Mostafa A. Fouad

Cesdiurins I–III, steroidal saponins from Cestrum diurnum L.

Phytochemical investigation of a methanolic extract of leaves of Cestrumdiurnum L (Solanaceae) resulted in isolation of several furostanol steroidal saponins, named cesdiurins I–III (1–3). Their structures of the isolated compounds were determined by spectroscopic analyses, including by use of 1D and 2D NMR spectroscopic techniques as well as by mass spectral analyses.

Iotrochotamides I and II: New ceramides from the Indonesian sponge Iotrochota purpurea

Our search for biologically active marine natural products led to the isolation of two new ceramides, iotrochotamide I (1) and iotrochotamide II (2), together with three known 6-bromoindole alkaloids (6-bromo-1H-indole-3-carbaldehyde (3), 6-bromo-1H-indole-3-carboxylic acid methyl ester (4), and 6-bromo-1H-indole-3-carboxylic acid ethyl ester (5)) from the sponge Iotrochota purpurea collected in Indonesia. The structure elucidation of these compounds was secured by spectroscopic methods (1H, 13C, DEPT, COSY, HMQC and HMBC), accurate mass measurements (ESI, EI and GS-MS) as well as comparison with known compounds.

Rhodozepinone, a new antitrypanosomal azepino-diindole alkaloid from the marine sponge-derived bacterium Rhodococcus sp. UA13

A new azepino-diindole alkaloid; rhodozepinone (1), along with five known compounds, including 2-amino-3-[2(1H)-quinolinon-4-yl]propionic acid (2), 3-hydroxy-2-methyl-4H-pyran-4-one (maltol) (3), phenyl acetic acid methyl ester (4), indole-3-acetic acid (5), and 2-amino-3-(1H-indol-3-yl) propanoic acid (tryptophan) (6) were isolated and identified from the broth culture of Rhodococcus sp. UA13, which had been previously recovered from the Red Sea sponge Callyspongia aff. Implexa. The structures of compounds (1–6) were determined by spectroscopic analyses, including 1D and 2D NMR experiments in combination with HR-ESI-MS, as well as comparison with the literature. All the characterized metabolites were firstly reported herein from this marine sponge-associated actinomycete, and among them, (3), (4), and (6) were characterized for the first time from the genus Rhodococcus, whereas this is the first report for isolation of compound (2) from a natural source. Moreover, both the antimicrobial and antitrypanosomal properties of the isolated metabolites (1–6) were evaluated, and only rhodozepinone (1) exhibited significant antibacterial and antitrypanosomal activities against Staphylococcus aureus NCTC 8325 (IC50 = 8.9 µg/ml) and Trypanosoma brucei brucei TC221 [IC50 = 16.3 (48 h) and 11.8 (72 h) µg/ml], respectively. These results totally reflected the potential of sponge-derived actinomycetes as a rich source of new natural products with interesting bioactivities, as well as their promising future contribution to drug discovery.

Alnuheptanoid A: a new diarylheptanoid derivative from Alnus japonica

Extensive chromatographic investigation of the ethanolic extract of Alnus japonica Steud stem bark led to the isolation of a new diarylheptanoid named alnuheptanoid A [(5S)-7-(3,4-dihydroxyphenyl)-1-(4-hydroxyphenyl)-5-methoxyheptan-3-one] (8), together with seven known diarylheptanoid derivatives: platyphyllenone (5), (5S)-1,7-bis(4-hydroxyphenyl)-5-methoxyheptan-3-one (6), 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-4-hepten-3-one (7), hirsutenone (9), (5R)-O-methylhirsutanonol (10), hirsutanonol (11) and oregonin (13), three triterpenes: α-amyrin (1), betulinaldehyde (3) and betulinic acid (4), and two sterols: β-sitosterol (2) and daucosterol (12). Compound 6 was isolated for the first time from natural source. The structures of the isolated compounds were determined on the basis of spectroscopic measurements (UV, IR, HR-ESI-MS, 1D and 2D NMR).

Bioactive Natural Products of Marine Sponges from the Genus Hyrtios

Marine sponges are known as a rich source for novel bioactive compounds with valuable pharmacological potential. One of the most predominant sponge genera is Hyrtios, reported to have various species such as Hyrtios erectus, Hyrtios reticulatus, Hyrtios gumminae, Hyrtios communis, and Hyrtios tubulatus and a number of undescribed species. Members of the genus Hyrtios are a rich source of natural products with diverse and valuable biological activities, represented by different chemical classes including alkaloids, sesterterpenes and sesquiterpenes. This review covers the literature until June 2016, providing a complete survey of all compounds isolated from the genus Hyrtios with their corresponding biological activities whenever applicable.

