Silk fibroin (SF) and alginate (AA) have been proved to be invaluable natural materials in the field of biomedical engineering. This study was designed to compare the wound healing effect of SF, AA and SF/AA-blended sponge (SF/AA) with clinically used Nu Gauze(TM) (CONT) in a rat full thickness wound model. Two circular skin wounds on the back of rat were covered with either of CONT, SF, AA or SF/AA. On the postoperative days of 3, 7, 10 and 14, residual wound area was calculated, and skin wound tissues were biopsied to measure the area of regenerated epithelium and collagen deposition as well as the number of proliferating cell nuclear antigen (PCNA)-immunoreactive cells. Half healing time (HT(50)) of SF/AA was dramatically reduced as compared with that of SF, AA or CONT. Furthermore, SF/AA significantly increased the size of re-epithelialization and the number of PCNA positive cells, whereas the effect of SF/AA on collagen deposition was not significantly different as compared with that of SF or AA. These results demonstrate that the wound healing effect of SF/AA is the best among other treatments including SF and AA, and this synergic effect is mediated by re-epithelialization via rapid proliferation of epithelial cell.

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Abstract:The global burden of bacterial infections is very high and has been exacerbated by increasing resistance to multiple antibiotics. Antibiotic resistance leads to failed treatment of infections, which can ultimately lead to death. To overcome antibiotic resistance, it is necessary to identify new antibacterial agents. In this study, a total of 662 plant extracts (diverse parts) from 222 plant species (82 families, 177 genera) were screened for antibacterial activity using the agar cup plate method. The aqueous and methanolic extracts were prepared from diverse plant parts and screened against eight bacterial (two Gram-positive and six Gram-negative) species, most of which are involved in common infections with multiple antibiotic resistance. The methanolic extracts of several plants were shown to have zones of inhibition ě 12 mm against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration was calculated only with methanolic extracts of selected plants, those showed zone of inhibition ě 12 mm against both Gram-positive and Gram-negative bacteria. Several extracts had minimum inhibitory concentration ď 1 mg/mL. Specifically Adhatoda vasica, Ageratum conyzoides, Alangium salvifolium, Alpinia galanga, Andrographis paniculata, Anogeissus latifolia, Annona squamosa, A. reticulate, Azadirachta indica, Buchanania lanzan, Cassia fistula, Celastrus paniculatus, Centella asiatica, Clausena excavate, Cleome viscosa, Cleistanthus collinus, Clerodendrum indicum, Croton roxburghii, Diospyros melanoxylon, Eleutherine bulbosa, Erycibe paniculata, Eryngium foetidum, Garcinia cowa, Helicteres isora, Hemidesmus indicus, Holarrhena antidysenterica, Lannea coromandelica, Millettia extensa, Mimusops elengi, Nyctanthes arbor-tristis, Oroxylum indicum, Paederia foetida, Pterospermum acerifolium, Punica granatum, Semecarpus anacardium, Spondias pinnata, Terminalia alata and Vitex negundo were shown to have significant antimicrobial activity. The species listed here were shown to have anti-infective activity against both Gram-positive and Gram-negative bacteria. These results may serve as a guide for selecting plant species that could yield the highest probability of finding promising compounds responsible for the antibacterial activities against a broad spectrum of bacterial species. Further investigation of the phytochemicals from these plants will help to identify the lead compounds for drug discovery.

Plants harbor diverse communities of bacterial species in their internal compartments. Here we isolated and identified bacterial endophytes from mountain-cultivated ginseng (MCG, Panax ginseng Meyer) to make working collection of endophytes and exploit their potentially beneficial properties toward plants and human being. A total of 1,886 bacteria were isolated from root, stem and leaf of MCGs grown in 24 different sites across the nation, using culture-dependent approach. Sequencing of 16S rDNA allowed us to classify them into 252 distinct groups. Taxonomic binning of them resulted in 117 operational taxonomic units (OTUs). Analysis of diversity indices across sampling sites and tissues suggested that composition of bacterial endophyte community within ginseng could differ substantially from one site to the next as well as from one host compartment to another. Assessment of 252 bacterial isolates for their beneficial traits to host plants showed that some bacteria possesses the ability to promote plant growth and produce ß-glucosidase, indicating their potential roles in plant growth promotion and bio-transformation. Taken together, our work provides not only valuable resources for utilization of bacterial endophytes in ginseng but also insights into bacterial communities inside a plant of medicinal importance.

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