Mat Ropi Mukhtar

Anti-acetylcholinesterase, anti-α-glucosidase, anti-leishmanial and anti-fungal activities of chemical constituents of Beilschmiedia species

Phytochemical investigation of Beilschmiedia alloiophylla has resulted in the isolation of one new alkaloid, 2-hydroxy-9-methoxyaporphine (1), and ten known natural products, laurotetanine (2), liriodenine (3), boldine (4), secoboldine (5), isoboldine (6), asimilobine (7), oreobeiline (8), 6-epioreobeiline (9), β-amyrone (10), and (S)-3-methoxynordomesticine (11). Chemical studies on the bark of B. kunstleri afforded compounds 2 and 4 along with one bisbenzylisoquinoline alkaloid, N-dimethylphyllocryptine (12). Structures of compounds 1-12 were elucidated on the basis of spectroscopic methods. All of these isolates were evaluated for their anti-acetylcholinesterase (AChE), anti-α-glucosidase, anti-leishmanial and anti-fungal activities. Compounds 1-12 exhibited strong to moderate bioactivities in aforementioned bioassays.

Triterpenes and steroids from the leaves of Aglaia exima (Meliaceae)

A study on the leaves of Aglaia exima led to the isolation of one new and seven known compounds: six triterpenoids and two steroids. Their structures were elucidated and analyzed mainly by using spectroscopic methods; 1D and 2D NMR, mass spectrometry, UV spectrometry and X-ray. All the triterpenoids and steroids were measured in vitro for their cytotoxic activities against eight cancer cell lines; lung (A549), prostate (DU-145), skin (SK-MEL-5), pancreatic (BxPC-3), liver (Hep G2), colon (HT-29), breast (MCF-7) and (MDA-MB-231). The new cycloartane triterpenoid, 24(E)-cycloart-24-ene-26-ol-3-one 1, showed potent cytotoxic activity against colon (HT-29) cancer cell line (IC(50) 11.5μM).

Chisomicines A-C, limonoids from Chisocheton ceramicus.

Three new limonoids, chisomicines A-C (1-3), have been isolated from the bark of Chisocheton ceramicus. Their structures were determined by 2D NMR, CD spectroscopic methods, and X-ray analysis. Chisomicine A (1) exhibited NO production inhibitory activity in J774.1 cells stimulated by LPS dose-dependently at high cell viability.

Rearranged Diterpenoids from the Biotransformation of ent-Trachyloban-18-oic Acid by Rhizopus arrhizus

In our search for inhibitors of the antiapoptotic protein Bcl-xL, investigation of Xylopia caudata afforded a new diterpenoid, ent-trachyloban-4beta-ol (2), and five known ent-trachylobane or ent-atisane compounds. Only ent-trachyloban-18-oic acid (1) exhibited weak binding activity to Bcl-xL. These compounds exhibited cytotoxicity against KB and HCT-116 cell lines with IC(50) values between 10 and 30 microM. Bioconversion of compound 1 by Rhizopus arrhizus afforded new hydroxylated metabolites (3-7) of the ent-trachylobane and ent-kaurene type and compound 8, with a rearranged pentacyclic carbon framework that was named rhizopene. Compounds 3-8 were noncytotoxic to the two cancer cell lines, and compounds 3 and 5 exhibited only weak binding affinity for Bcl-xL.

Naucline, a New Indole Alkaloid from the Bark of Nauclea officinalis

A new indole alkaloid, naucline (1) together with four known alkaloids, angustine (2), angustidine (3), nauclefine (4) and naucletine (5), were isolated from the bark of Nauclea officinalis. The structures of all isolated compounds were elucidated with various spectroscopic methods such as 1D- and 2D- NMR, IR, UV and LCMS-IT-TOF. In addition to that of alkaloid 1, the complete 13C-NMR data of naucletine (5) were also reported. Naucline (1) showed a moderate vasorelaxant activity (90% relaxation at 1 × 10−5 M) whereas, angustine (2), nauclefine (4), and naucletine (5) showed potent vasorelaxant activity (more than 90% relaxation at 1 × 10−5 M) on an isolated rat aorta.

