Comparative Study of the Biological Activity of Allantoin and Aqueous Extract of the Comfrey Root

Abstract

This study investigates the biological activity of pure allantoin (PA) and aqueous extract of the comfrey (Symphytum officinale L.) root (AECR) standardized to the allantoin content. Cell viability and proliferation of epithelial (MDCK) and fibroblastic (L929) cell line were studied by using MTT test. Anti-irritant potential was determined by measuring electrical capacitance, erythema index (EI) and transepidermal water loss of artificially irritated skin of young healthy volunteers, 3 and 7 days after application of creams and gels with PA or AECR. Pure allantoin showed mild inhibitory effect on proliferation of both cell lines at concentrations 40 and 100 µg/ml, but more pronounced on MDCK cells. Aqueous extract of the comfrey root effect on cell proliferation in concentrations higher than 40 µg/ml was significantly stimulatory for L929 but inhibitory for MDCK cells. Pharmaceutical preparations that contained AECR showed better anti-irritant potential compared with PA. Creams showed better effect on hydration and EI compared with the gels that contained the same components. Our results indicate that the biological activity of the comfrey root extract cannot be attributed only to allantoin but is also likely the result of the interaction of different compounds present in AECR. Topical preparations that contain comfrey extract may have a great application in the treatment of skin irritation.

Stability, antioxidant activity, in vivo safety and efficacy of creams with standardized wild apple fruit extract: a comparison of conventional and biodegradable emulsifiers

“…Electrical conductivity of investigated creams during the entire study period was more than 50 S cm −1 (Table ), implying the o/w type of emulsion system with creamy consistency . It was shown that CEW after 7 and 180 days of storage at 22 ± 2°C had significantly higher electrical conductivity compared to electric conductivity of PL (Table ).…”

“…Organoleptic characteristics of the creams have remained the same after 180 days of storage in dark at 22 ± 2°C (Table ), which might be an indicator of a good physico‐chemical stability of investigated samples. CEW cream was of denser consistency after 180 days of storage compared to consistency recorded after 7 days, which might be a result of subsequent structuration of the system in terms of solidification because of the presence of used conventional non‐ionic mixed emulsifier .…”

“…The acidic nature of the wild apple fruit extract (EW), with standardized concentration of FAs (pH value of the EW was 3.25 ) certainly affected the pH of the cream with EW as CAS. Insignificant changes in pH values over time could be disregarded, since the pH values of the investigated creams after the preparation and over the investigated time were within the recommended pH values for products intended for application to the skin .…”

“…It is possible that after using of conventional non‐ionic mixed emulsifier, a larger amount of the water remains free, so called ‘free water’ placed within the emulsion system independently on liquid‐crystalline lamellar system (shown by polarization micrographs, Fig. ) , while after using the biodegradable mixed emulsifiers of alkyl polyglucoside type, water is bound intralamellarly within the structures of liquid crystals . Certainly, stable and unchanged values of pH and electrical conductivity hold at almost same level during the study period might be one of the indicators of samples physico‐chemical stability.…”

“…Cosmetic products containing bioactive substances (fruit acids‐FAs and polyphenolic compounds‐PFCs) after application on the skin might prevent, reduce and/or eliminate the adverse consequences of oxidative stress‐OS (wrinkles, hyperpigmentation), might effectively moisturize dry and irritated skin and improve skin functions and structure, as well as aesthetic appeal . In addition, favourable safety profile of these bioactive substances from plant extracts is in line with the current needs and expectations of modern consumers/users .…”