Lie-Feng Ma

Terpenoids with alpha-glucosidase inhibitory activity from the submerged culture of Inonotus obliquus

Lanostane-type triterpenoids, inotolactones A and B, a drimane-type sesquiterpenoid, inotolactone C, and five known terpenoids 6β-hydroxy-trans-dihydroconfertifolin, inotodiol, 3β,22-dihydroxyanosta-7,9(11),24-triene, 3β-hydroxycinnamolide, and 17-hydroxy-ent-atisan-19-oic acid, were isolated from the submerged culture of chaga mushroom, Inonotus obliquus. Their structures were characterized by spectroscopic methods, including MS and NMR (1D and 2D) spectroscopic techniques. Inotolactones A and B, examples of lanostane-type triterpenoids bearing α,β-dimethyl, α,β-unsaturated δ-lactone side chains, exhibited more potent alpha-glucosidase inhibitory activities than the positive control acarbose. This finding might be related to the anti-hyperglycemic properties of the fungus and to its popular role as a diabetes treatment. In addition, a drimane-type sesquiterpenoid and an atisane-type diterpenoid were isolated from I. obliquus.

New Eudesmane Sesquiterpenoids from Salvia plebeia R. Br.

Three new sesquiterpenoids, salplebeones A – C (1 – 3), were isolated from the ethanol‐soluble extract of the aerial part of Salvia plebeia R. Br. Their structures were established by detailed analysis of NMR and MS spectra. Salplebeone A was an eudesmane lactone, while salplebeones B and C were rare eudesmane sesquiterpenoids, containing 12,8‐lactam groups. Antiproliferative activities of salplebeones A – C to myeloid leukemia cell lines were evaluated.

Antiproliferative Prenylated Xanthones from the Pericarps of Garcinia mangostana

Xanthones are a kind of natural products bearing a unique tricyclic aromatic system (C6–C3–C6) [1]. The structural diversities of these compounds arise mainly from the different substitutions of the A and B rings in the skeleton, with isoprene, methoxyl, and hydroxyl groups, being the most frequently occurring substituents. Accordingly, xanthones can be classied into several groups including simple oxygenated xanthones, prenylated xanthones, xanthone glycosides, and xanthonolignoids based on these substituents [2]. In recent years, xanthones have been identified as promising bioactive compounds with wide ranging and potentially usefull biological activities such as anticancer, anti-HIV, anti-inflammatory, antibacterial, and neurotrophic activities [3]. Garcinia mangostana is a tropical fruit native to Southeast Asia that has long been noted for its medicinal and health promoting properties [4]. Compared to the other species in the genus Garcinia, G. mangostana has captured the most attention due to its fruit, which was always referred to as the “queen of fruits.” The pericarps of G. mangostana fruit, a traditional medicine used for the treatment of infection, wounds, inflammation, and diarrhea in Southeast Asia, have recently been noted to be an abundant source of xanthones [1]. Herein, as part of our ongoing programs on the exploration of bioactive xanthones from Garcinia [5] and other related genus [6], eight prenylated xanthones were identified from the pericarps of G. mangostana and subjected to antiproliferative assay. G. mangostana fruits were purchased from the fruit market in Hangzhou and identified by Prof. Fa-Song Wang (Hubei University for Nationalities, P. R. China). A voucher specimen (No. ZJUTGM201009) was deposited with the Zhejiang University of Technology. The air-dried pericarps of G. mangostana fruits (4.5 kg) were crushed and extracted with ethanol (3 30 L). The extracts, after vacuum evaporation, was suspended in 2 L of distilled water and partitioned successively with petroleum ether (4 4 L) and CHCl3 (4 4 L) to give the petroleum ether-soluble and the CHCl3-soluble residues, respectively. The CHCl3-soluble residue (425 g) was subjected to column chromatography (CC) on silica gel eluting with petroleum ether– EtOAc (10:1 0:1) to furnish three fractions A–C. Fraction A was seprated by CC (MCI-CHP20P, CH3OH–H2O, 5:5 10:0) to afford two subfractions A1 and A2. Subfraction A1 (175.8 mg) was further purified by CC (HW-40, CH3OH) to give 2 (46.7 mg). Subfraction A2 (330.4 mg) was purified on CC (silica gel, petroleum ether–EtOAc, 15:1 10:1) to give 1 (16.2 mg), 5 (7.1 mg), and 8 (3 mg). Fraction B (2 g) was first separated by CC (silica gel, petroleum ether–acetone, 6:1) to give two subfractions B1 and B2, which were purified by CC (HW-40, CH3OH) to furnish 3 (25.7 mg) and 4 (30.0 mg), respectively. Fraction C was first recrystallized and filtered to produce 7 (ca. 100 g), and the filtrate was subjected to CC (silica gel, petroleum ether–acetone, 6:1) followed by CC (HW-40, CH3OH) to afford 6 (17.9 mg). The compounds were identified as 7-O-methylgarcinone E (1) [7], 8-desoxygartanin (2) [8], gartanin (3) [8], garcinone E (4) [9], 4 ,5 -dihydro-1,3,6-trihydroxy-6 ,6 -dimethyl-2,5-bis(3-methylbut-2-en-1-yl)pyrano[2 ,3 :7,8]xanthone (5) [10], 9-hydroxycalabaxanthone (6) [8, 11], -mangostin (7) [12], and tovophyllin A (8) [13] by spectroscopic methods, including NMR and mass spetrometry. These compounds have been previously isolated from the G. mangostana, but this is the first report of their co-occurrence at the same time in the plants.

Studies on the Chemical Diversities of Secondary Metabolites Produced by Neosartorya fischeri via the OSMAC Method

The One Strain Many Compounds (OSMAC) method was applied to explore the chemical diversities of secondary metabolites produced by Neosartorya fischeri NRRL 181. Four pyripyropenes 1–4, eight steroids 5–11, and four prenylated indole alkaloids 12–15, were obtained from the fungus cultured in petri dishes containing potato dextrose agar (PDA). 1,7,11-trideacetylpyripyropene A (1) and 1,11-dideacetyl pyripyropene A (2) were obtained and spectroscopically characterized (1D, 2D NMR, and HR-ESI-MS) from a natural source for the first time. It offered a sustainable source of these two compounds, which were usually used as starting materials in preparing pyripyropene derivatives. In addition, as compared with all the other naturally occurring pyripyropenes, 1 and 2 possessed unique acetylation patterns that did not follow the established late-step biosynthetic rules of pyripyropenes. The natural occurrence of 1 and 2 in the fungus implied that the timing and order of hydroxylation and acetylation in the late-step biosynthetic pathway of pyripyropenes remained to be revealed. The isolation and identification of 1–15 indicated that the OSMAC method could remarkably alter the metabolic profile and enrich the chemical diversities of fungal metabolites. Compounds 1–4 exhibited no obvious cytotoxicity against the triple-negative breast cancer cell line MDA-MB-231 as compared with taxol.