Natural Product Potential of the Genus Nocardiopsis

Actinomycetes are a relevant source of novel bioactive compounds. One of the pharmaceutically and biotechnologically important genera that attract natural products research is the genus Nocardiopsis, mainly for its ability to produce a wide variety of secondary metabolites accounting for its wide range of biological activities. This review covers the literature from January 2015 until February 2018 making a complete survey of all the compounds that were isolated from the genus Nocardiopsis, their biological activities, and natural sources, whenever applicable.

A new antitrypanosomal alkaloid from the Red Sea marine sponge Hyrtios sp.

The antitrypanosomally active crude extract of the sponge Hyrtios sp. was subjected to metabolomic analysis using liquid chromatography coupled with high resolution electrospray ionization mass spectrometry (LC–HR-ESIMS) for dereplication purposes. As a result, a new alkaloid, hyrtiodoline A (1), along with other four known compounds (2–5) were reported. The structures of compounds 1–5 were determined by spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESI-MS) experiments, as well as comparison to the literature. We further investigated the antitrypanosomal activity of the five compounds, where compound 1 exhibited the most potent antitrypanosomal activity, with a half-maximal inhibitory concentration (IC50) value of 7.48 µM after 72 h.

New Cytotoxic Cyclic Peptide from the Marine Sponge-Associated Nocardiopsis sp. UR67

A new cyclic hexapeptide, nocardiotide A (1), together with three known compounds—tryptophan (2), kynurenic acid (3), and 4-amino-3-methoxy benzoic acid (4)—were isolated and identified from the broth culture of Nocardiopsis sp. UR67 strain associated with the marine sponge Callyspongia sp. from the Red Sea. The structure elucidation of the isolated compounds were determined based on detailed spectroscopic data including 1D and 2D nuclear magnetic resonance (NMR) experimental analyses in combination with high resolution electrospray ionization mass spectrometry (HR-ESI-MS), while the absolute stereochemistry of all amino acids components of nocardiotide A (1) was deduced using Marfey’s method. Additionally, ten known metabolites were dereplicated using HR-ESI-MS analysis. Nocardiotide A (1) displayed significant cytotoxic effects towards the murine CT26 colon carcinoma, human HeLa cervix carcinoma, and human MM.1S multiple myeloma cell lines. The results obtained revealed sponge-associated Nocardiopsis as a substantial source of lead natural products with pronounced pharmacological activities.

Tanzawaic acid derivatives from freshwater sediment-derived fungus Penicillium sp.

Chemical investigation of a freshwater sediment-derived fungus, Penicillium sp. (S1a1), led to the isolation of three new tanzawaic acid derivatives, including penitanzchroman (1), tanzawaic acids Y (2) and Z (3), along with six known tanzawaic acid analogues (4-9), three known isochromans (10-12) and two known benzoquinones (13 and 14). The structures of the new compounds were established based on high-resolution mass spectrometry, and detailed analysis of one- and two-dimensional NMR spectroscopy. The relative configuration of the new compounds was assigned on the basis of NMR spectroscopic data including ROESY spectra. The absolute configuration was determined based on the specific optical rotation, in addition to biogenetic considerations in comparison with related co-isolated known metabolites. Penitanzchroman (1) constitutes a hitherto unprecedented skeleton, formed of tanzawaic acid A (5) and (3S)-6-hydroxy-8-methoxy-3,5-dimethylisochroman (10) linked by a CC bond. Moreover, all compounds were evaluated for their antibacterial and cytotoxic activities.

Chemical and Biological Studies of Russelia Equisetiformis (SCH.&CHAM.) Aerial Parts

From the aerial parts of Russelia equisetiformis, eight compounds were isolated (1–8) and identified by different spectral techniques as well as comparison with reported data or authentic samples. The isolated compounds included an alkane (n-pentatriacontane) (1), a mixture of β-sitosterol and stigmasterol (2), a triterpene (lupeol) (3), a mixture of β-sitosteroland stigmasterol-1-O-β-D-glucopyranosides (4), a phenylpropanoidglucoside (4-Allyl-2,6-dimethoxyphenol-1-O-β-D-glucopyranoside(5), a flavonoid (vitexin) (6) and the two closely related phenylethanoids (acteoside) (7) and isoacteoside (8). The anti-inflammatory, antipyretic and antihyperglycemic activities were carried out on different plant fractions.