Chiang Mai Journal of Science

Endophytic fungi from medicinal plants are prolific producers of bioactive secondary metabolites. The present study aimed to evaluate the antioxidant and antitumor activities of mycelia of an endophytic Phomopsis liquidambari (strain QH4), from Artemisia annua. The antioxidant activities of QH4 extracts extracted from methanol, acetone, ethyl acetate, chloroform and hexane were determined via five different antioxidant models namely free radical scavenging capacity using 2, 2’-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS⁺), 2,2- diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals, reducing power assay and ferrous ion chelating ability. The antitumor activity was determined by MTT assay. The methanol extract (200 μg/ml and 4.0mg/ml) exhibited strong antioxidant capacity in each antioxidant model systems, while the ethyl acetate extract (20 μg/ml) was active against HL-60 leukemia, MCF-7 breast and COLO205 colon cell lines with a growth inhibition of 71.99 %, 53.66 % and 92.70 %, respectively. Total phenolic contents (TPC) of the extracts with different solvents were determined using the Folin-Ciocalteu method. The TPC was highest in methanol extract (60.07 ± 0.31 mg gallic acid equivalent/g dry weight of the mycelia) and lowest in hexane extract (6.54 ± 0.29 mg GAE/g DW of the mycelia). The correlation coefficients from regression analysis showed various relationships between TPC in the extracts and antioxidant activities tested via different models including ABTS⁺ (R² = 0.9651), DPPH (R² = 0.8490), hydroxyl radical scavenging ability (R² = 0.9438), reducing power assay (R² = 0.8266) and ferrous ion chelating ability (R² = 0.4836). The endophytic Phomopsis liquidambari QH4 may have the potential to become a source of natural antioxidant and/or antitumor agents.