The chief constituent of Bearberry leaves is a crystallizable glucoside
named Arbutin. Arbutin is a natural, plant derived, highly-effective,
stable skin whitening agent that works on the skin by transforming
excessive melanin production into colorless substances as well as
competing with certain enzymes that inhibit tyrosine oxidation
by tyrosinase (a main cause of hyper-pigmentation).
Applications: crafting own skin care/creams and lotions
Titre du document / Document title
Antioxidant activity of polyphenolics from a bearberry-leaf (Arctostaphylos uva-ursi L. Sprengel) extract in meat systems
Auteur(s) / Author(s)
PEGG Ronald B. ; AMAROWICZ Ryszard ; NACZK Marian ;
Résumé / Abstract
Bearberry-leaf (Arctostaphylos uva-ursi L. Sprengel) extract possesses marked antioxidant activity in model and meat systems. A crude ethanolic extract ofbearberry leaves was dechlorophyllized using a silicic acid column,and then fractionated by Sephadex LH-20 column chromatography using ethanol (95%, v/v) and acetone (50%, v/v) as the mobile phases. According to a mass balance, the ethanol fraction comprised 79.2% of the starting material, while the acetone fraction consisted of 9.7%. The content of total phenolics for the fractions and subtractions ranged from 2135 to 9110 Abs725 units/g extract. Even though the acetone fraction was only ca. 10% of the crude extract, its vanillin response was five times greater than that of the ethanol fraction. According to a mass balance of this fraction, ca. 50% of the polyphenolics remained in the aqueous phase when partitioned between water and ethyl acetate. refrigerated storage by 97.0,49.1 and 100%, respectively, when added at a 200-ppm concentration. The ethanol fraction exhibited a classical dose response: when incorporated in meat systems at levels of 200- and 500-ppm before thermal processing, TBARS development was inhibited by 49.7 and 93.9%, respectively, after seven days. This [ethanol] fraction was further subdivided into vanillin-positive constituents; the vanillin-positive fraction possessed weak antioxidant activity in meat model systems, and in some cases demonstrated a slight pro-oxidant effect. The acetone fraction also showed a classical dose response. When added to meat systems at levels of 25-, 50- and 100-ppm, TBARS formation was inhibited by 36.7, 91.4 and 100%, respectively, after seven days of refrigerated storage. It was interesting to note that a subfraction from the acetone product, which was soluble in ethyl acetate but did not have a positive reaction with vanillin, imparted strong antioxidant activity in meat systems. Therefore, vanillin-positive reaction constituents (i.e., condensed tannins) are not solely responsible for the antioxidant activity observed from the bearberry-leaf extract.