Records of Natural Products

Fourteen secondary metabolites, including one cinnamate derivative (1), three spirocyclic nortriterpenoids (2–4), three phenylethanoid glycosides (5–7), four lignans (8–11) and three phenolic compounds (12–14) were isolated from the EtOH extract of Leonuri Fructus. Their structures were elucidated on the basis of 1D NMR, 2D NMR and HR-ESI-MS data analysis. All isolates were tested for their antioxidant, tyrosinase and acetylcholinesterase inhibitory activities. Most of them showed moderate antioxidant activities. Compounds 2–4 exhibited obvious inhibitory activities against mushroom tyrosinase at 25 μM, with %inhibition values of 49.36 ±2.69%, 43.43 ± 3.35%, 51.69 ± 2.81%, respectively, with arbutin used as the positive control (51.90 ± 2.57%). Compounds 3, 5–6 and 9–10 exhibited significant inhibitory activities against acetylcholinesterase, similar to the positive control, galantamine

Chemical investigation of the marine-derived fungus Aspergillus flavipes 297 led to the isolation and identification of three drimane-type sesquiterpenoids, asperflavinoid A (1) and (6-strobilactone-B) esters of (E,E)-6,7-dihydroxy-2,4-octadienoic acids (2 and 3). Asperflavinoid A (1) was characterized as unseparated diastereomers and its chemical structure was determined by spectroscopic analysis of NMR and MS data. In the cytotoxic assay, compound 1 showed promising inhibitory effects on HepG2 and MKN-45 cell lines.

A phytochemical investigation of the stems of Myoporum bontioides (Sieb. et Zucc.) A. Gray, a semi-mangrove plant distributed along coastlines of north-eastern Vietnam and some Asian countries led to the isolation of a new iridoid glucoside (1), named myobontioside E, together with fourteen known compounds (2-15). Their structures were elucidated by means of HR ESI-MS, 1D and 2D NMR spectroscopy as well as comparison with the data reported in the literature. The cytotoxic effects on 8505C, MKN7, HT29, and T24 cell lines were assessed using SRB assay. Only iridoid 2 exhibited weak cytotoxicity against all tested cell lines with IC50 values ranging from 60.19 to 69.14 µM.

Two new guaiane-type sesquiterpenoids, nicotiasesquiterpenes A (1) and B (2), and seven known cembrane-type diterpenoids (3−9), were isolated from glandular trichome secretions of fresh flowers of Nicotiana tabacum L. These new chemical structures were established by extensive analyses of HRESIMS and 1D and 2D NMR data, while the other structures were elucidated by comparison of 1D NMR data with those reported in the literature. All of the isolated compounds were tested for their antiphytopathogenic fungal activity against Valsa mali var. mali, Alternaria porri, and Botrytis cinerea at a concentration of 10 µg/mL. Compounds 3, 4, and 5 exhibited medium antifungal effects against Valsa mali var. mali, with inhibitory rates of 45.3±16.1, 53.4± 4.6, and 40.1±4.5%, respectively, while the other compounds showed only insignificant activities.