Efficient Synthesis of cis- and trans-3,4-Dihydroxy-3,4-dihydromollugin

Visible light-induced aerobic dioxygenation of α,β-unsaturated amides/alkenes toward selective synthesis of β-oxy alcohols using rose bengal as a photosensitizer

The first visible light-induced aerobic dioxygenation of alkenes for the selective synthesis of β-oxy alcohols was developed using non-toxic rose bengal as a photosensitizer.

Unified synthesis and cytotoxic activity of 8-O-methylfusarubin and its analogues

A simple and unified synthesis of four related pyranonaphthoquinone natural products, e.g. 8-O-methylfusarubin, 8-O-methylanhydrofusarubin, fusarubin and anhydrofusarubin, is reported. The key synthetic features include the precedented Diels-Alder cycloaddition to assemble the naphthalene skeleton, selective formylation and acetonylation and intramolecular acetalization to construct the pyran ring. Manipulation of the oxidation state of the naphthoquinone core was performed to construct the two analogues, fusarubin and anhydrofusarubin. This work also highlights an unprecedented directing effect of the hydroxymethylene group in the selective hypervalent iodine-mediated quinone oxidation. The four synthetic compounds were evaluated for their in vitro cytotoxic activities against six human cancer cells. 8-O-Methylfusarubin was the most potent analogue and displayed excellent cytotoxic activity against MCF-7 breast cancer cells with an IC₅₀ value of 1.01 μM with no cytotoxic effect on noncancerous Vero cells, which could potentially be a promising lead compound for anti-breast cancer drug discovery.

Simple crystallization approach for enhancing function of plant-based madder dye and performance of dyed fabric

In the present study, the natural madder dye was investigated to the simultaneous extraction and dyeing of cotton (natural fiber) and nylon (synthetic fiber). The optimum dye extraction conditions were found to be 80 °C, 60 min, and 1:6 with ethyl alcohol after madder had been fermenting for 24 hours with water as solvent. Interestingly, crystallization can be done to separate crystal mollugin from dyed solution. And then, dyed fabrics exhibited improved color strength and ultraviolet protection factor. Meanwhile, the mollugin showed a strong fluorescence emission with maximum emission band at 464 nm with 372 nm excitation in the solid state, which may provide potential molecular system for bio-based optoelectronics and chemical sensors.

Synthesis of novel and diverse mollugin analogues and their antibacterial and antioxidant activities

Novel and diverse mollugin analogues (1-12) were synthesized using PhB(OH)2/AcOH-mediated electrocyclization reaction as a key step. The newly synthesized compounds were screened for antioxidant and antibacterial activities. Compounds 1, 2, 5, 6, 8, and 10-12 showed high antioxidant activities in DPPH inhibition (IC50=0.52-1.11 μM) compared with BHT (IC50=9.67 μM). Compounds 3 exhibited potent antibacterial activity against Staphylococcus aureus (KCTC-1916) bacterial strain at 100 μg/mL. Structures of newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR data and high-resolution mass spectrometry.

Busseihydroquinones A-D from the roots of Pentas bussei

Four new naphthohydroquinones, named busseihydroquinones A-D (1-4), along with a known homoprenylated dihydronaphthoquinone (5), were isolated from the CH(2)Cl(2)/MeOH (1:1) extract of the roots of Pentas bussei. Although the genus Pentas is frequently used by traditional healers for the treatment of malaria, only marginal activities against the chloroquine-sensitive (D6) and the chloroquine-resistant (W2) strains of Plasmodium falciparum were observed for the crude root extract and the isolated constituents of this plant.