Wan Chun Lai

Antitumor agents. 271: Total synthesis and evaluation of brazilein and analogs as anti-inflammatory and cytotoxic agents

The first total synthesis of the naturally occurring tetracyclic homoisoflavonoid brazilein (1) and 14 new analogs (1a-n) is reported. Target compounds and intermediates were assayed for anti-inflammatory effects on superoxide anion generation and elastase release by human neutrophils in response to fMLP/CB, and for cytotoxic activity against nasopharyngeal (KB), vincristine-resistant nasopharyngeal (KBvin), lung (A549) and prostate (DU-145) human cancer cell lines. The most active compound 1b showed potent effects on superoxide anion generation and elastase release with IC(50) values of 1.2 and 1.9 microM, respectively, and was 65 times more potent than phenylmethylsulfonyl fluoride (PMSF), the positive control, in the latter assay. Additionally, 1b exhibited broad spectrum in vitro anticancer activity with IC(50) values of 6-11 microM against the four tested cancer cell lines.

The oestrogenic and anti-platelet activities of dihydrobenzofuroisocoumarins and homoisoflavonoids from Liriope platyphylla roots

The ethanolic extract of Liriope platyphylla (Liliaceae) roots showed potential oestrogenic and anti-platelet activities. Twenty-six compounds were isolated and classified as 10 skeletons, including two unusual new dihydrobenzofuroisocoumarins, (+)-platyphyllarin A (1) and B (2), one new butanoate, ethyltributanoate (3), and two new homoisoflavanones, (-)-liriopein A (4) and B (5), along with 21 known compounds, including six homoisoflavonoids, one chalcone, six amides, one lignan, one fatty acid derivative, one alkaloid, three benzenoids, and two steroids. The biosynthetic pathway of compounds 1 and 2 was proposed in the current investigation. The oestrogenic activity of the isolates was evaluated utilising the pER8:GUS reporter assay system in transgenic Arabidopsis plant as well as the SEAP reporter assay system in MCF-7 breast cancer cell-line; the anti-platelet activity was evaluated using the anti-platelet aggregation assay. Several components exhibited significant oestrogenic and anti-platelet activities; demonstrating for the first time the potential use of L. platyphylla as a nutritional supplement for cardiovascular and endocrine diseases.

Using the pER8:GUS reporter system to screen for phytoestrogens from Caesalpinia sappan.

Arabidopsis thaliana pER8:GUS, a low-cost, highly efficient, and convenient transgenic plant system, was used to assay the estrogen-like activity of 30 traditional Chinese medicines. The MeOH extract of Caesalpinia sappan exhibited significant bioactivity in this assay, and subsequent bioactivity-guided fractionation of the extract led to the isolation of one new compound, (S)-3,7-dihydroxychroman-4-one (1), and 10 known compounds. Both the plant pER8:GUS and in vitro estrogen response element reporter assays were used to evaluate the estrogenic activity of the isolated compounds, and these two systems produced comparable results. Compounds 6, 8, and 11 showed significant estrogenic activity comparable to genistein. These active compounds were determined to be nontoxic new sources of phytoestrogens. In addition, compounds 2 and 3 inhibited ERE transcription induced by 17β-estradiol. A docking model revealed that compounds 6, 8, and 11 showed high affinity to the estrogen receptor. The pER8:GUS reporter system was demonstrated to be a useful and effective technique in phytoestrogen discovery.

Phyto-SERM Constitutes from Flemingia macrophylla

The methanolic extract of Flemingia macrophylla roots exhibited significant estrogenic activity in the transgenic plant assay system which was comparable to the activity of soybean extract. Utilizing estrogenic activity-guided fractionation, one new compound, fleminigin, together with 23 known compounds were isolated from F. macrophylla roots’ methanolic extract. The structure of the new compound was identified based on intensive spectroscopic analysis and the full spectral data for one of the isolated compounds, flemichin E, was introduced for the first time in the current investigation. The estrogenic and anti-estrogenic activities of the isolated compounds were evaluated revealing that the isolated isoflavonoids may act as partial estrogen agonists, as well as antagonists. Additionally, the anti-inflammatory and the cytotoxic activities of the isolated compounds were studied. These results suggested the potential applications of F. macrophylla extract and its isolated compounds as selective estrogen receptor modulators (SERMs).

Bioactive constituents of Cirsium japonicum var. australe.

Cirsium japonicum var. australe, used as a folk medicine in Taiwan, has been employed traditionally in the treatment of diabetes and inflammatory symptoms. Bioactivity-guided fractionation of its ethanolic extract, utilizing centrifugal partition chromatography monitored by DPPH-TLC analysis, led to the isolation of three new acetylenic phenylacrylic acid esters (1-3) and two new polyacetylenes (4 and 5), together with seven known compounds (6-12). The structures of 1-5 were elucidated by spectroscopic methods including 1D and 2D NMR techniques. The absolute configurations of 4 and 7 were determined utilizing Moshers method and ECD/CD experiments. The DPPH scavenging activity of the constituents isolated from the C. japonicum var. australe ethanolic extract was evaluated. The potential antidiabetic activity of some of the isolates was evaluated using in vitro cellular glucose uptake and oil red staining assays.

