Location: Natural Products Utilization Research2012 Annual Report
1a. Objectives (from AD-416):
The long-term objective of this project is to identify and chemically characterize secondary metabolites from natural sources with nutraceutical and/or pesticidal properties as chemical markers for selection of high value crops and/or lead compounds for structure-activity optimization. Over the next 5 years, we will focus on the following objectives: Objective 1. Profile phytochemicals of selected crops (blueberry and rice) to identify species or cultivars with high contents of compounds with beneficial health and/or fungicidal properties to promote development as high value crops. Objective 2. Discover and identify technologies based on secondary metabolites that facilitate the development of commercially viable herbicides, fungicides, insecticides, insect repellants, fish bacterides, and health promoters.
1b. Approach (from AD-416):
Blueberry and rice samples will be extracted with appropriate solvents and the extracts will be analyzed by liquid chromatography-mass spectrometry, as well as by gas chromatography-mass spectrometry. The extracts will also be tested for antioxidant activity using a cell-based antioxidant assay. The chemical profiles of the extracts will be correlated with disease resistance of the samples, as well as antioxidant activity. A bioassay-guided investigative approach will be performed on bioactive extracts in efforts to discover herbicides, fungicides, insecticides, insect repellents, fish bactericides and health promoters. General procedures for isolation of active compounds such as solvent extractions, distillations, column chromatography and thin layer chromatography will be employed. Extracts, fractions and pure compounds will be tested for phytotoxicity, antifungal and insecticidal activity in assays being carried out routinely at NPURU and at collaborator's laboratories. Identification of active compounds will be done using spectroscopic methods (Ultraviolet (UV), Infrared (IR), Mass Spectroscopy (MS), Nuclear Magnetic Resonance (NMR)). Chemical studies modification will be performed on compound(s) that will be identified as "highly active" to improve activity or bioavailability.
3. Progress Report:
Objective 1 of the project (Profile phytochemicals of selected crops to identify species or cultivars with high contents of compounds with beneficial health and/or fungicidal properties to promote development as high value crops) was met. Field-grown blueberry cultivars Duke, Spartan, Berkeley and Brigitta Blue were received from collaborator. Chemical profiling has been completed and data analysis is currently being undertaken. The antioxidant activity of the extracts is also currently being performed by a collaborator. Objective 2 of the research project (Discover and identify technologies based on secondary metabolites that facilitate the development of commercially viable herbicides, fungicides, insecticides, insect repellants, fish bacterides, and health promoters) was met. In continuing studies to discover health promoting properties of pterostilbene, it was shown to have anti-obesity effect in animals fed high-fat diet. Two doses of pterostilbene were used in the study: 15 and 30 mg/kg body weight; PT15 and PT30 group, respectively. Pterostilbene significantly reduced total adipose tissue mass (15.1% in PT15 group and 22.9% in PT30 group) without changes in food intake. Biochemical analyses showed pterostilbene inhibited the activities of key enzymes involved in lipid synthesis, in the live and adipose tissue. Additionally, the PT30 dose also increased fatty acid oxidation in the liver. Serum levels of pterostilbene were also determined, and correlated with results obtained from biochemical analyses. These new findings led to a patent application on the use of pterostilbene as anti-obesity agent. In a continuing study on breadfruit, Artocarpus altilis, to identify chemicals responsible for mosquito deterrence, capric, undecanoic, and lauric acid were identified as the primary components responsible for the activity. All three of these compounds were significantly more effective than DEET at repelling mosquitoes. During the past year scientists with the Natural Products Utilization Research Unit (NPURU) at Oxford, Mississippi, have extensively expanded international collaborations in China and Brazil to discover and evaluate natural products that would not normally be accessible to NPURU scientists. Research involvement in the Deployed War-Fighter Protection Program that began in 2007 continued to expand in 2012 as NPURU increased its output of extracts and pure compounds for evaluations for insecticidal and mosquito deterrent activity through collaborations with the Center for Medical, Agricultural, and Veterinary Entomology and an entomologist at the National Center for Natural Products Research. Phytochemical investigation was performed on the following plants: Angelica sinensis, Evodia rutaecarpa, and Pileostegia viburnoides to isolate and identify insecticidal and fungicidal compounds. In yet another study relevant to Objective 2, compounds were prepared by synthetic modification of the structure of the natural compound wogonin and were tested for inhibition of the fish bacteria Flavobacterium columnare. Some analogs showed good activity.