Evaluation of stability,Antioxidative and free radical scavenging activities of Artocarpus Lakoocha heartwood extract

Abstract

This study was aimed to determine the physical and biochemical stabilities of dried aqueous extract of Artocarpus lakoocha, Ma-Haad (Puag-Haad) in solution, with and without antioxidants, Addition of sodium metabisulfite, either alone or in combination with BHA and Rovisome® was able to maintain the original color. After 24 weeks, the values of % tyrosinase inhibition of Puag-Haad solutions, with and without stabilizers, were not different among each other. However, this could be due to saturation of tyrosinase under the current testing conditions. Oxyresveratrol was also purified from Puag-Haad by column chromatography and the yield was 14.83 % w/w. Antioxidant properties of Puag-Haad was subsequently tested for the scavenging effect on DPPH radical, superoxide anion, hydroxyl radical and singlet oxygen. Puag-Haad and oxyresveratrol exhibited a comparable but generally lower antioxidant activity against DPPH than other reference antioxidants (IC₅₀ = 8.25 and 8.78 µg/ml, respectively). Similar result was found in the superoxide anion scavenging activity with the IC₅₀ of 46.11 µg/ml for Puag-Haad and 44.31 µg/ml for oxyresveratrol. Regarding the hydroxyl radical scavenging activity, Puag-Haad and oxyresveratrol appeared to have potency comparable to EGCG but slightly less potent than l-ascorbic acid and Trolox®. The lC₅₀ values were 9.47 and 7.41 µg/ml, respectively. Singlet oxygen scavenging activity was carried out via red blood cell hemolysis test. Puag-Haad, oxyresveratrol and pine bark extract were equally potent singlet oxygen scavengers whereas EGCG was much less effective. On the other hand, l-ascorbic acid and Trolox® did not show any anti-hemolytic activity in the concentration range studied (200-600 µg/ml). These results suggested that Puag-Haad and oxyresveratrol were capable of scavenging several reactive oxygen species with varying potency when compared to other antioxidants commonly used in the cosmetic products. Considering its various antioxidative properties together with the previously reported antityrosinase activity, the inexpensive and easily available A. lakoocha extract or Puag-Haad has a very promising potential for use as an antioxidant ingredient for both the pharmaceutical and cosmetic applications.