Abdel-Nasser B. Singab

Bioactive Terpenes from Marine-Derived Fungi

Marine-derived fungi continue to be a prolific source of secondary metabolites showing diverse bioactivities. Terpenoids from marine-derived fungi exhibit wide structural diversity including numerous compounds with pronounced biological activities. In this review, we survey the last five years’ reports on terpenoidal metabolites from marine-derived fungi with particular attention on those showing marked biological activities.

Two new triterpenoids and a new naphthoquinone derivative isolated from a hard coral-derived fungus Scopulariopsis sp.

Scopulariopsis sp. isolated from the Red Sea hard coral Stylophora sp. yielded two new triterpenoids (1-2) and a new naphthoquinone derivative (8) when cultured on white beans. In addition, fourteen known compounds including three triterpene analogues (3-5), two sesquiterpenoids (6-7), two polyketides (9-10) and seven nitrogenous compounds (11-17) were isolated. All structures were determined through extensive analysis of the NMR and MS data as well as by comparison with literature data. All isolated compounds were evaluated for their cytotoxic, antibacterial and antitubercular activities. However, none of them showed significant activity.

Chemical Composition of Essential Oil from Doum Fruits Hyphaene thebaica (Palmae)

Abstract Results of GC and GC-MS analysis of essential oil isolated from doum fruits (Hyphaene thebaica) revealed the presence of fifty-seven compounds. Fifty of them could be identified with monoterpenes represent 15.97 % including compounds such as sabinene (0.82 %), β-pinene (1.98 %), limonene (2.42 %), terpinen 4-ol (1.77 %) %), α-terpineol (0.95 %). While diterpenes represent 40.49 %, of which incensole (17.52 %) and incensole acetate (19.81 %) were found to be the main components. Oxygenated compounds constituted 66.78 % of the total compounds identified which indicated the economical value of this oil. The scent of doum oil fruits may be attributed to the presence of volatile diterpenes as cembrene A, cembrene C, incensole and incensole acetate; these compounds are reported here for the first time in family Palmae.

Hydroquinone derivatives from the marine-derived fungus Gliomastix sp.

Eight new hydroquinone derivatives, gliomastins A–D (1–4), 9-O-methylgliomastin C (5), acremonin A 1-O-β-D-glucopyranoside (6), gliomastin E 1-O-β-D-glucopyranoside (7), and 6′-O-acetyl-isohomoarbutin (8), together with seven known analogues were isolated from the marine-derived fungus Gliomastix sp. Their structures were elucidated by extensive spectroscopic analysis including 1D and 2D NMR measurements aided by DFT NMR calculations as well as MS data. TDDFT-ECD and OR calculations were performed to determine the absolute configurations of 1 and the aglycones of 6 and 7. Compound 1 features a novel skeleton, biogenetically derived from a Diels–Alder reaction between derivatives of 11 and 13. Compound 2 represents a rare sulfur-containing alkaloid derived from the known hydroquinone 13. Compounds 1, 10 and 12 showed strong cytotoxicity against the L5178Y mouse lymphoma cell line with IC50 values of 1.8, 1.0 and 1.1 μM, respectively. Compound 3 exhibited moderate antitubercular activity against Mycobacterium tuberculosis with a MIC value of 12.5 μM.