Bioactivity studies of different solvent extracts of partially defatted coconut testa obtained from selected coconut cultivars

Abstract

Purpose: Coconut testa is a byproduct of coconut industry and is currently used for oil extraction. The partially defatted residue of testa is underutilized despite being able to convert into coconut testa flour (CTF). The objective of the present study was to compare the bioactivity of different solvent extracts of CTF obtained from selected Sri Lankan coconut cultivars namely, Gon Thambili (GT), Ran Thambili (RT), San Raman (SR), Tall×Tall (TT) and commercial hybrid (COM).Research Method: CTF of individual cultivars was sequentially extracted with hexane, ethyl acetate (EtOAc) and methanol (MeOH). The total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP), DPPH radical scavenging activity, alpha amylase (Alpha-amy) and alpha-glucosidase (Alpha-glu) inhibitory activities were established in vitro using relevant assays. The phytochemical profiling of CTF was done using ultra high pressure liquid chromatography coupled with mass spectrometry.Findings: Among solvent extracts, MeOH extracts of all cultivars displayed significantly higher TPC, TFC, antioxidant and Alpha-amy inhibitory activities. GT exhibited the highest TPC (102.48 ± 3.46 GAE/g of crude extract), TFC (63.49 ± 4.47 CE/g of crude extract), FRAP value (1097.23 ± 1.24 µmol FeSO4 /g of crude extract), DPPH radical scavenging activity (IC50, 45.37 ± 1.94 ppm) while TT resulted in the highest Alpha-amy inhibitory activity (IC50, 80.09 ± 4.67 ppm). The EtOAc extract of TT showed the highest Alpha-glu inhibitory activity (IC50, 7.82 ± 0.40 ppm). The distribution of phenolic constituents was found to vary among the different cultivars.Originality/value: This study concludes that the extracts of CTF is a potent source of bioactive compounds that claim various bioactivities which can be used in developing functional foods.

FTIR spectral correlation with alpha-glucosidase inhibitory activities of selected leafy plants extracts

“…The Unscrambler 9.7 (Camo, USA) software was used to perform the PLS regression analysis for spectral data of crude extracts as described by Gunarathne et al (2022a). Initially, four replicates of 14 crude extracts were collected and followed by randomly dividing into two sets (i.e., 38 elements to use for calibration and crossvalidation and 18 elements to test the predictive models).…”

“…Although this technique was used in the early days for the identification of functional groups in organic molecules, its application range has now broadened to include complex issues related to chemical and biological systems. In food industries, FTIR spectroscopy has been widely investigated for authentication and quality control of food and drugs (Gunarathne et al, 2022a), determination of enzyme activity of sea buckthorn substrate (Adina et al, 2010), and efficacy of herbal medicinal formulations (Ashokkumar & Ramaswamy, 2014;Bunaciu et al, 2011). In comparison to chromatographic techniques, FTIR has become popular due to its rapidity and ease of operation.…”

Nutritional Properties of De-fatted Coconut (<em>Cocos nucifera</em> L.) Testa Flour Incorporated Sri Lankan Traditional Food: Roti

“…Methanol extract of all cultivar displayed presence of phenolic compounds and flavonoid compounds such as caffeic acid, chlorogenic acid, gallic acid, ellagic acid, ferulic acid, p-coumaric acid, sinapic acid, vanillic acid, epigallocatechin, gallates, quercetin and rutin. In addition to the presence of above bioactive compounds, it also showed antioxidant and alfa-amylase inhibitory activity (Gunarathne et al, 2022). Extruding of coconut paring flour and wheat flour is possible to make string hopper which is a wheat flour or rice flour based-based extruded product (Rushdha et al, 2022).…”