Herbal Research

Chai Hu

RADIX BUPLEURI (HARE'S EAR ROOT)

Chai Hu is the dried root of Bupleurum chinensis DC. or Bupleurum scorzonerifolium Willd. (Umbelliferae). Both are perennial plants found on dry grassland, in fields and by roadsides. The herb from B. chinensis is mainly produced in the provinces of Liaoning, Gansu, Hebei and Henan, and that from B. scorzonerifolium in Hubei, Jiangsu and Sichuan. It is collected in the spring and autumn, removed from aerial part and is dried in the sun. The root of B. falcatum L. is used in Japan under the name Chai Hu.

CHEMISTRY

A series of triterpene saponins including saikosaponins (saikosides) a, b1-b4, c, d, e and f, have been isolated from the roots of several Bupleurum species. From the root of B. chinensis, saikosaponins a, b3, b4 and d, 3"-O-acetyl saikosaponins a, b4 and d, 6"-O-acetyl saikosaponins a and d, chikusaikosides I, II and 11 a-methoxyosaikosaponin f were isolated. In the root of B. scorzonerifolium saikosaponins a, c and d were identified1. Saikosaponins b1- b3 were later revealed to be the artifacts derived from saikosaponins a and d during processing2,3. The yields of saponins is correlated with the size of the root: the contents of saikosaponins in the root of B. chinensis with diameters of 9.5 mm, 5.4 mm and 2.7 mm were 1.24%, 3.18% and 4.86%, respectively4.
In addition to saponins, the herb contains small amount of essential oil, with bupleurmol as the major component. Besides, a-spinasterol, stigmasterol, Ä22-stigmasterol and adonitol were also. isolated from the herb. The aerial parts of Bupleu rum plants yield flavones as well as saikosaponins1,5,6.

PHARMACOLOGY

Effect on the CNS
Antipyretic effect

The herb is primarily an antipyretic agent. The decoction or aqueous solution of the ethanolic extract of the herb reduced fever in rabbits induced by triple vaccine, yeast or colibacillus. Hypothermal and antipyretic effects of the saponin fraction of the herb were also observed in rats at oral doses of less than 1/5 LD50. Intraperitoneal administration of 300 mg/kg of the essential oil from B. chinense, or 380 and 635 mg/kg of the saponin fraction (1/5 and 1/3 of the LD50 values, respectively) also exhibited antipyretic effect in mice with fever induced by subcutaneous injection of the suspension of cerevisiae fermentum6-8. The active constituents of the oil were identified as eugenol, hexanoic acid, c-undecalactone and q-methoxyacetophenone9. a-Spinasterol also significantly reduced the fever induced by subcutaneous injection of 15% yeast suspension rats 10.

Sedative effect

At oral doses of 200-800 mg/kg, saikosaponins produced sedative effect in mice. The hexabarbital sleeping time of mice was extended by oral administration of 500 mg/kg of saikosaponins. The sapogenin A of saikosaponins also antagonized the stimulant action of methyl amphetamine, deoxyephedrine and caffeine in mice. In a climbing experiment with mice, the saponin fraction of the herb exhibited a similar tranquillizing activity as miltown; its CD50 value by oral administration was 347 mg/kg7.

Analgesic and antitussive effects

Oral or intraperitoneal administration of the saponin fraction of the herb exhibited analgesic effect in mice, whereas the essential oil showed no analgesic activity. The sapogenin A of the saponins inhibited acetic acid-induced writhing in mice at intraperitoneal doses of 50 and 100 mg/kg7. The saponin fraction of the herb produced a potent antitussive effect. Its intraperitoneal ED50 in guinea pigs was 9.1 mg/kg, comparing to 7.6 mg/kg of codeine phosphate7,11.

Antiinflammatory Effect

The saponins and the essential oil from the root of B. chinense inhibited carrageenininduced rat paw edema at intraperitoneal doses of 478 and 400 mg/kg (1/4 LD50). Oral administration of 600 mg of the saponin fraction also inhibited the mouse paw edema induced by dextran, 5-HT or croton oil. Saikosaponins significantly inhibited the carrageenininduced paw edema, leukocyte migration and histamine release at the intraperitoneal dose of 300 mg/kg in rats, while the release of 5-HT or prostaglandins was not affected7. The saponins from the root of B. chinense antagonized serotonin- or histamine-induced increase of capillary permeability12. The saponin fraction suppressed the vascular permeability increase caused by acetic acid, histamine or 5-HT, but did not affect the effect of PGE1.

