Cyclodextrins - Science topic
A homologous group of cyclic GLUCANS consisting of alpha-1,4 bound glucose units obtained by the action of cyclodextrin glucanotransferase on starch or similar substrates. The enzyme is produced by certain species of Bacillus. Cyclodextrins form inclusion complexes with a wide variety of substances.
Questions related to Cyclodextrins
I use the kneading method in order to encapsulate silicon phthalocyanine dichloride in cyclodextrins (β-CD, γ-CD, HP-β-CD and Me-β-CD). My last calculations gave me encapsulation efficiency greater than 100%. Something went wrong... The protocol I follow is: Add i.e 5 mg of the dry complex of the cyclodextrin to 5 mL of DMF. The system is left under stirring for at least 24 hours. The solution is then filtered and fluorescence is measured.
Has anybody ever had a problem like this before and how did you overcome? How can I separate cyclodextrin complexes from the not encapsulated drug? I tried centrifugation without result.
I am investigating interactions of poorly soluble pharmaceutical (nabumetone) with cyclodextrins in solution and solid-state. Complexes of nabumetone and beta cyclodextrins were prepared in different molar ratios by grinding in high-energy vibrational mills and corresponding physical mixtures were prepared using a mortar and the pestle as well (n:n = 5;1, 3:1, 2:1, 1:1, 1:2, 1:3 and 1:5). In the ATR spectra of ground samples with higher content of the pharmaceutical, I noticed an increase in the intensity of characteristic bands of the pharmaceutical (in comparison to corresponding spectra of physical mixture) but I didn't observe the same phenomena in the corresponding transmission spectra. Usually when these kinds of samples are investigated by infrared spectroscopy decrease in the intensity of the characteristic bands of the guest molecule is explained by the inclusion of the molecule in the hydrophobic cavity of cyclodextrin. What is the possible cause of these increments in nabumetone band intensities in ATR spectra? Why aren't these increments visible in transmission spectra as well?
I'm trying to separate Alpha, Beta and Gamma cyclodextrins from each other in a mixed aqueous solution. Now I know that there are slight differences in polarity of the different cyclodextrin molecules so my idea was to try and separate them using SPE.
The components have excellent separation on a silver-ion HPLC column, which suggests to me that SPE could work.
However after a few attempts I have noticed that the CDs have barely any retention on the SPE column.
I would love any suggestions on how to improve separation :)
I am using C-18 column for my analysis. I noticed that after injecting some of my samples which contain cyclodextrins and drug, the back pressure increase. Even after I wash with mobile phase, 80% MeOH, 80% Water and 50:50 MeOH:Water for the whole day.
May I know is there any solutions for this problem?
Before trying different approaches I want to ask the experts in here!
- Is it necessary a supersaturated solution of β-CD? In the literature the amount of β-cyclodextrin always exceeds its solubility. Why?
- Are cyclodextrins able to form host-guest complexes with hydrophilic molecules? Or just hydrophobic molecules?
- Will the precipitate be crystalline and visibly colored? how should the precipitate be washed?
we have a material containing cyclodextrins and cellulose-derived compounds linked with a crosslinker. All components of the polymer contain the same functional groups (such as OH, COOH). The material is insoluble in water and organic solvents. How can I check the degree of cross-linking and the way the how the components are linked with each other? I will be grateful for any suggestions.
I have some samples with cyclodextrins (beta-CD and its derivatives), and I noticed increase in back pressure of HPLC column (C18 column) after each run. Since the samples consist only of drug and cyclodextrin I concluded that the cyclodextrins are the cause.
So, I wonder if you have any suggestion how to wash them out of column.
I tried backflushing it with high water content but it doesn't help much. I also found an article that had similar problem, where they found that backflushing with phosphate buffer and MeOH (90:10) helps, but that was only for sulphobutyleter-B-cyclodextrin. Since I am working with other cyclodextrins I am wondering if anybody else had similar issue and how did you solve it?
Note: after each sequence run I flush my column with 80% water for an hour, and after that with 90% acetonitrile. That helps a little but the pressure still increases slightly.
Thank you in advance.
I am working with 3 different types of cyclodextrins and forming complex with lidocaine. I want to determine the association constant and dissociation constant of the cyclodextrin-lidocaine complex by HPLC method. Any direct references or similar work recommendations to follow/read would be highly helpful. Thanks
I build a complex of cyclodextrin / perfume for use in detergent powder.
How Do I Know perfume (guest molecule) have Appropriate characteristics for complexation with ß-cyclodextrin?
How Do I Know the guest really included in the ß-cyclodextrin cavity?
