Bioprospecting in the nepeta, salvia, and clinopodium genera under controlled growing environments for application in natural products and cimex lectularius l repellency
Creators: name: Zorde, Martin Daniel
Publisher: name: No Publisher Supplied
Year: 2024

description: The Nepeta genus is a diverse clade within the mint family (Lamiaceae) with a wide geographic distribution and long history of ethnobotanical. Many of the traditional uses and more recent discovered uses of the genus are tied to chemical compounds these plants produce. Nepeta ssp. are probably most well-known for the euphoric effect they can have on cats. This effect and the more recent discoveries of repellency against disease vectoring arthropods like mosquitoes, ticks, and bedbugs has been attributed to Nepeta ssp. containing a class of volatile iridoid monoterpenes known as nepetalactones. There exist 8 possible isomers of nepetalactone with 6 being having been found to be naturally occurring within the genus and are typically extracted via distillation as an essential oil. The different isomers of nepetalactone have been demonstrated to have varying potency, effects, and applications relative to each other. Additionally, the production of nepetalactone isomers is dependent on both the growing condition and genetics of the Nepeta ssp. In addition, many of the Nepeta ssp. that have been studied for their secondary metabolites including nepetalactone content have not been with plants grown under the same environmental conditions. Given the lack of available literature on germplasm grown under the same conditions and need for arthropod control this dissertation was undertaken. The goal of this dissertation was to identify and improve Nepeta germplasm, as well as identify new sources, methods of extraction, and natural product for the repellency and control of bed bugs Cimex lectularius L. This lead to the largest known study of Nepeta by number of accessions grown under a controlled environment in history. A total of 85 Nepeta accession including multiple accessions across 11 species (N. cataria, N. clarkei, N. × faassenii, N. grandiflora, N. govaniana, N. nervosa, N. nuda, N. parnassica, N. racemosa, N. subsessilis, and N. stewartiana) grown under a controlled environment. Chemical and statistical analysis of extracts made from these identified 9 distinct chemotypes across the study population relative to nepetalactoid and other bioactive compound content. A subset of this population including at least one accession from each of the above species in addition to an accession of N. nepetella and 5 previously untested Salvia species (S. apiana, S. azurea, S. dorrii, S. mellifera, and S. verbenaca) were grown out and extracted with several methods including soxhlet with differing extract solvents and hydrodistillation. None of these species with the exception of N cataria had previously been tested for bed bug repellency. These extracts were then chemically analyzed via GCMS and tested for potential repellency C. lectularius. This identified ethanol as a more effective extract of the bioactive responsible for repellency in N cataria with the likely compound responsible for the observed repellency being dihydronepetalactone. Additionally, the N. clarkei accession was identified as having some repent effect and was unique for being high in dehydronepetalactone compared to all other accessions in this dissertation. The essential oil of S apiana was found to have strong repellent effect against bed bugs with the main compound responsible being camphor in the oil. Notably the S. apiana was able to produce 622% more oil per dry weight when compared to N. cataria making it a perfect candidate for future development as a natural product for bed bug control. The improvement of N. cataria germplasm was also explored on the nepetalactone-rich catnip cultivars CR3 and lead the development and first successful polyploidy induction using colchicine in N. cataria L. Lastly, this dissertation also reports the first discovery of nepetalactones in three accessions of Clinopodium nepeta. The significance of the discoveries in this dissertation are discussed in the context of identifying and or improving germplasm for natural product development.