The effect of fermentation on total phenolic, flavonoid and tannin content and its relation to antibacterial activity in jaruk tigarun (Crataeva nurvala, Buch HAM)

Jaruk tigarun is a traditional fermented food from South Borneo Indonesia, made from tigarun flower (Crataeva nurvala, Buch HAM) . It has been used traditionally to reduce fever and to cure disease for postpartum women. Although it has been consumed for generations and believed to have health benefit, limited scientific research have been done to evaluated it. The study aimed to determine total phenolic, tannin and flavonoid content and evaluated the antibacterial activities of fresh and fermented tigarun flower extract. The fresh and fermented flowers (jaruk tigarun) were freeze dried, powdered and extracted using methanol, ethanol and ethyl acetate solvent. The total phenolic and total tannin were determined using Folin-Ciocalteu methods while total flavonoid content by aluminium trichloride (AlCl3). Antibacterial activity in each extract and MIC were evaluated using well diffusion and macrodilution methods. The result showed that the highest total phenolic content was obtained in methanolic extract of jaruk tigarun (53.24 ± 0.21 mg GAE/g). After fermentation, total phenolic and flavonoid content of tigarun flower generally increased while total tannin content was decreased. The increasing of total phenolic and flavonoid content consequently exhibited the strongest antibacterial activities. Methanolic extract of jaruk tigarun showed high inhibition compared to ethanolic and ethyl acetic extract. The highest inhibition of methanolic extract was on Pseudomonas flourescens (8.62 ± 0.54 mm). However the antibacterial activity is lower than that chloramphenicol. Pseudomonas flourescens and Staphylococcus aureus showed the most susceptibility to methanolic extract with MIC concentration 6,250 μg/mL. The result indicated that the fermentation increase the total phenolic and antibacterial activity of jaruk tigarun.