Terphenyllin

The protective effects of 3,3"-di-OH-terphenyllin (3,3"-DHT) and 3-OH-terphenyllin (3-HT), two secondary metabolites produced by Aspergillus candidus (CCRC31543), against hydrogen peroxide-induced oxidative damage to Int 407 cells, were evaluated. The results showed that H2O2 caused an increase in lactate dehydrogenase (LDH) leakage and DNA damage in Int 407 cells; however, the addition of 3,3"-DHT and 3-HT significantly reduced this effect (P0.05), but oxidized glutathione levels increased when Int 407 cells were pre-incubated with these two compounds. These findings suggest that 3,3"-DHT and 3-HT have the ability to protect against oxidative damage to Int 407 cells and that this protective effect may be associated with the ability to reduce ROS formation and increase catalase activity.

Terphenyllin (1), a naturally abundant p-terphenyl metabolite, was isolated from the coral derived fungus Aspergillus candidus together with four natural analogues 2-5. To evaluate their potency and selectivity, a series of new derivatives of 1 were designed and semisynthesized. They were evaluated for their α-glucosidase inhibitory, cytotoxic, and antibacterial activities. Compounds 1, 3, 4, 7, 8, 10, 11, 14, 15, 21, 23, 24, 29, 39, and 40 showed significant α-glucosidase inhibitory activity with IC50values of 4.79-15 μM, which were stronger than that of the positive controls, 1-deoxynojirimycin (IC50= 192.0 μM) and acarbose (IC50= 707.9 μM). Compounds 7 and 10 have relatively higher therapeutic indices (CC50/IC50= 17 and 10, respectively), representing potential promising leads. The enzyme kinetic studies of compounds 1 and 24 showed a non-competitive inhibition on α-glucosidase with Ki values of 1.50 and 3.45 μM, respectively. Additionally, compounds 14, 21, 26, 29, 32, 35, and 37 were found to exhibit strong cytotoxicity against three tumor cell lines A549 (lung adenocarcinoma epithelial), HeLa (cervical carcinoma), and HepG2 (hepatocellular liver carcinoma) with IC50values ranging from 0.15 to 5.26 μM. Further study indicated that 32 could induce S-phase arrest in the cell cycle progression.

Three novel compounds, 4-methyl-candidusin A (1), aspetritone A (2) and aspetritone B (3), were obtained from the culture of a coral-derived fungusAspergillus triticiSP2-8-1, together with fifteen known compounds (4-18). Their structures, including absolute configurations, were assigned based on NMR, MS, and time-dependent density functional theory (TD-DFT) ECD calculations. Compounds2and5exhibited better activities against methicillin-resistant strains ofS. aureus(MRSA) ATCC 43300 and MRSA CGMCC 1.12409 than the positive control chloramphenicol. Compound5displayed stronger anti-MRSA and lower cytotoxic activities than2, and showed stronger antibacterial activities against strains ofVibrio vulnificus,Vibrio rotiferianus, andVibrio campbelliithan the other compounds. Compounds2and10exhibited significantly stronger cytotoxic activities against human cancer cell lines HeLa, A549, and Hep G2 than the other compounds. Preliminary structure-activity relationship studies indicated that prenylation of terphenyllin or candidusin and the tetrahydrobenzene moiety in anthraquinone derivatives may influence their bioactivity.