An endophyte is a fungus or bacterium that lives within a plant in a symbiotic relationship. Extensive colonization of the plant tissue by endophytes creates a barrier effect, where they outcompete and prevent pathogenic organisms from taking hold. This happens by producing secondary metabolites that inhibit the growth of the competitors or pathogens. In this way they play a very important role in the plant defence mechanisms. The metabolites produced by these endophytes fall within a wide range of classes of compounds that include peptides which are the focus of this review. Peptides are increasingly being selected for drug development because they are specific for their targets and have a higher degree of interactions. There have been quite a number of endophytic peptides reported in the recent past indicating that endophytes can be used for the production of peptide based drugs. Molecular screening for NRPS, which shows peptide producing capability, has also shown that endophytes are potential producers of peptides. The presence of NRPS also offers the possibility of genetic modifications which may generate peptides with high pharmacological activities. This review, therefore, aims to show the current status of peptides isolated from endophytic bacteria and fungi in the recent decade. Endophytes as potential sources of peptides according to NRPS studies will also be discussed.

Phytochemical reinvestigation on the cultural broth of Boreostereum vibrans led to the isolation of six new vibralactone derivatives, vibralactone N(1), vibralactone O(2), vibralactone P(3), 10-lactyl vibralactone G(4),(3S^*, 4R^*)-6-acetoxymethyl-2, 2-dimethyl-3, 4-dihydro-2H-chromene-3, 4-diol(5), vibralactone Q(6). Their structures were elucidated by extensive spectroscopic methods.

Gastric ulcer is a very common gastrointestinal disorder affecting a large number of people worldwide. It arises due to an imbalance between aggressive(acid, pepsin and Helicobacter pylori infection) and protective(mucin secretion, prostaglandin, epidermal growth factors and bicarbonate) factors in the stomach. In this study, the gastroprotective activity has been investigated of the active constituents from Xylocarpus molluccensis. Antiulcer activity of xyloccensins X+Y was investigated and found to be active in various ulcer models in Sprague-Dawley(SD) rats. To understand the mechanism of action of active constituent of natural products, the effects of the compounds on antisecretory and cytoprotective activities were studied. Air dried fruits were extracted with ethanol and fractionated into four fractions. Xyloccensins X+Y were isolated from the active fraction and was tested against different ulcer models. Xyloccensins X+Y were found to possess anti-ulcerogenic activity. The antiulcer activity might be due to its anti-secretory activity and subsequent strengthening of the defensive mechanism. The present study has helped us in identifying a new lead in the form of xyloccensins that could be exploited in the treatment of gastric ulcer disease.

Coiled-coils are well known protein-protein interaction motifs, with the leucine zipper region of activator protein-1(AP-1) consisting of the c-Jun and c-Fos proteins being a typical example. Molecular dynamics(MD) simulations using the MM/GBSA method have been used to predict the free energy of interaction of these proteins. The influence of force field polarisation and capping on the predicted free energy of binding of complexes with different electrostatic environments(net charge) were investigated. Although both force field polarisation and peptide capping are important for the prediction of the absolute free energy of binding, peptide capping has the largest influence on the predicted free energy of binding. Polarisable simulations appear better suited to determine structural properties of the complexes of these proteins while non-polarisable simulations seem to give better predictions of the associated free energies of binding.

"Long-Dan" and "Qin-Jiao" are two important TCM herbs since ancient times in China. In the Chinese Pharmacopoeia, the dried roots and rhizomes of four species from the genus Gentiana, e.g. Gentiana manshurica, G. scabra, G. triflora and G. rigescens, are recorded under the name of Gentianae Radix et Rhizoma("Long-Dan" in Chinese), while the other four species from the same genus including G. macrophylla, G. crassicaulis, G. straminea and G. duhurica are recorded and used as the raw materials of Gentianae Macrophyllae Radix("Qin-Jiao" in Chinese). On the basis of the establishment of a validated HPLC-UV method for quantifying simultaneously, five iridoid glycosides, e.g. loganic acid(1), swertiamarinin(2), gentiopicroside(3), sweroside(4) and 2'-(o, m-dihydroxybenzyl) sweroside(5) have been used successfully as chemical markers for the comparison of the species used as "Long-Dan", "Qin-Jiao" and their adulterants in the present study. The results suggested that four iridoid glycosides 1-4 commonly existed in both "Long-Dan" and "Qin-Jiao", while 2'-(o, m-dihydroxybenzyl) sweroside(5) also existed as one of the major components in "Dian-Long-Dan" species. Moreover, the contents of compounds 1-5 were various in different "LongDan" and "Qin-Jiao" species. Herein, we profiled and compared three "Long-Dan" species, four "Qin-Jiao" species and five adulterants by applying multivariate statistical techniques to their HPLC data sets to establish the differences and/or similarities.

Various kinds of biologically active peptides have previously been isolated from the skin secretions of Amolops loloensis frog, such as antimicrobial peptides, bradykinin-like peptides and algesic peptides. A novel insulinotropic peptide named amolopin was identified in A. loloensis frog's skin secretion. Its primary structure sequence was determined by Edman degradation as: FLPIVGKSLSGLSGKL-NH2. BLAST search indicates that the amino acid sequence of amolopin is quite different from other known insulin secretagogues, including mastoparan, exendins and a-latrotoxin, nor does it like incretins(e.g. glucagons like peptide-1 and glucose-dependent insulinotropic ploypeptide) either. However, amolopin shows certain structural similarity with amphibian antimicrobial temporins and vespid chemotactic peptides isolated from Vespa magnifica. Amolopin can stimulate insulin release in INS-1 cells in a dose-dependent manner. Primary investigation on its action mechanisms reveals that amolopin does not increase the influx of Ca²⁺. In conclusion, a novel 16-amino acid peptide with insulin-releasing activity is initially discovered from the skin secretion of A. loloensis frog. Further work is necessary to evaluate its potential as novel anti-diabetic candidate.