The researchers studied the antioxidant properties of extracts from mango and cumin to prevent rubber from darkening. They extracted crude extracts using acetone and ethanol then tested antioxidant activity using DPPH radical scavenging assays. Ethanol extracts of mango showed the highest inhibition of radicals. These extracts along with ascorbic acid best prevented darkening of rubber samples over time compared to synthetic antioxidants. The ethanol mango extract performed nearly as well as a commercial rubber antioxidant at a lower cost, making it suitable for use in rubber production in southern Thailand.

1. Siwakorn Nopsuwan Pongphak Chidchob Pichet Praveschotinunt Researchers Mr.Sorachai Sae-lim Advisor

2. Background

3. autoxidative reaction

4. Antioxidants

5. Studying the most efficiently antioxidant compound to protect dark color in rubber Objective

6. Studying antioxidant property by using DPPH radical scavenging assay Extracting the crude extracts from mangos teen and cumin Studying the efficiency of antioxidants in the Para rubber water to prevent artificial flower from changing to a dark color Analyzing the color from Para rubber Preparing the mixture of Para rubber water for the artificial flower Method

7. Extracting the crude extracts from mangos teen and cumin

8. Studying the efficiency of antioxidants by using DPPH radical scavenging assay Evaluation of Antioxidation Activity Absorbance at 517 nm The DPPH radical scavenging assay Sample ( 30 ml ) 2 mg/100ml DPPH ( 3 mL ) UV-Vis Spectrophotometer

9. Detecting absorbance at Wave length 517 nm

10. The efficiency of antioxidants by using DPPH radical scavenging assay Absorbance 0 min 15 min 30 min 45 min 60 min Absorbance of antioxidant A-G per minute Antioxidants MR Wingstay L 1 Na 2 S 2 O 5 (A) 2 Ascorbic acid (B) 3 BHT(C) 4 Acetone extract from cumin (D) 5 Ethanol extract from cumin (E) 6 Acetone extract from mangos teen (F) 7 Ethanol extract from mangos teen (G)

11. % inhibit Percent inhibition A-G Antioxidants MR Wingstay L 1 Na 2 S 2 O 5 (A) 2 Ascorbic acid (B) 3 BHT(C) 4 Acetone extract from cumin (D) 5 Ethanol extract from cumin (E) 6 Acetone extract from mangos teen (F) 7 Ethanol extract from mangos teen (G)

12. Antioxidants MR Wingstay L 1 Na 2 S 2 O 5 (A) 2 Ascorbic acid (B) 3 BHT(C) 4 crude extract from cumin by acetone (D) 5 crude extract from cumin by ethanol (E) 6 crude extract from mangos teen by acetone (F) 7 crude extract from mangos teen by ethanol (G)

13. Studying the efficiency of antioxidants in the Para rubber water to prevent artificial flower from changing to a dark color Preparing the mixture of Para rubber water for the artificial flower Analyzing the color from Para rubber

14. Preparing the mixture of Para rubber water for the artificial flower substance percert ( phr) 60 % crude para rubber 100 KOH 0.1 20 % K+L- 0.1 ZDBC 0.7 ZnO 0.5 S 0.7 Antioxidant compound 1.0

15. Preparing the mixture of Para rubber water for the artificial flower Antioxidants MR Wingstay L 1 Na2S2O5 (A) 2 Ascorbic acid (B) 3 BHT(C) 4 Acetone extract from cumin (D) 5 Ethanol extract from cumin (E) 6 Acetone extract from mangos teen (F) 7 Ethanol extract from mangos teen (G)

16. Analyzing the color from Para rubber

17. MVH PC image V.8 program John Pickle and Jacqueline Kirtley Copyright 2004 by the Regents of the University of California

18. The efficiency of antioxidants in the Para rubber water to prevent artificial flower from changing to a dark color 0 hr 24 hr 48 hr 60 hr

19. Antioxidants Rate of changing Rate of changing the RGB color

20. Conclusion The antioxidants that have the best percent inhibition are ascorbic acid and ethanol extract from mangos teen. The IC 50 of them are 31.7 and 35.61 mg/ml. The Para rubber waters that have ascorbic acid and ethanol extract from mangos teen are the best mixtures that can prevent Para rubber from changing to a dark color but they can do it less than the MR Para rubber water.

21. Conclusion The ethanol extract from mangos teen is suitable antioxidant that we should use for the Para rubber water in that it has low price in south of Thailand and the antioxidant property of its is near to wingstay L in the MR Para rubber water.