Phytochemical Compositions of Some Red Sea Halophyte Plants with Antioxidant and Anticancer Potentials.

The aim of this study was to determine the compositions of carbohydrates, phenolic compounds, fatty acids (FAs), and amino acids (AAs) of four Rea Sea halophytes: Anabasis ehrenbergii, Suaeda aegyptiaca, Suaeda monoica, and Zygophyllum album. The results showed that S. aegyptiaca and S. monoica were rich in gallic acid with 41.72 and 47.48 mg/g, respectively, while A. ehrenbergii was rich in naringenin with 11.88 mg/g. The polysaccharides of the four species were mainly composed of galactose (54.74%) in A. ehrenbergii, mannose (44.15%) in S. aegyptiaca, glucose and ribose (33 and 26%, respectively) in S. monoica, and arabinose and glucose (36.67 and 31.52%, respectively) in Z. album. Glutamic acid and aspartic acid were the major AAs in all halophyte species with 50-63% and 10-22% of the total AAs, respectively. The proportion of unsaturated fatty acids (UFA) of the four species was 42.18-55.33%, comprised mainly of linolenic acid (15.54-28.63%) and oleic acid (5.68-22.05%), while palmitic acid (23.94-49.49%) was the most abundant saturated fatty acid (SFA). Phytol and 9,19-cyclolanost-24-en-3ß-ol represented the major unsaponifiable matter (USM) constituents of S. monoica and A. ehrenbergii with proportions 42.44 and 44.11%, respectively. The phenolic fraction of S. aegyptiaca and S. monoica demonstrated noteworthy antioxidant activity with IC50 values of 9.0 and 8.0 µg/mL, respectively, while the FAs fraction of Z. album exhibited potent cytotoxic activity against Huh-7, A-549, and Caco-2 cancer cell lines with IC50 values of 7.4, 10.8, and 11.8 µg/mL, respectively. Our results indicate that these plants may be considered a source of naturally occurring compounds with antioxidant and anticancer effects that could be suitable for future applications.

Sesquiterpenes from the Saudi Red Sea: Litophyton arboreum with their cytotoxic and antimicrobial activities.

A new pseudoguaiane-type sesquiterpene named litopharbol (1) was isolated from the methanolic extract of the Red Sea soft coral Litophyton arboreum, along with known sesquiterpenoids alismol (2), alismorientol B (3), teuhetenone A (4), and calamusin I (5); steroid, 24-methyl-cholesta-5,24(28)-diene-3ß-ol (6), alkyl glyceryl ether, chimyl alcohol (7); sphingolipid, erythro-N-dodecanoyl-docosasphinga-(4E,8E)-dienine (8); and nitrogenous bases, thymine (9) and thymidine (10). The structures were determined on the basis of nuclear magnetic resonance (NMR) spectroscopic (1D and 2D NMR data including heteronuclear single quantum coherence spectroscopy, heteronuclear multiple-bond correlation spectroscopy, and nuclear Overhauser effect spectroscopy) and mass spectrometric analyses. Compounds 1-5 were explored for antimicrobial activity and cancer cell line sensitivity tests. Compound 1 exhibited antibacterial activity against Bacillus cereus with a minimum inhibition concentration of 1.8 µg/mL, whereas compound 3 showed significant potent cytotoxic effect against MCF-7 (breast cancer cells) with IC50 4.32 µM.

Genetic regulation and manipulation for natural product discovery.

Natural products are an important source of modern medical development, e.g., antibiotics, anticancers, immune modulators, etc. and will continue to be a powerful driving force for the discovery of novel potential drugs. In the heterologous hosts, natural products are biosynthesized using dedicated metabolic networks. By gene engineering, pathway reconstructing, and enzyme engineering, metabolic networks can be modified to synthesize novel compounds containing enhanced structural feature or produce a large quantity of known valuable bioactive compounds. The review introduces some important technical platforms and relevant examples of genetic regulation and manipulation to improve natural product titers or drive novel secondary metabolite discoveries.

Different Culture Metabolites of the Red Sea Fungus Fusarium equiseti Optimize the Inhibition of Hepatitis C Virus NS3/4A Protease (HCV PR).

