Detail chemical studies on Carcinia maingayi have yielded one xanthone, 1,3,7-trihydroxy-2-(3-methylbut-2-enyl)-xanthone, one benzophenone, isoxanthochymol, one benzoic acid derivative 3,4-dihydroxy-methylbenzoate and two triterpenoids, stigmasterol and sitosterol. Meanwhile, investigations on Carcinia parvifolia have afforded one triterpenoid, a-amyrin and two xanthones, cowanin and rubraxanthone. Their structures were derived based on spectroscopic evidence, mainly ID and 2D NMR spectroscopy. Acetylation reaction was carried out on rubraxanthone to yield triacetate rubraxanthone. It was found that the pure rubraxanthone was strongly active against the larvae of Aedes aegypti with LC50 value of 15.49 {lg/ ml and HL-60 cells line with an IC50 value of 7.5 {lg/ ml.
Four types of crude extracts were obtained from the stem bark of Garcinia mangostana from which six xanthone derivatives: α-mangostin, β-mangostin, garcinone D, mangostenol, fuscaxanthone C and dulcisxanthone F were isolated. The structures of these compounds were elucidated and determined using spectroscopic techniques such as MS, 1D and 2D NMR. The in vitro anti-Bacillus assay was performed using the crude extracts as well as α-mangostin and β-mangostin against four Bacillus species; B. subtilis ATCC 6633, B. cereus ATCC 33019, B. megaterium ATCC 14581 and B. pumilus ATCC 14884. The ethyl acetate extract showed strong inhibitory activity against B. subtilis, B. cereus, B. megaterium and B. pumilus in disc diffusion assay with 10.33 ± 0.44 mm, 10.33 ± 0.44 mm, 9.00 ± 0.00 mm and 11.33 ± 0.17 mm inhibition zones, respectively. Nitric oxide inhibition activities indicated that two major compounds (α-mangostin, β-mangostin) exhibited very significant activity in the inhibition of LPS/IFN-γ stimulated RAW 264.7 macrophages with IC50 values of 29.81 ± 0.77 and 11.72 ± 1.16 μM, respectively. The chloroform and ethyl acetate extract of G. mangostana showed very potent activities.
Our continuing interest in anthraquinones from the Guttiferae family has led us to look at the genus Cratoxylum. A detailed chemical study on Cratoxylum aborescens resulted in the isolation of three anthraquinones, namely 1,8-dihydroxy-3-methoxy-6-methylanthraquinone (1), vismiaquinone (2) and vismione (3). These compounds were identified using 1D and 2D NMR spectroscopy. This is the first report on the chemistry of Cratoxylum aborescens.
The roots of Calophyllum inophyllum (Guttiferae), furnished six xanthones which are brasilixanthone (1), 1,3,5-trihydroxy-2- methoxy xanthone (2), caloxanthone A (3), pyranojacareubin (4), caloxanthone B (5) and tovopyrifolin (6), Structural elucidations of these compounds, were achieved through 1D and 2D NMR andMS techniques. In this paper, the isolation and structural elucidation data for these xanthones are reported.
An investigation, on the roots of Piper nigrum and the aerial parts of Piper betle, has yielded several alkaloids. The dried root sample of Piper nigrum was extracted using various solvents in increasing polarity. The dried aerial part of Piper betle was extracted using the Soxhlet extraction method. The alkaloids isolated were pellitorine(1), (E)-1-[3’,4’- (Methylenedioxy)cinnamoyl]piperidine(2), piperine(3), piperolactam D(4), cepharadione A(5), and 2,4-tetradecadienoic acid isobutyl amide(6). These compounds were isolated using chromatographic methods, while the elucidation of the structures was carried out using MS, IR and NMR techniques. The xtracts of Piper nigrum and Piper betle were also tested for cytotoxicity activities. This is the first report on E)-1-[3’,4’-(Methylenedioxy)cinnamoyl] piperidine(2) from Piper nigrum as a natural product.
The extract of Cinnamomum microphyllum showed strong antioxidant activity when it was tested against auto-oxidation of linoleic acid, superoxide, and DPPH radical scavenging activity. Further detailed investigations of the plant constituents and bioactivity studies led to the isolation and identification of known compounds consisting of three lignans, a coumarin, an ester and β-sitosterol. The structures of the compounds were determined using detailed spectroscopic analysis. The lignans were found to possess a significant antioxidant activity when tested against the three assay systems.