Phytochemical Screening and Potential Antibacterial Activity of Defatted and Nondefatted Methanolic Extracts of Xao Tam Phan (Paramignya trimera (Oliv.) Guillaum) Peels against Multidrug-Resistant Bacteria.

Xao tam phan (Paramignya trimera (Oliv.) Guillaum) is a traditional herbal medicine in Vietnam. Previous investigations reported mainly compounds and bioactivities of roots, stems, and leaves while there is limited information about those of fruits. This study aims to reveal the difference in the chemical profile of defatted peel (DP) and nondefatted peel (NDP) methanolic extracts of P. trimera using colorimetric reactions and liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) analysis. We also showed the potential antibacterial activity of two extracts against clinically isolated bacteria strains including P. aeruginosa, Salmonella sp., and S. aureus with the MIC values < 100 µg/mL. This preliminary result proves the traditional usage of this herbal medicine and can be helpful for further investigation on the isolation and identification of the new compounds in P. trimera peels.

Auto-flocculation through cultivation of Chlorella vulgaris in seafood wastewater discharge: Influence of culture conditions on microalgae growth and nutrient removal.

Nowadays, the pretreatment of wastewater prior to discharge is very important in various industries as the wastewater without any treatment contains high organic pollution loads that would pollute the receiving waterbody and potentially cause eutrophication and oxygen depletion to aquatic life. The reuse of seafood wastewater discharge in microalgae cultivation offers beneficial purposes such as reduced processing cost for wastewater treatment, replenishing ground water basin as well as financial savings for microalgae cultivation. In this paper, the cultivation of Chlorella vulgaris with an initial concentration of 0.01 ± 0.001 g⋅L-1 using seafood sewage discharge under sunlight and fluorescent illumination was investigated in laboratory-scale without adjusting mineral nutrients and pH. The ability of nutrient removal under different lighting conditions, the metabolism of C. vulgaris and new medium as well as the occurrence of auto-flocculation of microalgae biomass were evaluated for 14 days. The results showed that different illumination sources did not influence the microalgae growth, chemical oxygen demand (COD) and biochemical oxygen demand (BOD) significantly. However, the total nitrogen (total-N) and total phosphorus (total-P) contents of microalgae were sensitive to the illumination mode. The amount of COD, BOD, total-N and total-P were decreased by 88%, 81%, 95%, and 83% under sunlight mode and 81%, 74%, 79%, and 72% under fluorescent illumination, respectively. Furthermore, microalgae were auto-flocculated at the final days of cultivation with maximum biomass concentration of 0.49 ± 0.01 g⋅L-1, and the pH value had increased to pH 9.8 ± 0.1 under sunlight illumination.

Symmetric dimers of ent-kaurane diterpenoids with cytotoxic activity from Croton tonkinensis.

Breast cancer is the most common malignant tumor in women these days accounting for approximately 24% of all cancer. During our screening program searching for cytotoxic materials from natural products, two new symmetric dimers of ent-kaurane diterpenoid, crotonkinensins C (1) and D (2), with connectivity at C-17 were isolated from the leaves of the Vietnamese endemic medicinal plant Croton tonkinensis. Their structures were determined on the basis of physicochemical and spectroscopic data. Compound 2 showed a potent cytotoxic activity against MCF-7, tamoxifen-resistant MCF-7 (MCF-7/TAMR), adriamycin-resistant MCF-7 (MCF-7/ADR), and MDA-MB-231 breast cancer cell lines.

SIRT1 inhibitory diterpenoids from the Vietnamese medicinal plant Croton tonkinensis.

Silent information regulator two ortholog 1 (SIRT1) is a member of the sirtuin deacetylase family of enzymes that removes acetyl groups from the lysine residues in histones and other proteins. It has been suggested that SIRT1 inhibitors might be beneficial in the treatment of cancer and neurodegenerative diseases. Bioassay-guided fractionation of the MeOH extract of the leaves of CROTON TONKINENSIS resulted in the isolation of a new ENT-kaurane diterpenoid (1) along with 11 known compounds (2- 12). The structure of the new compound 1 was determined to be ENT-11 alpha-acetoxy-7 beta-hydroxykaur-16-en-15-one based on spectroscopic analyses. Compounds 3, 4, 6- 9, 11, and 12 exhibited SIRT1 inhibitory activity in an IN VITRO assay, with IC (50) values ranging from 16.08 +/- 0.11 to 44.34 +/- 2.32 microM. This is the first report showing the potential of ENT-kaurane diterpenoids as a new class of natural SIRT1 inhibitors.

New prenylated flavanones from Erythrina abyssinica with protein tyrosine phosphatase 1B (PTP1B) inhibitory activity.

As the insulin and leptin signaling pathway can be regulated by PTP1B, it has been suggested that compounds that reduce PTP1B activity or expression levels can be used for treating type 2 diabetes and obesity. In the course of our screening efforts on new PTP1B inhibitors, six new flavanones ( 1- 6) with dihydrofuran moiety and two known flavanones ( 7 and 8) were isolated from the stem bark of Erythrina abyssinica (Leguminosae). Their structures were elucidated on the basis of spectroscopic (including UV, CD, MS, 1D, and 2D NMR) and physicochemical analyses. With the exception of 3 and 5, the compounds inhibited PTP1B activity in an IN VITRO assay with IC (50) values ranging from 15.2 +/- 1.2 to 19.6 +/- 2.3 microM, whereas RK-682 as a positive control displayed an IC (50) value of 4.7 +/- 0.5 microM.

Crotonkinensins A and B, diterpenoids from the Vietnamese medicinal plant Croton tonkinensis.

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.