Antioxidant Activity and Chemical Profile of Fiddler Crabs as a Form of Self-Defense Against Various Anthropogenic Activities Along Urban Rivers

Fiddler crabs utilize bioactive compounds for defense against environmental stressors. The study aimed to determine the antioxidant activity, bioactive compound profile of fiddler crab extracts as a form of self-defense against various anthropogenic activities along urban rivers. The fiddler crabs (Uca spp.) were collected from the Tanjung Api-Api Port area and Sungsang Village, located in Banyuasin Regency, South Sumatra, Indonesia. Fiddler crab samples were extracted by maceration in ethanol. The antioxidant activity of the extracts was evaluated using the 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging assay. Bioactive compounds profile was determined by qualitative phytochemical screening, followed by gas chromatography-mass spectrometry (GC-MS). Fiddler crab extracts of samples obtained from both locations exhibited weak antioxidant activity with IC50 values of 174.617 μg/mL and 190.786 μg/mL for crab extracts from Tanjung Api-Api area, and Sungsang village, respectively. Phytochemical screening of crab extract from Tanjung Api-Api area revealed the presence of alkaloid, triterpenoids, and saponins. GC-MS analysis identified hexadecanoic acid, trans-13-octadecenoic acid, (E)-9-octadecenoic acid ethyl ester, and cholesterol as the major bioactive compound groups in Tanjung Api-Api Fiddler crab extract. This findings suggest that fiddler crabs produce bioactive chemicals that could help combat oxidative stress caused by pollutants in urban rivers. Further research is needed to characterize these compounds in greater depth and explore their mechanisms of facilitating the adaptation of fiddler crabs to stressful environmental conditions.