Hello to everyone! I need to solubilize an hydrophobic molecule whose diameter (approximately 11 Å) is slightly larger than the one of gamma cyclodextrin, do you know any other host molecule that can be suitable for the purpose or any lab/seller that can supply delta or epsilon cyclodextrins? Micelles and liposomes are not suitable for my purposes.
Thank you very much!
I am not an expert in that field so please help me to do it properly. I would like to obtain cationic beta-cyclodextrin in order to modify zeolite surface. I do not have acces to the particular literature reports unfortunatelly. What chemicals should I use ( I have found some amine derivatives) and how to do this? - I need practical tips.
The work reported by Enrico Redenti and Laura Ribeiro states that hydroxy acid increases the complexation efficiency of beta-cyclodextrin. They have prepared ternary (Drug/CD/Hydroxy acid) and quaternary (Drug/CD/Hydroxyacid/Hydrophilic polymer) inclusion complexes and found promising dissolution results. However, it is unclear that how much amount of hydroxy acid must be used for preparing this complex. There are some reports where the authors have used drug, CD and hydroxy acid in the molar ratio 1:1:0.5, whereas some have used 1: 1:1. But, on what basis this has been decided is still an unanswered question for me. Increasing the amount of citric acid will ionize the drug (off course the above mentioned complexes are related to the poorly soluble weak bases) and consequently dissolve it. The phase solubility study and Jobs plot help us to decide the molar ratio of drug and CD. I want to know that how to decide the number of moles of hydroxy acid (e.g. citric acid) that will be required for preparation of a ternary complex if we are preparing drug:CD complex in 1:1 molar ratio.
1. Redenti et al. Drug/cyclodextrin/hydroxy acid multicomponent systems. Properties and pharmaceutical applications. J. Pharm. Sci. Vol. 89, 1–8 (2000).
2. Ribeiro et al. Multicomponent complex formation between vinpocetine, cyclodextrins, tartaric acid and water-soluble polymers monitored by NMR and solubility studies. European Journal of Pharmaceutical Sciences Vol. 24, 1–13 (2005).
I am currently working on the inclusion complexation of ochratoxin A with several cyclodextrins derivatives. To find out which cyclodextrin has the highest inclusion efficiency, I plan to do a phase solubility study for all inclusion complexes. The thing is I have dissolved all of my ochratoxin A sample into organic solvent to prepare a stock, and dilute it multiple times before use. This is because ochratoxin A is quite expensive, and we cannot afford to put milligrams of it to run a single analysis. I just realised that phase solubility is only applicable to solid samples, so I guess my aqueous solution of ochratoxin A cannot be worked? If that’s the case, any other analysis that I can use to investigate the inclusion efficiency of diffferent cyclodextrins to encapsulate ochratoxin A?
Hope I made myself clear.
Much appreciated for any suggestions.
Dear formulation experts,
We are facing a challenge when dosing the compound into the eye as eye-drops, aiming at the systemic exposure. Dosed compound caused mild irriation, and we are looking the ways to minimize that. Increasing the viscosity seems to work, but not enough. Also cyclodextrines are planned to be tested. Any insight and potential ideas related to composition or formulation technology to mask compound eye irritation will be highly appreciated.
Thank you for your time and effort!
As we know, Cyclodextrins are cyclic hexamer, heptamer and octamer of α-D-glucose having 6, 7 & 8 numbers of glucopyranose units respectively bound by α-(1–4) linkages. Though, There is no terminal 1-4 linkage as they are cyclic....
as you know, cyclodextrins have a 3 reactive alcohols. 2-OH, 3-OH and 6-OH, I am gonna to bind 2 molecules to them. what should i do?
We tried freeze drying, solvent evaporation and kneading methods but didn't get substantial XRD patterns of comlexes.
In some articles, it was stated that the mixture was filtered before freeze-drying. But will filtration not cause material loss?
Some of the molecule is complexed with cyclodextrins, remeaning part of the drug gives the crystalline peak in XRD. Do you have a suggestion to increase the interaction between niclosamide and cyclodextrin?
We observed decreased sensitivity of our LCMS measurement data of plasma samples after analysing cyclodextrins.
is it possible interaction between hydoxyl (OH) group of Cyclodextrins and Amine (NH2) and Amide group of other materials at 130 C temperature (High Temperature condition)?
solution pH : Alkaline (10-11) ,aqueous
I am looking to encapsulate some plant extracts in cyclodextrins, but I am unable to decide either water or ethanol based extracts or essential oils of particular plant will be more suitable. And, if possible, could anyone clarify the difference in extract and essential oil.
Thanks in advance.
