Thick-film is a unique and valuable traditional Chinese medicinal material and rare protected plant in China. For a long time, the medicinal use of thick-film mainly relied on wild resources. However, due to the increasing demand and decreasing resources, it has been listed as a second-class protected Chinese medicinal material. At the same time, thick-film is a more primitive species in the Magnoliaceae family, and it also has a special status in taxonomy, which is of scientific significance for the study of plant distribution and Magnoliaceae classification. Therefore, it has been listed as a second-class protected plant.
1. Historical records in traditional Chinese medicine
Thick-film is a unique traditional Chinese medicine in China, first recorded in the "Shennong's Herbal Classic", listed as a middle-grade medicine. It has been included in various herbal books throughout history. It has a bitter and pungent taste, warm in nature, and functions in warming the middle and regulating qi, dispersing fullness and reducing swelling, and drying dampness and resolving accumulation. It has been used for the treatment of digestive tract diseases since ancient times, as well as for sedation and relief of skeletal tension. Many traditional Chinese medicine prescriptions and patent medicines contain thick-film. Among Zhang Zhongjing's 210 ancient prescriptions, 25 prescriptions contain thick-film, accounting for 11.9%, indicating the important position of thick-film in clinical applications.
2. Taxonomic research
In terms of taxonomy, thick-film has been the focus of taxonomists and pharmacists since its formal naming in 1913. Taxonomists have been continuously conducting taxonomic research on thick-film. For example, concave leaf thick-film was separated from thick-film in terms of taxonomy in 1913, and it was later upgraded to a species in 1957. In recent years, it has been reclassified as a subspecies in 1996.
3. Phytochemical research
In terms of phytochemical research, since the isolation of magnolol from the bark of thick-film by Sakai (Japan) in 1930, more than 70 years have passed. Pharmacists and chemists have conducted extensive research on the chemical components and pharmacological effects of the bark and leaves of thick-film, achieving significant progress and guiding clinical applications. This has brought broad prospects for the better development of thick-film resources and has also raised higher requirements for the quantity and quality of thick-film medicinal materials.
4. Modern medical research
With the expansion of clinical applications, population growth, and the development of foreign trade, the demand for thick-film has been increasing. In particular, the medicinal use of thick-film has long relied on wild resources, leading to a sharp decrease in the resources of this tree species, and the distribution area has become smaller and smaller. Wild resources are on the verge of depletion.
In order to protect, develop, and utilize thick-film resources and improve their quality, relevant departments of the country have established thick-film bases in some provinces since 1970. However, due to backward technology and extensive management, there are common problems such as inappropriate site selection, excessive density, mixed varieties, and low efficiency. Therefore, many forestry and medical technology workers have conducted extensive research on high-yield cultivation techniques for thick-film.
