Terpenes are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. In plants, terpenes and terpenoids are important mediators of ecological interactions, while some insects use some terpenes as a form of defense. Other functions of terpenoids include cell growth modulation and plant elongation, light harvesting and photoprotection, and membrane permeability and fluidity control.
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of Heliconius butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.
Saponins, also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed but found particularly in soapwort, a flowering plant, the soapbark tree, common corn-cockle, baby’s breath and soybeans. They are used in soaps, medicines, fire extinguishers, as dietary supplements, for synthesis of steroids, and in carbonated beverages. Saponins are both water and fat soluble, which gives them their useful soap properties. Some examples of these chemicals are glycyrrhizin and quillaia, a bark extract used in beverages.
Squalene is an organic compound. It is a triterpene with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as Squalus is a genus of sharks). An estimated 12% of bodily squalene in humans is found in sebum. Squalene has a role in topical skin lubrication and protection.
Quillaia is the milled inner bark or small stems and branches of the soapbark. Other names include Murillo bark extract, Panama bark extract, Quillaia extract, Quillay bark extract, and Soapbark extract. Quillaia contains high concentrations of saponins that can be increased further by processing. Highly purified saponins from quillaia are used as adjuvants to enhance the effectiveness of vaccines. Other compounds in the crude extract include tannins and other polyphenols, and calcium oxalate.
Quillaja saponaria, the soap bark tree or soapbark, is an evergreen tree in the family Quillajaceae, native to warm temperate central Chile. In Chile it occurs from 32 to 40° South Latitude approximately and at up to 2000 m (6500 ft) above sea level. It can grow to 15–20 m (50–65 ft) in height. The tree has thick, dark bark; smooth, leathery, shiny, oval evergreen leaves 3–5 cm long; white star-shaped flowers 15 mm diameter borne in dense corymbs; and a dry fruit with five follicles each containing 10–20 seeds. The tree has several practical and commercial uses.
Moronic acid is a natural triterpene. Moronic acid can be extracted from Rhus javanica, a sumac plant traditionally believed to hold medicinal applications. The molecule has also been extracted from mistletoe.
Agenus Inc. is a Lexington, Massachusetts-based biotechnology company focused on immunotherapy including immuno-oncology, a field that uses the immune system to control or cure cancer. The company is developing checkpoint modulators (CPMs), patient-specific anti-cancer vaccines, and adjuvants desugned for use with various vaccines. CPM development is a particularly fast-moving field, since early products have produced unprecedented clinical benefits for patients.
A zoster vaccine is a vaccine that reduces the incidence of herpes zoster (shingles), a disease caused by reactivation of the varicella zoster virus, which is also responsible for chickenpox. Shingles provokes a painful rash with blisters, and can be followed by chronic pain, as well as other complications. Older people are more often affected, as are people with weakened immune systems (immunosuppression). Both shingles and postherpetic neuralgia can be prevented by vaccination.
A cell-free system is an in vitro tool widely used to study biological reactions that happen within cells apart from a full cell system, thus reducing the complex interactions typically found when working in a whole cell. Subcellular fractions can be isolated by ultracentrifugation to provide molecular machinery that can be used in reactions in the absence of many of the other cellular components. Eukaryotic and prokaryotic cell internals have been used for creation of these simplified environments. These systems have enabled cell-free synthetic biology to emerge, providing control over what reaction is being examined, as well as its yield, and lessening the considerations otherwise invoked when working with more sensitive live cells.
In immunology, an adjuvant is a substance that increases or modulates the immune response to a vaccine. The word "adjuvant" comes from the Latin word adiuvare, meaning to help or aid. "An immunologic adjuvant is defined as any substance that acts to accelerate, prolong, or enhance antigen-specific immune responses when used in combination with specific vaccine antigens."
The enzyme amorpha-4,11-diene synthase (ADS) catalyzes the chemical reaction
Oleanolic acid or oleanic acid is a naturally occurring pentacyclic triterpenoid related to betulinic acid. It is widely distributed in food and plants where it exists as a free acid or as an aglycone of triterpenoid saponins.
Immune stimulating complexes (ISCOMs) are spherical open cage-like structures (typically 40 nm in diameter) that are spontaneously formed when mixing together cholesterol, phospholipids and Quillaja saponins under a specific stoichiometry. The complex displays immune stimulating properties and is thus mainly used as a vaccine adjuvant in order to induce a stronger immune response and longer protection. A specific adjuvant based on ISCOM technology is Matrix-M.
A subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response. Subunit vaccine can be made from dissembled viral particles in cell culture or recombinant DNA expression, in which case it is a recombinant subunit vaccine.
Oxidosqualene cyclases (OSC) are enzymes involved in cyclization reactions of 2,3-oxidosqualene to form sterols or triterpenes.
Anne Elisabeth Osbourn is a professor of biology and group leader at the John Innes Centre, where she investigates plant natural product biosynthesis. She discovered that in the plant genome, the genes involved with biosynthesis organise in clusters. She is also a popular science communicator, poet and is the founder of the Science, Art and Writing (SAW) Initiative. She was elected a member of the National Academy of Sciences in 2022.
Cannabinoids, including tetrahydrocannabinol (THC), the active drug in cannabis, can also be produced by bioengineered yeast, a process colloquially known as pharming. In 2007, a research group reported the successful transgenic placement of a THCA synthase gene from Cannabis plant into the Pichia pastoris yeast, giving the yeast the ability to turn the precursor molecule cannabigerolic acid into THCA. In 2019, researchers at University of California, Berkeley reported in Nature that they had bioengineered yeast able to completely synthesize THC, CBD, and other cannabinoids, using only sugar as a food.
Matrix-M is a vaccine adjuvant, a substance that is added to various vaccines to stimulate the immune response. It was patented in 2020 by Novavax and is composed of nanoparticles from saponins extracted from Quillaja saponaria (soapbark) trees, cholesterol, and phospholipids. It is an immune stimulating complex (ISCOM), which are nanospheres formed when saponin is mixed with two types of fats.
Cyclamin is an organic compound that has been used by the pharmaceutical industry as an ingredient for nasal sprays.
