Pharmacognosy of Shark Liver Oil

                    SHARK LIVER OIL

Synonym: Oleum Selachoide.

Biological source:

Shark liver oil is extracted from the livers of deep-water sharks which typically inhabit the cold, non-polluted waters of the sea. Shark liver oil is typically obtained from sharks that are caught as a by-product of deep-sea fishing, making a valuable remedy from a natural resource that would have otherwise gone to waste. Shark liver oil is the fixed oil obtained from the fresh and carefully preserved livers of various species of shark, mainly Hypoprion brevirostris (lemon shark), family- Pleuonectidae, order-Selachii and Galeorhinus zyopterus.

In India, Scoliodon, Carcharias, and Sphyrna are abundant among the species, and are generally utilize for the extraction purpose.

Geographical Source:

The oil is produced mainly on large scales in many European countries. In India, it is produced in Tamil Nadu, Maharashtra and Kerala states.

Preparation:

Livers removed from the shark are thoroughly cleaned, freed from fatty material and adhering tissues. The cleaned livers are minced and heated in a boiling pot at a temperature not exceeding 80 C. The oil thus extracted is kept in contact with dehydrating agent to eliminate water. The oil

freed from water is chilled to separate stearin. It is then centrifuged to get clear oil after removing the suspended material. The oil may further be manipulated to adjust vitamin strength as per requirement and sometimes it is fortified with vitamin D, if so desired.

With a little variation, the principle involved in extraction of oil from livers is uniform in almost all the cases. Government factories in Tamil Nadu and Maharashtra are processing livers for extracting oil.

Description:

Color: Pale yellow to brownish or yellow

Odor: Characteristic fishy, but not rancid

Taste: Bland or fishy

Solubility: Shark liver oil is soluble in solvent ether, chloroform, and light petroleum ether. However, it is insoluble in water and slightly soluble in ethyl alcohol.

Standards:

The shark liver oil complies with following standards:

Specific Gravity:         0.912 to 0.916.

Refractive Index:        1.459 to 1.477 at 40 C.

Acid Value:                  not more than 2.

Iodine Value:               not less than 90.

Saponification Value:  175 to 200.

Moisture Content:        less than 1%

Impurities:                    less than 1%

Chemical constituents:

Shark liver oil is rich in alkylglycerols, which are naturally found in mother's milk and in bone marrow. It also contains pristane, squalene, vitamins A(whose concentration varies from 15000 to 30000 International units per g), D, omega-3 fatty acids[Eciosapentaenoic acid (EPA), Docasahexaenoic acid (DHA)], triglycerides, glycerol ethers, and fatty alcohols. 

Identification Test:

(1) Dissolve one or two drops of shark liver oil in 1ml of chloroform in a dry test

tube. Add a drop of concentrated sulphuric acid, a violet color which changes to purple or brownish is obtained. This is due to the presence of vitamin A.

(2) One ml of the oil is dissolved in 10 ml of chloroform in a dry test tube. On addition of few drops of saturated solution of antimony trichloride in the chloroform solution a blue colour is formed. This is also due to the presence of vitamin A.

Uses:

·        Shark liver oil is promoted as a dietary supplement used to boost the immune system, fight off infections, heal wounds, and to treat cancer and lessen the side effects of conventional cancer treatment.

·        Depending on the commercial preparation, shark liver oil may also be rich in omega-3 fatty acids and vitamin A [which is used in the treatment of Xerophthalmia (abnormal dryness of the surface of conjunctiva)]. Shark liver oil has also been used in some moisturizing skin creams and lotions, although several cosmetics companies have recently removed this ingredient because of concern regarding the decline of some shark species.