Xanthine oxidase inhibitory constituents from the roots of <i>Ampelopsis japonica</i>

Bioassay-guided purification of the xanthine oxidase (XOD) inhibitory extract of the roots of Ampelopsis japonica resulted in the isolation of two new triterpenoids (1-2), designated Ampejaponoside A and B, along with sixteen known compounds (3-18). The structures of Ampejaposide A and B were elucidated by comprehensive analysis of spectroscopic data with the structures of the known compounds 3-18 confirmed by comparison the spectral data with corresponding values reported in literatures. All the isolates were evaluated for their XOD inhibitory activity in vitro. As a result, compounds 2, 8, and 14-16 displayed significant XOD inhibitory effect, particularly 16 being the most potent with an IC50 value of 0.21 μM, superior to positive substance allopurinol (IC50 1.95 μM). Molecular docking uncovered a unique interaction mode of 16 with the active site of XOD. The current study showed that the triterpenoids and polyphenols from A. japonica could serve as new lead compounds with the potential to speed up the development of novel XOD inhibitors with clinical potential to treat hyperuricaemia and gout.</p

Three new kavalactone dimers from <i>Piper methysticum</i> (kava)

<p>Three new dimeric kavalactones, designated as diyangonins A–C (<b>1–3</b>), along with two known analogs were isolated from the roots of <i>Piper methysticum</i>. Their structures were elucidated by means of extensive analysis of their 1D, 2D NMR, and mass spectroscopic data. All these dimers possess a skeleton featuring a cyclobutane ring connecting two kavalactone units in head-to-tail or head-to-head mode. Compounds <b>1</b>–<b>5</b> were evaluated for their cytotoxic activities against human tumor cell lines.</p

Diacyl Disulfide: A Reagent for Chemoselective Acylation of Phenols Enabled by 4‑(<i>N</i>,<i>N</i>‑Dimethylamino)pyridine Catalysis

A general and excellent acylation reagent, diacyl disulfide, was uncovered for efficient ester formation enabled by DMAP (4-(<i>N</i>,<i>N</i>-dimethylamino)­pyridine) catalysis. This protocol offered a promising synthetic platform on site-selective acylation of phenolic and primary aliphatic hydroxyl groups, which greatly expanded the realm of protecting group chemistry. The importance of the reagent was also reflected by its excellent moisture tolerance, high efficiency, and potential in synthetic chemistry and biologically meaningful natural product modification

Two new 12-membered macrolides from the endophytic fungal strain <i>Cladosprium colocasiae</i> A801 of <i>Callistemon viminalis</i>

<p>Two new polyketide metabolites, the 12-membered macrolides 4-hydroxy-12-methyloxacyclododecane-2,5,6-trione (<b>1</b>) and 12-methyloxacyclododecane-2,5,6-trione (<b>2</b>), were isolated from the endophytic fungal strain <i>Cladosprium colocasiae</i> A801 of the plant <i>Callistemon viminalis</i>, together with five known derivatives<i>.</i> Their structures were fully characterized by means of detailed spectroscopic analysis for new structures, and in comparison with published data for known compounds. The antibacterial, cytotoxic, and α-glucosidase inhibitory activities of the new compounds <b>1</b> and <b>2</b> were evaluated.</p

Two new <i>ent</i>-kaurane diterpenes from the stems of <i>Eurya chinensis</i>

<p>Two new <i>ent</i>-kaurane diterpenes (<b>1</b>–<b>2</b>), together with five known analogs, were isolated from the stems of <i>Eurya chinensis</i>. The structures of new compounds were established by extensive analysis of mass spectrometric and 1D and 2D NMR spectroscopic data. Compound <b>3</b> exhibited noticeable anti-inflammatory activity as denoted by inhibiting LPS-induced nitric oxide (NO) production in RAW264.7 cells with an IC₅₀ value of 7.82 μM. Compound <b>4</b> showed potent cytotoxic activity against human cancer cell lines NCI-H46, HepG2 and SW480 with IC₅₀ values ranging from 7.45 to 8.54 μM.</p

A new <i>ent</i>-kaurane diterpene derivative from the stems of <i>Eurya chinensis</i> R.Br

<p>One new <i>ent</i>-kaurane diterpene derivative (<b>1</b>), along with four known diterpenes, was isolated from the stems of <i>Eurya chinensis</i> R.Br. The structure of the new compound was established by extensive analysis of mass spectrometric and 1D and 2D NMR spectroscopic data. Compound <b>1</b> showed moderate anti-inflammatory activities with IC₅₀ value of 8.12 μM. This is the first example of diterpenoids with 4-hydroxy-4-(2-hydroxyethyl)-1-hydroxyl-cyclohexanoyl substituent.</p