The antiinflammatory effects were also observed for a mixture of saikosaponins a, b1, b2, c and d, among which saikosaponins a and d showed the strongest antiinflammatory activity13-15.
Intramuscular injection of 1 mg/kg or oral administration of 10 mg of saikosaponin a or saikosaponin d, or oral administration of 100 mg/kg of the saponin fraction also exhibited antiexudative and anti-granulomatous activities. Adrenomegaly and thymic atrophy were caused when they inhibited granuloma, indicating that, in addition to stimulating adrenal cortex, saikosaponins have a very complex anti-inflammatory mechanism by influencing various procedures of inflammation such as exudation, capillary permeability, the release of inflammatory factors, leukocyte migration and connective tissue proliferation5.
a-Spinasterol suppressed the carrageenin-induced hind paw edema of intact and adrenalectomized rats and mice. It also inhibited edema of the hind paw caused by scalding and the proliferation of granulation tissue in croton oil-induced air pouch granulomas in rats10.

Effect on the Digestive System
Hepatoprotective and choleretic effects

The decoction of the herb significantly alleviated the liver injury, degeneration and cirrhosis caused by carbon tetrachloride (CC14) and decreased serum glutamic-pyruvic transaminase (GPT) level3. Saikosaponins, particularly saikosaponins a and d, inhibited D-galactosamine (GalN) or CCl4-induced hepatic injury. A significant inhibition of lipid peroxidation induced by a single dose of CC14 in the liver of rats retreated with saikosaponin d was also noted and liver cirrhosis caused by continuous doses of CC14 was alleviated by simultaneous treatment with saikosaponin d. Administration of saikosaponin a or d produced marked decrease in activities of microsomal enzymes, glucose-6-phosphatase and NADPHcytochrome C reductase, and a significant increase in activity of 5'-nucleotidase.
The herb and saikosaponins may also exert protective action against immunologically induced liver injury because they prevented antibody-dependent cell-mediated cytotoxicity (ADCC), which is considered to be involved in liver cell damage in hepatitis. They also activated macrophage-mediated cytotoxicity13. Choleretic effect of the decoction of the herb has also been observed in dogs7.

Gastrointestinal effect

The saikosaponin fraction of the herb was effective in preventing and treating rat gastric and duodenal ulcer induced by acetic acid, histamine or by pylorus ligation6'7.

Hypolipemic Effect

Saikosaponins, given intramuscularly to hyperlipemic rats, decreased the blood levels of cholesterol, triglycerides and lipolipids, particularly of triglycerides and accelerated the feces excretion of 14C-cholesterol and its metabolites. a-Spinasterol and bupleurmol were also found to be able to reduce plasma cholesterol level of cholesterol-fed animals6'7.

Antimicrobial Activity

The decoction of the herb was bactericidal in vitro against Streptococcus hemolyticus, Vibrio comma, Mycobacterium tuberculosis and leptospira. It also inhibited the growth of influenza and virus viruses, and the cell damages caused by poliovirus6.

Other Effects

Saikosaponin d was active against kidney damage in rats caused by aminonucleoside. It prevented the development of proteinuria and significantly lowered the electron microscopic abnormality in glomerular epithelial cells16.

FUNCTIONS AND APPLICATIONS

Traditional Description

Chai Hu has bitter and pungent tastes and a slightly cold in property, acting on the liver and gall bladder channels. It has the functions of:

(i) reducing fever, used for influenza and common cold with fever, alternate chills and fever such as malaria;
(ii) soothing the liver, used for distending pain in the chest and hypochondriac regions and menstrual disorders; and
(iii) curing drooping and ptosis, used in prolapse of the uterus or the rectum.

Applications
Fever

The herb had an optimal antipyretic effect in fever due to common cold, influenza, malaria and pneumonia. In a clinical study involving 143 cases treated with the herb, fever subsided within 24 h in 98.1% of the influenza cases and 87.9% of the common cold cases. In another 40 cases of pathological fever, the herb also produced an antipyretic action in 97.5% patients. However, only a transient antipyretic effect was achieved in case of infection unless antibiotics were given concomitantly7.

Hepatitis

Satisfactory effects were obtained in 100 cases of infectious hepatitis treated with the 20-40 ml of the 1:2 injection solution of the herb daily for 10 days as a treatment course. After treatment, patients usually showed improvement in mental state, appetite and subjective symptoms; amelioration or disappearance of pain over the liver area was reported in 4-5 days in most of the patients. For patients with hepatosplenomegaly, shrinkage to costal margin position occurred in children after one treatment course, and the recovery in adults was slower. For the liver functions, the transaminase activity and icterus index recovered faster than the thymol turbidity and flocculation tests. Sixteen cases of hepatitis B registered negative for HBAg after 1-7 treatment courses7.
Clinical trails for the effectiveness of saikosaponins on chronic hepatitis showed that long term of oral administration of a mixture of saikosaponins a and d (3:2) at a very low daily dose of 6 mg resulted in remarkable reduction of serum glutamic-oxalacetic transaminase (GOT) and GPT levels. Statistical significance was observed at 3, 6 and 12 months after the start of the medication with saikosaponins, compared with controls13.