The endophytic fungus Fusarium equiseti was isolated from the brown alga Padina pavonica, collected from the Red Sea. The fungus was identified by its morphology and 18S rDNA. Cultivation of this fungal strain in biomalt-peptone medium led to isolation of 12 known metabolites of diketopeprazines and anthraquinones. The organic extract and isolated compounds were screened for their inhibition of hepatitis C virus NS3/4A protease (HCV PR). As a result, the fungal metabolites showed inhibition of HCV protease (IC50 from 19 to 77 µM), and the fungus was subjected to culture on Czapek's (Cz) media, with a yield of nine metabolites with potent HCV protease inhibition ranging from IC50 10 to 37 µM. The Cz culture extract exhibited high-level inhibition of HCV protease (IC50 27.6 µg/mL) compared to the biomalt culture extract (IC50 56 µg/mL), and the most potent HCV PR isolated compound (Griseoxanthone C, IC50 19.8 µM) from the bio-malt culture extract showed less of an inhibitory effect compared to isolated ω-hydroxyemodin (IC50 10.7 µM) from the optimized Cz culture extract. Both HCV PR active inhibitors ω-hydroxyemodin and griseoxanthone C were considered as the lowest selective safe constituents against Trypsin inhibitory effect with IC50 48.5 and 51.3 µM, respectively.

An efficient method for the in vitro production of azol(in)e-based cyclic peptides.

Heterocycle-containing cyclic peptides are promising scaffolds for the pharmaceutical industry but their chemical synthesis is very challenging. A new universal method has been devised to prepare these compounds by using a set of engineered marine-derived enzymes and substrates obtained from a family of ribosomally produced and post-translationally modified peptides called the cyanobactins. The substrate precursor peptide is engineered to have a non-native protease cleavage site that can be rapidly cleaved. The other enzymes used are heterocyclases that convert Cys or Cys/Ser/Thr into their corresponding azolines. A macrocycle is formed using a macrocyclase enzyme, followed by oxidation of the azolines to azoles with a specific oxidase. The work is exemplified by the production of 17 macrocycles containing 6-9 residues representing 11 out of the 20 canonical amino acids.

Hepatitis C virus NS3-NS4A protease inhibitors from the endophytic Penicillium chrysogenum isolated from the red alga Liagora viscida.

Hepatitis C virus (HCV) NS3-NS4A protease is an attractive target for anti-HCV agents because of its important role in replication. In this work, we demonstrated that the ethyl acetate extract of the endophytic fungus Penicillium chrysogenum exhibited a potent activity against HCV NS3-NS4A protease with an IC50 value of 20 microg/ml. The fungus was isolated from the red alga Liagora viscida and identified by its morphology and 18S rDNA. Large-scale fermentation of the fungus in Czapek's peptone liquid medium followed by chromatographic purification of the active extract from the liquid medium allowed the isolation of twelve known metabolites. The biological properties of the isolated compounds were explored for anti-HCV protease as well as antimicrobial and anticancer activities. A computational docking study of the active isolated compounds against HCV protease was used to formulate a hypothetical mechanism for the inhibitory activity of the active compounds on the tested enzymes.

A new flavonoid C-glycoside from Solanum elaeagnifolium with hepatoprotective and curative activities against paracetamol-induced liver injury in mice.

A new flavonoid C-glycoside, kaempferol 8-C-beta-galactoside, along with twelve known glycosidic flavonoids was isolated from the aqueous methanolic extract of Solanum elaeagnifolium Cav. (Solanaceae), by conventional chromatographic methods; their structure elucidation was achieved using UV, ESI-MS, and NMR spectral analyses. Groups of six mice were administered S. elaeagnifolium extracts at 25, 50, and 75 mg/kg body weight (BW) prior to or post administration of a single dose of paracetamol (500 mg/kg BW). The extract showed significant hepatoprotective and curative effects against histopathological and histochemical damage induced by paracetamol in liver. The extract also ameliorated the elevation in glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), and alkaline phosphatase (ALP) levels. These findings were accompanied by a nearly normal architecture of the liver in the treated groups, compared to the paracetamol control group. As a positive control, silymarin was used, an established hepatoprotective drug against paracetamol-induced liver injury. This study provides the first validation of the hepatoprotective activity of S. elaeagnifolium.

Induction of caspase-8 and death receptors by a new dammarane skeleton from the dried fruits of Forsythia koreana.

A new naturally occurring compound based on the dammarane skeleton, i.e. cabralealactone 3-acetate-24-methyl ether, was isolated from the aqueous methanolic extract of Forsythia koreana fruits, along with eight known compounds: cabralealactone 3-acetate, ursolic acid, arctigenin, arctiin, phillyrin, rutin, caffeic acid, and rosmarinic acid. The identification of the isolated compounds was based on their spectral analysis including: HREI-MS, 1D and 2D NMR spectroscopy. The selected compounds and the aqueous methanolic extract were evaluated for their cytotoxic activity against human solid tumour cell lines. Cabralealactone 3-acetate-24-methyl ether and ursolic acid were found to be active against human breast cancer cells (MCF-7). The cytotoxicity was associated with the activation of caspase-8, the induction of the death receptors DR4 and DR5, as well as DNA fragmentation, and was thus due to apoptosis rather than necrosis.