(6,7-Dimethoxy-4-methylisoquinolinyl)-(4 \-methoxyphenyl)-methanone, a New Benzylisoquinoline Alkaloid from Beilschmiedia brevipes

The leaves of Beilschmiedia brevipes provided a new benzylisoquinoline alkaloid: (6,7-dimethoxy-4-methylisoquinolinyl)-(4’-methoxyphenyl)-methanone (1) and O,O-dimethylannocherin A (2), a new natural compound which has been synthesized before. Complete 1H- and 13C-NMR data of both compounds were reported. The structures were established through various spectroscopic methods notably 1D- and 2D-NMR, UV, IR and HRESIMS.

Antimicrobial activities of marine fungi from Malaysia

Abstract In a systematic screening effort, extracts of marine fungi from Malaysia were investigated for antimicrobial activity and potentially active secondary metabolites. In preliminary experiments, the plug assay method was employed to screen 152 strains for antimicrobial activity. Of these, 82 exhibited biological activity, with most of the active strains (90.2%) having antibacterial activity, mainly towards Gram-positive bacteria, while only 9.6% had antifungal activity. On the basis of these results, five marine fungi, Fasciatispora nypae, Caryosporella rhizophorae, Melaspilea mangrovei, Leptosphaeria sp. and ascomycete strain 19 (NF) were selected for further investigation to confirm their biological activity by the disc diffusion assay method. The selected species had various degrees of activity against the test microorganisms, depending on culture conditions (stationary vs. shaking cultures) and incubation time (10–25 days). Only F. nypae showed a wider range of antifungal and antibacterial activity as compared to the remaining fungal strains under investigation. Therefore, bioactivity-guided fractionation was undertaken to isolate the active principles, resulting in the characterisation of 2,2,7-trimethyl-2H-chromen-5-ol (1) which had antimicrobial activity towards test microorganisms. The structure of 1, which previously had only been reported as a synthetic intermediate, but not as a natural product, was elucidated by mass spectrometry in conjunction with one- and two-dimensional NMR spectroscopy.

New phenantrene alkaloids from Cryptocarya crassinervia.

The bark of Cryptocarya crassinervia provided two new phenantrene alkaloids, 2-hydroxyatherosperminine (1) and N-demethyl-2-methoxyatherosperminine (2).

Antifeedant Triterpenoids from the Seeds and Bark of Lansium domesticum cv Kokossan (Meliaceae)

Two tetranortriterpenoids, kokosanolide A (1) and C (2) were isolated from the seeds and three onoceranoid-type triterpenoids: kokosanolide B (3), 8,14-secogammacera-7,14-diene-3,21-dione (4) and a 1.5:0.5 mixture of 8,14-secogammacera-7,14(27)-diene-3,21-dione (5) and compound 4 were isolated from the bark of kokossan (Lansium domesticum). Complete 1H- and 13C-NMR data of the triterpenoids 1-5 are reported. The triterpenoids’ structures were elucidated primarily by means of high field 1D- and 2D-NMR, IR and HRMS spectral data. Triterpenoids 1-5 exhibited moderate to strong antifeedant activity against the fourth instar larvae of Epilachna vigintioctopunctata.

(+)-Kunstlerone, a new antioxidant neolignan from the Leaves of Beilschmiedia kunstleri gamble.

A new neolignan, 3,4-dimethoxy-3′,4′-methylenedioxy-2,9-epoxy-6,7-cyclo-1,8-neolign-11-en-5(5H)-one, which has been named (+)-kunstlerone (1), together with six known alkaloids: (+)-norboldine (2), (+)-N-methylisococlaurine (3), (+)-cassythicine (4), (+)-laurotetanine (5), (+)-boldine (6) and (-)-pallidine (7), were isolated from the leaves of Beilschmiedia kunstleri. The structures were established through various spectroscopic methods notably 1D- and 2D-NMR, UV, IR and LCMS-IT-TOF. (+)- Kunstlerone (1) showed a strong antioxidant activity, with an SC50 of 20.0 µg/mL.