Isolation and Identification of Taiwanins E and H from Bald Cedar, as well as Their Herbicidal and Cytotoxic Studies
Finding active substances from plants is one of the important ways to create pesticides, such as pyrethroid insecticides, neonicotinoid insecticides, and lead compounds of ketone herbicides, all of which come from plants. Taiwania flousiana Gaussen (also known as Taiwania cryptomerioides Hayata), also known as Taiwan fir, belongs to the family Cupressaceae and the genus Taiwan fir. It is a tall evergreen tree with high timber and ornamental value. It is naturally distributed in western Hubei, western Yunnan, and southeastern Guizhou in China, and has various biological activities. He et al. conducted early research on the biological activity of bald cypress and found that it has insecticidal activity against saltwater shrimp and Aedes aegypti, and has inhibitory effects on tumor cells. Subsequently, the antibacterial, acaricidal, anti termite, anti-inflammatory, and anti-tumor activities of bald cypress essential oil and extract were reported successively. In terms of component research, essential oils from the heartwood, tender branches, leaves, and stem bark of bald cypress have been isolated and identified, and chemical components such as lignans, sesquiterpenes, diterpenes, triterpenes, phenols, and glycosides have been isolated and identified from their extracts. However, there have been no research reports on the herbicidal activity of this plant. In the screening of herbicide active plants, our research group found that bald cypress has a significant inhibitory effect on weed growth, and conducted research on the plant extract, aiming to provide theoretical reference for the development of plant-based herbicides and promote the comprehensive development and utilization of bald cypress.

Bald cypress is a tall tree with good anti-corrosion properties. Studies have found that it has antifungal, antibacterial, termite resistant, mite resistant, and cellular activity, indicating that the plant contains a variety of secondary metabolites. This article found that the plant extract has herbicidal activity, and two active ingredients, Taiwanin E and Taiwanin H, were isolated from it through activity tracking, providing a theoretical basis for the comprehensive development and utilization of the plant.
At present, there is no report on the biological activity of taiwanin H, while taiwanin E has inhibitory activity on lung cancer, breast cancer, colon adenocarcinoma and other tumor cells. The study on weed control activity found that both exhibited certain root length and fresh weight inhibition effects on several tested weeds. Their activity against broad-leaved weeds was higher than that of Poaceae, and the activity of Taiwanin H was generally better than Taiwanin E. Taiwanin E and Taiwanin H are both lignans, and their structures are not significantly different. It is speculated that the reason for the difference in their activities may be related to the higher hydroxyl groups and stronger water solubility of Taiwanin H. In the comparison of the activity of tumor cells, Taiwanin E containing one hydroxyl group has higher cell activity than Taiwanin C without hydroxyl group (no hydroxyl group at position 4, the rest is the same), and shows a similar pattern.
This article is the first study and report on the herbicidal activity of bald cypress and its chemical components Taiwanin E and Taiwanin H. There is relatively little research on Taiwanin H, which has only been isolated from bald cypress (genus Taiwanin) and the Rutaceae plant Haplophyllum buxbaumii distributed in northern Jordan. There have been many studies on Taiwanin E, which have been isolated from plants such as bald cypress, Justicia procumbens, Justicia patentiflora, Chamaecyparis formosensis, and Eleutherococcus trifoliatus branches in the family Araliaceae. The anti-tumor activity of Taiwanin E and other lignans has received much attention. However, currently used herbicide pesticide varieties do not have lignans in their structural categories. This study is expected to provide new structural template references for herbicide development, enrich the research content of plant derived herbicides, and provide theoretical basis for the development and utilization of plant resources containing these two components.
The development and application of Taiwanin E and Taiwanin H as herbicides have obtained patent authorization. Further research is needed to determine whether they also have biological activity against other harmful organisms and whether bald cypress contains other active ingredients.