Aim: Symphytum officinale (comfrey) is a medicinal plant commonly used in decoction and ailments. It protects the skin against UV-irradiation. Ultraviolet irradiation may induce variable effects on the constituents of herbal extracts and thereby may limit or improve the advantages of using these extracts as medicinal supplements. This study aimed to assess the effect ultraviolet radiations including UVA, UVB and UVC on the constituents of Symphytum officinale aqueous and alcoholic extracts.
Materials and Methods: Comfrey extracts (1% w/v) were prepared using distilled water, ethanol and methanol and exposed to wide spectra of wavelength of UVA, UVB, and UVC for 10 minutes. The principal peak on the UV-spectroscopy scanning, the flavonoids, reducing power, and the allantoin levels were determined before and after irradiation.
Results: Ultraviolet irradiation reduces the magnitude of the principle peak at 355nm wavelength of the aqueous infusion and methanol extracts. It improves the levels of flavonoids and reducing power of the aqueous extracts, and increases the levels of allanotoin in aqueous and methanol extracts.
Conclusions: UV-radiation enhances the yields of active ingredient, of comfrey extracted with methanol whereas improves the flavonoids, reducing power and allantoin levels of comfrey extracted by the aqueous infusion method. UV-radiation reduces the levels of flavonoids, reducing power and allantoin when the comfrey extracted by alcohols
Key words: Comfrey, ultraviolet irradiation, flavonoids, reducing power, allantoin
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