Records of Natural Products

A new sesquiterpene, named todasinoid A (1), together with eight known compounds (2-9) were isolated from the roots of Toddalia asiatica. The gross structure of todasinoid A were established by analyses of the NMR and HRESIMS data. A comparison of the experimental ECD spectrum of 1 with the calculated ECD spectra for a model compound (1a) resolved the absolute configuration of 1. The known compounds were identified to be bullatantriol (2), aculeatin (3), 6-(3-ethoxy-2-hydroxy-3-methylbutyl)-5,7-dimethoxy-2H-1-benzopyran-2-one (4), trans-N-p-coumaroyltyramine (5), feruloyltyramine (6), b-sitosterol (7), sitosterol D-glucoside(8), 7α-hydroxysitosterol (9) by comparing the NMR data and specific rotations with reported data in literature. Compound 1 is an eremophilane-type sesquiterpenoid containing a mercaptolactate side-chain that is rarely found in nature. Compounds 2, 5, and 9 were isolated from this plant for the first time. Bioassay study revealed that compound 5 exhibited inhibitory effects against a-glucosidase with an IC50 of 320 mM, being more active than the positive control acarbose.

 A novel β-carboline, namely Plagranline A (1), and a known alkaloid (2) were isolated from the roots of Platycodon grandiflorus. Their structure was elucidated using a combination of spectroscopic analyses and computational chemistry, including electronic circular dichroism (ECD) and optical rotatory dispersion (ORD). Alkaloids 1 and 2 exhibited moderate inhibitory effects against NO production. Interestingly, 1 and 2 are the first alkaloid constituents reported from the plant P. grandifloras.

One new monoterpene alkaloid (1) and eight known compounds (2–9), belonging to two monoterpene alkaloids (1–2), one pyridine alkaloid (3), four phenylpropanoid derivatives (4–7), and two matrine-type alkaloids (8–9), were isolated from Rauvolfia vomitoria Afzel. The structure of new compound 1 was determined by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation. Notably, this is the first reported monoterpene alkaloids from R. vomitoria. Besides, compounds 3, 5, and 7–9 were first discovered in the Apocynaceae family and compounds 4 and 6 were first reported in the Rauvolfia genus. This is also the first example of matrine-type alkaloids reported in the Apocynaceae family, indicating that matrine-type alkaloids are not unique to the Leguminosae/Fabaceae family. All isolated compounds were evaluated for their anti-acetylcholinesterase, anti-α-glucosidase, and antioxidant activities. Compound 6 showed significant α-glucosidase inhibitory activity and remarkable DPPH radical scavenging capacity, both of which are superior to the positive controls. Molecular docking of compound 6 with α-glucosidase was further performed, suggesting that compound 6 could form hydrogen bonds with residues ALA-292, ASN-259, and ARG-263.

Genus Lactuca L. belongs to one of the major families of flowering plants, Asteraceae. It includes about 150 species, distributed in warm and temperate areas, commonly in the Northern Hemisphere. Since ancient times, numerous Lactuca L. species have been cultivated for their economic and medicinal significance. Cultivated lettuce (Lactuca sativa), a representative member of the genus, is the most important leafy salad vegetable. The current review aims to provide comprehensive information on the taxonomy, phytochemistry, traditional uses, and biological activities of plants of the genus Lactuca.