Two new pyrrolo-2-aminoimidazoles from a Myanmarese marine sponge,Clathria prolifera

Marine organisms such as marine sponges and soft corals are valuable sources of pharmacologically active secondary metabolites. In our ongoing research on the discovery of new secondary metabolites from marine organisms, two new pyrrolo-2-aminoimidazoles, clathriroles A (1) and B (2), were isolated from the water-soluble portion prepared from the methanol and acetone (2:1) extract of the marine sponge, Clathria prolifera, collected in Myanmar. The chemical structures of the isolated compounds were determined using extensive spectroscopic techniques, including NMR, HRESIMS, IR, and optical rotation, and comparisons with the reported literature. The spectroscopic analyses of 1 and 2 suggested that 1 is an enantiomer of antifungal N-methylmanzacidin C isolated from the marine sponge Axinella brevistyla, whereas 2 is a diastereomer of manzacidin D at C-11 isolated from the marine sponge Astrosclera willeyana. To the best of our knowledge, this is the first report of the isolation of the pyrrolo-2-aminoimidazole compounds from C. prolifera. Furthermore, in contrast to the potency of N-methylmanzacidin C against Saccharomyces cerevisiae, the antifungal assay revealed that 1 and 2 lack any activity against this strain. Thus, these observations may suggest that the absolute configurations at both C-9 and C-11 play an important role in controlling the antifungal activity of this type of compound.

     

Anti-melanin deposition activity and active constituents of Jatropha multifida stems

Journal of Natural Medicines - Jatropha multifida is a medicinal plant that belongs to the Euphorbiaceae family. Our investigation revealed that the chloroform extract of J. multifida stems showed...     

Anti-metastatic effects of ergosterol peroxide from the entomopathogenic fungus Ophiocordyceps gracilioides on 4T1 breast cancer cells

Journal of Natural Medicines - Ophiocordyceps gracilioides is an entomoparasitic ascomycetes whose bioactivity has not been examined in detail. In this study, we identified the bioactive compounds...     

Three new sesquiterpene aminoquinones from a Vietnamese Spongia sp. and their biological activities

Journal of Natural Medicines - Sesquiterpenoid quinones with remarkable properties, such as anti-inflammatory, antibacterial, antiviral, antitumor, antiangiogenic, and differentiation-inducing...     

Two new quassinoids and other constituents from Picrasma javanica wood,and their biological activities

Picrasma javanica Blume (Simaroubaceae) is a medium-sized tree that is distributed widely in tropical Asia. In our previous study, we isolated quassinoids from P. javanica bark collected in Myanmar, and reported their antiproliferative activities. In our ongoing research for the discovery of bioactive compounds from Myanmar medicinal plants, two new quassinoids, (16R)-methoxyjavanicin B (1) and (16S)-methoxyjavanicin B (2), along with seven known compounds (3–9), were isolated during the phytochemical investigation of the CHCl₃ soluble portion of the MeOH extract of P. javanica wood. The structures of the new compounds were elucidated by analyses of their spectroscopic data (1D- and 2D-NMR, HRESIMS, and CD). A cytotoxicity assay revealed that compound 8 showed moderate activities against all tested cancer cell lines, the human lung (A549), breast (MCF7), and cervical (HeLa), and the normal fibroblast cell line, with IC₅₀ values ranging from 48.6 to 65.9 μM. Furthermore, the antibacterial assay demonstrated that 1 and 2 had the highest activities (MIC value of 1.6 μM each), followed by 5 and 3 (MIC values of 3.1 and 6.3 μM, respectively) against the Gram-positive bacterium B. subtilis.

     

Bioactive secondary metabolites from Boesenbergia pandurata of Myanmar and their preferential cytotoxicity against human pancreatic cancer PANC-1 cell line in nutrient-deprived medium

The chloroform extract of rhizomes of Boesenbergia pandurata demonstrated marked preferential cytotoxicity against human pancreatic PANC-1 cancer cells in nutrient-deprived medium. Bioactivity-directed investigation of this extract yielded four new secondary metabolites, geranyl-2,4-dihydroxy-6-phenethylbenzoate ( 1), 2',4'-dihydroxy-3'-(1'-geranyl)-6'-methoxychalcone ( 2), (1' R,2' S,6' R)-2-hydroxyisopanduratin A ( 3), and (2 R)-8-geranylpinostrobin ( 4), and twenty known compounds ( 5- 24). Among the known compounds, (2 S)-6-geranylpinostrobin ( 5), (+/-)-6-methoxypanduratin A ( 6), and (2 S)-7,8-dihydro-5-hydroxy-2-methyl-2-(4'-methyl-3'-pentenyl)-8-phenyl-2 H,6 H-benzo[1,2- b:5,4- b']dipyran-6-one ( 7) were isolated for the first time from a natural source. The structures of these compounds were elucidated using extensive spectroscopic techniques including CD measurements. All the isolated compounds showed varying degrees of in vitro preferential cytotoxicity against PANC-1 cells. Nicolaioidesin B ( 11) and panduratin A ( 17) were most potent, each showing a PC 100 at 2.5 microM.     

Anti-inflammatory activities of isopimara-8(9),15-diene diterpenoids and mode of action of kaempulchraols B–D from Kaempferia pulchra rhizomes

Kaempulchraols B–D (2–4), isopimara-8(9),15-diene diterpenoids isolated from Kaempferia pulchra rhizomes collected in Myanmar, were identified as potent NF-κB inhibitors. These compounds were also effective as NO inhibitory agents, with IC50 values of 47.69, 44.97, and 38.17 μM, respectively, without showing any cytotoxicity against LPS-induced RAW264.7 cells. Investigations of the mechanisms of action of 2–4 revealed that they inhibit the NF-κB-mediated transactivation of a luciferase reporter gene, IL-6 production, and COX-2 expression, with an effective dose of 25 μM. Thus, isopimarane diterpenoids are suggested to be potent inhibitors of NF-κB pathways and could be further explored as potential anti-inflammatory lead compounds.