Warts

Twenty daily intramuscular administration of 2 ml of the injection solution of the distillate of the herb (equivalent to 1 g of the herb) was effective in 60% of the 25 cases of warts. In 6 vulgaris verruca cases, 3 were cured, 1 improved and 2 unresponsive; of 12 verruca plana cases, 3 were improved and 1 unresponsive; one case of verruca accuminata was cured. Local adupoint injection produced a more effective result in 5 cases of warts. Skin lesions rapidly sloughed off or disappeared in 4 cases after 2-6 injections7.

DOSAGE

3-9g.

SIDE EFFECTS AND TOXICITY

Mild lassitude, sedation and drowsiness occurred in 30% of patients taking small doses (equivalent to 0.6 g of the herb) of the granulated herb. These reactions did not affect daytime activities. Large doses, however, produced deep sedation in 80% of the subjects and poor sleep in l7%⁷.
The oral LD50 of the powdered herb in mice was >3 g/kg. The LD50 values of the saponin fraction of the herb were 4.7 g/kg by oral administration, 1.9 g/kg by subcutaneous administration and 70 mg/kg by intravenous administration. The intraperitoneal LD50 values of the saponin fraction were 58.3 mg/kg in guinea pigs and 479 mg/kg in mice. Saikosaponins are hemolytic10-13.

NOTE

Bupleurum longiradiatum Turcz. is highly toxic and should not be used as a substitute for Chai Hu. The oral LD511 of powdered root of B. Ion giradiatum was 500 mg/kg in mice, whereas that of the powdered Chai Hu root was >3 g/kg. The toxic constituents of B. ion giradiatum have been isolated and identified as bupleurotoxin, bupleuonol, acetylbupleurotoxin and bupleurynol, of which bupleurotoxin and acetyl-bupleurotoxin were particularly toxic. Their LD50 values were 3.03 mg/kg and 3.13 mg/kg, respectively1.

REFERENCES

1. Zhou, R.H. (1993) Resource Science of Chinese Medicinal Materials, pp. 384-391. Beijing: China Medical & Pharmaceutical Sciences Press.
2. Kubota, T., Hinob, H. (1968) The constitution of saponins isolated from Bupleurumfalcatum. Tetrahedron Letters, 303-306.
3. Shimaoka, A., Seo, S., Hitoshi, M. (1975) Saponins isolated from Bupleurum falcatum. Components of saikosaponin B. Journal of the Chemical Sociely Perkin Transactions, 1:2043-2048.
4. Zhang, J. (1985) Comparison on saikosaponin content in the root of Bupleurum chinense of different sizes. Bulletin of Chinese Materia Medico, 10, 157-158.
5. Su, Z.W., Qiao, C.Z. (1989) Pharmacognosy, pp. 144-147. Shanghai: Shanghai Medical University Press.
6. Wang, J.M. (1985) Chinese Herbal Pharmacology, pp. 28-30. Shanghai: Shanghai Science & Technology Publisher.
7. Wang, Y.S. (1983) Pharmacology and Applications of Chinese Materia Medico, pp. 886-898. Beijing: People's Health Publisher.
8. Huang, K.C. (1993) The Pharmacology of Chinese Herbs, pp. 15 1-152. Boca Raton: CRC Press.
9. Annonymous. (1982) Studies of the antipyretic and antiinflammatory principles of the volatile ailBupleurum chinense. Chinese Pharmaceutical Bulletin, 17, 202-205.
10. Zhou, CC., Sun, X.B., Liu, JY., Luo, SQ., Lu, C.Y. (1985) Anti-inflammatory effect of a-spinasterol. Acta Pharmaceutica Sinica, 20, 257-261.
II. Takagi, K., Shibata, M. (1969j Pharmacological studies on Bupleurumfalcatum. I. Acute toxicity and central depressant action of crude saikosides. Yakugaku Zasshi, 89, 712-720.
12. Wang, B.X., Wang, G.Z., Liu, A.J. (1981) Antiinflammatory effect of saikosaponins. Acta Pharmacological Sinica, 2, 60-63.
13. Hikino, H., Kiso, Y. (1988) Natural products for liver diseases. In Economic and Medicinal Plant Research, Vol. 2, edited by H. Wagner, H. Hikino, N.R. Farnsworth, pp. 39-72. London: Academic Press.
14. Takagi, K., Shibata, M. (1969) Pharmacological studies on Bupleurumfalcatum. II. Antiinflammatory and other pharmacological actions of crude saikosides. Yakugaku Zasshi, 89, 1367-1378.
15. Yamamoto, M., Kumagai, A., Yamamura, Y. (1975) Structure and actions of saikosapoins isolated from Bupleurum falcatum. I. Antiinflammatory action of saikosaponins. A rzneimittelforschung, 25, 1021-1023.
16. Abe, H., Orita, M., Konishi, H., Archi, S., Odashima, S. (1986) Effects of saikosaponin don aminonucleoside nephrosis in rats. European Journal of Pharmacology, 120, 17 1-178.