Abstract: Our previous work revealed berberine can significantly enhance the susceptibility of fluconazole against fluconazole-resistant Candida albicans, which suggested that berberine has synergistic antifungal activity with fluconazole. Preliminary SAR of berberine needs to be studied for the possibility of investigating its target and SAR, improving its drug-likeness, and exploring new scaffold. In this work, 13-substitutited benzyl berberine derivatives and N-benzyl isoquinoline analogues were synthesized and characterized by 1H NMR and MS. Their synergetic activity with fluconazole against fluconazole-resistant Candida albicans was evaluated in vitro. The 13-substitutited benzyl berberine derivatives 1a-1e exhibited comparable activity to berberine, which suggested that the introduction of functional groups to C-13 can maintain its activity. The N-benzyl isoquinolines, which were designed as analogues of berberine with its D ring opened, exhibited lower activity than berberine. However, compound 2b, 2c, and 4b showed moderate activity, which indicated that berberine may be deconstructed to new scaffold with synergistic antifungal activity with fluconazole. The results of our research may be helpful to the SAR studies on its other biological activities.
Antifungal Agents ; pharmacology ; Berberine ; pharmacology ; Candida albicans ; drug effects ; Drug Resistance, Fungal ; Drug Synergism ; Fluconazole ; pharmacology ; Isoquinolines ; pharmacology ; Microbial Sensitivity Tests

Two new labdane diterpenoids were isolated from 95% ethanol extract of the leaves of Callicarpa formosana Rolfe by using silica gel column, MCI column, ODS column and HPLC. Their structures were elucidated by HR-ESI-MS, NMR and ECD spectral data. All of them are new compounds, named 13E-6β-hydroxylabda-8(17),13-dien-15-oic acid (1) and 13E-7α-hydroxylabda-8(17),13-dien-15-oic acid (2). Compounds 1 and 2 were tested for antioxidant activity, and none of them had obvious activity.

A new carbazole alkaloid was isolated from the aqueous extract of the stems of Clausena lansium (Lour.) Skeels by various chromatographic methods, including HPD-100, PRP-512A, silica gel, and reverse phase C18. Its structure was determined by spectroscopic and chemical methods, including UV, IR, HR-ESI-MS, 1D/2DNMR and ECD. Compound 1, named as Claulamine F, showed no antimicrobial activity on Staphylococcus aureus, Escherichia coli or Pseudomonas aeruginosa. In addition, compound 1 exhibited no cytotoxicity on five kinds of cancer cells through MTT methods.

Three new anthraquinones were isolated from the 80% ethanol extract of Prismatomeris tetrandra by silica gel, MCI, ODS column chromatography and high performance preparative liquid chromatography (HPLC). The structures of the new compounds were identified by mass spectrometry, nuclear magnetic resonance and other spectroscopic methods as 6-hydroxy-1,2,3-trimethoxy-7-methylanthracene-9,10-dione (1), 6-(hydroxymethyl)-1,2,3-trimethoxyanthracene-9,10-dione (2) and 7-hydroxy-6-(hydroxymethyl)-1,2-dimethoxyanthracene-9,10-dione (3). Compounds 1, 2 and 3 showed protective effects against monosodium glutamate-induced damage in SH-SY5Y neuroblastoma cells, with the cell survival rates elevated 18.45%, 4.31%, and 7.65%, respectively.

Two new ursane triterpenoids along with twelve known compounds were isolated from 80% ethanol extract of Agastache rugosa (Fisch. et. Mey.) O. Kuntze by using silica gel column, MCI column, ODS column and HPLC. The structures of the new compounds were identified as 2α,3α-dihydroxy-24-nor-urs-4(23),12(13)-dien-28-oic acid (1) and 2α,3α-dihydroxy-24-nor-urs-4(23),12(13),20(30) -trien-28-oic acid (2) by HR-ESI-MS, NMR and ECD spectral data, named agasursacid A and agasursacid B. In addition, compounds 3, 4, 6, 8 showed anti-coxsackievirus B3 (CVB3) activities with a IC₅₀ as 4.77, 1.59, 11.11 and 25.87 μmol·L^-1, resepectively.