From molecular modeling to Raman microspectroscopy: unprecedented demonstration of the hygroscopic properties of apiogalocturonans
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Presented by: Laurie Verzeaux
Introduction
To meet the needs of dehydrated skin, molecules with a high hygroscopic potential are necessary to effectively and durably hydrate it. In this context, SILAB was interested in pectins. Indeed, these molecular structures found in plant walls are at the heart of the water exchange regulation. Among the pectins, we focused on apiogalacturonans, a singular pectin that is currently only found in a few species of aquatic plants. As these molecules are key structures in water regulation of aquatic plants, we hypothesized that it could have beneficial role for skin hydration. SILAB thus supplied in Spirodela polyrhiza, a duckweed used in traditional Chinese medicine for its effects on water metabolism and known to be naturally rich in apiogalacturonans. A controlled hydrolysis was applied to purify these molecules while maintaining its original structure.
Aim
The aim of this study was to investigate the hygroscopic potential of apiogalacturonans and their moisturizing potential on skin suffering from dehydration.
Methods
1) In silico prediction of 3D structure and hygroscopic potential of apiogalacturonans
First, several models of apiogalacturonan were built based on structural information obtained from the literature. For this purpose, chains of galacturonic acid were branched with mono-and di-apiose residues. Molecular dynamics (MD) simulations were performed using GLYCAM06j-1 force field, and apiose parameters derived from quantum mechanics calculations, with TIP3P water model. Then, the hygroscopic potential was predicted in silico by analyzing the frequency of interaction of water molecules with each apiogalacturonan residue.
2) In vivo investigation of the apiogalacturonan hygroscopic potential
The water capture in the skin was investigated directly in vivo by Raman microspectroscopy by using D20 on the arm of 8 volunteers. For this purpose, an emulsion containing apiogalacturonans was applied at the surface of the skin for 3 hours and then, an occlusive patch containing D20 was applied for 30 minutes. This molecule displays the same behavior than H20 but with a characteristic Raman spectrum allowing it to be tracked specifically. Raman microspectroscopy acquisitions were conducted on different skin depths for 15 minutes.
Moreover, to determine and validate the cosmetic interest, in vivo measurements were conducted on Caucasian and Asian volunteers with a dehydrated skin by using a corneometer and a moisturemeter to investigate respectively the stratum corneum and epidermis to superficial dermis hydration levels.
Results
1) In silico prediction of 3D structure and hygroscopic potential of apiogalacturonans
For the first time, molecular modeling investigations allowed us to characterize the 3D structure and dynamics of apiogalacturonans. MD simulations revealed that these molecules have characteristic shell of waters in their solvation process. Quantification of interactions identified the presence of 23 water molecules on average in contact with each residue of apiogalacturonan. From a theoretical point of view, this building fragments have an interesting hygroscopic potential that seems twice as high as the one of hyaluronic acid (Taweechat et al., 2020).
2) In vivo investigation of the apiogalacturonan hygroscopic potential
Thanks to the in vivo D20 tracking by Raman microspectroscopy, investigations revealed that after 3 hours of application at the surface of the skin, apiogalacturonans significantly capture and retain more water in the epidermis and deeper than a placebo control. 3 hours after a unique application, apiogalacturonans significantly hydrate the stratum corneum (+17.8%) up to the superficial dermis (+11.9%) of Caucasian volunteers with dehydrated skin. These effects are increased 6 hours after the application and maintained after 21 and 42 days of application. This hydrating potential is also validated on Asian skin.
Conclusion and Discussion
By combining molecular modeling and in vivo investigation, these results evidenced for the first time the high hygroscopic potential of apiogalacturonans. Not only do these original natural molecules interact with water molecules, but they capture and retain them efficiently and durably in the skin. Hence, apiogalacturonans are of great interest for the care of dehydrated skin.
To meet the needs of dehydrated skin, molecules with a high hygroscopic potential are necessary to effectively and durably hydrate it. In this context, SILAB was interested in pectins. Indeed, these molecular structures found in plant walls are at the heart of the water exchange regulation. Among the pectins, we focused on apiogalacturonans, a singular pectin that is currently only found in a few species of aquatic plants. As these molecules are key structures in water regulation of aquatic plants, we hypothesized that it could have beneficial role for skin hydration. SILAB thus supplied in Spirodela polyrhiza, a duckweed used in traditional Chinese medicine for its effects on water metabolism and known to be naturally rich in apiogalacturonans. A controlled hydrolysis was applied to purify these molecules while maintaining its original structure.
Aim
The aim of this study was to investigate the hygroscopic potential of apiogalacturonans and their moisturizing potential on skin suffering from dehydration.
Methods
1) In silico prediction of 3D structure and hygroscopic potential of apiogalacturonans
First, several models of apiogalacturonan were built based on structural information obtained from the literature. For this purpose, chains of galacturonic acid were branched with mono-and di-apiose residues. Molecular dynamics (MD) simulations were performed using GLYCAM06j-1 force field, and apiose parameters derived from quantum mechanics calculations, with TIP3P water model. Then, the hygroscopic potential was predicted in silico by analyzing the frequency of interaction of water molecules with each apiogalacturonan residue.
2) In vivo investigation of the apiogalacturonan hygroscopic potential
The water capture in the skin was investigated directly in vivo by Raman microspectroscopy by using D20 on the arm of 8 volunteers. For this purpose, an emulsion containing apiogalacturonans was applied at the surface of the skin for 3 hours and then, an occlusive patch containing D20 was applied for 30 minutes. This molecule displays the same behavior than H20 but with a characteristic Raman spectrum allowing it to be tracked specifically. Raman microspectroscopy acquisitions were conducted on different skin depths for 15 minutes.
Moreover, to determine and validate the cosmetic interest, in vivo measurements were conducted on Caucasian and Asian volunteers with a dehydrated skin by using a corneometer and a moisturemeter to investigate respectively the stratum corneum and epidermis to superficial dermis hydration levels.
Results
1) In silico prediction of 3D structure and hygroscopic potential of apiogalacturonans
For the first time, molecular modeling investigations allowed us to characterize the 3D structure and dynamics of apiogalacturonans. MD simulations revealed that these molecules have characteristic shell of waters in their solvation process. Quantification of interactions identified the presence of 23 water molecules on average in contact with each residue of apiogalacturonan. From a theoretical point of view, this building fragments have an interesting hygroscopic potential that seems twice as high as the one of hyaluronic acid (Taweechat et al., 2020).
2) In vivo investigation of the apiogalacturonan hygroscopic potential
Thanks to the in vivo D20 tracking by Raman microspectroscopy, investigations revealed that after 3 hours of application at the surface of the skin, apiogalacturonans significantly capture and retain more water in the epidermis and deeper than a placebo control. 3 hours after a unique application, apiogalacturonans significantly hydrate the stratum corneum (+17.8%) up to the superficial dermis (+11.9%) of Caucasian volunteers with dehydrated skin. These effects are increased 6 hours after the application and maintained after 21 and 42 days of application. This hydrating potential is also validated on Asian skin.
Conclusion and Discussion
By combining molecular modeling and in vivo investigation, these results evidenced for the first time the high hygroscopic potential of apiogalacturonans. Not only do these original natural molecules interact with water molecules, but they capture and retain them efficiently and durably in the skin. Hence, apiogalacturonans are of great interest for the care of dehydrated skin.