ฤทธิ์ยับยั้งเอนไซม์ไทโรซิเนสและฤทธิ์ต้านเชื้อจุลินทรีย์จากสมุนไพรไทย

Thesis (M.Pharm., Pharmaceutical Sciences)--Prince of Songkla University, 201

ANTI-RADICAL ACTIVITIES OF XANTHONES AND FLAVONOIDS FROM GARCINIA SCHOMBURGKIANA

Objective: The present study aimed to isolate and identify the phytochemical constituents of Garcinia schomburgkiana branches and evaluate the antioxidant activity of the compounds.Methods: The chromatographic and spectroscopic (UV, IR, NMR and MS) techniques were used for the isolation and elucidation of the compounds, respectively. The antioxidant activity of the isolated compounds was examined through DPPH, ABTS, nitric oxide and hydroxyl radical scavenging assay.Results: The (-)-5,7,3′,5′-tetrahydroxyflavanone (1), which was firstly found in the Garcinia species, together with kaempferol (2), (-)-dihydrokaempferol (3), euxanthone (4), gentisein (5) and norathyriol (6) were isolated from G. schomburgkiana. Among the isolated compounds, compound 1 and 6 exhibited the highest potential for anti-radical activities.Conclusion: Compound 1 could be used as the chemotaxonomic marker of G. schomburgkiana. The branches of G. schomburgkiana could be the alternative source of the antioxidants. The possible inhibitory mechanisms were proposed through the action of electron transfer, chelation, and nitrosylation.Â

Synergistic Effect of Pericarp of Mangosteen and Propolis from Stingless Bee Extracts on Nitric Oxide Scavenging Activity

The aim of this research is to study the synergistic effect on the nitric oxide scavenging activity of mangosteen pericarp and the stingless bee (Tetragonula laviceps) propolis extracts and their phytochemical constituents. The propolis and mangosteen pericarp were extracted by reflux method with ethanol. TPC and TFC of propolis extract were 123.73±2.80 mg GAE/g extract and 70.65±11.21 mg QE/g extract, respectively, and mangosteen pericarp extract was 387.93±15.10 mg GAE/g extract and 87.00±5.06 mg QE/g extract, respectively. The ESI-LC-MS data displayed that both extracts have a variety of phytochemical constituents, such as xanthones, flavonoids, and miscellaneous. The synergistic effect of Nitric oxide scavenging activities of propolis and mangosteen pericarp extracts showed higher activity than individual extracts with various concentrations. Thus, the synergistic effect of propolis and mangosteen pericarp extracts may be an alternative source of inflammatory drug development in the future