Oligosaccharides

• Oligosaccharides are carbohydrates made of 2-10 monosaccharide units linked together.
• Oligosaccharides are defined as oligo means few, saccharides-sugars.
• They are found in vegetables, fruits, legumes, and grains.
• They play various roles in biological processes and are found in many plants and human milk.
• Oligosaccharides can function as prebiotics, stimulating the growth of beneficial bacteria in the gut.
• They are also involved in cell recognition and signaling processes.
• Due to their complex structure, oligosaccharides can affect the body differently, contributing to health and disease prevention.
• These carbohydrates are less commonly used as direct energy sources than simpler sugars and starches.

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Classification of Oligosaccharides

They are classified based on number of monosaccharides units they are made up of.

Trisaccharides

This type of trisaccharide is made up of three monosaccharide units.

For Example:

Raffinose: Raffinose is a trisaccharide containing three sugar units ( Galactose + Glucose + Fructose). It is found in cabbage, beans, and grains. The enzyme that is responsible for its hydrolyzes is absent in humans, due to this reason it cannot be easily digestible in humans. It is responsible for gas production after consumption.

Manninotriose: Manninotrios is made up of (Mannose + Glucose + Fructose). It is less common and found in plants.

Panose: Panose contains three monosaccharide units ( Glucose + Glucose + Fructose). It is found in honey. It can be broken down by digestive enzymes and used as an energy source.

Tetrasaccharides

These are made up of four sugar units.

For Example:

Stachyose: Stachyose contains four sugar units ( Two galactose units + one glucose unit + one fructose unit). It is present in legumes, beans, and soybeans. It is not easily digestible and causes gas and bloating.

Scordoside: Scordoside made up of ( Mannose + Mannose + Glucose + Galactose ). It is found in garlic (due to this, the name Scordoside is derived from Scordo, which means “garlic”.

Pentasaccharides

Pentasaccharides are made up of five monosaccharide units.

For Example:

Verbascose: contains ( three galactose units + one glucose unit + one fructose unit ). It is found in legumes such as beans, peas, and lentils. Similar to raffinose and stachyose, verbascose is not easily digestible by humans and can cause gas and bloating.

Fructooligosaccharides (FOS): They have Fructose units linked to a terminal glucose unit. Found in many plants, including chicory root, Jerusalem artichoke, onions, and bananas. FOS are used as prebiotics to promote gut health by stimulating the growth of beneficial bacteria.

Hexasaccharides

This type of oligosaccharide contains six monosaccharides linked together.

For Example:

Isomaltose (α-D-Glucopyranosyl-(1→6)-α-D-glucopyranose): It is composed of two glucose molecules connected by an α(1→6) bond and can be repeated to form a hexasaccharide with a specific sequence.

Cyclohexaamylose (α-cyclodextrin): It is a cyclic hexasaccharide consisting of six glucose units linked by α(1→4) bonds, forming a ring structure.

Heptasaccharides

Heptasaccharides have seven sugar monomers.

For Example:

Maltoheptaose: Contain ( α-D-Glucopyranosyl-(1→4)-α-D-Glucopyranosyl-(1→4)-α-D-Glucopyranosyl-(1→4)-α-D-Glucopyranosyl-(1→4)-α-D-Glucopyranosyl-(1→4)-α-D-Glucopyranosyl-(1→4)-D-Glucopyranose ).These seven glucose units are linked by α(1→4) glycosidic bond. It is a linear heptasaccharide and a component of amylose and amylopectin.

Lacto-N-heptaose: It contains glucose and galactose. This heptasaccharide is found in human milk oligosaccharides and is involved in infant nutrition and gut health.

Applications

Oligosaccharides, short chains of monosaccharides, have diverse applications across various fields.

Food industry

Oligosaccharides in the food industry act as prebiotics, promoting gut health and making the immune system strong. They improve texture, serve as low-calorie sweeteners, and enhance moisture retention in products. Additionally, they stabilize and emulsify food, extending shelf life and improving the quality of baked goods, dairy, and beverages.

Pharmaceuticals

In pharmaceuticals, they modulate the immune system, exhibit antiviral properties, and improve drug delivery. Cosmetically, they moisturize and aid in anti-aging. Oligosaccharides in pharmaceuticals enhance drug stability and solubility as excipients, support gut health and immunity through prebiotic effects, and improve the efficacy of probiotics. They aid in immunomodulation, potentially boosting vaccine responses, and enhancing mineral absorption for bone health, making them valuable in digestive and bone health supplements.

Agriculturally

Oligosaccharides enhance plant growth and act as biopesticides. Oligosaccharides play a vital role in agriculture by enhancing plant growth, improving resistance to diseases and pests, and boosting stress tolerance. They act as bio-stimulants, promoting beneficial soil microbes, improving nutrient uptake, and increasing crop yield and quality, ultimately contributing to sustainable and resilient agricultural practices.

Biotechnology

They are crucial in glycoconjugate synthesis and diagnostic tools. In biotechnology, oligosaccharides are crucial for developing bio-based products, such as biopharmaceuticals and biofuels. They serve as building blocks in glycoconjugate vaccines, enhance the stability and delivery of drugs, and are used in the production of functional biomaterials. Their role in cell signaling and molecular recognition also aids in diagnostics and therapeutic developments.