A. Wibowo

Malaysianol A, a new trimer resveratrol oligomer from the stem bark of Dryobalanops aromatica

A new resveratrol trimer, malaysianol A (1), five known resveratrol oligomers: laevifonol (2), ampelopsin E (3), α-viniferin (4), ε-viniferin (5), diptoindonesin A (6), and bergenin (7) have been isolated from the acetone extract of the stem bark of Dryobalanops aromatica by combination of vacuum and radial chromatography techniques. Their structures were established on the basis of their spectroscopic evidence and comparison with the published data. The cytotoxic activity of the compounds was tested against several cell lines in which compound 4 was found to inhibit strongly the growth of HL-60 cell line.

Malaysianol B, an oligostilbenoid derivative from Dryobalanops lanceolata

A new oligostilbenoid tetramer, malaysianol B (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata along with seven oligostilbenoids tetramers; hopeaphenol (2), stenophyllol A (3), nepalensinol B (4), vaticanol B (5) and C (6), upunaphenol D (7), and flexuosol A (8). The structures of the isolated compounds were established on the basis of their spectroscopic data evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay.

A new symmetrical tetramer oligostilbenoid containing tetrahydrofuran ring from the stem bark of Dryobalanops lanceolata

A new tetramer oligostilbenoid possessing tetrahydrofuran ring, malaysianol C (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata, together with four known oligostilbenoids nepalensinol E (2), ϵ-viniferin (3), laevifonol (4), and ampelopsin F (5). The structures of isolated compounds were elucidated on the basis of spectral evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay, whereas the cytotoxic activity was tested using MTT assay. The plausible biogenetic routes of the isolated compounds are also discussed.

Antibacterial Activity of Oligostilbenoid Derivatives from the Stem Bark of Dryobalanops Lanceolata

Oligostilbenoid (oligomers of 3,5,4’-trihydroxystilbene) have drawn much attention due to its structure complexity, diversity and biological activities. The differences in the structures of oligostilbenoids in each family or genera has attracted interests from scientists of various disciplines to investigate its properties such as phytochemical, biogenetic pathway and chemotaxonomic. The oligostilbenoids in Dryobalanops species (Dipterocarpaceae) is unique due to the unusual condensation type displayed in Dipterocarpaceae family as compared to other oligostilbenoids from other families. In this study, eight oligostilbenoid tetramers derivatives, including malaysianol B (1) [1], hopeaphenol (2) [2], stenophyllol A (3) [3], nepalensinol B (4) [4], vaticanol B (5) and C (6) [5], upunaphenol D (7) [6], and flexuosol A (8) [7] have been isolated from D. lanceolata by using combination of vacuum and radial chromatography techniques. Their structures were established on the basis of their spectroscopic evidences and comparison with published data. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay against Gram-positive and Gram-negative bacterial strains. Compounds 7 and 8 exhibited promising antibacterial property as they inhibited the cell growth of three Gram-positive strains, Staphylococcus epidermidis, S. aureus and S. xylosus with MIC 25/75, 50/100 and 25/75 μM, respectively. If compared with compounds 1-6, the presence of free resveratrol in the skeleton of 7 and 8 showed significance effect to their activity. In addition, the position of isolated free resveratrol unit in 8 gave less activity than terminal in 7 due to a disruption of the double bond resonance in the free resveratrol.

Bioassay-guided fractionation of Artocarpus heterophyllus L. J33 variety fruit waste extract and identification of its antioxidant constituents by TOF-LCMS

We have previously reported on the antioxidant potential of Artocarpus heterophyllus J33 (AhJ33) variety fruit waste from different extraction methods. In the study, the rind maceration extract (RDM) exhibited the highest phenolic and polyphenolic contents and strongest antioxidant potential measured by the DPPH assay (R2 = 0.99). In this paper, we now report on the bioassay-guided fractionation of the active ethyl acetate (EtOAC) fraction of RDM and its TOF-LCMS analysis. Seven sub-fractions resulting from the chromatographic separation of the EtOAC fraction showed radical scavenging activities between 80 and 94% inhibition. Subsequent LCMS analysis led to the identification of fifteen compounds comprising 5 phenolics and 10 non-phenolic compounds, 11 of which are reported for the first time from AhJ33 variety. Most of the identified compounds have been reported to possess antioxidant activity in many previous studies. This indicates that AhJ33 is a promising source of antioxidants for the development of food and nutraceutical products.

Resveratrol oligomers from the tree bark of Shorea accuminatissima: Their properties and significance

This study was aimed to isolate and structure elucidate the resveratrol oligomers from the acetone extract of the tree bark of S. accuminatissima. Five resveratrol oligomers, namely vaticanol-A, davidiol-A, α-viniferin, hopeaphenol and hemsleyanol-D have been isolated for the first time from this plant. The structures of these compounds were established based on the spectroscopic data evidence, including UV, IR, 1H NMR, and 13C NMR spectra, and compared to their reported data. Hopeaphenol showed cytotoxicity and strongly inhibited murine leukemia P-388 cells.