Total antioxidant capacity of fresh plants (IC50 mg dry extract) determined by DPPH and ABTS ranged from 0.37-1.23 and 0.29-0.89, respectively. Boiling caused the highest losses of TPC, resulting in a reduction of the TPC on dry weight (DW) basis ranging from 9.37% in O. linearis up to 25.97% in Z. acanthopodium whereas microwave cooking enhanced TPC ranging from 4.09% to 10.38%. Similarly, boiling treatment decreased the DPPH radical scavenging activities ranging from 10.65 to 29.77% and ABTS radical scavenging activities ranging from 5.88-16.35%, whereas microwave cooking increased the DPPH and ABTS radical scavenging activities ranging from 8.02-24.20% and 9.86 to 19.70% respectively, in the studied plants.Conclusion: The results suggest that the best cooking method for increasing the concentration of polyphenols and antioxidants was microwave cooking while boiling was the least recommended method.

Quantitative HPLC analysis of phenolic acids, flavonoids and ascorbic acid in four different solvent extracts of two wild edible leaves, Sonchus arvensis and Oenanthe linearis of North-Eastern region in India.

A reversed-phase high-performance liquid chromatographic method using photodiode array detector with gradient elution has been developed and validated for the simultaneous estimation of ascorbic acid, free phenolic acids and flavonoids (catechin, rutin, quercetin, myrecetin, apigenin and Kaempferol) in four different solvent extracts of two wild edible leaves of viz. Sonchus arvensis and Oenanthe linearis, collected from North-eastern region in India . The chromatographic separation was carried out on Acclaim C 18 column (5 μm particle size,250 x 4.6 mm), Dionex Ultimate 3000 liquid chromatograph and detection was carried out at three different wave lengths (272, 280 and 310 nm) using a mobile phase of acetonitrile and 1% aqueous acetic acid solution with gradient elution. The experimental results showed high amount of ascorbic acid in S. arvensis and O. Linearis (1.2% and 2.3 % respectively) and gallic acid (0.02% and 0.06% respectively) in 1% aq. acetic acid extract of these two plants. The high percentage of recovery (96-103%), low coefficient of variation ( R2 > 0.99) and low limit of detection (LOD) and limit of quantitation (LOQ) confirm the suitability of the method for simultaneous quantification of ascorbic acid and all phenolic compounds in the two plants under investigation.

Ethnobotanical Importance and Nutritional Potential of Wild Leafy Vegetables of Meghalaya State in India.

The nutritional potential of five wild edible leaves of the plant e.g. Chenopodium album, Alternanthera philoxeroides, Homalomena aromatica, Zanthoxylum rhetsa and Cajanus indicus collected from Meghalaya state in India were evaluated by determining proximate and phytochemical composition. These plants are used by the local people of Meghalaya state in India as their food. The present study revealed that for different plant species, the crude fat content ranged between 0.69±0.02-2.30±0.02%. The crude protein content was determined high in the leaves of Cajanus indicus (15.77±0.03 %) and in Zanthoxylum rhetsa (13.75±0.05%) while the available carbohydrate content was the highest in the leaves of Alternanthera philoxeroides (73.67±0.30 %). The nutritive value ranged from 77.41±0.53-344.52±0.33 kcal/100g in the various wild edible plants. Among the various macronutrients estimated in the plant samples of different wild edible plants potassium was present in the highest quantity (10.42±0.10- 45.86±0.22mg /g) followed by calcium (5.93±0.15 -26.47±0.18 mg/g) and sodium (0.32±0.01-8.25±0.07 mg /g). Micronutrients, such as iron, zinc, copper, manganese and magnesium were also analyzed in the different plant specimens. The result indicates that the nutritional values and mineral contents of these leafy vegetables under investigation were richer than that of the commercial vegetables and could be used for nutritional purpose. The present study also gives an account of ethnobotanical importance of the wild plants under investigation.