Saponins

It has long been known that some holothurian species contain toxins. In the southern Pacific and Tokara Islands (islands of southern Japan), a peculiar fishing method using sea cucumbers is employed. The autochthones catch paralyzed fish after they throw extracts or fragments of sea cucumbers into tidal pools. This toxic effect results from saponins. Cooper (1880) reported that some holothurians discharged white filamentous structures, called Cuvierian tubules. Contact with these tubules also caused skin irritation. Saponins concentrate in Cuvierian tubules. On the other hand, in holothurian species without these structures, saponins are distributed in the body wall. Dried sea cucumbers were used as a home remedy for skin diseases, and powdered starfish was employed as a pesticide in Japan. The pharmacological activity described is assumed to be due to saponins. In the animal kingdom, the occurrence of saponins is limited to only two echinoderm classes, namely holothurians and asteroids; in contrast, saponins are widely distributed in the plant kingdom. Saponins have been used as an expectorant, a cure for conges tive heart failure and as a component of contraceptives and antirheumatic agents. The surfactant activity of saponins has been known and utilized for a long time in medicine. Studies on toxic and pharmaceutical activities of holothurians were initiated by Yamanouchi in the 1940s (Yamanouchi 1942, 1943a, b). Later, Nigrelli and Zahl (1952) named the toxic substance from Cuvierian tubules of Actinpya agassizi holothurin, and initiated a series of further investigations into the chemical and pharmacological properties of the substance. They demonstrated its lethal activities towards various organisms in e.g., Protozoa, Cnidaria, Nematoda, Mollusca, Annelida, and Amphibia. Antifungal activity of the holothurian saponin, holotoxin, was reported by Shimada (1969). He patented holotoxin as a cure for athlete's foot disease and commercialized it. Kitagawa et al. (1976a, b) showed that holotoxin is in fact composed of three molecules, holotoxin A, B and C. The inhibitory activities on fungal growth were much higher than those of various plant saponins (Table 1). Aglycons of holothurian saponins are terpenoids (Fig. 1), whereas those of asteroid saponins are sterols (Fig. 2). The molecular difference in saponins between the asteroid and holothurian seems to reflect phylogenic differences. Recently, novel cytotoxic triterpene glycosides have been isolated from sea cucumbers Pentamera calcigera (Avilov et al. 2000), Staurocucumis liouvillei (Maier et al. 2001), Hemoiedema spectabilis (Chludil et al. 2002) and Mensamaria intercedens (Zou et al. 2003). The glycosides from P calcigera, S. liouvillei and M. intercedens showed antineoplastic activity against mammalian cancer cells. Terpene glycosides deserve to be investigated as anticancer pharmaceuticals. Two triterpene glycosides from H. spectabilis also showed antifungal activity against the phytopathogenic fun-gus.Antifungal activities of substances from sea cucumbers are thought to be due to their terpenoid structures.

Table 1. Antifungal activities of holotoxins. Minimum inhibitory concentration for growth of microorganisms (|g/ml)

Species

A

B

C

Trichophyton rubrum

0.78

0.78

6.25

Trichophyton mentagrphyte

1.56

1.56

12.5

Mictosporum gypseum

3.12

1.56

12.5

Candida albicans

6.25

6.25

25.0

Candida utilis

3.12

3.12

12.5

Tomla utilis

3.12

3.12

12.5

Aspergillus oryzae

6.25

12.52

5.0

Penicillium chrysogenum

3.12

6.25

12.5

Trishomonas vaginalis

3.12

1.56

3.12

Fig. 2. Structural formula of asterosaponin

Na 0,s0

CHjOH

CHjOH

Na 0,s0

chrt 0

chrt 0

How To Cure Yeast Infection

How To Cure Yeast Infection

Now if this is what you want, you’ve made a great decision to get and read this book. “How To Cure Yeast Infection” is a practical book that will open your eyes to the facts about yeast infection and educate you on how you can calmly test (diagnose) and treat yeast infection at home.

Get My Free Ebook


Post a comment