Harry H. S. Fong

Antitumorigenic effect of a mammalian lignan precursor from flaxseed.

Secoisolariciresinol diglycoside (SD), a mammalian lignan precursor found in high-fiber foods, was isolated from flaxseed and tested for effects on mammary tumorigenesis in rats fed a high-fat (20%) diet. Ingestion of purified SD at 1.5 mg/day for 20 weeks starting 1 week after treatment with the carcinogen dimethylbenzanthracene resulted in a 37% reduction (p < 0.05) in the number of tumors per tumor-bearing rat and a 46% reduction (p < 0.05) in the number of tumors per tumor-bearing rat and a 46% reduction (p < 0.05) in the number of tumors per number of rats in each group. Urinary mammalian lignan excretion significantly increased (p < 0.0001) with SD treatment, indicating the conversion of SD to mammalian lignans. No enlargement or gross abnormalities of the major organs were observed in the SD-treated rats. This study showed, for the first time, that SD has an antitumor effect when provided at the early promotion stage of tumorigenesis and may contribute to the health benefits of high-fiber foods.

Rotenoids mediate potent cancer chemopreventive activity through transcriptional regulation of ornithine decarboxylase

For the discovery of new cancer chemopreventive agents, we have studied the potential of plant extracts to inhibit phorbol ester-induced ornithine decarboxylase (ODC) activity in cell culture. Four active rotenoids were obtained from the African plant Mundulea sericea (Leguminosae). These isolates were highly potent when evaluated for inhibition of chemically induced preneoplastic lesions in mammary organ culture and inhibition of papillomas in the two-stage mouse skin model, and they appear to function by a unique mechanism at the level of ODC messenger RNA expression. Based on our findings, rotenoids can be regarded as promising new chemopreventive or anticancer agents.

Isolation and characterization of bioactive principles of the leaves and stems of Physalis philadelphica

Abstract An ethyl acetate-soluble extract of the leaves and stems of Physalis philadelphica has been investigated, leading to the isolation of three new withanolides, philadelphicalactones A ( 1 ) and B ( 2 ), and ixocarpalactone B ( 3 ), four known withanolides, ixocarpalactone A ( 4 ), withaphysacarpin ( 5 ), 18-hydroxywithanolide D ( 6 ), and withanone ( 7 ), one new ceramide, (2S,3S,4R,9E)-1,3,4-trihydroxy-2-[(2′R)-2′-hydroxytetracosanoylamino]-9-octadecene ( 8 ), two known ceramides, (2S,3S,4R)-2-[(2′R)-2′-hydroxytetracosanoylamino]-1,3,4-octadecanetriol ( 9 ), and (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol ( 10 ), as well as the known chlorophyllide a ( 11 ). The structures of the new compounds were elucidated based on spectroscopic and chemical methods. Single-crystal X-ray diffraction analysis was used to confirm the relative stereochemistry of compounds 1 and 4 . The absolute stereochemistry of compounds 1–4 and 8 was established by Mosher ester methodology and chemical transformation. All isolates were evaluated for their potential cancer chemopreventive properties utilizing in vitro assays to determine quinone reductase induction and inhibition of murine epidermal JB6 cell transformation.

Computer-assisted structure elucidation: application of CISOC-SES to the resonance assignment and structure generation of betulinic acid

The application of a computer‐assisted structure elucidation expert system, CISOC–SES, leading to the unequivocal 1H, 13C and NOE resonance assignment of betulinic acid, a biologically active triterpenoid with complicated NMR resonances, is described. The procedure consists of peak picking that is independent of background information, systematic interpretation of connectivity information from 2D NMR into bond constraints and resonance assignment based on the proposed structure. De novo structure generation based solely on the molecular formula and spectral data is also described. This application demonstrates the potential of efficient and systematic structure elucidation of natural products with modern high‐resolution NMR spectroscopy combined with artificial intelligence.

Isolation of linoleic acid as an estrogenic compound from the fruits of Vitex agnus-castus L. (chaste-berry)

A methanol extract of chaste-tree berry (Vitex agnus-castus L.) was tested for its ability to displace radiolabeled estradiol from the binding site of estrogen receptors alpha (ERalpha) and beta (ERbeta). The extract at 46 +/- 3 microg/ml displaced 50% of estradiol from ERalpha and 64 +/- 4 microg/ml from ERbeta. Treatment of the ER+ hormone-dependent T47D:A18 breast cancer cell line with the extract induced up-regulation of ERbeta mRNA. Progesterone receptor (PR) mRNA was upregulated in the Ishikawa endometrial cancer cell line. However, chaste-tree berry extract did not induce estrogen-dependent alkaline phosphatase (AP) activity in Ishikawa cells. Bioassay-guided isolation, utilizing ER binding as a monitor, resulted in the isolation of linoleic acid as one possible estrogenic component of the extract. The use of pulsed ultrafiltration liquid chromatography-mass spectrometry, which is an affinity-based screening technique, also identified linoleic acid as an ER ligand based on its selective affinity, molecular weight, and retention time. Linoleic acid also stimulated mRNA ERbeta expression in T47D:A18 cells, PR expression in Ishikawa cells, but not AP activity in Ishikawa cells. These data suggest that linoleic acid from the fruits of Vitex agnus-castus can bind to estrogen receptors and induce certain estrogen inducible genes.

