Antibacterial potential of extracts of various parts of Catunaregam tomentosa (Blume ex DC) Tirveng and their effects on bacterial granularity and membrane integrity

Purpose: To investigate the antibacterial activity of extracts from Catunaregam tomentosa on Bacillus subtilis and Staphylococcus aureus, and the bacterial responses to the extracts.Methods: The antibacterial activity of fruit, leaf and stem bark extracts were  evaluated against B.subtilis (ATCC6633) and S. aureus (ATCC25923). Using a disc diffusion method, extracts at concentrations ranging from 50 – 1,000 μg/disc were tested. The minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) of the extracts against the test bacteria were determined. Fluorescent activated cell sorting (FACS) was used to assess the responses of both types of bacteria to the extracts.Results: The fruit and leaf extracts at 1,000 μg/disc showed optimum efficacy against B. subtilis and S. aureus with MIC of 1,000 μg/mL against both B. subtilis and S. aureus, for the fruit and the leaf extracts. With increasing doses of fruit and leaf extracts at 6 h of incubation, FACS profiles revealed that cell death for B. subtilis increased. The fruit and leaf extracts of C. tomentosa also exhibited antibacterial activity against S. aureus in a dose- and time-dependent manner. The bacteria initially lost their granularity, then lost membrane integrity, and consequently died. Conclusion: The fruit and leaf extracts of C. tomentosa exhibit significant antibacterial potential against Gram-positive bacteria by damaging bacterial granularity and membrane integrity. Keywords: Catunaregam tomentosa, Flow cytometry, Programmed cell death, Response pattern, Bacterial granularity, Membrane integrit

Fungal endophytes from arid areas of Andalusia: high potential sources for antifungal and antitumoral agents

Native plant communities from arid areas present distinctive characteristics to survive in extreme conditions. The large number of poorly studied endemic plants represents a unique potential source for the discovery of novel fungal symbionts as well as host-specific endophytes not yet described. The addition of adsorptive polymeric resins in fungal fermentations has been seen to promote the production of new secondary metabolites and is a tool used consistently to generate new compounds with potential biological activities. A total of 349 fungal strains isolated from 63 selected plant species from arid ecosystems located in the southeast of the Iberian Peninsula, were characterized morphologically as well as based on their ITS/28S ribosomal gene sequences. The fungal community isolated was distributed among 19 orders including Basidiomycetes and Ascomycetes, being Pleosporales the most abundant order. In total, 107 different genera were identified being Neocamarosporium the genus most frequently isolated from these plants, followed by Preussia and Alternaria. Strains were grown in four different media in presence and absence of selected resins to promote chemical diversity generation of new secondary metabolites. Fermentation extracts were evaluated, looking for new antifungal activities against plant and human fungal pathogens, as well as, cytotoxic activities against the human liver cancer cell line HepG2. From the 349 isolates tested, 126 (36%) exhibited significant bioactivities including 58 strains with exclusive antifungal properties and 33 strains with exclusive activity against the HepG2 hepatocellular carcinoma cell line. After LCMS analysis, 68 known bioactive secondary metabolites could be identified as produced by 96 strains, and 12 likely unknown compounds were found in a subset of 14 fungal endophytes. The chemical profiles of the differential expression of induced activities were compared. As proof of concept, ten active secondary metabolites only produced in the presence of resins were purified and identified. The structures of three of these compounds were new and herein are elucidated.This work was supported by Fundación MEDINA and the Andalusian Government grant RNM-7987 ‘Sustainable use of plants and their fungal parasites from arid regions of Andalucía for new molecules useful for antifungals and neuroprotectors’

องค์ประกอบทางเคมีจากกิ่งวา (Garcinia hombroniana) ใบจุมพุต (Garcinia prainiana) และรากท้าวยายม่อม (Clerodendrum petasites S. Moore)

Thesis (M.Sc., Organic Chemistry)--Prince of Songkla University, 200

Natural products with protein tyrosine phosphatase inhibitory activity

Protein tyrosine phosphatases (PTPs) play an essential role in maintaining the proper tyrosine phosphorylation state of proteins. Abnormal tyrosine phosphorylation has been implicated in diseases as diverse as type 2 diabetes, cancer, immune disorders and neurological disorders, and thus inhibitors of PTPs have been investigated as potential treatments of these diseases. Natural products are widely regarded to be privileged structures in drug discovery efforts, and are therefore a good starting point for the development of PTP inhibitors. Here we describe reported natural product PTP inhibitors as well as methods to screen for natural product PTP inhibitors using bioassay-guided fractionation. These methods are illustrated using the example of a family of bromotyrosine-derived PTP inhibitors isolated from two marine sponges. We also identify potential pitfalls and false-positives, in particular compounds that are oxidizing agents that react irreversibly with the PTP

γ‑Butyrolactone, Cytochalasin, Cyclic Carbonate, Eutypinic Acid, and Phenalenone Derivatives from the Soil Fungus <i>Aspergillus</i> sp. PSU-RSPG185

Purification of an extract from the broth of the soil fungus <i>Aspergillus</i> sp. PSU-RSPG185 resulted in the isolation of two new cyclic carbonate derivatives, aspergillusols A (<b>1</b>) and B (<b>2</b>), and one new eutypinic acid derivative, aspergillusic acid (<b>3</b>), along with six known secondary metabolites. Compounds <b>1</b> and <b>2</b> contain an unusual cyclic-carbonate functionality. In addition, the mycelial extract afforded two new phenalenones, aspergillussanones A (<b>4</b>) and B (<b>5</b>), one new cytochalasin, aspergilluchalasin (<b>6</b>), and one new γ-butyrolactone, aspergillulactone (<b>7</b>). Their structures were established by interpretation of spectroscopic evidence. Compound <b>4</b> exhibited weak activity toward KB and Vero cells with IC₅₀ values of 48.4 and 34.2 μM, respectively