Areca nut contains a large number of phenolic
compounds in substantial quantity. Depending on the stage of maturity they are
harvested, and the method of processing, the concentration of phenolic content
and type of phenolic compounds can vary. In general, total phenolic content are
found to be highest in the areca nuts of 4-5 months maturity and keeps
decreasing as it reaches maturity. Flavonoids (flavones, flavanones, flavanols,
flavonols), phenolic acids and polyphenols (procyanidins, areca tannins etc.)
are some of the important classes of phenolic compounds found in areca nuts.
These compounds are responsible for the dark brownish colour in the boiled nuts
(Red supari). They impart astringent taste to the nut. They turn red in the
presence of lime. Most of the perceived therapeutic properties of areca nut are
attributed to these flavonoids, phenolic acids and polyphenols. Almost all of
them are highly potent antioxidants.
B-type procyanidins are found to be one of the most
abundant phenolic compounds found in Areca nuts. B-type procyanidins can be categorized
by their degree of polymerization: monomers form linkages leading to oligomers.
The most common monomeric unit is (–)-epicatechin. B-type procyanidins
containing 2–7 monomeric units are defined as oligoprocyanidins. They are
abundantly available in Red supari (kempadike), produced out of areca nuts of 6-7 months maturity and Bing lang. These procyanidins
are also present in abundance in Cocoa, apples, grape seeds, and red wine.
Various conclusive evidence suggests
that the intake of foods rich in B-type procyanidins is linked to reduced risk
for cardiovascular disease including coronary heart disease, myocardial
infarction, and stroke. Randomized controlled trials and subsequent
meta-analyses have confirmed that the dark chocolate containing large amounts
of B-type procyanidins can mitigate states related to the metabolic syndrome,
including hypertension, dyslipidemia (abnormally high levels of fats in the
blood) and glucose intolerance. In addition, the latest largescale study found
a 27% reduction in cardiovascular death by ingestion of cocoa flavanol
fraction, which is rich in B-type procyanidin monomer and oligomers, for 3.6
years. Recent studies have focused on the benefit of B-type procyanidin
ingestion for the central nervous system (CNS).
Almost all B-type procyanidins ingested
in food move into the colon, and some are degraded by the beneficial bacteria
residing in the small intestine. Further it is broken down into low molecular
weight phenolic acids in the large intestine (colon). Because of their smaller
size, monomeric procyanidins are more absorbable than dimeric procyanidins.
References
1. Osakabe et al., (2023) Hormetic response to B-type procyanidin ingestion involves stress-related neuromodulation via the gut-brain axis: Preclinical and clinical observations, Frontier in Nutrition, DOI 10.3389/fnut.2022.969823.
2. Dasiman et al., (2022) A Review of Procyanidin: Updates on
Current Bioactivities and Potential Health Benefits, Biointerface Research in
Applied Chemistry, Vol. 2 (5), pp. 5918 - 5940
