Records of Natural Products

Elaeocarpus hainanensis has been used in the Oriental medicine but there are very few studies on its phytochemical profile. Our ongoing research on chemical constituents from Elaeocarpus plants in Vietnam led to the isolation of a new oleanane-type saponin from the aerial part of E. hainanensis. Its structure was identified as 1α-hydroxy-olean-11-oxo-12-en-3-O-β-L-arabinopyranoside (1) on the basis of extensive chemical and spectroscopic analyses including NMR and MS spectra. The occurence of the unique oleanane-type saponins in E. hainanensis contributed to impact phytochemical profile associated with chemotaxanomy meaning of the title plant.

The chemical composition and biological activities of the essential oil from Ficus tikoua Bur. were reported for the first time. Fifty-three compounds, accounting for 99.60% of the total essential oil composition, were identified and the main components were palmitic acid (51.13%) and linoleic acid (47.54%). The essential oil revealed significant antibacterial activity with the inhibition zones (7.89–10.59 mm), MIC (0.20–6.25 mg/mL) and MBC (0.20–12.50 mg/mL) against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris. The essential oil exhibited significant cytotoxicity against A549, NCI-H1299, PC-3 and K562 tumor cells with the IC50 values of 131.08, 50.32, 120.58 and 31.68 μg/mL, respectively. The essential oil exhibited selective cytotoxic activity to human tumor cell lines, with a significantly lower cytotoxicity to human normal cell line (MRC-5, IC50 = 161.75 μg/mL) than to tumor cells. Additionally, palmitic acid, as the major compound, aslo revealed significant antibacterial and cytotoxic activities.

A new sesquiterpene (1) and nine known alkaloids (2-10) were isolated from the roots of Toddalia asiatica. The structure of compound 1 were resolved by NMR and HRESI data, as well as ECD calculation for determining the absolute configuration. The known compounds were identified to be 8-acetonyldihydronitidine (2), 8-acetonyldihydroavicine (3), dihydronitidine (4), oxynitidine (5), decarine (6), skimmianine (7), g-fagarine (8), N-methylflindersine (9), and 4-methoxy-N-methyl-2-quinolone (10) by comparing the NMR data with those in the literature. Compound 1 is the first eremophilane-type sesquiterpenoid isolated from this species. The known compounds 2, 3, and 6 were discovered for the first time from the genus Toddalia. All the isolated compounds were evaluated for their inhibitory effects against phosphodiesterase-4, as result, compound 2 showed strong inhibitory effect against phosphodiesterase-4 with an IC50 value of 5.14 mM.

Abstract:  A new monocyclic diterpenoid, cassipouryl formate, (1) together with three known diterpenoids (2−4) and five known sesquiterpenoids (5−9) were isolated from the twigs and leaves of Syzygium fluviatile. The new isolate was elucidated by various spectroscopic technologies. This was the first example of the chemical constituents from this species and the first report on the diterpenoids from genus Syzygium.