Bitter melon, Momordica charantia L. is a member of the Cucurbitaceae family. It is
widely cultivated in tropical and subtropical countries, where it is a popular
traditional medicinal fruit. In the scientific
literature, it has been linked with a wide range of therapeutic effects,
including anticancer, anti-viral, anti-inflammatory, hypolipidaemic,
hypocholesterolaemic, immuno-modulatory and anti-diabetic properties. And some
of the proposed therapeutic effects have been in part attributed to its content
of flavonoids. To determine its total flavonoid content (TFC)
and to prepare extracts for use as nutritional supplements or ingredients for
nutraceutical functional foods, various solvents have been used, including
water, which is the preferred solvent because it is inexpensive, safe and
environmentally friendly.
The study aimed to extract bitter melon, using five solvents (ethanol,
methanol, n-butanol, acetone and water) before and after the optimal conditions
for water were determined in terms of extraction temperature, time, ratio of
water to bitter melon (mL/g) and number of times the same material was
extracted. Six varieties, Moonlight, Hanuman, White,
Jade, Niddhi and Indra were analyzed in the present study. The TFC of six varieties of bitter melon was
also determined.
The results indicated that acetone was the best of the five solvents for
extracting flavonoids from the Moonlight variety (23.2 mg Rutin Equivalents
(RE)/g). Even after increasing the extraction by 88% (1.24 vs 0.66 mg RE/g)
using optimised conditions for the aqueous extraction (two extractions at 40℃ for 15 min at a ratio of 100:1 mL/g of bitter melon powder), the
flavonoids extracted from the Moonlight variety using water was very little
(5.4%) compared to acetone. Furthermore, using acetone, it was shown that the
Moonlight variety (23.2 mg RE/g) bought at a local market had higher levels of
flavonoids than the greenhouse-grown Jade (15.3 mg RE/g), Niddhi (16.9 mg
RE/g), Indra (15.0 mg RE/ g), Hanuman (3.9 mg RE/g) and White (6.9 mg
RE/g) varieties.
In conclusion, acetone was the best solvent for extracting flavonoids
from bitter melon and the aqueous extraction could only be improved to extract
5.4% of the flavonoids extracted with acetone from the Moonlight variety, which
had the highest TFC of the six varieties of bitter melon.
Article by Sing
Pei Tan, et al, from Australia.
Full access: http://mrw.so/2WASRs
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