First of all, treat the DNA with RNase enzyme for ~1 hr then with Proteinase K enzyme for another ~1 hr (both at 37 Celsius)

Follow the general process of DNA extraction (from step of Phenol: chloroform method).

I think you will get good quality of DNA

If your extracted DNA is contaminated with protein, you can follow the following protocol -

1. Take 100 ul of stock DNA in 2 ml centrifuge tube

2. Add equal volume of phenol:chloroform:isoamyl alcohol (25:24:1)

3. Thoroughly mix by inversion

4. Spin at 8000 rpm for 15 minutes at 10oC

5. Transfer the supernatant in a new tube

6. Add 200 ul of pre-chilled isopropanol/ethanol and 50 ul of 5M NaCl

7. Incubate at -20oC for at least 1 hr

8. Spin at 8000 rpm for 15 minutes at 10oC

9. Discard the supernatant

10. Wash the pellet twice with 76% ethanol

11. Air-dry the pallet at 37oC until the ethanol smell goes-off

12. Resuspend the pellet in TE buffer

When you went to extract DNA from plant l prever to extrasct it from the leaf

Extract it manual using CTAB ....protocol