Xian-Wen Yang

Phytochemical and Biological Studies of Abies Species

In the present review, the literature data on the phytochemical and biological investigations on the genus of Abies are summarized with 110 references. Up to now, 277 compounds were isolated from 19 plants of Abies species. The chemical constituents are mostly terpenoids, flavonoids, and lignans, together with minor constituents of phenols, steroids, and others. The crude extracts and metabolites have been found to possess various bioactivities including insect juvenile hormone, antitumor, antimicrobial, anti‐ulcerogenic, anti‐inflammatory, antihypertensive, antitussive, and CNS (central nervous system) activities.

Rapid identification of acetophenones in two Cynanchum species using liquid chromatography–electrospray ionization tandem mass spectrometry

Acetophenones in Cynanchum species, especially cynandione A and its derivatives, whose utilization and toxicity in herbal drugs and folk medicines has caused great interest in the chemical investigation, have extensive biological activities. In this paper, a facile method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS(n)) was developed for the analysis of cynandione A derivatives in the roots of the Cynanchum wilfordii and C. auriculatum. ESI-MS/MS and ESI-MS(n) analysis of cynandiones A and B in negative ion mode were firstly performed employing two mass spectrometers each equipped with an ion-trap and a quadrupole time-of-flight (Q-TOF) mass analyzer. The results drawn from both instruments were similar to each other. Characteristic fragmentation pathways were proposed by comparing the spectra of two standards acquired in the experiments. The fragment ions at m/z 283 and 268 were obtained, and then were used as diagnostic ions to screen and identify cynandione A derivatives from the roots of above two species, together with an HPLC-MS(n) method. Total of 28 cynandione A derivatives comprising 4 reported and 24 novel components were identified or tentatively identified. Furthermore, breakdown curves were constructed to distinguish two types of isomers among these compounds. To our knowledge, this is the first report on characterization of acetophenones by HPLC-ESI-MS(n), which allows a rapid and complete analysis of cynandione A derivatives in roots of Cynanchum species.

Chemical constituents of Abies fabri.

Systematic phytochemical investigations on Abies fabri resulted in the isolation of 94 compounds, consisting of 68 terpenoids, six lignans, seven flavonoids, and 13 other miscellaneous chemical constituents. Their structures were elucidated on the basis of spectroscopic methods, and the absolute configurations of three of these previously unknown compounds were determined by Cu-Kα X-ray crystallographic analysis. Twelve previously unreported compounds, one artifact, and one potential artifact were identified, including six triterpenoids, four diterpenoids, two sesquiterpenoids, one lignan, and one phenol. 23-Hydroxy-3-oxolanosta-8,24-dien-26,23-olide showed weak cytotoxic activity against A549 and THP-1 cells with the IC50 values of 5.3 and 5.1 μM, respectively.

Two new norbisabolane sesquiterpenoid glycosides from Glochidion coccineum

Two new norbisabolane sesquiterpenoid glycosides, glochicoccinosides A (1) and B (2), together with two known compounds, have been isolated from the rhizomes of Glochidion coccineum. Their structures were elucidated by the combination of 1D NMR, 2D NMR, and MS spectral analysis, as well as chemical evidence. Cytotoxic activities and the antioxidant effect of these compounds were evaluated, but none of them showed activity.

Three decomposition products of valepotriates from Valeriana jatamansi and their cytotoxic activity

Three new decomposition products of valepotriates, valtrals A–C (1–3), and two known products, baldrinal and homobaldrinal, are formed during the isolation procedure of the ethanol extract of the whole plants of Valeriana jatamansi. Their structures were determined by spectroscopic methods including IR, MS, 1D, and 2D NMR experiments. Compounds 1–3 showed selective cytotoxicity against metastatic prostate cancer (PC-3M) and colon cancer (HCT-8) cell lines.

Three minor valepotriate isomers from Valeriana jatamansi and their cytotoxicity

Abstract Three new minor valepotriate isomers, jatamanvaltrates Z1 (1), Z2 (2), and Z3 (3), have been isolated from the whole plants of Valeriana jatamansi (syn. Valeriana wallichii.). Their structures were elucidated by extensive spectroscopic analysis, especially 2D NMR and ESI-MS/MSn. All isolated compounds displayed moderate cytotoxicity against the lung adenocarcinoma (A549), metastatic prostate cancer (PC-3 M), colon cancer (HCT-8), and hepatoma (Bel7402) cell lines with IC50 values of 2.8–8.3 μM.

