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Bioactive Hydantoin Alkaloids from the Red Sea Marine Sponge Hemimycale arabica.

Youssef DT, Shaala LA, Alshali KZ - Mar Drugs (2015)

Bottom Line: Hemimycalins A (2) and B (3) represent the first examples of the natural N-alkylated hydantoins from the sponge Hemimycale arabica.Compounds 1-3 displayed variable antimicrobial activities against E. coli, S. aureus, and C. albicans.These findings provide further insight into the chemical diversity as well as the biological activity of this class of compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Products, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia. dyoussef@kau.edu.sa.

ABSTRACT
In the course of our continuing efforts to identify bioactive secondary metabolites from Red Sea marine invertebrates, we have investigated the sponge Hemimycale arabica. The antimicrobial fraction of an organic extract of the sponge afforded two new hydantoin alkaloids, hemimycalins A and B (2 and 3), together with the previously reported compound (Z)-5-(4-hydroxybenzylidene)imidazolidine-2,4-dione (1). The structures of the compounds were determined by extensive 1D and 2D NMR (COSY, HSQC and HMBC) studies and high-resolution mass spectral determinations. Hemimycalins A (2) and B (3) represent the first examples of the natural N-alkylated hydantoins from the sponge Hemimycale arabica. Compounds 1-3 displayed variable antimicrobial activities against E. coli, S. aureus, and C. albicans. In addition, compound 1 displayed moderate antiproliferative activity against the human cervical carcinoma (HeLa) cell line. These findings provide further insight into the chemical diversity as well as the biological activity of this class of compounds.

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Selected HMBC correlations of compounds 2 and 3.
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marinedrugs-13-06609-f002: Selected HMBC correlations of compounds 2 and 3.

Mentions: Compound 2 (Figure 1) was purified as a yellow amorphous solid with the molecular formula C14H15N3O4, as established from the HRESIMS pseudomolecular ion peak at m/z 312.0961 [M + Na]+, suggesting nine degrees of unsaturation. The 1H and 13C NMR data of compound 2 (Table 2) showed a similarity to those of 1 (Table 1) with additional signals for two N-methyls [20,21,22] and an N-methylfromamide moiety [23,24]. The signals at δH/δC 2.77/31.2, 3.23/29.3, and 2.80/33.5 were assigned as H-13/C-13, H-14/C-14, and H-15/C-15, respectively. The downfield NMR signals at δH/δC 7.98 (s)/166.1 are characteristic for a formamide methine [23,24]. Furthermore, the 1H-1H COSY spectrum supported the p-substituted phenyl ring. The location of N-methyl groups at N-1 and N-3 was established from HMBC correlations. HMBC cross-peaks (Figure 2) of H-13/C-2, H-14/C-2 (δC 153.4), and H-14/C-4 (δC 149.9) supported the location of these N-methyl groups. Furthermore, the location of the N-methylformamide moiety at C-6 was secured from HMBC correlations of H-15/C-6 (δC 126.0) H-15/C-5 (δC 93.8), H-15/C-16 (δC 166.1), and H-16/C-15 (δC 33.5) (Figure 1 and Figure 2). Finally, the chemical shift values of the para-substituted benzene ring were in good agreement with those of 1 (Table 1). From the above discussion, compound 2 was assigned as N-((E)-(4-hydroxyphenyl) (1,3-dimethyl-2,5-dioxoimidazolidin-4-ylidene)methyl)-N-methylformamide) Figure 1 and Figure 2). To the best of our knowledge, compound 2 is reported here for the first time from a natural source and is considered as a new compound. The generic name hemimycalin A was given to 2.


Bioactive Hydantoin Alkaloids from the Red Sea Marine Sponge Hemimycale arabica.

Youssef DT, Shaala LA, Alshali KZ - Mar Drugs (2015)

Selected HMBC correlations of compounds 2 and 3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663544&req=5

marinedrugs-13-06609-f002: Selected HMBC correlations of compounds 2 and 3.
Mentions: Compound 2 (Figure 1) was purified as a yellow amorphous solid with the molecular formula C14H15N3O4, as established from the HRESIMS pseudomolecular ion peak at m/z 312.0961 [M + Na]+, suggesting nine degrees of unsaturation. The 1H and 13C NMR data of compound 2 (Table 2) showed a similarity to those of 1 (Table 1) with additional signals for two N-methyls [20,21,22] and an N-methylfromamide moiety [23,24]. The signals at δH/δC 2.77/31.2, 3.23/29.3, and 2.80/33.5 were assigned as H-13/C-13, H-14/C-14, and H-15/C-15, respectively. The downfield NMR signals at δH/δC 7.98 (s)/166.1 are characteristic for a formamide methine [23,24]. Furthermore, the 1H-1H COSY spectrum supported the p-substituted phenyl ring. The location of N-methyl groups at N-1 and N-3 was established from HMBC correlations. HMBC cross-peaks (Figure 2) of H-13/C-2, H-14/C-2 (δC 153.4), and H-14/C-4 (δC 149.9) supported the location of these N-methyl groups. Furthermore, the location of the N-methylformamide moiety at C-6 was secured from HMBC correlations of H-15/C-6 (δC 126.0) H-15/C-5 (δC 93.8), H-15/C-16 (δC 166.1), and H-16/C-15 (δC 33.5) (Figure 1 and Figure 2). Finally, the chemical shift values of the para-substituted benzene ring were in good agreement with those of 1 (Table 1). From the above discussion, compound 2 was assigned as N-((E)-(4-hydroxyphenyl) (1,3-dimethyl-2,5-dioxoimidazolidin-4-ylidene)methyl)-N-methylformamide) Figure 1 and Figure 2). To the best of our knowledge, compound 2 is reported here for the first time from a natural source and is considered as a new compound. The generic name hemimycalin A was given to 2.

Bottom Line: Hemimycalins A (2) and B (3) represent the first examples of the natural N-alkylated hydantoins from the sponge Hemimycale arabica.Compounds 1-3 displayed variable antimicrobial activities against E. coli, S. aureus, and C. albicans.These findings provide further insight into the chemical diversity as well as the biological activity of this class of compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Products, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia. dyoussef@kau.edu.sa.

ABSTRACT
In the course of our continuing efforts to identify bioactive secondary metabolites from Red Sea marine invertebrates, we have investigated the sponge Hemimycale arabica. The antimicrobial fraction of an organic extract of the sponge afforded two new hydantoin alkaloids, hemimycalins A and B (2 and 3), together with the previously reported compound (Z)-5-(4-hydroxybenzylidene)imidazolidine-2,4-dione (1). The structures of the compounds were determined by extensive 1D and 2D NMR (COSY, HSQC and HMBC) studies and high-resolution mass spectral determinations. Hemimycalins A (2) and B (3) represent the first examples of the natural N-alkylated hydantoins from the sponge Hemimycale arabica. Compounds 1-3 displayed variable antimicrobial activities against E. coli, S. aureus, and C. albicans. In addition, compound 1 displayed moderate antiproliferative activity against the human cervical carcinoma (HeLa) cell line. These findings provide further insight into the chemical diversity as well as the biological activity of this class of compounds.

Show MeSH
Related in: MedlinePlus