As part of an ongoing study focused on the discovery of anti-influenza agents from plants, four new (1-4) and 10 known (5-14) C-methylated flavonoids were isolated from a methanol extract of Cleistocalyx operculatus buds using an influenza H1N1 neuraminidase inhibition assay. Compounds 4, 7, 8, and 14, with a chalcone skeleton, showed significant inhibitory effects on the viral neuraminidases from two influenza viral strains, H1N1 and H9N2. Compound 4 showed the strongest inhibitory activity against the neuraminidases from novel influenza H1N1 (WT) and oseltamivir-resistant novel H1N1 (H274Y mutant) expressed in 293T cells with IC50 values of 8.15 ± 1.05 and 3.31 ± 1.34 μM, respectively. Compounds 4, 7, 8, and 14 behaved as noncompetitive inhibitors in the kinetic studies. These results indicate that C-methylated flavonoids from C. operculatus have the potential to be developed as neuraminidase inhibitors for novel influenza H1N1.

As part of our ongoing search for new antidiabetic agents from medicinal plants, we found that a methanol extract of Morinda citrifolia showed potential stimulatory effects on glucose uptake in 3T3-L1 adipocyte cells. Bioassay-guided fractionation of this active extract yielded two new lignans (1 and 2) and three new neolignans (9, 10, and 14), as well as 10 known compounds (3-8, 11-13, and 15). The absolute configurations of compounds 9, 10, and 14 were determined by ECD spectra analysis. Compounds 3, 6, 7, and 15 showed inhibitory effects on PTP1B enzyme with IC50 values of 21.86 ± 0.48, 15.01 ± 0.20, 16.82 ± 0.42, and 4.12 ± 0.09 μM, respectively. Furthermore, compounds 3, 6, 7, and 15 showed strong stimulatory effects on 2-NBDG uptake in 3T3-L1 adipocyte cells. This study indicated the potential of compounds 3, 6, 7, and 15 as lead molecules for antidiabetic agents.

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As part of an ongoing search for new antidiabetic agents from medicinal plants, three new (2, 4, and 5) and two known selaginellin derivatives (1 and 3) were isolated from a methanol extract of Selaginella tamariscina. The structures of the new compounds were determined by spectroscopic data analysis. All isolates showed strong glucose uptake stimulatory effects in 3T3-L1 adipocyte cells at a concentration of 5 μM. Furthermore, these compounds were found to possess inhibitory effects on PTP1B enzyme activity with IC50 values ranging from 4.6 ± 0.1 to 21.6 ± 1.5 μM. Compound 2 showed the greatest potency, with an IC50 value of 4.6 ± 0.1 μM, when compared with the positive control (ursolic acid, IC50 = 3.5 ± 0.1 μM). Therefore, these selaginellin derivatives may have value as new lead compounds for the development of agents against type 2 diabetes.

Sorghum contains diverse pharmacologically active phytochemicals including tannins, phenolic acids and anthocyanins. In the present study, we show that caffeoylglycolic acid methyl ester (CGME), a major constituent of the grains of Sorghum bicolor, exerted anti-inflammatory effects by inducing HO-1 expression. Treatment of RAW264.7 cells with CGME induced HO-1 protein and mRNA expression. CGME increased nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) and knockdown of Nrf2 by siRNA blocked CGME-mediated HO-1 induction. SP600125 (a JNK inhibitor) or LY294002 (a PI3K inhibitor) blocked CGME-induced HO-1 expression and nuclear translocation of Nrf2, suggesting that CGME induces HO-1 expression via activating Nrf2 through a PI3K and JNK pathway. Consistent with the notion that HO-1 has anti-inflammatory properties, CGME inhibited the production of nitric oxide (NO), prostaglandin E 2 (PGE 2 ) and interleukin-6 (IL-6) as well as the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and IL-6 in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. CGME also protected C57BL/6 mice from LPS-induced mortality. However, inhibition of HO-1 abrogated the inhibitory effects of CGME on the production of NO, COX-2 and IL-6 in LPSstimulated RAW264.7 cells. Taken together, these findings suggest that CGME exerts an antiinflammatory effect through the Nrf2/HO-1 pathway, and may be a potential HO-1 inducer for preventing or treating inflammatory diseases.

Two new diterpenoids, crotonkinensins A (1) and B (2), were isolated from the leaves of the Vietnamese endemic medicinal plant Croton tonkinensis. Their structures were determined to be 7alpha,10alpha-epoxy-14beta-hydroxygrayanane-1(5),16(17)-dien-2,15-dione (1) and 7alpha,10alpha-epoxy-14beta-hydroxygrayanane-1(2),16(17)-dien-15-one (2) by spectroscopic analysis. Compounds 1 and 2 showed strong anti-inflammatory effects on the LPS-induced COX-2 promoter activity and COX-2 expression in Raw 264.7 cells.

Objective: This study characterizes the isolated compounds from the aerial parts of A. pilosa and evaluates their PTP1B and a-glucosidase inhibitory properties. Materials and methods: Ethanol extract of A. pilosa was found to inhibit 64% PTP1B activity at 30 mg/mL. The ethanol extract was partitioned with methylene chloride, ethyl acetate, n-butanol, and water fractions. Among these, the ethyl acetate fraction displayed the most potent PTP1B activity. The ethyl acetate extract was separated by chromatographic methods to obtain flavonoids and triterpenoids (1-11); which were evaluated for their inhibitory effects on PTP1B activity with p-nitrophenyl phosphate (p-NPP) as a substrate, and also a-glucosidase enzyme. Results: Compounds 1-11 were identified as apigenin-ursolic acid, tormentic acid, methyl 2-hydroxyl tricosanoate, and palmitic acid. Compounds 8, 9, and 11 displayed inhibitory effects on PTP1B activity with IC 50 values of 3.47 ± 0.02, 0.50 ± 0.06, and 0.10 ± 0.03 mM, respectively. Compounds 3, 4, 6, and 9 exhibited inhibition of the a-glucosidase activity with IC 50 values of 11.2 ± 0.2, 29.6 ± 0.9, 28.5 ± 0.1, and 23.8 ± 0.4 mM, respectively. Discussion and conclusion: As major ingredients of A. pilosa, compounds 1, 6, 8, and 9 showed the greatest inhibitory potency on PTP1B activity. Compounds 3, 6, 8, and 9 also showed potent inhibitory effects on a-glucosidase enzyme. This result suggested the potential of these compounds for developing antidiabetic agents.

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