Antioxidant activity and compounds identification of Sauropus androgynus (L.) merr. and Moringa oleifera lam leaves combination fermented with Kombucha consortium

Kombucha is a fermented drink from herbs that provides many benefits for health, including antioxidant activity. Katuk (Sauropus androgynus (L.) Merr. ) leaves and kelor (Moringa oleifera Lam) leaves are common vegetables in Indonesia, and these plants were reported to contain natural antioxidants. This study aims to examine the antioxidant activity of single and mixture of katuk and kelor leaves before and after fermentation with Kombucha and identify the bioactive compounds of those samples. Katuk and kelor leaves were collected around the Serang Banten area. Antioxidant activity analysis was performed using free radicals DPPH method. Total phenolic content (TPC) and total flavonoids content (TFC) were measured. Compounds identification was conducted using liquid chromatography-mass spectrometry (LC-MS/MS). The results showed that the mixture of katuk and kelor fermented with Kombucha (KoKtKl 3:1) in the 50μl sample had the highest antioxidant activity (80.5% inhibition of DPPH), while under the same conditions, the unfermented sample only had 56.1% DPPH inhibition. Fermentation of katuk and kelor leaves with Kombucha for 7 days decreased pH, and increased antioxidant activity, TPC and TFC. The samples with the highest antioxidant activity (KoKtKl 3:1) were identified as containing kaempferol-3-O-rutinoside, kaempferol-3-O-β-D-glucopyranoside and quercimetrin, which are flavonoid glycosides that may be responsible for the antioxidant activity. In conclusion, katuk and kelor leaves showed antioxidant activity before and after fermentation with Kombucha, both as single preparations and mixtures which showed the potential to be studied further as a functional beverage for antioxidants.