QS-21

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QS21
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Basic structure of QS-21, consisting of a quillaic acid triterpene (black) substituted with a branched trisaccharide (blue) and a linear tetrasaccharide (green), which is in turn connected to an acyl chain (red) via a hydrolytically labile ester. QS-21 is a 65:35 mixture of the Apiose- and the Xylose-substituted variants of above molecule.

QS-21 is a purified

soap bark tree (Quillaja saponaria), which is native to the countries of Chile, Peru, and Bolivia.[1] The crude drug (Quillajae cortex) is imported from Peru and Chile.[2]

The extract contains

water-soluble triterpene glycosides, which are members of a family of plant-based compounds called saponins. It has been tested as an adjuvant in various vaccines in attempts to improve their efficacy. It is believed to enhance both humoral and cell-mediated immunity.[1]

Isolation of QS-21 destroys the soap bark tree, which has resulted in regulation of the tree by the governments where it is grown. A

acyl chain compositions.[3]

QS-21 has undergone clinical evaluation as an additive for various trial vaccines, including those for

Shingrix vaccine[4] and of the Matrix-M adjuvant used in the Novavax COVID-19 vaccine
.

Agenus Inc. is the sole US-manufacturer of an FDA-approved, patented extract. Supplies are tightly controlled, and the US has invoked the US Defense Production Act to preserve vaccine raw materials for its own companies.[5][6]

See also

References

  1. ^
    PMID 21506644
    .
  2. ^ Max Wichtl, ed. (2004). Herbal Drugs and Phytopharmaceuticals: A Handbook for Practice on a Scientific Basis. Medpharm Publishers. p. 492. ISBN 3-88763-100-5.
  3. PMID 22866694
    .
  4. ^ "SHINGRIX package insert" (PDF). Food and Drug Administration. Retrieved 7 April 2019.
  5. ^ VISWANATH, P. (April 29, 2021) "COVID-19: Raw material crunch pushes vaccine makers to look at indigenization". moneycontrol.com. Retrieved 30 April 2021.
  6. ^ Wang Pengfei (March 2021). "Natural and Synthetic Saponins as Vaccine Adjuvants" Vaccines 9(3):222. PMID: 33807582 PMCID: PMC8001307 DOI: 10.3390/vaccines9030222.

External links

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