Mohamed A. Ghandourah

The role of new eudesmane-type sesquiterpenoid and known eudesmane derivatives from the red alga Laurencia obtusa as potential antifungal–antitumour agents

A new eudesmane sesquiterpenoid, eudesma-4(15),7-diene-5,11-diol (1) along with the known trinor-sesquiterene, teuhetenone (2), and a seco-eudesmane sesquiterpene, chabrolidione B (3), have been isolated from the Red Sea red alga Laurencia obtusa. The chemical structures were elucidated on the basis of extensive spectroscopic analysis. The antifungal and cytotoxic activities of the isolated metabolites were tested against several fungi, yeast and human mammary carcinoma cell line (MCF-7). Compounds 1 and 3 showed a much better activity [minimum inhibitory concentration (MIC): 2.9 μM] than that of amphotericin B (MIC: 4.6 μM). Interestingly, compound 2, the least active antifungal compound, retained the high anticancer activity against MCF-7 (22 μM) in comparison with cisplatin (59 μM), which was determined by employing lactate dehydrogenase assay. Compounds 1–3 are recorded here for the first time from algal flora. The chemotaxonomic importance of the isolated metabolites was discussed.

Two new polyacetylene derivatives from the Red Sea sponge Xestospongia sp.

Abstract Two new polyacetylenes (1 and 2), along with two known C-30 steroids (3 and 4) were identified from the Red Sea sponge, Xestospongia sp. The chemical structures were determined based on extensive spectroscopic measurements 1D (1H, 13C and DEPT) and 2D (COSY, HSQC and HMBC) NMR, UV, IR and MS. The new compounds 1 and 2 were evaluated for their antimicrobial and antitumor activities. 1 and 2 were active against multidrug- resistant bacteria with MICs ranged from 2.2 to 4.5 μM. No toxicity was recorded for the two tested compounds up to 5 μM using Artemia salina as a test organism. Compound 2 showed excellent antifungal activity against some pathogenic fungi such as Aspergillus niger and Candida albicans (MIC 2.2–2.5 μM) and antitumor activity against both Ehrlich ascites carcinoma and lymphocytic leukemia (LD50 5.0 μM).

Cytotoxic scalarane-type sesterterpenes from the Saudi Red Sea sponge Hyrtios erectus

Abstract The CHCl3/MeOH extract of the marine sponge Hyrtios erectus showed cytotoxicity against three cancer cell lines HepG2, A549, and PC-3 with IC50 0.055, 0.044, and 0.023 μg/ml, respectively. The CH2Cl2 soluble fraction afforded three scalarane sesterterpenes (1–3) along with a cholestane derivative (4) and an indole alkaloid (5). Chemical structures were established by spectroscopic techniques and comparison with data reported in the literature. Scalarinol (1) was found as a new metabolite, while heteronemin (2) and 12-O-deacetyl-19-deoxyscalarin (3) are known compounds. 1–3 exhibited cytotoxic activity against the cancer cell lines with IC50 values ranging from 14 to 230 μM. The molecular affinity to the DNA was employed as marker to examine the proposed mechanism of cytotoxic activities. Compound 2, with IC50 28 μg/ml, displayed the highest affinity to the DNA.

Isolation, antimicrobial and antitumor activities of a new polyhydroxysteroid and a new diterpenoid from the soft coral Xenia umbellata.

Abstract A new C-30 steroid, 3β-,5α-,6β-,11α-,20β-pentahydroxygorgosterol (1), and a new diterpenoid, xeniumbellal (2), along with three known aromadendrane-type sesquiterpenes, aromadendrene (3), palustrol (4) and viridiflorol (5), were isolated from the soft coral Xenia umbellata. Chemical structures were determined by analyzing their NMR and MS data. The antimicrobial and antitumor activities of the isolated compounds were examined. Both 1 and 2 showed moderate antibacterial activities, especially against the multidrug-resistant Acinetobacter baumannii (MIC 0.22 and 0.28 mM, respectively); while 2 showed antitumor activity against a lymphoma cell line with LD50 0.57 mM and was nontoxic to Artemia salina at all tested concentrations up to about 4 mM.

Antimicrobial sesquiterpenoids from Laurencia obtusa Lamouroux

Abstract Purification of the organic extract of Laurencia obtusa Lamouroux by column chromatography and preparative thin layer chromatography provided four new compounds: a eudesmane-type sesquiterpenoid [eudesma-4(15),11-diene-5,7-diol (1)], a cuparane-type sesquiterpenoid [10-hydroxycuparaldehyde (2)], and two nor-cuparanes [3-hydroxy-15-nor-cuparan-10β-ol (3) and 2-bromo-3-hydroxy-15-nor-cuparan-10β-ol (4)]. Structural identification was made possible by comparison of spectral data with those reported in the literature. Compounds 3 and 4 are significant as nor-cuparanes are rarely isolated from marine environment. 1 showed moderate anticandidal activity, whereas 2 exhibited reasonable antibacterial activity against multidrug-resistant bacteria (especially Gram-positive). All the compounds are nontoxic to Artemia salina.

Differential cytotoxic activity of the petroleum ether extract and its furanosesquiterpenoid constituents from Commiphora molmol resin

Abstract This study revealed a differential cytotoxic activity of the petroleum ether extract (IC50=5 μg/mL) of the resinous exudates of Commiphora molmol against two mouse cell lines KA31T and NIH3T3 (untransformed and transformed mouse fibroblasts, respectively). Four new compounds (1–4) and five known compounds (5–9) were isolated from the petroleum ether extract. The identity of these new compounds was determined as γ-elemane lactone (1), 5-αH,8-βH-eudesma-1,3,7(11)-trien-8,12-olide (2), 2-hydroxy-11,12-dihydrofuranodiene (3), and 2-hydroxyfuranodiene (4). 1 and 2 displayed the highest cytotoxic activity against NIH3T3 cells. 7 and 9 exhibited moderate cytotoxic activity against KA31T cells. Compounds 3–6 showed weak cytotoxic activities against both cell lines. These results may explain the high efficacy of the petroleum ether fraction in several myrrh-derived pharmaceutical preparations.

Isolaurenidificin and Bromlaurenidificin, Two New C15-Acetogenins from the Red Alga Laurencia obtusa

Chromatographic fractionation of the CH2Cl2/MeOH extract of the Red Sea red alga Laurencia obtusa gave two new hexahydrofuro[3,2-b]furan-based C15-acetogenins, namely, isolaurenidificin (1) and bromlaurenidificin (2). The chemical structures were elucidated based on extensive analyses of their spectral data. Compounds 1 and 2 showed no toxicity (LC50 > 12 mM) using Artemia salina as test organism. Both compounds showed weak cytotoxicity against A549, HepG-2, HCT116, MCF-7, and PC-3 cells, however, they exhibited a relatively potent cytotoxic activity against peripheral blood neutrophils. This can be attributed partly to induction of apoptosis.