Japanese Folk Medicine
-Vol. 3 - Swertiae Herba (Swertia Herb)- センブリ（当薬）-
Swertiae Herba (senburi in Japanese) is derived from the entire plant (in the flowering season) of Swertia japonica Makino, which belongs to the Gentianaceae family.
S. japonica is a biennial plant that grows on sunny hills and low grass-covered mountain slopes and is native to Japan (from Hokkaido to Kyushu), the Korean Peninsula, and China. It has straight dark violet-tinged cuboidal stems, which diverge from the base or not, and yellow roots and reaches 20 to 25 centimeters in height. Its leaves are arranged in an opposite pattern and are often tinged with violet. They take a linear or oblanceolate shape and have acute tips and entire margins. In addition, they measure 1.5 to 3.5 centimeters in length and 1 to 3 millimeters in width. From August to October, S. japonica produces panicles from its terminal branches, which are composed of white flowers with violet lines on their petals. Each flower possesses five linear shaped sepals, and the corolla is divided into 5 parts. A dehiscent fruit forms after the flowering season, and it splits in two after maturing. In the past, demand for S. japonica was met by collecting wild plants; however, recently it has not been possible to meet demand because of habitat loss and a decrease in the number of people who collect the plant, so it has been cultivated in Nagano and Kochi prefectures.
Some other Swertia species also grow in Japan; i.e., S. tosaensis Makino (inusenburi), which grows in marshes, and S. pseudochinensis Hara (murasakisenburi), whose petals are slightly purple; however, these plants are not suitable for medicinal use because they only contain small amounts of bitter compounds.
S. diluta Benth. et Hook. is described in the 'Zhongyao-dacidian (中薬大辞典)' under the name 淡味当薬; however, in China it is not used as a stomachic (as it is in Japan), but rather is used as a treatment for osteomyelitis, adenoiditis, and conjunctivitis. In addition, S. chirata Buch. (chiretta) has been used as a stomachic and antipyretic in India and Tibet since ancient times.
The Swertia genus is named in honor of the Dutch botanist Emanuel Sweert, and japonica means Japanese. The Japanese Pharmacopoeia describes Swertiae Herba as senburi (当薬); however, senburi is not a Kampo medicine, but rather is a typical Japanese folk medicine that stands with dokudami and gennoshoko as one of the three major folk medicines. The Japanese name senburi is derived from the fact that it is said to remain bitter even after being soaked in hot water and shaken out a thousand times. It is also called toyaku (当薬), which means 'It is truly (当に) medicine (薬)'. Its other names include isyadaoshi, kusurikusa, hinfuri, senfuri, and 苦草, etc.
Senburi has been used as a medicine in Japan since the end of the Muromachi era; however, it was initially used as an insecticide to kill fleas and lice. For example, it was used to dye underwear in order to protect it against fleas and lice, and the decoction of senburi was used as a pediculicide for killing hair lice. In addition, the liquid remaining after senburi has been boiled or powdered senburi was contained in pastes which were pasted onto folding screens and sliding doors as anti-insect agents. Senburi was mainly described as an insecticide in the 'yamato honzo (大和本草)' by Ekken Kaibara and the 'somoku zusetsu (草木図説)' by Yokusai Inuma, both of which were written in the Edo era, so herbologists in this period also seem to have largely ignored it. After the middle of the Edo era, when Western medicine was first imported into Japan, senburi was used for treating stomach ache, and it became accepted as bitter stomachics as well as the Dutch medicine Gentianae Radix.
Toyaku was included as a substitute for Gentianae scabrae Radix (root and rhizome of Gentiana scabra) in the 2nd Japanese Pharmacopoeia printed in the year Meiji 25, and it was officially described in 4th Japanese Pharmacopoeia printed in the year Taisho 9. Senburi, senburi powder, and senburi powder mixed with sodium bicarbonate are included in the 16th Japanese Pharmacopoeia (2011), and senburi remains in widespread use today, e.g., it is contained in home remedies as a bitter stomachic.
Swertiae Herba contains the following compounds: bitter glycosides (swertiamarin, sweroside,amarogentin, and gentiopicroside) and xanthone derivatives (bellidifolin and swertianin), etc.
