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Characterization of α-tocopherol as interacting agent in polyvinyl alcohol-starch blends

Sin LT, Bee ST, Tee TT, Kadhum AA, Ma C, Rahmat AR, et al.

Carbohydr Polym, 2013 Nov 6;98(2):1281-7.
PMID: 24053804 DOI: 10.1016/j.carbpol.2013.07.069

In this study, the interactions of α-tocopherol (α-TOH) in PVOH-starch blends were investigated. α-TOH is an interacting agent possesses a unique molecule of polar chroman "head" and non-polar phytyl "tail" which can improve surface interaction of PVOH and starch. It showed favorable results when blending PVOH-starch with α-TOH, where the highest tensile strengths were achieved at 60 wt.% PVOH-starch blend for 1 phr α-TOH and 50 wt.% for 3 phr α-TOH, respectively. This due to the formation of miscible PVOH-starch as resulted by the compatibilizing effect of α-TOH. Moreover, the enthalpy of melting (ΔHm) of 60 wt.% PVOH-starch and 50 wt.% PVOH-starch added with 1 and 3 phr α-TOH respectively were higher than ΔHm of the neat PVOH-starch blends. The thermogravimetry analysis also showed that α-TOH can be used as thermal stabilizer to reduce weight losses at elevated temperature. The surface morphologies of the compatible blends formed large portion of continuous phase where the starch granules interacted well with α-TOH by acting as compatilizer to reduce surface energy of starch for embedment into PVOH matrix.

Matched MeSH terms: alpha-Tocopherol/chemistry*
An improved method for the preparations of nanostructured lipid carriers containing heat-sensitive bioactives

Hung LC, Basri M, Tejo BA, Ismail R, Nang HL, Abu Hassan H, et al.

Colloids Surf B Biointerfaces, 2011 Oct 1;87(1):180-6.
PMID: 21652183 DOI: 10.1016/j.colsurfb.2011.05.019

Heat-sensitive bioactive compounds such as β-carotene and tocols, are widely used in the pharmaceutical and cosmetic fields. Their chemical stability in delivery systems is one of the major concerns in the production of nanostructured lipid carriers (NLCs). A previously established high-temperature high-pressure homogenisation technique involved in the preparation of NLCs can cause degradation of heat-sensitive compounds. Therefore, a novel preparation process needs to be developed to minimise the degradation of heat-sensitive active compounds during the preparation of NLCs. In this work, modified methods A and B were designed to minimise the degradation of β-carotene and tocols during the production of NLCs. These methods improved the chemical stability of heat-sensitive bioactive compounds (β-carotene and tocols) significantly compared to the previously established method. The physical stability of the formulation was maintained throughout study duration.

Matched MeSH terms: alpha-Tocopherol/chemistry*
Antioxidant synergism between ethanolic Centella asiatica extracts and α-tocopherol in model systems

Thoo YY, Abas F, Lai OM, Ho CW, Yin J, Hedegaard RV, et al.

Food Chem, 2013 Jun 1;138(2-3):1215-9.
PMID: 23411234 DOI: 10.1016/j.foodchem.2012.11.013

The synergistic antioxidant effects of ethanolic extracts of Centella asiatica (CE), and α-tocopherol have been studied. The types of interactions exhibited by CE and α-tocopherol combined at different ratios were measured using three assays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical-scavenging capacity, the β-carotene bleaching system and liposome peroxidation assays. Fixed-fraction isobolographic analysis was used to detect any inducement of the antioxidant activity compared with the individual activities of CE and α-tocopherol. Of all synergistic combinations of CE and α-tocopherol, only fraction 2/3 showed the synergistic combination that fits well in three different assays and can be explained by the regeneration of α-tocopherol by CE despite the interaction effect of β-carotene present in the analytical assay. This phenomenon involved complex interactions between CE and α-tocopherol to exhibit different degrees of interactions that eventually increased antioxidant activity.

Matched MeSH terms: alpha-Tocopherol/chemistry*
Migration of antioxidants from polylactic acid films, a parameter estimation approach: Part I - A model including convective mass transfer coefficient

Samsudin H, Auras R, Burgess G, Dolan K, Soto-Valdez H

Food Res Int, 2018 03;105:920-929.
PMID: 29433289 DOI: 10.1016/j.foodres.2017.11.065

A two-step solution based on the boundary conditions of Crank's equations for mass transfer in a film was developed. Three driving factors, the diffusion (D), partition (Kp,f) and convective mass transfer coefficients (h), govern the sorption and/or desorption kinetics of migrants from polymer films. These three parameters were simultaneously estimated. They provide in-depth insight into the physics of a migration process. The first step was used to find the combination of D, Kp,f and h that minimized the sums of squared errors (SSE) between the predicted and actual results. In step 2, an ordinary least square (OLS) estimation was performed by using the proposed analytical solution containing D, Kp,f and h. Three selected migration studies of PLA/antioxidant-based films were used to demonstrate the use of this two-step solution. Additional parameter estimation approaches such as sequential and bootstrap were also performed to acquire a better knowledge about the kinetics of migration. The proposed model successfully provided the initial guesses for D, Kp,f and h. The h value was determined without performing a specific experiment for it. By determining h together with D, under or overestimation issues pertaining to a migration process can be avoided since these two parameters are correlated.