Angoline and Chelerythrine, Benzophenanthridine Alkaloids That Do Not Inhibit Protein Kinase C

Starting with an extract derived from the stem ofMacleaya cordata (Papaveraceae) that was active in the process of inhibiting phorbol 12,13-dibutyrate binding to partially purified protein kinase C (PKC), the benzophenanthridine alkaloid angoline was isolated and identified. This discovery appeared in context, as a related benzophenanthridine alkaloid, chelerythrine, has been reported to mediate a variety of biological activities, including potent and selective inhibition of protein kinase C (PKC). However, in our studies, angoline was not observed to function as a potent inhibitor of PKC. Moreover, we were unable to confirm the reported inhibitory activity of chelerythrine. In a comprehensive series of studies performed with various PKC isozymes derived from a variety of mammalian species, neither chelerythrine nor angoline inhibited activity with high potency. To the contrary, chelerythrine stimulated PKC activity in the cytosolic fractions of rat and mouse brain in concentrations up to 100 μm. In addition, chelerythrine and angoline did not inhibit [3H]phorbol 12,13-dibutyrate binding to the regulatory domain of PKC at concentrations up to 40 μg/ml, and no significant alteration of PKC-α, -β, or -γ translocation was observed with human leukemia (HL-60) cells in culture. Further, chelerythrine did not inhibit 12-O-tetradecanoylphorbol 13-acetate-induced ornithine decarboxylase activity with cultured mouse 308 cells, but angoline was active in this capacity with an IC50 value of 1.0 μg/ml. A relatively large number of biological responses have been reported in studies conducted with chelerythrine, and alteration of PKC activity has been considered as a potential mechanism of action. In light of the current report, mechanisms independent of PKC inhibition should be considered as responsible for these effects.

Discovery of cyclooxygenase inhibitors from medicinal plants used to treat inflammation

Eleven authenticated botanicals used in the traditional Chinese medicine Huo-Luo-Xiao-Ling Dan were screened for ligands to cyclooxygenase (COX) using pulsed ultrafiltration liquid chromatography-mass spectrometry, and a mass spectrometry-based enzyme assay was used to determine the concentration of each of 17 ligands that inhibited COX-1 or COX-2 by 50% (IC(50)). Acetyl-11-keto-beta-boswellic acid, beta-boswellic acid, acetyl-alpha-boswellic acid, acetyl-beta-boswellic acid, and betulinic acid were COX-1 selective inhibitors with IC(50) values of approximately 10 microM. Senkyunolide O and cryptotanshinone were COX-2 selective inhibitors with IC(50) values of 5 microM and 22 microM, respectively. Roburic acid and phenethyl-trans-ferulate inhibited COX-1 and COX-2 equally. COX inhibition and the IC(50) values of most of these natural product ligands have not been reported previously.

Extract of the Chinese herbal formula Huo Luo Xiao Ling Dan inhibited adjuvant arthritis in rats

ETHNOPHARMACOLOGICAL RELEVANCE The herbal formula Huo Luo Xiao Ling Dan (HLXL) and its modifications have been used in traditional Chinese medicine for about one hundred years to alleviate pain and inflammation. AIM To investigate the effects of HLXL on complete Freunds adjuvant (CFA)-induced multiple-joint arthritis in rats. MATERIALS AND METHODS Male Lewis rats, 190-210 g, were immunized subcutaneously at the base of the tail with 200 microl of heat-killed Mycobacterium tuberculosis in mineral oil (5 mg/ml). HLXL (2.30 and 4.60 g/kg) or vehicle control (n=8 per group) was administered orally (i.g.) once a day between days 16 and 25 post-CFA injection. The rats were observed for signs of arthritis with arthritic changes (erythema, edema, induration) being scored on a scale of 0-4 of increasing severity using a standard scoring system. The maximum arthritis score per rat was 16. A plethysmometer was used to measure edema volume in each paw. Adverse effects of HLXL were monitored by closely observing the animals for unusual behavioral changes. Levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) in local tissue were measured by enzyme-linked immunosorbent assay on day 25 post-CFA. RESULTS HLXL significantly decreased arthritis scores between days 23-25 in the 2.30 g/kg group and 21-25 in the 4.60 g/kg group (p<0.05). It reduced paw edema on days 22 and 24 in the 2.30 g/kg group and on days 20, 22 and 24 in the 4.60 g/kg group compared to control (p<0.05). Local tissue TNF-alpha and IL-1beta levels on day 25 post-CFA injection were significantly (p<0.05) lower in rats treated with HLXL than in control rats. No observable adverse effects were found. CONCLUSION The data suggest that HLXL produces significant anti-arthritic effects that may be mediated by suppressing pro-inflammatory cytokines, and it appears to be safe.

Peltogynoids and homoisoflavonoids from Caesalpinia pulcherrima

Abstract From the stem part of Caesalpinia pulcherrima Swartz (Leguminosae) two new peltogynoids, pulcherrimin and 6-methoxypulcherrimin and two homoisoflavonoids, the recently reported compound bonducellin and a new derivative 8-methoxy-bonducellin, were isolated. The structures of these constituents were deduced by consideration of their spectral data. Also isolated were the known compounds, 2,6-dimethoxybenzoquinone and 4′-methylisoliquiritigenin, which displayed cytotoxic activity.

ROTENOIDS AND CHALCONES FROM MUNDULEA SERICEA THAT INHIBIT PHORBOL ESTER-INDUCED ORNITHINE DECARBOXYLASE ACTIVITY

Abstract Two novel rotenoids, (−)-13α-hydroxydeguelin and (−)-13α-hydroxytephrosin, and a new chalcone, munsericin, were isolated from the bark of Mundulea sericea , and their structures were elucidated by spectroscopic methods. Also obtained were the parent rotenoids, deguelin and tephrosin, and the known chalcone, 4-hydroxy-lonchocarpin. The rotenoids and chalcones exhibited potent inhibitory activity against phorbol ester-induced ornithine decarboxylase activity in cultured mouse 308 epidermal cells.