Shengxiang Qiu

Antioxidant and Anticancer Activities of Wampee (Clausena lansium (Lour.) Skeels) Peel

Antioxidant activities of wampee peel extracts using five different solvents (ethanol, hexane, ethyl acetate, butanol and water) were determined by using in-vitro antioxidant models including total antioxidant capability, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, reducing power, and superoxide scavenging activity. Ethyl acetate fraction (EAF) exhibited the highest antioxidant activity compared to other fractions, even higher than synthetic antioxidant butylated hydroxyl toluene (BHT). In addition, the EAF exhibited strong anticancer activities against human gastric carcinoma (SGC-7901), human hepatocellular liver carcinoma (HepG-2) and human lung adenocarcinoma (A-549) cancer cell lines, higher than cisplatin, a conventional anticancer drug. The total phenolic content of wampee fraction was positively correlated with the antioxidant activity. This is the first report on the antioxidant and anticancer activities of the wampee peel extract. Thus, wampee peel can be used potentially as a readily accessible source of natural antioxidants and a possible pharmaceutical supplement.

Isolation and biomimetic total synthesis of tomentodiones A–B, terpenoid-conjugated phloroglucinols from the leaves of Rhodomyrtus tomentosa

Tomentodiones A (1) and B (2), a pair of C-11′ epimers of caryophyllene-conjugated phloroglucinols with an unprecedented skeleton, were isolated from the leaves of Rhodomyrtus tomentosa. Their structures were elucidated through the application of extensive spectroscopic measurements with the absolute configuration of 1 determined by single-crystal X-ray diffraction analysis and electronic circular dichroism (ECD) calculations. The biogenetic pathways of 1 and 2 were proposed to involve an intermolecular, inverse electron demand Diels–Alder cycloaddition reaction as the key step, and their biomimetic total synthesis was accomplished.

Biomimetic-Inspired Syntheses of Myrtucommuacetalone and Myrtucommulone J

Driven by bioinspiration and appreciation of their structures, the first biomimetic total syntheses with structural revision of the acylphloroglucinols myrtucommulone J and myrtucommuacetalone, two biologically meaningful natural products, were achieved through a biosynthetic hemiacetalization/dehydration/[3 + 3]-type cycloaddition domino sequence with high step efficiency. These syntheses result in a corrected structure for myrtucommulone J.

A Bioinspired Cascade Sequence Enables Facile Assembly of Methanodibenzo[b,f][1,5]dioxocin Flavonoid Scaffold

A remarkable bioinspired EDDA-mediated method for the selective construction of biologically interesting and highly strained bridged methanodibenzo[b,f][1,5]dioxocin flavonoid scaffold was uncovered by starting from a variety of readily available acylphloroglucinol and 2-hydroxycinnamaldehyde substrates. This method merges a fascinating olefin isomerization/hemiacetallization/dehydration/[3 + 3]-type cycloaddition cascade reaction driven by an in situ generated chromenylium intermediate and provides a convenient and viable synthetic strategy for the efficient access of such flavonoid analogues.