Screening of antibacterial activity of Goniothalamus calvicarpa extracts against Xanthomonas axonopodis pv. citri in vitro

Citrus canker caused by Xanthomonas axonopodis pv. citri (Xac) is a serious disease in many parts of the world and is difficult to control. The use of copper-based pesticides is becoming a concern due to the accumulation of heavy metals in orchard soils and more benign treatment methods are needed. Eighteen Thai native plant extracts were screened for antibacterial activity against a Thai isolate of Xac and it was found that ethanolic extracts of Goniothalamus calvicarpa leaves showed the strongest antibacterial activity against Xac in vitro. The G. calvicarpa extracts were then sequentially dissolved with hexane, ethyl acetate and methanol and retested. A 70% aqueous ethanol extract and a methanol soluble extract produced strong inhibition zones against Xac. Although thin layer chromatographic profiles revealed the likely presence of flavonoids in the biologically active extracts of G. calvicarpa, the active compounds have yet to be identified. Work is proceeding to determine whether specific extracts of G. calvicarpa have biological activity against citrus canker in the field

Novel 3D porous semi-IPN hydrogel scaffolds of silk sericin and poly(N-hydroxyethyl acrylamide) for dermal reconstruction

In this work, a novel semi-interpenetrating polymer network (semi-IPN) hydrogel scaffold based on silk sericin (SS) and poly(N-hydroxyethyl acrylamide) (PHEA) was successfully fabricated via conventional free-radical polymerization. The porous structure of the scaffolds was introduced using a lyophilization technique and the effect of cross-linker (XL) on morphology, gelation time and physical properties of hydrogel scaffold was first studied. The results show that using low cross-linker content (0.125, 0.25 and 0.5 wt% XL) produced flexible scaffolds and appropriate gelation times for fabricating the scaffold. Therefore, the polymerization system with a constant percentage of XL at 0.5 wt% was chosen to study further the effect of SS on the physical properties and cell culture of the scaffolds. It was observed that the hydrogel scaffold of PHEA without SS (PHEA/SS-0) had no cell proliferation, whereas hydrogel scaffolds with SS enhanced cell viability when compared to the positive control. The sample of PHEA/SS at 1.25 wt% of SS and 0.5 wt% of cross-linker was the most suitable for HFF-1 cells to migrate and cell proliferation due to possessing a connective porous structure, along with silk sericin. The results proved that this novel porous semi-IPN hydrogel has the potential to be used as dermal reconstruction scaffold

Chemistry and biochemistry of Terpenoids from Curcumaand related species

Several curcuminoids have been identified from rhizome of the common spice Curcuma longa (Zingaberaceae) and related plant species. Curcuminoids are known to display several pharmacological properties summed up in numerous papers and reviews. In addition to curcuminoids, more than 250 mono-, sesqui- di-, and triterpenoids have been identified from curcuma species. These lipophilic compounds have better absorption than curcuminoids and also exhibit a wide spectrum of pharmacological properties. Little attention has been paid to these lipophilic compounds, which may be as physiologically active, if not more, as curcuminoids. This review focuses on Curcuma terpenoids and their physiological properties