Chemistry and biological activity of flavonoids from zest and pith of kinnow peel
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Date
2016
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Publisher
Punjab Agricultural University Ludhiana
Abstract
Different extracts from zest (flavedo, orange part) and pith (albedo, white part) of kinnow
peel were prepared by three extraction procedures i.e. conventional, ultrasonic assisted
extraction and soxhlet extraction methods using different solvents (hexane, benzene,
isopropylalcohol, ethylacetate and acetone). Soxhlet extraction method was found to be the
best method giving maximum total phenolic and flavonoid content for kinnow zest extracts
in isopropylalcohol solvent with values 40.41 mg gallic acid equivalent (GAE) g-1 dry weight
(DW) and 6.07 mg quercetin equivalent (QE) g-1 DW, respectively whereas the values were
found to be 37.34 mg GAE g-1 DW and 5.08 mg QE g-1 DW, respectively in kinnow pith
extracts. The yields of hesperidin isolated from zest and pith of kinnow peel were found to be
0.6 and 1.4%, respectively. Whereas, yields of naringin were found to be 0.032 and 0.05%
from zest and pith of kinnow peel, respectively. Aglycone forms, methylated and acetylated
derivatives of isolated compounds were prepared which were identified by melting point,
TLC, FT-IR and 1HNMR data. All zest and pith extracts, isolated compounds, their aglycone
forms and derivatives were investigated for their 2,2-diphenyl-1-picrylhydrazyl (DPPH)
radical scavenging activity using 3,5-di-tert-butyl-4-hydroxytoluene (BHT) as a standard and
antibacterial activity by disc plate method against Bacillus aryabhattai, Acinetobacter sp. and
Klebsiella sp. using tetracycline as standard. Among all the extracts, isopropylalcohol extract
showed highest antioxidant and antibacterial activities, whereas among different isolated and
synthesized compounds, aglycone forms were found to be more effective than isolated
compounds.
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Keywords
Chemistry, zest, Biochemistry, pith, kinnow peel, hesperidin