Matched MeSH terms: alpha-Tocopherol/chemistry*
Effect of steam sterilisation on lipophilic nutrient stability in a chloroplast-rich fraction (CRF) recovered from postharvest, pea vine field residue (haulm)

Wattanakul J, Syamila M, Briars R, Ayed C, Price R, Darwish R, et al.

Food Chem, 2021 Jan 01;334:127589.
PMID: 32707366 DOI: 10.1016/j.foodchem.2020.127589

Postharvest, pea vine field residue (haulm) was steam-sterilised and then juiced; a chloroplast-rich fraction (CRF) was recovered from the juice by centrifugation. The stability of selected nutrients (β-carotene, lutein, and α-tocopherol) in the freeze-dried CRF material was measured over 84 days; the impact of temperature (-20 °C, 4 °C, 25 °C and 40 °C), light and air on nutrient stability was established. All three nutrients were stable at -20 °C and 4 °C in the presence or absence of air; this stability was lost at higher temperatures in the presence of air. The extent and rate of nutrient breakdown significantly increased when the CRF samples were exposed to light. β-Carotene appeared to be more susceptible to degradation than lutein and α-tocopherol at 40 °C in the presence of air, but when CRF was exposed to light all three nutrients measured were significantly broken down during storage at 25 °C or 40 °C, whether exposed to air or not.

Matched MeSH terms: alpha-Tocopherol/chemistry
Fulltext The Effect of Pressure and Solvent on the Supercritical Fluid Chromatography Separation of Tocol Analogs in Palm Oil

Ng MH, Kushairi A

Molecules, 2017 Aug 29;22(9).
PMID: 28850073 DOI: 10.3390/molecules22091424

There are six tocol analogs present in palm oil, namely α-tocopherol (α-T), α-tocomonoenol (α-T₁), α-tocotrienol (α-T₃), γ-tocotrienol (γ-T₃), β-tocotrioenol (β-T₃) and δ-tocotrienol (δ-T₃). These analogs were difficult to separate chromatographically due to their similar structures, physical and chemical properties. This paper reports on the effect of pressure and injection solvent on the separation of the tocol analogs in palm oil. Supercritical CO₂ modified with ethanol was used as the mobile phase. Both total elution time and resolution of the tocol analogs decreased with increased pressure. Ethanol as an injection solvent resulted in peak broadening of the analogs within the entire pressure range studied. Solvents with an eluent strength of 3.4 or less were more suitable for use as injecting solvents.

Matched MeSH terms: alpha-Tocopherol/chemistry
Identification of α-tocopherol as a bioactive component of Dicranopteris linearis with disrupting property against preformed biofilm of Staphylococcus aureus

Mawang CI, Lim YY, Ong KS, Muhamad A, Lee SM

J Appl Microbiol, 2017 Nov;123(5):1148-1159.
PMID: 28869803 DOI: 10.1111/jam.13578

AIMS: The potential of Dicranopteris linearis leaves' extract and its bioactive components were investigated for the first time for its disrupting ability against Staphylococcus aureus biofilms.
METHODS AND RESULTS: The leaves of D. linearis were subjected to sonication-assisted extraction using hexane (HEX), dichloromethane, ethyl acetate and methanol (MeOH). It was found that only the MeOH fraction exhibited antimicrobial activity using broth microdilution assay; while all four fractions do not exhibit biofilm inhibition activity against S. aureusATCC 6538P, S. aureusATCC 43300, S. aureusATCC 33591 and S. aureusATCC 29213 using crystal violet assay. Among the four fractions tested, only the HEX fraction showed biofilm disrupting ability, with 60-90% disruption activity at 5 mg ml-1against all four S. aureus strains tested. Bioassay-guided purification of the active fraction has led to the isolation of α-tocopherol. α-Tocopherol does not affect the cells within the biofilms but instead affects the biofilm matrix in order to disrupt S. aureus biofilms.
CONCLUSIONS: α-Tocopherol was identified to be the bioactive component of D. linearis with disruption activity against S. aureus biofilm matrix.
SIGNIFICANCE AND IMPACT OF THE STUDY: The use of α-tocopherol as a biofilm disruptive agent might potentially be useful to treat biofilm-associated infections in the future.

Matched MeSH terms: alpha-Tocopherol/chemistry