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「Dr. Da Zhen Talks About Chinese Medicine」Of the film, an introduction:
「With leaves as large as ears, the branches bear fruit so sweet. A single branch could fill a plate, its bounty complete. Like lychee, it yields a single seed, A golden orange, but without the sour need. Rain weighs down the branches, heavy with juice, Each sip chills the taste buds, what a delicious ruse! Changqing still lives, so let him be, No need to make him a gardener, you see.」
—-宋 楊萬里《枇杷》
According to the fourth edition of the Taiwan Chinese Pharmacopoeia (https://reurl.cc/9p5R5V), loquat leaf is the dried leaf of the plant Eriobotrya japonica (Thunb.) Lindl., which belongs to the Rosaceae family. The use of loquat leaf as a medicine can be traced back to the Classic of Famous Physicians during the Wei, Jin, Southern, and Northern Dynasties. According to Illustrations and Descriptions of Plants, a book by the Qing Dynasty botanist Wu Qi-jun, loquat leaves produced in Zhejiang province have large fruits and few seeds. Based on the above records and the accompanying illustration of loquat, the plant is named loquat due to its leaf shape resembling a Chinese lute. In traditional Chinese medicine, loquat leaf is commonly used in formulas such as Ganlu Yin, Chuanbei Pipa Gao, and Qingzao Jiufei Tang. Originally from China, loquat has a long cultivation history. In Compendium of Materia Medica by Li Shizhen of the Ming Dynasty, it is recorded that “seedless loquat, known as Jiaozi, comes from Guangzhou. Loquats produced in Zhejiang have large fruits and few seeds.” Currently, loquat is cultivated in provinces such as Gansu, Shaanxi, Jiangsu, Anhui, Zhejiang, Jiangxi, Hubei, Sichuan, Yunnan, and Fujian. Loquat leaves produced in Guangdong and Fujian are specifically called “Guangpa leaves,” characterized by large, thick leaves with fewer hairs and higher quality. Large-scale cultivation also occurs in central Taiwan, and loquat is grown in countries such as Japan, India, Myanmar, Thailand, and Indonesia. Loquat leaves can be harvested throughout the year. After harvesting, they are dried to about 80% of their original weight, bundled into small bundles, and then completely dried for storage. The quality of loquat leaves is considered superior when they are dry, have large leaves, are green or reddish-brown in color, are free of breakage and yellowing, have a slight odor, and a slightly bitter taste. Other names for loquat leaf include “paye,” “lujuye,” “luju,” and “wuyoushan.” This medicinal material has the functions of clearing the lungs and stopping coughs, descending qi and stopping vomiting. It is primarily used for symptoms such as lung heat cough, qi逆喘急 (qi ni chuan ji, a type of shortness of breath), stomach heat vomiting, and fever with thirst.
Commonly seen loquat leaf slices in the market are usually cut into strip-like shapes, about 1 cm wide. The cross-section of the main leaf vein reveals a ring-shaped vascular bundle. The upper surface of the leaf is smooth and glossy, while the lower surface typically has the绒毛 (绒毛, róng máo, fine hair or fuzz) removed. The main leaf vein is prominent on the back of the leaf, and the lateral veins extend diagonally. The leaf margin has sparse serrations and is entire near the leaf base. The leaf is leathery and brittle, making it easy to break. When smelled, the aroma is faint, and the taste is slightly bitter.
Depending on clinical applications, there are different processing methods for loquat leaves. In classic formulas, there are often footnotes indicating that the hair should be brushed off, or that the leaf should be honey-coated after brushing off the hair, or that the hair should be brushed off and honey-coated until yellow. However, loquat leaf must have its hair removed; if the hair is not completely removed, it can cause coughing. Modern research has compared the chemical composition of loquat leaf with and without the绒毛. The results show that the chemical composition of the two is basically the same.
，The fine hairs (绒毛) do not contain any components that can induce coughing or produce other side effects. Therefore, the ancient herbal books’ statement that “if the hair is not removed cleanly, it will enter the lungs and cause persistent coughing” is mainly because the hairs, when inhaled directly, can irritate the pharyngeal mucosa and cause coughing. During the decoction process of loquat leaves, some hairs may not easily fall off, so it is necessary to strengthen the filtration process to avoid irritation from the hairs. Therefore, some scholars believe that for loquat leaves used in decoctions, strengthening filtration is sufficient and brushing off the hair is unnecessary. However, when used as raw medicinal materials or in pills and powders, the hair should be brushed clean to avoid direct irritation of the throat and causing coughing.
The process of making honey-coated loquat leaves involves first diluting a suitable amount of refined honey with hot water, then mixing it with the loquat leaf strips, allowing them to absorb the moisture, and then placing them in a hot pan and stir-frying over low heat until they turn a deep yellow color and are no longer sticky.
After being sliced, the leaves should be spread out to air dry until completely cool, and then stored promptly. The dried herb should resemble loquat leaf strips and have a dark brownish-yellow color.
A common adulterant is the dried leaf of Michelia champaca. Its leaves are obovate, rounded at the apex, with sparsely spaced small teeth along the margin. The upper surface is dark brownish-gray, and the lower surface is brown, covered with short, rusty hairs. The odor is faint, and the taste is slightly astringent.
Another adulterant is the leaf of Magnolia grandiflora. It is characterized by thick, leathery, elliptical leaves with a broadly wedge-shaped base. The entire leaf is deep green, glossy on the upper surface, and covered with rusty short hairs on the lower surface.
Loquat leaf is a commonly used ingredient in traditional Chinese medicine. The famous Qing Dynasty physician Ye Tianshi invented Chuanbei Pipa Gao (a loquat syrup), which is a household remedy. Therefore, the Department of Chinese Medicine and Pharmacy of the Ministry of Health and Welfare has set standards for the amount of sulfur dioxide and the limit of heavy metals such as arsenic, cadmium, mercury, and lead contained in this medicinal material. Additionally, since it is a leaf-based medicinal material, specific standards for pesticide residues have also been established. Therefore, the public can use it with peace of mind. It can provide a good improvement effect for symptoms related to Long COVID.
Image provided by Professor Zhang Xian-zhe, Authentic Medicinal Materials Illustrated http://en.whatsintcm.com