This article covers some important aspects regarding popular cyclodextrin compounds and answers the following questions:
- What are cyclodextrins?
- Are they natural?
- Are they biodegradable?
- Are they safe for the environment?
- Are they sustainable compounds?
- How should they be disposed of?
- Is there any greener alternative in the market?
Is Cyclodextrin biodegradable?
Yes, Cyclodextrin is biodegradable in nature but there are a few things to be understood here. Cyclodextrins are basically a complex form of glucose and glucose is a compound required by every living organism, even microorganisms, to survive and live and that they are non-toxic to the environment but still the biodegradability will depend on several factors.
One important factor is that the microorganisms responsible for degrading the compound have different numbers of presence in different mediums. That is why when it comes to cyclodextrins, it is said that they are only biodegradable in soil which essentially means that soil is the only medium in which they are degraded by a large number of microorganisms.
Does cyclodextrin occur naturally?
Yes, as discussed earlier that it is a form of oligosaccharide. Oligosaccharides are complex sugar molecules produced by plants in nature so cyclodextrins are naturally occurring compounds but obtaining them naturally from plants is a cost-intensive process and for that reason, another method is used.
Cyclodextrins are basically complex forms of oligosaccharide sugars. Cyclo- refers to the shape of the compound which is circular and dextrins mean that it is a form of dextrose sugar which means that it has 5 or more glucose molecules attached together in a circular shape.
There are typically three types of cyclodextrins each of which has a different shape and different sets of functions for which they can be used:
- α (alpha)-cyclodextrin: 6 glucose subunits
- β (beta)-cyclodextrin: 7 glucose subunits
- γ (gamma)-cyclodextrin: 8 glucose subunits
Today, most of the cyclodextrins are synthesized in the industries by enzymatic breakdown of starch. Starch is a higher form of sugar known as a polysaccharide which when broken converts into simpler form i.e., oligosaccharides but this process can not be done by mechanical means hence amylase enzyme is used to break down starch and convert it into cyclodextrins.
Is it a sustainable product?
Yes, It is a sustainable product. It is natural and biodegradable, and it comes from or is manufactured from those sources which are abundant in nature and are replenished from time to time so it is considered a sustainable product.
The fact that its production requires enzymes which are not cheap such as Cyclodextrin glycosyltransferases (CGTases). Still, the benefits cyclodextrins offer to the environment are much higher than the overall cost of production.
How to properly dispose of cyclodextrins after use?
Disposal of cyclodextrins has to be done in accordance with the safety data sheet which refers to each type of cyclodextrin differently, However, a few things are common among all types of cyclodextrins in terms of their disposal that they should not be thrown directly down the drain nor in any of the waterways.
The biodegradability of cyclodextrins is low in the water as compared to soil and it may cause an imbalance in the nutritional properties of water in freshwater bodies which may cause problems.
The fact that their biodegradability has been proven in the soil means that the safest way to dispose of them is to send the waste products to a landfill site where they can degrade easily when mixed with soil. The normal period for 90% degradation is 8 days.
What are the uses of cyclodextrins?
Cyclodextrins are used in multiple industries due to their versatility. These industries include food, chemical, environmental engineering, agriculture and pharmaceutical industries.
In the food industry, the potential of cyclodextrins as a good packaging material additive has only been realised recently due to their non-toxicity, increasing shelf life and effective protection from sunlight. They are used in the pharmaceutical industry as drug carriers which carry medicine safely into our bodies.
The usage of cyclodextrins that benefits the environment, however, is the most significant. The solubility of organic contaminants and the enhancement and removal of heavy metals from the soil, water, and environment depend heavily on Cyclodextrins. Given their superior physicochemical characteristics and capacity to increase the stability, encapsulation, and adsorption of contaminants,
As next-generation adsorbents for wastewater treatment, Cyclodextrin-based adsorbents have drawn attention from all around the world. The preparation procedure has a role in the removal processes for Cyclodextrin-based adsorbents. All aromatic hazardous hydrocarbons, including phenol, p-chlorophenol, and benzene, are significantly reduced in wastewater levels after treatment with Cyclodextrin.
Are there greener alternatives available in the market?
Finding an alternative means that something that can do the same function but has other benefits such as economic or environmental benefits attached. The thing about cyclodextrin is that they have their unique function in industries for which there is no alternative substance available as such.
Mechanical methods are often expensive and time-consuming and they often use chemicals which may be cheap but are extremely dangerous for the environment around us. The benefits cyclodextrins offer have made them of keen interest to researchers who find them very good, versatile compounds which have multiple uses and are safe for the environment.
Conclusion:
Cyclodextrins are very important substances for different types of industries as they are a sustainable way of cleaning our environment, keeping our food safe, making safe drug delivery and reduction of pollutants from the environment.
The benefits are second to none. Hence the only concern that remains is the enzymes that are used for its production. Cyclodextrin glycosyltransferases (CGTases) are the enzymes that convert starch into cyclodextrins and this enzyme does not come cheap. More research should be focused on the cheap production of cyclodextrins and their efficient use.
References:
- Beta-Cyclodextrin: Safety Data Sheet. Retrieved from https://www.parchem.com/siteimages/Attachment/GHS%20Beta-Cyclodextrin%20MSDS.pdf
- Fenyvesi E, Gruiz K, Verstichel S, De Wilde B, Leitgib L, Csabai K, Szaniszlo N. Biodegradation of cyclodextrins in soil. Chemosphere. 2005 Aug;60(8):1001-8. doi: 10.1016/j.chemosphere.2005.01.026. Epub 2005 Apr 14. PMID: 15993146.
- Velázquez-Contreras F, Zamora-Ledezma C, López-González I, Meseguer-Olmo L, Núñez-Delicado E, Gabaldón JA. Cyclodextrins in Polymer-Based Active Food Packaging: A Fresh Look at Nontoxic, Biodegradable, and Sustainable Technology Trends. Polymers (Basel). 2021 Dec 28;14(1):104. doi: 10.3390/polym14010104. PMID: 35012127; PMCID: PMC8747138.
- Chaudhuri, S., DiScenza, D. J., Boving, T. B., Burke, A., & Levine, M. (2020). Use of α-cyclodextrin to Promote Clean and Environmentally Friendly Disinfection of Phenolic Substrates via Chlorine Dioxide Treatment. Frontiers in Chemistry, 8, 641.
- Del Valle, E. M. (2004). Cyclodextrins and their uses: a review. Process Biochemistry, 39(9), 1033-1046.