Shugeng Cao

Activation of the Nrf2 Cell Defense Pathway by Ancient Foods: Disease Prevention by Important Molecules and Microbes Lost from the Modern Western Diet

The Nrf2 (NFE2L2) cell defense pathway protects against oxidative stress and disorders including cancer and neurodegeneration. Although activated modestly by oxidative stress alone, robust activation of the Nrf2 defense mechanism requires the additional presence of co-factors that facilitate electron exchange. Various molecules exhibit this co-factor function, including sulforaphane from cruciferous vegetables. However, natural co-factors that are potent and widely available from dietary sources have not been identified previously. The objectives of this study were to investigate support of the Nrf2 cell defense pathway by the alkyl catechols: 4-methylcatechol, 4-vinylcatechol, and 4-ethylcatechol. These small electrochemicals are naturally available from numerous sources but have not received attention. Findings reported here illustrate that these compounds are indeed potent co-factors for activation of the Nrf2 pathway both in vitro and in vivo. Each strongly supports expression of Nrf2 target genes in a variety of human cell types; and, in addition, 4-ethylcatechol is orally active in mice. Furthermore, findings reported here identify important and previously unrecognized sources of these compounds, arising from biotransformation of common plant compounds by lactobacilli that express phenolic acid decarboxylase. Thus, for example, Lactobacillus plantarum, Lactobacillus brevis, and Lactobacillus collinoides, which are consumed from a diet rich in traditionally fermented foods and beverages, convert common phenolic acids found in fruits and vegetables to 4-vinylcatechol and/or 4-ethylcatechol. In addition, all of the alkyl catechols are found in wood smoke that was used widely for food preservation. Thus, the potentially numerous sources of alkyl catechols in traditional foods suggest that these co-factors were common in ancient diets. However, with radical changes in food preservation, alkyl catechols have been lost from modern foods. The absence of alkyl catechols from the modern Western diet suggests serious negative consequences for Nrf2 cell defense, resulting in reduced protection against multiple chronic diseases associated with oxidative stress.

Meroterpenoids with Antiproliferative Activity from a Hawaiian-Plant Associated Fungus Peyronellaea coffeae-arabicae FT238

Three unusual polyketide-sesquiterpene metabolites peyronellins A-C (1-3), along with the new epoxyphomalin analog 11-dehydroxy epoxyphomalin A (4), have been isolated from the endophytic fungus Peyronellaea coffeae-arabicae FT238, which was isolated from the native Hawaiian plant Pritchardia lowreyana. The structures of compounds 1-4 were characterized based on NMR and MS spectroscopic analysis. The absolute configuration (AC) of the compounds was determined by electronic circular dichroism (ECD). Compound 4 showed antiproliferative activity with an IC50 of 0.5 μM against OVCAR3, and it also strongly inhibited Stat3 at 5 μM.

Verbenanone, an octahydro-5H-chromen-5-one from a Hawaiian-plant associated fungus FT431

A new secondary metabolite verbenanone (1) with a unique (4aS,8aS)-octahydro-5H-chromen-5-one moiety has been obtained from the endophytic fungus FT431, which was isolated from the native Hawaiian plant Verbena sp. The structure of compound 1 was characterized based on NMR and MS spectroscopic analysis. The absolute configuration (AC) of compound 1 was determined by Mosher acids. Compound 1 was tested against A2780 and A2780cisR, but it was inactive.