Lignan and Flavonoid Phytoestrogens from the Seeds of Cuscuta chinensis

In a search for natural phytoestrogens, 130 traditional Chinese medicinal extracts related to gynecological disorders were investigated by the Arabidopsis pER8:GUS reporter assay system. The EtOH extract of Cuscuta chinensis showed estrogenic activity (100 μg/mL) and affored three new lignans, cuscutaresinols A−C (1−3), and 16 known compounds. Cuscutaresinols A−C (1−3), (+)-sesamin (4), (+)-xanthoxylol (5), 9-hydroxysesamin (6), (+)-pinoresinol (7), kaempferol (8), and isorhamnetin (9) showed estrogenic activity, with 8 and 9 exhibiting the most potent activity. Kaempferol (8) and isorhamnetin (9) are the major components of C. chinenesis EtOH extract and the key contributors to its estrogenic activity in the Arabidopsis pER8:GUS reporter assay system. P are natural secondary metabolites that exhibit several positive effects on human health, such as improving menopausal syndrome, resisting oxidative damage accompanying neurological and cardiovascular diseases, and inhibiting tumor growth. Currently, phytoestrogens are one of the most important nutritional supplements. Phytoestrogens either are absorbed directly from the gastrointestinal tract or undergo metabolic conversion to the active form by gut microflora before absorption. Despite the wealth of evidence showing the biological importance of dietary phytoestrogens, their use for postmenopausal syndrome is still a controversial issue. Thus, finding new sources of phytoestrogens and developing feasible protocols for their detection in natural products will promote our understanding of their actual role. In 2005, we introduced a cross-kingdom bioassay to test animal biological functions utilizing a higher plant bioassay model. In this system, the transgenic Arabidopsis thaliana plant with the pER8:GUS reporter, bearing a human estrogenic receptor, is used as a tool for screening phytoestrogens from natural sources. The system was utilized for screening different plant extracts used to treat postmenopausal syndrome in traditional Chinese or folk medicine. Among the tested extracts, an EtOH extract of Cuscuta chinensis Lam. Received: December 16, 2011 Article

Rapid, laser-induced conversion of 20-hydroxyecdysone – A follow-up study on the products obtained

We have recently reported the set-up of an experimental system for the laser-induced photochemical modification of bioactive substances, where two ecdysteroids, 20-hydroxyecdysone (20E) and its diacetonide derivative served as probes. As a direct continuation of our previous work, three new compounds together with five other ecdysteroid derivatives, have been identified from the novel, laser-induced photo-transformation reaction of 20E. The structures and NMR signal assignment were established by comprehensive one- and two-dimensional NMR spectroscopy supported by mass spectroscopy. Possible ways for the formation of each species is also discussed. Similar to their parental compound, the products obtained are potentially bioactive and worthy for further investigations; due to the low yields, however, a different approach for their higher scale production is suggested.

Anti-allergic hydroxy fatty acids from Typhonium blumei explored through ChemGPS-NP

Increasing prevalence of allergic diseases with an inadequate variety of treatment drives forward search for new alternative drugs. Fatty acids, abundant in nature, are regarded as important bioactive compounds and powerful nutrients playing an important role in lipid homeostasis and inflammation. Phytochemical study on Typhonium blumei Nicolson and Sivadasan (Araceae), a folk anti-cancer and anti-inflammatory medicine, yielded four oxygenated fatty acids, 12R-hydroxyoctadec-9Z,13E-dienoic acid methyl ester (1) and 10R-hydroxyoctadec-8E,12Z-dienoic acid methyl ester (2), 9R-hydroxy-10E-octadecenoic acid methyl ester (3), and 12R*-hydroxy-10E-octadecenoic acid methyl ester (4). Isolated compounds were identified by spectroscopic methods along with GC-MS analysis. Isolated fatty acids together with a series of saturated, unsaturated and oxygenated fatty acids were evaluated for their anti-inflammatory and anti-allergic activities in vitro. Unsaturated (including docosahexaenoic and eicosapentaenoic acids) as well as hydroxylated unsaturated fatty acids exerted strong anti-inflammatory activity in superoxide anion generation (IC50 2.14–3.73 μM) and elastase release (IC50 1.26–4.57 μM) assays. On the other hand, in the anti-allergic assays, the unsaturated fatty acids were inactive, while hydroxylated fatty acids showed promising inhibitory activity in A23187- and antigen-induced degranulation assays (e.g., 9S-hydroxy-10E,12Z-octadecadienoic acid, IC50 92.4 and 49.7 μM, respectively). According to our results, the presence of a hydroxy group in the long chain did not influence the potent anti-inflammatory activity of free unsaturated acids. Nevertheless, hydroxylation of fatty acids (or their methyl esters) seems to be a key factor for the anti-allergic activity observed in the current study. Moreover, ChemGPS-NP was explored to predict the structure-activity relationship of fatty acids. The anti-allergic fatty acids formed different cluster distant from clinically used drugs. The bioactivity of T. blumei, which is historically utilized in folk medicine, might be related to the content of fatty acids and their metabolites.