Pharmacological effects and toxicity
Various pharmacological effects of the decoction of Swertiae Herba have been reported, e.g., it has been found to induce gastric secretion,increase acid production, decrease pepsin activity, and increase lipase activity. The alcohol extract of Swertiae Herba has a blood glucose lowering effect,and its active compound is bellidifolin. In rats, the oral administration of the methanol extract of Swertiae Herba was found to inhibit the large intestine contractions induced by the local administration of carbachol, and swertiamarin was identified as the active compound responsible for this effect.
Swertiamarin is known to increase the secretion of saliva,bile, and pancreatic juice and has a central depressant effect. It was reported that amarogentin and other compounds inhibit hepatopathy, whereas xanthone derivatives were found to have mutagenic effects. The oral or subcutaneous administration of gentiopicroside and sweroside, which are present in the butanol-soluble fraction of Swertiae Herba extract, has also been demonstrated to inhibit LPS-induced hepatopathy.
Medicinal effects, dosage, and administration
Swertiae Herba has a bitter taste. It is considered to have a “cooling” effect and is used as a stomachic and to treat baldness. It has been used as a bitter stomachic or intestinal remedy for treating stomach ache, asitia, dyspepsia, etc., since ancient times in Japan. In addition, the infusion produced by boiling one or two pieces of the dried plant (0.3 to 1.5 g for 1 day) is taken to treat asitia, stomachic, dyspepsia, and diarrhea, etc.Swertiae Herba can also be taken after being soaked in distilled spirit (medicinal liquor). Alternatively, 0.03 to 0.05 g (a cup of earpick) of powdered Swertiae Herba can be taken immediately after eating or about 30 minutes before eating three times a day. The bitter taste stimulates the tastes buds on the tip of the tongue and reflexively activates stomach motility. In addition, it is said to be effective against hangovers, hives, cardiopathy, phthisis, chest pain, high blood pressure, liver disease, and kidney disease, etc. Swertiae Herba should not be taken for a long period but taken as needed, and severely debilitated individuals and those with extremely cold constitutions should not take this medicine.
For hair loss, about 3 g of the dried plant are used to produce a thick decoction, which is rubbed into areas of hair loss caused by alopecia after hair washing to promote hair growth. Alternatively, 100 g of dried Swertiae Herba are cut into pieces and soaked in 1.8 L of white liquor (alcohol tincture) and then stored for 3 months in a sealed container in a cold dark place. After the storage period, a small amount of the liquor is taken in fist and is rubbed into the hair loss area once a day. Recently, the blood circulation-promoting effects of Swertiae Herba have drawn attention, and a hair growth tonic containing Swertiae Herba extract has been developed with the aim of improving the circulation around hair roots.
The decoction of Swertiae Herba is also used as a cleaning liquid for conjunctivitis, and women with menstrual disorder or cramps add a concentrated decoction of Swertiae Herba to their bath water. In addition, Swertiae Herba can be decocted with the skinless fruit of Aesculus turbinata Blume (tochinoki) and used as an externally applied treatment for athlete's foot.
Essentially, the entire plant is collected during the flowering season; however, attempts are often made to collect plants that have finished flowering and dispersed their seeds in order to avoid extirpation. After being collected, the plant is washed in water, dried, and stored in light-resistant containers in a drafty place. Swertiae Herba is composed of the flowers, leave, stems, and usually short woody roots of the plant. The stems are cuboidal in shape. The leaves and stems are dark green to dark violet in color, while the flowers are white/creamy white and the roots are yellowy-brown. It has a characteristic weak odor and tastes extremely bitter, and its taste remains on the tongue for a while.
S. japonica is difficult to cultivate; however, demand for the crude drug was expected to increase so cultivation experiments using seeds collected from wild plants were started and then cultivation was gone into full swing with improved breed began from 1975 to 1980. However, we need to develop a technique for produce required quantity of S. japonica constantly, because it is only cultivated in parts of Nagano and Kochi prefectures at present.
F. Ikegami, Wakanyaku, 709, 10-11, (2012.6)