Saponin


Saponins are a class of chemical compounds found in particular abundance in various plant species. More specifically, they are amphipathic glycosides grouped phenomenologically by the soap-like foam they produce when shaken in aqueous solutions, and structurally by having one or more hydrophilic glycone moieties combined with a lipophilic triterpene or steroid derivative.

Structural variety and biosynthesis

The aglycone portions of the saponins are termed sapogenins. The number of saccharide chains attached to the sapogenin/aglycone core can varygiving rise to another dimension of nomenclature as can the length of each chain. A somewhat dated compilation has the range of saccharide chain lengths being 1–11, with the numbers 2–5 being the most frequent, and with both linear and branched chain saccharides being represented. Dietary monosaccharides such as D-glucose and D-galactose are among the most common components of the attached chains.
The lipophilic aglycone can be any one of a wide variety of polycyclic organic structures originating from the serial addition of 10-carbon terpene units to compose a C30 triterpene skeleton, often with subsequent alteration to produce a C27 steroidal skeleton. The subset of saponins that are steroidal have been termed saraponins. Aglycone derivatives can also incorporate nitrogen, so some saponins also present chemical and pharmacologic characteristics of alkaloid natural products. The figure at right above presents the structure of the alkaloid phytotoxin solanine, a monodesmosidic, branched-saccharide steroidal saponin.

Test

; Froth Test:
Uses plant Gogo Entada phaseoloides as control. The positive result shows a honeycomb froth that is higher than 2 cm that persists for 10 minutes or longer.
Blood Agar Media :
Is an agar cup semi-quantitative method that shows positive result of hemolytic halos.

Role in plant ecology and impact on animal foraging

In plants, saponins may serve as anti-feedants, and to protect the plant against microbes and fungi. Some plant saponins may enhance nutrient absorption and aid in animal digestion. However, saponins are often bitter to taste, and so can reduce plant palatability, or even imbue them with life-threatening animal toxicity. Some saponins are toxic to cold-blooded organisms and insects at particular concentrations. Further research is needed to define the roles of these natural products in their host organisms, which have been described as "poorly understood" to date.

Ethnobotany

Most saponins, which readily dissolve in water, are poisonous to fish. Therefore, in ethnobotany, they are primarily known for their use by indigenous people in obtaining aquatic food sources. Since prehistoric times, cultures throughout the world have used fish-killing plants, mostly those containing saponins, for fishing.
Although prohibited by law, fish-poison plants are still widely used by indigenous tribes in Guyana.
On the Indian subcontinent, the Gondi people are known for their use of poison-plant extracts in fishing.
Many of California's Native American tribes traditionally used soaproot, and/or the root of various yucca species, which contain saponin, as a fish poison. They would pulverize the roots, mixing in water to create a foam, and then add the suds to a stream. This would kill, or incapacitate, the fish, which could be gathered easily from the surface of the water. Among the tribes using this technique were the Lassik, the Luiseño, and the Mattole.

Research and uses

The amphipathic nature of saponins gives them activity as surfactants with potential ability to interact with cell membrane components, such as cholesterol and phospholipids, possibly making saponins useful for development of cosmetics and drugs. Saponins have also been used as adjuvants in development of vaccines, such as Quil A, an extract from the bark of Quillaja saponaria. This makes them of interest for possible use in subunit vaccines and vaccines directed against intracellular pathogens. In their use as adjuvants for manufacturing vaccines, toxicity associated with sterol complexation remains a concern.
While saponins are promoted commercially as dietary supplements and are used in traditional medicine, there is no high-quality clinical evidence that they have any beneficial effect on human health. Quillaja is toxic when consumed in large amounts, involving possible liver damage, gastric pain, diarrhea, or other adverse effects.
The plant Çöven, Gypsophila simonii is widely distributed throughout Çankırı, where it is a native species, and Turkey. In this study, chemical and physical properties of unripe saponins obtained by extraction from the roots of Gypsophila simonii, an endemic plant, were isolated and investigated. Purified aglycones recovered from acid hydrolysis of the saponins were separated by reversed chromatography on a thin layer of silica gel. Phytochemical tests showed the presence of terpenoids in the crude extracts.
Saponins are used for their effects on ammonia emissions in animal feeding. In the United States, researchers are exploring the use of saponins derived from plants to control invasive worm species, including the jumping worm.
Dioscin, the saponin from Dioscorea spp. remains an important source for diosgenin, which is then utilized in the semi-synthetic or biosynthetic production of progesterone and corticosteroids.
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