Evaluation of Antibacterial Activity, Total Phenolic and Flavonoid Contents of Extracts of Endophytic Fungi Associated with Tinospora crispa (L.) Hook. f. & Thomson

Abstract

In the preliminary study, endophytic fungi associated with Tinospora crispa have been reported as antibacterial that assayed by TLC-bioautography. While more comprehensive studies for antibacterial activity using microdilution, total phenolic, flavonoid contents, and their relationship of extracts of fungal endophytes from this plant have never been investigated yet. This research aims to assess antibacterial activity, total phenolic, total flavonoid, and their relationship of fungal extracts associated with T. crispa. Based on morphological identification, this study revealed that endophytic Phomopsis sp. is the most isolated fungi (35% of fungal isolate composition). Based on the microdilution method, morphological and molecular identification showed that the fungal extracts performing a vigorous antibacterial activity (MIC value: <64 μg.ml-1) against S. aureus InaCC-B4 were three extracts i.e., Colletotrichum brevisporum TcDn1Bd-01, and Diaporthe passifloricola TcBt2Bo-03, and Alternaria alstroemeriae TcTd2Bo-07. While one extracts, Phomopsis sp. TcBt1Bo-06, have potent bacterial growth inhibition toward E. coli InaCC-B5 (MIC value: <64 μg.ml-1). The highest of both total phenolic content (TPC) and total flavonoid content (TFC) values of the extract is A. alstroemeriae TcTd2Bo-07 which are 166.210 ± 0.000 GAE/extract (mg/g) and 339.991 ± 0.136 QE/extract (mg/g), respectively. There is a negative and significantly very high Pearson’s correlation TPC values toward the MIC value of antibacterial against S. aureus and E. coli (r = -0.671 and -0.969, respectively, P<0.01). The results suggest that the extracts of endophytic fungi can be used as antibacterial sources. Evaluation of chemical structure and antibacterial activity of pure compound need to be solved.