Raffinose

Chemical properties

The raffinose family of oligosaccharides (RFOs) are α-galactosyl derivatives of sucrose, the most common being the trisaccharide raffinose, the tetrasaccharide stachyose, and the pentasaccharide verbascose. RFOs are almost ubiquitous across the plant kingdom, being found in a large variety of seeds from many different families. They rank second only to sucrose in abundance as soluble carbohydrates.

Raffinose typically crystallises as a pentahydrate white crystalline powder. It is odorless and has a sweet taste approximately 10% that of sucrose.

Biochemical properties

Energy source

It is non-digestible in humans and other monogastric animals (pigs and poultry) who do not possess the α-GAL enzyme to break down RFOs. These oligosaccharides pass undigested through the stomach and small intestine. In the large intestine, they are fermented by bacteria that do possess the α-GAL enzyme and make short-chain fatty acids (SCFA)(acetic, propionic, butyric acids), as well as the flatulence commonly associated with eating beans and other vegetables. These SCFAs have been recently claimed to impart a number of health benefits. α-GAL is present in digestive aids such as the product Beano.

Plant health

Cases of abiotic stress such as temperature, drought, and salinity have shown to increase RFO levels, especially raffinose, in plants. The functional role raffinose plays in abiotic stress tolerance is not well known, but its presence as a positive regulator of these stresses is established.

Galactinol synthase (GolS) is an enzyme key in the synthesis of RFOs. Studies which modify the expression of GolS have been done to understand the role of RFOs in stress response. GolS has been found to induce salicylic acid signalling pathways and expression of defence-related genes, showing RFOs to have a role in pathogen resistance.

RFOs have been seen to assist in seed germination. They are used as a source of energy and carbon for germination, and protect the seed from desiccation during the maturation process. One proposed mechanism of RFOs working against desiccation details the hydroxyl groups replacing water to maintain hydrophilicity ion the cell, which stabilizes the membrane structure and macromolecules needed for cellular function. Another mechanism, called "vitrification", has the cell taking on a highly viscous form, like that of a plastic solid. This maintains cellular stability and hydrogen bonding in the cell, and prevents cellular collapse.

In many plants, RFOs have been seen to act as an alternative to sucrose for sugar storage and transport.

Disease relevance

Research has shown that the differential ability to utilize raffinose by strains of the bacteria Streptococcus pneumoniae impacts their ability to cause disease and the nature of the disease.

Uses

Procedures concerning cryopreservation have used raffinose to provide hypertonicity for cell desiccation prior to freezing. Either raffinose or sucrose is used as a base substance for sucralose.

Raffinose is also used in:

• skin moisturizers and cosmetics
• prebiotics (it promotes growth of lactobacilli and bifidobacteria)
• food or drinks additive
• chiral stationary phase in HPLC

References

References

1. (2010). "Ullmann's Encyclopedia of Industrial Chemistry".
2. Pontis, Horacio G.. (2017-01-01). "Chapter 8 - Case Study: Raffinose". Academic Press.
3. (2022-12-01). "Rearrangement of hydrogen bonds in dehydrated raffinose tetrahydrate: a time-of-flight neutron diffraction study". Acta Crystallographica Section C: Structural Chemistry.
4. "D(+)-Raffinose pentahydrate {{!}} 17629-30-0".
5. (November 1994). "Does Beano prevent gas? A double-blind crossover study of oral alpha-galactosidase to treat dietary oligosaccharide intolerance". The Journal of Family Practice.
6. (2022-07-04). "Raffinose Family Oligosaccharides: Crucial Regulators of Plant Development and Stress Responses". Critical Reviews in Plant Sciences.
7. (2020-12-01). "Involvement of the galactinol synthase gene in abiotic and biotic stress responses: A review on current knowledge". Plant Gene.
8. (July 2013). "Plant sugars are crucial players in the oxidative challenge during abiotic stress: extending the traditional concept". Plant, Cell & Environment.
9. (October 2022). "Raffinose family oligosaccharides (RFOs): role in seed vigor and longevity". Bioscience Reports.
10. (2023-02-16). "The potential role of nondigestible Raffinose family oligosaccharides as prebiotics". Glycobiology.
11. (2019-01-15). "Capacity To Utilize Raffinose Dictates Pneumococcal Disease Phenotype". mBio.
12. Storey B., Noiles, E., Thompson, K.. (1998). "Comparison of Glycerol, Other Polyols, Trehalose, and Raffinose to Provide a Defined Cryoprotectant Medium for Mouse Sperm Cryopreservation". Cryobiology.
13. (2017-03-07). "The trisaccharide raffinose modulates epidermal differentiation through activation of liver X receptor". Scientific Reports.
14. (2018-03-21). "Fermentation of non-digestible raffinose family oligosaccharides and galactomannans by probiotics". Food & Function.
15. Anggraeni, A A. (2022-02-01). "Mini-Review: The potential of raffinose as a prebiotic". IOP Conference Series: Earth and Environmental Science.
16. (2011-04-01). "Development of silica-based stationary phases for high-performance liquid chromatography". Analytical and Bioanalytical Chemistry.