Bio-prospecting of natural products allows for the discovery of new agrochemicals for pest management and chemistry found from plants used in traditional medicines have often not been evaluated as bio-pesticides. TCM Bai Zhi is the root of Angelica dahurica which has been used as early as 400 BC in Ancient China for the treatment of illnesses such as headaches, nasal obstruction, detoxification of the blood, swollen gums, toothaches, anti-inflammatory, a laxative, sedative, and an anti-fungal cream for skin. The root of A. dahurica is also widely known to contain furanocoumarins. Our preliminary evaluations of several Angelica species were completed in 2012 for antifungal and mosquito deterrent activity. Several species of Angelica were shown to be active. TLC-bioautography with Colletotrichum species as the antifungal detection agents demonstrated that the ethyl acetate extract of A. dahurica showed strong antifungal activity. Current mosquito testing with new plant material failed to show significant biting deterence, or toxicant activity. In order to isolate and identify the antifungal constituents in the root of A. dahurica, a systematic bioassay-guided fractionation of the ethyl acetate extract was performed. Several active fractions were obtained by combining biotage with direct-bioautography. Two coumarins “bergapten (1)” and “suberosin (2)” were isolated from active fractions using biotage and HPLC and the structures were confirmed by 1H and 13C NMR spectroscopic analyses. Other active antifungal fractions are being purified. Our current goal is to test all pure compounds in a micro-dilution broth assay in comparison to bergapten, suberosin and commercial fungicide standards. Development of natural fungicides with low mammalian and environmental toxicity will help guarantee food safety and sustainability of the U.S. and Chinese agricultures.

Increasing resistance to agrochemicals by insects and plant pathogens and the loss of weed and disease control agents are factors that drive the need to search for new natural product derived plant protestants and agrochemicals. Bio-prospecting natural products allows discovery of new agrochemicals for pest management and chemistry found from plants used worldwide in traditional medicines have not been evaluated as potential bio-pesticides or new plant growth regulators. Pileostegia viburnoides var. glabrescens is a traditional Chinese medicine plant used for treating traumatic injury and fractures. Preliminary evaluations of P. viburnoides var. glabrescens was completed in 2012 for antifungal and herbicidal activity. N-Butanol extract from P. viburnoides var. glabrescens was shown to be active at higher concentrations to Agrostis (monocot) and less active against lettuce (dicots). Several pure compounds were separated by chromatography from n-butanol extract of P. viburnoides var. glabrescens. The pure compound skimmin in the active fractions obtained from n-butanol extract was identified. These fractions and skimmin showed phytotoxic activity against Iceberg lettuce and Agrostis seeds in primary research. Skimmin possessed high seed germination inhibition of monocot species and moderate seed germination inhibition against the dicot species. Therefore, we began a more in-depth evaluation of 8 pure compounds obtained from the active n-butanol extract of P. viburnoides and skimmin. Following natural product leads offers an efficient approach to discovering and optimizing new herbicides for weed management. Due to the continuing development of chemical resistance in agriculture, discovery of new herbicides is an important research objective. Natural product based herbicides with low mammalian and environmental toxicity will help guarantee food safety and sustainability of U.S. and Chinese agriculture.