Anti-inflammatory activity of Barleria lupulina: Identification of active compounds that activate the Nrf2 cell defense pathway, organize cortical actin, reduce stress fibers, and improve cell junctions in microvascular endothelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE Hot aqueous extracts of the plant Barleria lupulina (BL) are used for treating inflammatory conditions and diabetic vascular complications. AIM OF THE STUDY The goal was to identify active compounds in hot aqueous extracts of BL (HAE-BL) that are consistent with a role in reducing inflammation and reducing the vascular pathology associated with diabetes. In particular, we examined activation of the Nrf2 cell defense pathway because our initial findings indicated that HAE-BL activates Nrf2, and because Nrf2 is known to suppress inflammation. Activation of Nrf2 by HAE-BL has not been described previously. MATERIALS AND METHODS Human endothelial cells, real-time PCR, western blotting, cytoskeletal analyses, and assay-guided fractionation with HPLC were used to identify specific compounds in HAE-BL that activate the Nrf2 cell defense pathway and reduce markers of inflammation in vitro. RESULTS HAE-BL potently activated the Nrf2 cell defense pathway in endothelial cells consistent with its traditional use and reported success in reducing inflammation. Assay guided fractionation with HPLC identified three alkyl catechols: 4-ethylcatechol, 4-vinylcatechol, and 4-methylcatechol, that are each potent Nrf2 activators. In addition to activating Nrf2, HAE-BL and akyl catechols each profoundly improved organization of the endothelial cell actin cytoskeleton, reduced actin stress fibers, organized cell-cell junctions, and induced expression of mRNA encoding claudin-5 that is important for formation of endothelial tight junctions and reducing vascular leak. CONCLUSIONS HAE-BL contains important alkyl catechols that potently activate the Nrf2 cell defense pathway, improve organization of the endothelial cell cytoskeleton, and organize tight cell junctions. All of these properties are consistent with a role in reducing inflammation and reducing vascular leak. Because activation of the Nrf2 cell defense pathway also prevents cancers, neuro-degeneration, age-related macular degeneration, and also reduces the severity of chronic obstructive pulmonary disorder and multiple sclerosis, HAE-BL warrants additional consideration for these other serious disorders.

NF-κB inhibitors, unique γ-pyranol-γ-lactams with sulfide and sulfoxide moieties from Hawaiian plant Lycopodiella cernua derived fungus Paraphaeosphaeria neglecta FT462

LC-UV/MS-based metabolomic analysis of the Hawaiian endophytic fungus Paraphaeosphaeria neglecta FT462 led to the identification of four unique mercaptolactated γ-pyranol–γ-lactams, paraphaeosphaerides E–H (1–4) together with one γ-lactone (5) and the methyl ester of compound 2 (11). The structures of the new compounds (1–5 and 11) were elucidated through the analysis of HRMS and NMR spectroscopic data. The absolute configuration was determined by chemical reactions with sodium borohydride, hydrogen peroxide, α-methoxy-α-(trifluoromethyl)phenylacetyl chlorides (Mosher reagents), and DP4 + NMR calculations. All the compounds were tested against STAT3, A2780 and A2780cisR cancer cell lines, E. coli JW2496, and NF-κB. Compounds 1 and 3 strongly inhibited NF-κB with IC50 values of 7.1 and 1.5 μM, respectively.

Diketopiperazines from Costa Rican endolichenic fungus Colpoma sp. CR1465A.

Three new diketopiperazines (1-3), cyclo(l-Pro-d-trans-Hyp) (1), cyclo(l-Pro-d-Glu) (2), and cyclo(d-Pro-d-Glu) (3) and five known diketopiperazines (4-8) were isolated from the endolichenic fungus Colpoma sp. CR1465A identified from the Costa Rican plant Henriettea tuberculosa (Melatomataceae). The structures of the new compounds 1-3 were elucidated using a combination of extensive spectroscopic analyses, including 2D NMR and HR-MS, and their absolute configurations were determined by a combination of NOESY analysis and Marfeys method. Cyclo(l-Pro-d-allo-Thr) (4) was recently isolated from a South China Sea marine sponge Callyspongia sp., but its NMR spectroscopic data were not reported, and cyclo(l-Pro-l-Asp) (5) was previously reported but only as a synthetic product. The NMR data assignments of compounds 4 and 5 are reported for the first time. All of the isolated compounds were tested for antifungal and antimicrobial properties.

A new antibacterial octaketide and cytotoxic phenylethanoid glycosides from Pogostemon cablin (Blanco) Benth

A new octaketide, named cytosporone V (1), and two other known phenylethanoid glycosides (2-3), were isolated from the aerial parts of Pogostemon cablin (Blanco) Benth. The structure of 1 was elucidated by a combination of extensive spectroscopic analyses, including extensive 2D NMR and HR-MS. Compounds 1-3 displayed weak antibacterial activity against two gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus. All isolates were also evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15). Compounds 2 and 3 showed significant cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines with IC50 values ranging from 2.73 to 9.52 μM.