Background: Free radicals can cause various diseases, one of which is skin
disease in the form of premature aging. To prevent the bad effects of free radicals,
it can be overcome by giving antioxidants. Antioxidants are compounds that can
protect the body from damage to cells by free radicals. The content of flavonoids
can prevent damage to the skin, where this compound is also contained in sour sop
leaves (Annona muricata L.) which are thought to contain flavonoid compounds
that can act as antioxidants. Method: The ethanol extract nanoparticle
formulations were prepared using the ionic gelation method with NaTPP which
acts as a cross-linker, and chitosan as a polymer. Gel formulas are made using
variations in the concentration of active substances 10%, 20%, and 30%. Result:
Measurement of nanoparticles obtained% transmittance of 95.9%. The PSA test
resulted in a result of 1.57 pm with a Zeta Potential of75.0 mV The results of the
DPPH antioxidant measurement method showed that the JC50 results in formula
1 were 14.32 (very strong), formula 2 was 10.92 (very strong), and formula 3 was
8.39 (very strong). The results of antioxidant measurements show that the gel
formulation in this study has the efficacy of sunscreen and antioxidants.