ABSTRACT
In our antioxidant screening of some Vietnamese plant extracts, the CHCl3-soluble fraction from Calotropis gigantea (L.) W.T.Aiton flowers showed moderate DPPH free radical scavenging activity with an IC50 value of 55.8 µg/mL. Thus, a further phytochemical study was carried out to obtain five alkaloids, including a new ß-carboline-type alkaloid, caloside H (1). These known compounds were identified as 5-hydroxy-(2-methoxymethyl)pyridine (2), nicotinic acid (3), p-(acetylamino)phenol (4), and thymine (5). These structures were determined based on the NMR spectroscopic analysis. In antioxidant assay, caloside H at concentration of 100 µM showed DPPH radical scavenging capacity with a percentage of inhibition of 40.2%. In addition, a plausible biosynthetic pathway for the formation of caloside H was proposed based on the Schiff base formation and Mannich-like reaction.
ABSTRACT
Bioactivity-guided isolation of the CHCl3-soluble fraction of the stems of Salacia chinensis L. (Celastraceae) was carried out to obtain a new 7',9-epoxylignan (1) and three 7,9':7',9-diepoxylignans (2-4). The absolute configuration of 1 was elucidated based on NMR and ECD spectroscopic data interpretation. All isolated lignans showed intermediate α-glucosidase inhibitory activity with the IC50 values ranging from 28.5 to 85.6 µM.
Subject(s)
Celastraceae , Lignans , Salacia , Lignans/pharmacology , Magnetic Resonance Spectroscopy , Plant Extracts/chemistry , Salacia/chemistryABSTRACT
Two new stilbene derivatives, named strebluses C and D, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Its absolute configuration was elucidated based on NMR spectroscopic data interpretation and optical rotation calculation. Streblus C possesses strong tyrosinase inhibitory activity with an IC50 value of 0.01 µM. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. The analysis of the docked poses confirmed that 1 showed better binding affinity for oxy-tyrosinase than that of 2.
ABSTRACT
A methanolic extract of the rhizomes of Boesenbergia rotunda showed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrient deficiency conditions with a PC50 value of 6.6 µg/mL. Bioactivity-guided phytochemical investigation of the rhizomes of B. rotunda led to the isolation of nine undescribed dimeric metabolites, panduratins Q-Y. Their structures were elucidated based on NMR, MS, and ECD spectroscopic data interpretation. Panduratins Q-S and U-W exhibited potent cytotoxicity towards PANC-1 cell line with the PC50 values ranging from 0.8 to 6.3 µM. Panduratin W, which possessed a cyclohexenylchalcone-linked flavanone skeleton, showed the most cytotoxicity with a PC50 value of 0.8 µM under nutrient-deprived medium.
Subject(s)
Antineoplastic Agents, Phytogenic , Pancreatic Neoplasms , Zingiberaceae , Antineoplastic Agents, Phytogenic/pharmacology , Antineoplastic Agents, Phytogenic/therapeutic use , Cell Line, Tumor , Drug Screening Assays, Antitumor , Humans , Pancreatic Neoplasms/drug therapy , RhizomeABSTRACT
From a CHCl3-soluble extract of the stems of Semecarpus caudata (Anacardiaceae), two new diarylalkanoids, semedienone (1) and semetrienone (2), were isolated. Their structures were elucidated based on NMR spectroscopic data interpretation. These compounds possess strong tyrosinase inhibitory activity with the IC50 values of 0.033 and 0.11 µM, respectively. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. Accordingly, semedienone (1) showed good interactions with the peroxide group and amino acid residues. The biosynthesis of the isolated diarylalkanoids was proposed.
ABSTRACT
From an EtOAc-soluble fraction of the stem barks of Swintonia floribunda (Anacardiaceae), one new dimeric alkylresorcinol named integracin E (1), together with 4 known compounds (2-5) were isolated. Their chemical structures were elucidated based on the spectroscopic data interpretation. The absolute configuration of 1 was determined by the specific rotation analysis of its acid-catalyzed hydrolysis product. Compound 1 showed potent tyrosinase inhibitory activity with an IC50 value of 48.2 µM.
Subject(s)
Anacardiaceae/chemistry , Plant Bark/chemistry , Resorcinols/isolation & purification , Dimerization , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/isolation & purification , Inhibitory Concentration 50 , Molecular Structure , Monophenol Monooxygenase/antagonists & inhibitors , Spectrum AnalysisABSTRACT
Phytochemical analysis of an EtOAc extract of the stems of Artocarpus rigida led to the identification of seven new prenylated 4-chromenones, artocarmins G-M (1-7), and nine known compounds (8-17). Their structures were identified based on physical data analysis. In the tyrosinase inhibitory activity test, norartocarpetin (8) displayed the strongest effect, with an IC50 value of 0.023 µM.
