Nanoparticle encapsulation to deliver better bioavailability for tea polyphenols

The study, published in Food Hydrocolloids​, noted that while many studies have identified tea polyphenols like epigallocatechin gallate (EGCG) as having the potential to benefit human health – and the ability to extend shelf life by blocking oxidation in food systems – the stability and oral bioavailability of such polyphenols has limited applications.

“To date, great attention has been paid to protect tea polyphenols from premature reactions with oxygen and light within films and to enhance the oral bioavailability of TP by using nanoencapsulation systems,”​ said the researchers led by led by senior author Professor Fang Zhong of Jiangnan University, China. “However, to our knowledge, studies about the fabrication of nanoparticles incorporating soluble ingredients, such as TP, are rare.”​

Zhong and his colleagues tested a new nano-encapsulation method that uses cross-linked chitosan hydrochloride (CSH) and sulfobutyl ether-β-cyclodextrin sodium (SBE-β-CD) for the delivery of tea polyphenols – finding that CSH-SBE-β-CD nanoparticles (CSN) are “a promising carrier for the encapsulation of water soluble tea polyphenols.”​

Nano encapsulation​

The Jiangnan University research team initially prepared inclusion complexes of tea polyphenols and SBE-β-CD. These complexes were then cross linked with CSH to more effectively encapsulate the tea polyphenol as a CSN, said the team.

“Epigallocatechin gallate (EGCG), the most abundant compound in TP, was used to analyse the formation of inclusion complexes,”​ they wrote.

“The resulting CSNs were extensively characterized regarding their particle size, zeta potential, encapsulation efficiency (EE), and surface morphology,”​ they added. “Additionally, the interactions among CSH, SBE-β-CD, and TP were evaluated from the FTIR analysis.”​

The teams found that encapsulation efficiency increased with increasing CSH concentration or decreasing CSH/SBE-β-CD mass ratio - but decreased significantly with increasing TP concentration.

“Controlling the critical fabricating parameters such as, CSH/SBE-β-CD mass ratio, CSH and TP concentration, provides an opportunity for manipulating physicochemical characteristics of CSNs and their ability to load TP for intended application[s],”​ said the team – who noted that due to the core nature of the inclusion complexes, CSNs have the capacity to carry water soluble tea polyphenols such as EGCG together with hydrophobic compounds, like alpha-tocopherol.

“In conclusion, TP, a water soluble antioxidant, can be effectively encapsulated into nanoparticles ​via ionic gelation between CSH and SBE-β-CD by initially forming inclusion complexes of TP and SBE-β-CD,”​ wrote Zhong et al 

Source: Food Hydrocolloids​
Volume 57, June 2016, Pages 291–300, doi: 10.1016/j.foodhyd.2016.01.024​
“Chitosan/sulfobutylether-β-cyclodextrin nanoparticles as a potential approach for tea polyphenol encapsulation”​
Authors: Fei Liu, et al​