Illilanceolide A, a unique seco-prezizaane sesquiterpenoid with 5/5/6 tricyclic scaffold from the fruits of Illicium lanceolatum A. C. Smith

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Four Highly Oxygenated Sesquiterpenoids from the Fruits of Illicium micranthum Dunn

Four highly oxygenated sesquiterpenoids, illimicranolides A (1) and B (2), and illicinolides E (3) and F (4), were obtained from the fruits of Illicium micranthum Dunn, as well as one known analog, illicinolide B (5). The chemical structures of 1-4 were determined comprehensively by 1D (¹ H and ¹³ C) and 2D (HMBC, HSQC, ¹ H-¹ H COSY, and ROESY) NMR, and HR-ESI-MS data. Structurally, compound 1 was an unprecedented sesquiterpenoid with a 5/5/6/5-fused tetracyclic ring system and was the first seco-prezizaane sesquiterpenoid featuring a 11,8-γ-lactone ring. Compounds 3 and 4 were the fifth and sixth examples of illicinolide-type sesquiterpenoids. Moreover, compound 1 demonstrated neurotrophic activity of NGF-induced PC12 cells with differentiation rate of 10.34 % at a concentration of 10 μM.

seco-Prezizanne Sesquiterpenes and Prenylated C6-C3 Compounds from the Fruits of Illicium lanceolatum A. C. Smith

Two new seco-prezizaane-type sesquiterpenes, 2β-hydroxy-6-deoxyneoanisatin (1) and 3,4-anhydro-2-oxo-1α-hydroxy-6-deoxyneoanisatin (2), and two new prenylated C₆ -C₃ compounds, illilanceofunones A (3) and B (4), were obtained from the fruits of Illicium lanceolatum, along with four known prenylated C₆ -C₃ compounds (5-8). Their structures were proposed through HR-ESI-MS, ¹ H, ¹³ C, and 2D NMR data interpretation. Moreover, the absolute configuration of 1 and 2 were further assigned by single-crystal X-ray diffraction analysis and electronic circular dichroism (ECD) calculations, respectively. Illihenryipyranol A (6) exhibited neuroprotective activity against MPP⁺ -induced PC12 cell damage in a dose-dependent manner.