Investigating the Commercial Microwave Vacuum Drying Conditions on Physicochemical Properties and Radical Scavenging Ability of Thai Green Tea

The effects of drying conditions using a commercial microwave vacuum dryer on the physicochemical properties and antioxidant activity of Thai green tea were investigated. Nine different drying conditions (power 3200, 3600, and 4000 Watts vs. radiation time 20, 25, and 30 min) were applied in this study. The results showed that individual catechins, their total quantities, radical scavenging ability, and moisture content were significantly affected; however, total polyphenol content and color parameters were not significantly affected by these drying conditions. Based on this data, to obtain optimal physicochemical properties of green tea, drying conditions at 3600 Watts for 30 min were recommended.     

Novel in situ mucoadhesive gels based on Pluronic F127 and xyloglucan containing metronidazole for treatment of periodontal disease

Novel thermoresponsive in situ-forming hydrogels were prepared from co-solutions of Pluronic F127 (PF; triblock-copolymer of polyethylene oxide, polypropylene oxide and polyethylene oxide) and 0.1 wt% tamarind seed xyloglucan (0.1TSX). Based on test tube inversion method, co-solutions comprising 18 or 20 wt% PF and 0.1TSX (18PF/0.1TSX or 20PF/0.1TSX) gelled at 29 and 26 °C compared with 28 and 25 °C for equivalent concentration of PF solutions. DSC analyses indicated that 18PF/0.1TSX and 20PF/0.1TSX exhibited micellization temperatures of 15.5 and 14.9 °C, respectively, compared with 16.2 and 15.7 °C, respectively, for 18PF and 20PF. The lower micellization temperature but higher gel formation temperature suggests that 0.1TSX assists micelle formation but may interrupt order pack structure of micelle that is necessary for gelling. SEM revealed the cylindrical pore structure of lyophilized gels with diameters around 35 μm for 18PF, 20PF and 42 μm for 18PF/0.1TSX and approximately 78 μm for 20PF/0.1TSX. Extractables, released from PF/0.1TSX gels in phosphate buffered saline, did not reduce the viability of mouse osteoblast-like (MC3T3-E1) cells compared with the control, whereas those from PF gels were very cytotoxic with cell viability of 54–60% compared with the control. Therefore, the addition of 0.1TSX resulted in a significant decrease in cytotoxicity of PF. PF/0.1TSX gels exhibited improved mucoadhesive strength compared with PF gels and sustained the release of incorporated metronidazole antibacterial. These biocompatible systems which are in the liquid state before administration and undergo gelation in situ to form a gel at body temperature may, therefore, be injected into periodontal pockets to achieve sustained local delivery of antibacterials for the treatment of periodontitis.     

Antioxidant and anticancer capacity of saponin‐enriched Carica papaya leaf extracts

The papaya (Carica papaya) leaf (PL) contains high levels of saponins and polyphenolic compounds, and historically, it has been used as a folk medicine for numerous ailments, including cancer. PL is traditionally prepared by hot water extraction; however, optimised extraction conditions have not been assessed. This study optimised conditions for the extraction of saponins from PL and assessed their antioxidant capacity and antipancreatic cancer activity. Optimisation was achieved using response surface methodology. Saponins and total phenolic compounds were assessed for their antioxidant, free radical scavenging, ion‐reducing capacity, and antipancreatic cancer activity. Optimal aqueous extraction conditions were 85 °C, 25 min. and a water‐to‐leaf ratio of 20:1 mL g^?1. Ethanol extracts demonstrated higher antioxidant, free radical scavenging and ion‐reducing capacity, as well as antipancreatic cancer activity. This study revealed that the PL contains numerous bioactive compounds, with significant anticancer activity warranting further studies on the isolation and characterisation of individual bioactive compounds from the PL.     

Characterization of freeze-dried gallic acid/xyloglucan

Background: Tamarind seed xyloglucan (TSX) is generally used for drug delivery systems. Gallic acid (GA) possesses various pharmacological activities. It has a good solubility and bioavailability but short half-life.

Purpose: To prepare a sustained-release of GA to overcome its relatively short half-life. GA was blended with TSX and freeze-dried. The physicochemical properties of freeze-dried GA and freeze-dried GA/TSX were characterized, and the release profiles of GA from these freeze-dried samples were investigated.

Method: All freeze-dried samples were characterized by PXRD, spectroscopic and thermal analyses. The dissolution studies were performed according to the United States Pharmacopeia (USP) XXX.

Results: According to FTIR, FT-Raman and ¹³C CP/MAS NMR, the spectra of freeze-dried GA were similar to that of the anhydrous form. Nevertheless, DRIFTS and DSC were able to differentiate these two forms. The crystallinity of GA in the freeze-dried GA/TSX was the same as that of the freeze-dried GA. DSC indicates that there were interactions between GA and TSX. It was of interest that a freeze-dried sample with low amount of GA, 0.2% GA/1% TSX was mostly in an amorphous form. Moreover, all freeze-dried GA/TSX preparations demonstrated a sustained-release of GA compared to GA alone. The freeze-dried 1% GA/1% TSX provided the best sustained-release of GA of up to 240?min.

Conclusions: TSX could change a crystal form of a small molecule to a mostly amorphous form. It was of importance that the freeze-dried GA/TSX could effectively retard the release of GA. These samples may be able to overcome the limitation for the therapeutic use of GA due to its short biological half-life.     

Optimum aqueous extraction conditions for preparation of a phenolic‐enriched Davidson's plum (Davidsonia pruriens F. Muell) extract

This study aimed to optimise aqueous extraction conditions for total phenolic compounds (TPC) from Davidson's plum (Davidsonia pruriens F. Muell) and to assess the physicochemical and antioxidant properties of the phenolic‐enriched extract. The results showed that temperature, time and ratio significantly affected the extraction of TPC. Optimization of extraction conditions was performed using response surface methodology (RSM) utilising a Box–Behnken design. Optimal extraction conditions were determined to be temperature: 90 °C, extraction time: 30 min and solvent to mass ratio: 20:1 mL g^?1. The extracted solid obtained under these conditions had low‐moisture content, high water solubility and contained 45 mg GAE g^?1 of TPC, 22 mg RUE g^?1 of flavonoids, 3.2 mg CAE g^?1 of proanthocyanidins, 2 mg CGE g^?1 of anthocyanidins and 56 mg ACE g^?1 vitamin C. The extract possessed potent antioxidant capacity, but was comparatively lower than those of vitamin E and BHT. Thus, Davidson's plum should be further investigated for its potential health promoting benefits and utilisation in the nutraceutical and food industries.