Effect of extraction techniques and moisture levels on total phenols, flavonoids and antioxidant activity of Clove (Syzygium aromaticum L.) and Turmeric (Curcuma longa L.)
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Date
2014
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Publisher
CCSHAU
Abstract
The present study was undertaken to study the effect of extraction techniques viz. maceration
followed by mechanical shaking, refluxing, soxhlet extraction and centrifugation using three solvents
(acetone, ethanol and water) on phytoconstituents and antioxidant activities of clove buds and turmeric
rhizomes of var. BSR-2 & germplasm material. The effect of moisture levels viz. 5% moisture level
(more than normal), 10% moisture level (more than normal) and normal moisture level was also studied.
In clove buds, highest total phenols (127.26 mg GAE/g), flavonoids (26.72 mg CE/g), total sugars (28.91
mg/g), reducing sugars (28.50 mg/g) and non-reducing sugars (0.41 mg/g) contents were found in extracts
obtained by soxhlet technique followed by refluxing, mechanical shaking/centrifugation. In turmeric
rhizomes of var. BSR-2 & germplasm material, total phenols (18.47 & 15.78 mg GAE/g), flavonoids
(62.98 & 44.48 mg CE/g), total sugars (37.96 & 35.90 mg/g), reducing sugars (10.19 & 9.78 mg/g), nonreducing sugars (27.77 & 26.12 mg/g) and curcumin (2.936 & 2.149 g/100g) contents were highest in
extracts obtained by soxhlet technique followed by refluxing, mechanical shaking/centrifugation. For
clove buds and turmeric rhizomes of var. BSR-2 & germplasm material, DPPH free radical scavenging
activity (range of IC50 in three solvents: 89.9-125.3, 309.9-704.0 & 333.3-875.9 μg/mL) and antioxidant
activity (85.86, 67.75 & 66.52%) were found to be highest in extracts obtained by soxhlet technique
followed by refluxing, mechanical shaking/centrifugation. Amongst solvents, total phenols, DPPH free
radical scavenging activity and antioxidant activity in clove buds were highest in water extracts whereas
in turmeric rhizomes these parameters and curcumin contents were highest in acetone extracts. In clove
buds & turmeric rhizomes, flavonoids and sugars contents were highest in acetone and water extracts,
respectively. In clove buds, the contents of various phytoconstituents at 10%, 5% and normal moisture
level after 64 days of storage were 70.89, 73.76 & 96.07 mg GAE/g total phenols, flavonoids (21.02,
23.37 & 38.24 mg CE/g), DPPH free radical scavenging activity (IC50 : 253.0, 231.7 & 124.9 μg/mL) and
antioxidant activity (51.05, 55.19 & 84.67%). In turmeric rhizomes of var. BSR-2, the contents of various
phytoconstituents at 10%, 5% and normal moisture level after 64 days of storage were 21.05, 21.27 &
24.88 mg GAE/g total phenols, flavonoids (59.22, 64.61 & 87.27 mg CE/g), curcumin (4.432, 4.436 &
4.476 g/100g), DPPH free radical scavenging activity (IC50: 454.3, 421.1 & 307.2 μg/mL) and antioxidant
activity (57.00, 59.03 & 78.20%). In turmeric rhizomes of germplasm material, the contents of various
phytoconstituents at 10%, 5% and normal moisture level after 64 days of storage were 18.00, 18.17 &
22.68 mg GAE/g total phenols, flavonoids (43.79, 47.70 & 65.50 mg CE/g), curcumin (3.533, 3.541,
3.607 g/100g), DPPH free radical scavenging activity (IC50: 551.3, 500.6 & 332.8 μg/mL) and antioxidant
activity (51.90, 54.97 & 77.55%). Sugars contents in clove buds and turmeric rhizomes were also found to
be less at 10% moisture level in comparison to 5% and normal moisture levels. Thus, phytoconstituents
and antioxidant activity of clove buds and turmeric rhizomes were dependent on extraction techniques &
solvent polarity and decreased under moisture conditions during storage.
Description
Keywords
extraction, turmeric, cloves, sugar, antioxidants, aromatic compounds, alcohols, irrigation, budding, phenols