Rui-Feng Mei

A new C20-diterpenoid alkaloid from the lateral roots of Aconitum carmichaeli

Abstract A new C20-diterpenoid alkaloid carmichaedine (1) and six known alkaloids (2–7) were isolated from the lateral roots of Aconitum carmichaeli. Their structures were established on the basis of extensive spectroscopic analyses. Compound 1 exhibited potent antibacterial activity against Bacillus subtilis with minimum inhibitory concentration of 8 μg/mL.

Alkaloids with antioxidant activities from Aconitum handelianum

Abstract A new C20-diterpenoid alkaloid handelidine (1) and twenty-seven known alkaloids (2–28) were isolated from the roots of Aconitum handelianum. Their structures were established on the basis of extensive spectroscopic analyses. The study indicated that denudatine-type C20-diterpenoid alkaloids with vicinal-triol system and benzyltetrahydroisoquinoline alkaloids exhibited significant antioxidant activities measured by three antioxidant test systems. The aconitine-type C19-diterpenoid alkaloids could serve as potential secondary antioxidants for their strong binding effects to metal ions.

Fermentation of Illigera aromatica with Clonostachys rogersoniana producing novel cytotoxic menthane-type monoterpenoid dimers

Illigera aromatica, a medicinal liana, was fermented with Clonostachys rogersoniana. Two novel menthane-type monoterpenoid dimers, dimericilligerates E (1) and F (2) were isolated from the fermented material. Their structures were identified by 1D/2D NMR, electric circular dichroism, derivatization, and Moshers method. A novel elimination reaction that formed a benzene ring from a menthane moiety afforded derivative 1a, which possesses more resolved NMR signals than the dimeric monoterpenoid, dimericilligerate E (1). The determination of 1a verified the estimation of 1. Compounds 1 and 2 showed potent cytotoxic activities; especially, 1 possessed significant activities against the liver hepatocellular carcinoma cell line (SMMC-7721) with an IC50 value of 3.89 ± 0.23 μM. Three novel precursors, dimericilligerates A–C (3–5), were identified by HPLC-MS and isolated from the original I. aromatica. This paper presents a novel class of monoterpenoid dimers and suggests that C. rogersoniana-fermented I. aromatica is effective to produce cytotoxic dimeric monoterpenoids from inactive original materials.

Improving Antioxidant Activity of Ophioglossum thermale Kom. by Fermentation with Talaromyces purpurogenus M18-11

Ophioglossum thermale Kom. was fermented with several fungi. The total phenolic and flavonoid contents (TPCs and TFCs) and antioxidant activities of fermented and non-fermented O. thermale (FOT and NFOT) were investigated. The results showed that Talaromyces purpurogenus M18-11 fermented O. thermale possessed significantly improved TPC and TFC and exhibited significantly stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) (half maximal inhibitory concentration (IC50) = 75.7 ± 2.1 μg mL) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) (IC50 = 20.52 ± 1.68 μg mL) free-radical scavenging activities, ferric reducing antioxidant power (0.585 ± 0.045 mmol g), and reducing power (half maximal effective concentration (EC50) = 30.52 ± 1.91 μg mL) than original material. The determination of the contents of representative flavonoids and their glucosides revealed that the improvements are attributed to the hydrolysis of homoisoflavonoid and flavonoid glucosides, glycometabolism, as well as fungal metabolites. This paper is the first to report the fermentation of O. thermale with pure strains and T. purpurogenus is an effective strain to process O. thermale for improving the antioxidant activity.

A new menthane-type monoterpenoid from fermented Illigera aromatica with Clonostachys rogersoniana 828H2

Abstract A new menthane-type monoterpenoid, illigerate E (1), as well as two known ones, (1R*,3R*,4S*,6R*)-6,8-dihydroxymenthol (2) and cis-4-hydroxy-5-(1-hydroxy-1-methylethyl)-2-methyl-2-cyclohexene-1-one (3), were isolated from fermented Illigera aromatica with Clonostachys rogersoniana 828H2. Their structures were identified by HRESIMS and 1D/2D NMR spectra. Their inhibitory effects of NO production in RAW 264.7 macrophages were estimated.