Phytochemical and bioactivity studies of the leaves and stem barks of Tibouchina semidecandra L. have been carried out. The ethyl acetate extract of the leaves yielded four flavonoid compounds, identified as quercetin, quercetin 3-O-α-l-(2''-O-acetyl) arabinofuranoside, avicularin, and quercitrin, while the stem barks gave one ellagitannin, identified as 3,3'-O-dimethyl ellagic acid 4-O-α-l-rhamnopyranoside. Evaluation of the antioxidative activity on the crude extracts and pure compounds by electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectrophotometric assays showed that the pure isolated polyphenols and the EtOAc extract possessed strong antioxidative capabilities. Quercetin was found to be the most active radical scavenger in DPPH-UV and ESR methods with SC(50) values of 0.7 μM ± 1.4 and 0.7 μM ± 0.6 μM, respectively, in the antioxidant assay. A combination of quercetin and quercitrin was tested for synergistic antioxidative capacity;, however, there was no significant improvement observed. Quercetin also exhibited strong antityrosinase activity with a percent inhibition of 95.0% equivalent to the positive control, kojic acid, in the tyrosinase inhibition assay.

Objectives Chitosan, the N-deacetylated derivative of chitin, has useful biological properties that promote haemostasis, analgesia, wound healing, and scar reduction; chitosan is bacteriostatic, biocompatible, and biodegradable. This study determined the efficacy of chitosan derivative film as a superficial wound dressing. Methods This multicentre randomised controlled trial included 244 patients, of whom 86 were treated with chitosan derivative film and 84 with hydrocolloid. The percentage of epithelisation, as well as patient comfort, clinical signs, and patient convenience in application and removal of the dressings were assessed. Results The primary outcome of this study was the percentage of epithelisation. Except for race ( p = 0.04), there were no significant differences between groups in sex, age, antibiotic usage, or initial wound size ( p > 0.05). There was no significant difference in the mean epithelisation percentage between groups ( p = 0.29). Patients using chitosan derivative film experienced more pain during removal of dressing than those in the hydrocolloid group ( p = 0.007). The chitosan derivative film group showed less exudate ( p = 0.036) and less odour ( p = 0.024) than the control group. Furthermore, there were no significant differences between groups in terms of adherence, ease of removal, wound drainage, erythema, itchiness, pain, and tenderness. No oedema or localised warmth was observed during the study. Conclusion This study concluded that chitosan derivative film is equivalent to hydrocolloid dressing and can be an option in the management of superficial and abrasion wounds. Clinical trial No. NMRR-11-948-10565.

Several reactor designs have been described in the recent literature for continuous organic-phase enzymatic esterification reactions. While these designs have excellent performance characteristics, there are operational constraints in their use. The present article describes a new reactor design, the gas-phase hollow fiber reactor (GPHFR), which does not suffer from any such limitations. The reactor consists of, commonly available, hollow fiber dialyzer modules with enzyme immobilized on the lumen of the hollow fiber membranes by ultrafiltration. Substrate mixtures are passed through the fiber lumens and subjected to esterification with a constant humidity gas phase recirculated through the shell of the reactor, acting as the medium used to control water activity. The simplicity of the device renders it suitable for use over a wide range of water activities, and its modular nature facilitates easy scale-up. The use of the reactor for the fixed water activity esterification of an equimolar mixture of dodecanol and decanoic acid has been described. Under optimum conditions the reactor was found to give yields of ester as high as 97%. In continuous operation the immobilized enzyme was found to have a half-life of about 70 days.

These results indicate that the membrane film from O-C has potential application as a wound-dressing material.

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Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro.

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