Mass spectrometric profiling of valepotriates possessing various acyloxy groups from Valeriana jatamansi

Valepotriates, plant secondary metabolites of the family Valerianaceae, contain various acyloxy group linkages to the valepotriate nucleus and exhibit significant biological activities. Identification of valepotriates is important to uncover potential lead compounds for the development of new sedative and antitumor drugs. However, making their structure elucidation by nuclear magnetic resonance (NMR) experiments is too difficult to be realized because of the overlapped carbonyl carbon signals of acyloxy groups substituted at different positions. Thus, the mass spectrometric profiling of these compounds in positive ion mode was developed to unveil the exact linkage of acyloxy group and the core of valepotriate. In this study, electrospray ionization tandem multistage mass spectrometry (ESI-MS/MS(n)) in ion trap and collision-induced dissociation tandem MS were used to investigate the fragmentation pathways of four types of valepotriates in Valeriana jatamansi, including 5-hydroxy-5,6-dihydrovaltrate hydrin (5-hydroxy-5,6-dihydrovaltrate chlorohydrin), 5,6-dihydrovaltrate hydrin (5,6-dihydrovaltrate chlorohydrin), 5-hydroxy-5,6-dihydrovaltrate and valtrate hydrin (valtrate chlorohydrin). The high-resolution mass spectrum (HRMS) data of all the investigated valepotriates from quadrupole time-of-flight MS/MS were used as a supportive of the fragmentation rules we hypothesized from ion-trap stepwise MS(n). As a result, the loss sequence of acyloxy groups and the abundance of key product ions, in combination with the characteristic product ions corresponding to the valepotriate nucleus, could readily differentiate the four different types of valepotriates. The summarized fragmentation rules were also successfully exploited for the structural characterization of three new trace valepotriates from V. jatamansi. The results indicated that the developed analytical method could be employed as a rapid, effective technique for structural characterization of valepotriates, especially for the trace compounds that could not be identified by NMR techniques. This study may also arouse interest for further structural analysis of other valepotriate-containing type herbal medicines.

Polyketides from the fungus Penicillium decumbens

Abstract Two new polyketides, 3,11-dihydroxy-6,8-dimethyldodecanoic acid (1) and trichopyrone B (2), together with two known polyketides, sorbicillin (3) and penicillone A (4), have been isolated from the cultures broth of the fungus Penicillium decumbens. Their structures were elucidated by extensive spectroscopic analysis. All isolated compounds were evaluated for their antibacterial and cytotoxic activities. Of these, compound 3 showed antifungal activity toward Candida albicans Y0109 with a MIC value of 50 μM. Moreover, compounds 3 and 4 exhibited selective cytotoxicity against the human hepatocellular carcinoma (QGY-7703) cell line with the IC50 values of 32.5 and 22.8 μM, respectively.

Structure determination of two unusual C25 steroids with bicyclo[4.4.1]A/B rings from Penicillium decumbens by NMR spectroscopy

The genus Penicillium, despite the large numbers of natural products identified, still proves to be rich in structurally unique and biologically active secondary metabolites. A number of fascinating secondary metabolites with antibacterial, antifungal, cytotoxic, and free radical scavenging activities, including citrinadins, scalusamides, perinadine A, and C25 steroids, have been previously isolated from this genus. Our recent investigation of a Penicillium decumbens strain from a limestone soil led to the isolation of cyclopenicillone with a unique 2,5-dimethylcyclopent-2-enone carbon skeleton. It demonstrated a dose-dependent inhibition against LPS-induced NO production in RAW264.7 macrophages. As part of our ongoing effort to study the chemical and biological diversity of this strain, we report herein the isolation and structure elucidation of two unusual C25 steroids with bicyclo[4.4.1]A/B rings (Fig. 1), along with 12 known structurally related compounds. To our knowledge, C25 steroids with bicyclo[4.4.1]A/B rings from natural sources are extremely rare. The extensive application of 1D and 2D NMR techniques, high-resolution ESI-MS (HRESIMS) spectrometry, and circular dichroism spectral analysis were performed to characterize their structures and establish the complete H and C resonance assignments.