Chao-Yi Wang

Phyllodiumpulchellum has been traditionally used as a medicinal herb because of its health-promoting effects, such as its hepatoprotective and antioxidant activities. In the present study, the petroleum ether fraction, ethyl acetate fraction, n-butanol fraction, and aqueous fraction were successively obtained from the ethanol extract of P. pulchellum. Two fractions, ethyl acetate fraction and n-butanol fraction, were found to display hepatoprotective and antioxidant activities. Further chemical investigation of the active fractions led to the isolation of its main constituents, including 11 flavonoids (1–11) and 8 indole alkaloids (12–19). There were 9 flavonoids (1–9) that were obtained from the ethyl acetate fraction, and 2 flavonoids (10 and 11) and 8 alkaloids (12–19) from the n-butanol fraction. Compounds 1–11 and 16–19 were isolated for the first time from P. pulchellum, and 1, 2, 8, 11, and 18 were obtained from the genus Phyllodium initially. Subsequently, the isolated compounds were evaluated for their in vitro hepatoprotective effects on the human normal hepatocyte cell line L-O2 injured by d-galactosamine and radical scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH). The flavonoids (−)-epigallocatechin (5) and (−)-epicatechin (6) exhibited prominent hepatoprotective activities with higher cell viability values (65.53% and 62.40% at 10 μM·mL⁻¹, respectively) than the positive control, silymarin (61.85% at 10 μM·mL⁻¹). In addition, compared with the positive control of vitamin C (IC₅₀: 5.14 μg·mL⁻¹), (−)-gallocatechin (3) and (−)-epigallocatechin (5) exhibited stronger antioxidant activities with IC₅₀ values of 3.80 and 3.97 μg·mL⁻¹, respectively. Furthermore, the total flavonoids from P. pulchellum were characterized using a high-performance liquid chromatography-linear ion trap quadrupole-Orbitrap-mass spectrometry (HPLC-LTQ-Orbitrap-MS). In total, 34 flavonoids were tentatively identified, which had not been previously reported from P. pulchellum. In addition, we performed a semi-quantitative analysis of the isolated flavonoids. The contents of compounds 1–11 were 3.88, 17.73, 140.35, 41.93, 27.80, 4.34, 0.01, 0.20, 9.67, 795.85, and 5.23 μg·g⁻¹, respectively. In conclusion, this study revealed that the flavonoids that were isolated from P. pulchellum showed hepatoprotective and antioxidant activities, indicating that, besides alkaloids, the flavonoids should be the potential pharmacodynamic ingredients that are responsible for the hepatoprotective and antioxidant activities of P. pulchellum.

Marine organism-derived secondary metabolites are promising potential sources for discovering environmentally safe antifouling agents. In present study, 55 marine secondary metabolites and their synthesized derivatives were tested and evaluated for their antifouling activities and security. These compounds include 44 natural products isolated from marine invertebrates and their symbiotic microorganisms collected from the South China Sea and 11 structural modified products derived from the isolated compounds. The natural secondary metabolites, covering phenyl ether derivatives, terpenoids, 9, 11-secosteroids, anthraquinones, alkaloids, nucleoside derivatives and peptides, were isolated from two corals, one sponge and five symbiotic fungi. All of the isolated and synthesized compounds were tested for their antifouling activities against the cyprids of barnacle Balanus (Amphibalanus) amphitrite Darwin. Noticeably, five phenyl ether derivatives (9, 11, 13–15) exhibited potent anti-larval settlement activity with the EC50 values lower than 3.05 μM and the LC50/EC50 ratios higher than 15. The study of structure–activity relationship (SAR) revealed that the introduction of acetoxy groups and bromine atoms to phenyl ether derivatives could significantly improve their antifouling activities. This is the first report on the SAR of phenyl ether derivatives on antifouling activity against barnacle B. amphitrite. The polybrominated diphenyl ether derivative, 2, 4, 6, 2′, 4′, 6′-hexabromo-diorcinol (13), which displayed excellent antifouling activity, was considered as a promising candidate of environmentally friendly antifouling agents.

Two new naphthalenones, corynenones A and B (1 and 2), and one new depsidone, corynesidone E (3), together with one known depsidone, corynesidone A (4) and two known diphenyl ethers, corynethers A (5) and B (6), were isolated from the sponge-derived fungus Corynespora cassiicola XS-20090I7. Their structures including absolute configurations were determined by spectroscopic data and electronic circular dichroism (ECD) spectra. Compounds 4 and 5 showed cytotoxicity against human promyelocytic leukemia HL-60 and human cervical carcinoma HeLa cell lines.