Is there any commercial pharmaceutical product(s) developed using Solid dispersion technology with Cyclodextrins?
In order to facilitate the skin permeation of transdermal film of sodium hyaluronate , what possible strategies can be put into practice? Apart from using the permeation enhancer like cyclodextrins, any other changes in polymer selection or choosing particular solvent system or modification in film preparation by solvent casting method can be done? Thank you.
ε = AF −A0/S0. (doi:10.1016/j.jpba.2008.02.018)
AF being the absorbance value of drug when is complexed
the presence of cyclodextrin showed that there was decreased in extinction coefficient of the drug. is it true? if yes , so A0 > AF? and extinction coefficient(ε) would be negative?
Could not find enough information about cyclodextrine interaction with cholesterol. What are the concentrations and ratio of the components?
I'm theoretical chemist. The idea behind is to enhance publications for both. I´d like to find experimentalists or theoretical researchers on this topic.
Can anyone give me a step-by-step Autodock tutorial to small molecule dock antioxidant to cyclodextrins?
Do you know how to dock antioxidant to cyclodextrins?
Can you give me a step-by-step tutorial?
I want to dock small molecule and antioxidant to cyclodextrins?
In the literature there are several reports of crosslinking poly- or even oligosaccharides as cyclodextrins with sodium trimetaphosphate under relatively mild conditions (50-70 deg C, few hours) in the presence of sodium hydroxide. I tried to reproduce some of these papers using methlycellulose, an easily available, water soluble polysaccharide. I observed an unexpected phenomenon: the system gelled at 60 deg C but became a viscous fluid again after cooling back to room temperature. The same can be observed using simple methycellulose solution without STMP and sodium hydroxide. I could not find an easy explanation for this phenomenon. Especially the latter. (It may have happened that the crossliniking reaction itself was not completed or in a reversible way).
I would appreciate the comments of colleagues having practical experience in STMP crosslinking.
Since researchers are considering the use of cyclodextrins for removal of pollutants such as herbicide, heavy-metals, dyes etc through laboratory experiments. In practical vision, is it possible to remediate the environmental soil/water?
Can anyone highlight some papers relating cyclodextrins to 2D materials (single layer materials)? I am starting to work with 2D materials and trying to find a common ground/applications/sinthesys methods for these two kind of compounds. If anyone has some kind of review about it, I would be thankful!
I am performing a solubility test to compare the rate of solubility of a Tenoxicam-Betacyclodextrin complex to that of Tenoxicam alone.
For example,its known that 2.5 mg of Tenoxicam is excess in 25 mL of water.
Hence,i dissolve it accordingly and once saturated condition is achieved,the Tenoxicam is indeed,in excess.
On another note though, I estimated that 10.5 mg of my inclusion complex would consist of 2.5 mg of Tenoxicam.But,it could be lesser or higher than that right? And the parameter by which i am measuring the rate is time, hence I cannot add more inclusion complex once i have started the solubility studies.
How do I go about this? You may ask me in detail if there is anything I need to be clear about.
We are extracting curcuminoids from turmeric using ethyl acetate and IPA solvents.
The maximum recovery we get is about 55% of the total content of curcuminoids present in the raw material.
Is there any way to increase the recovery of curcuminoids?
Which group of thiomersal going to bind with cyclodextrin: either mercury ion or sulfur group? In some paper quoted that thiomersal with cyclodextrin reduces anti-microbial activity.
We have synthesized a push-pull 4,4'-bipyridine containing azobenzene dye and we have prepared its stoppered inclusion complexes (rotaxanes) with α and β cyclodextrin. (The inclusion complexes formation has been varified using various spectroscopic techniques).
Surprisingly, in the UV/Vis spectra of the rotaxanes, the molar extinction coefficient of the azo π-π* band increases (it gets even 50000 1/(M.cm) that is almost double as compared to the cyclodextrin-free dye. I cannot find any information which could explain this behavior, therefore I would be glad to read your opinion.
Curcumin we can measure in UV, but how can we measure the amount of cyclodextrin preset in the complex? In the following paper it has mentioned in 2.3 Formulation of the cyclodextrin complex of curcumin in that paragraph in 6th line you have mentioned that the "complex recovered contains 12 g/L curcumin and 93 g/L of Cyclodextrin.
I have a novel compound that is insoluble in water. I have tried cyclodextrines and varying pHs. I have also tried to presolubilize in a wide variety of solvents (hexane, ACN, alcohols, DMSO, chloroform, acetone, xylene, etc) and found it is only slowly soluble in toluene. Is there a standard way to prepare a salt I should try? I also welcome other suggestions.