Induction of apoptosis by emestrin from the plant endophytic fungus Emericella nidulans ATCC 38163 in Huh-7 human hepatocellular carcinoma cells.

This research aimed to investigate the anticancer properties of emestrin, a major constituent of Emericella nidulans ATCC 38163 through the induction of apoptosis in Huh-7 human hepatocellular carcinoma cells. In this study, this fungus was isolated from the fresh leaves of Ruprechtia salicifolia (Cham. & Schltdl.) C.A. Mey, and identified by morphology and 18S rDNA followed by large-scale fermentation in liquid biomalt broth medium. Epidithiodioxopiperazine derivative emestrin along with ten known metabolites were isolated and identified from the fungal extract. The cytotoxic assay revealed that emestrin had the strongest cytotoxicity against Huh-7 and A-549 cells with IC50 values of 4.89 and 6.3 µM, respectively. Using annexin V-FITC assay, treatment of Huh-7 cells with 4.89 µM for 24 h resulted in a significant increase in the percentage of early and late apoptosis (3.16% and 22.84%, respectively) compared to untreated cells. Additionally, Bax and bcl-2 protein levels were regulated, which induced apoptosis in treated cells. These results indicate that emestrin induces mitochondrial pathway to stimulate apoptosis and inhibits cell proliferation in hepatocellular carcinoma.

Digalacturonide flavones from Egyptian Lantana camara flowers with in vitro antioxidant and in vivo hepatoprotective activities.

A new digalacturonide flavone, luteolin 7-O-beta-galacturonyl-(2 --> 1)-O-beta-galacturonide (1), was isolated along with nine known flavone glycosides from the aqueous methanolic extract of Lantana camara (L.) flowers. Their structures were determined on the basis of the spectral data. The extract of L. camara was evaluated for antioxidant and hepatoprotective properties in the acetaminophen-induced mouse liver damage model. 1 exhibited significant antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay with an IC50 value of 27.2 microM. Pre-treatment with L. camara extract (25 and 75 mg/ kg body weight) decreased the activities of alkaline phosphatase (ALP), serum glutamate oxaloacetate transaminase (SGOT), and serum glutamate pyruvate transaminase (SGPT) enzyme levels that were elevated by acetaminophen. Both doses of the L. camara extract ameliorated the histopathological and histochemical alterations induced by acetaminophen. The results indicate that the L. camara extract possesses hepatoprotective activity against acetaminophen-induced liver damage.

A new acylated flavone glycoside, in vitro antioxidant and antimicrobial activities from Saudi Diospyros mespiliformis Hochst. ex A. DC (Ebenaceae) leaves.

Phytochemical investigation of Diospyros mespiliformis leaves resulted in the isolation of new acylated flavone isoscutellarein 7-O-(4'''-O-acetyl)-ß-allopyranosyl(1''' â†’ 2'')-ß-glucopyranoside (1), along with eight known flavonoid metabolites, luteolin 3',4',6,8-tetramethyl ether (2), luteolin 4'-O-ß-neohesperidoside (3), luteolin 7-O-ß-glucoside (4), luteolin (5), quercetin (6), quercetin 3-O-ß-glucoside (7), quercetin 3-O-α-rhamnoside (8), and rutin (9). Their structures were identified by analysis of spectroscopic (UV, NMR, and MS) data, as well as by acid hydrolysis for the isolated glycosides. The antioxidant activity of D. mespiliformis metabolites was determined by the DPPH radical-scavenging assay. The new acylated flavone (1) and flavonol O-rhamnoside (8) displayed the highest antioxidant activities with IC50 values 15.46 and 12.32 µg/mL, respectively, with respect to the antioxidant ascorbic acid (IC50 value 10.62 µg/mL). In addition, the isolated flavonoids were evaluated against four human pathogenic bacteria where the methylated flavone (2) exhibited potent activity against Escherichia coli with inhibition zone 34 mm, and mild activity of flavonol O-rhamnoside (8) against Staphylococcus aureus with MIC value 9.77 µg/mL. According to the MBC/MIC ratio, the antibacterial activity of the isolated flavonoids was considered flavonoid 2 is bactericidal nature against S. aureus, and flavonoids 3 and 4 are bactericidal against E. coli.

Bioactive sulfonyl metabolites from the Red Sea endophytic fungus Penicillium aculeatum.

Two new sulfonyl metabolites, pensulfonoxy (1) and pensulfonamide (2), together with four known metabolites were obtained from the fermentation extract of Penicillium aculeatum, an endophytic fungus isolated from the marine red alga Laurencia obtusa. The structures of the compounds were established on the basis of extensive NMR and MS spectroscopic analysis. The ethyl acetate extract exhibited potent antibacterial inhibitory activity against Escherichia coli, while compound 2 exhibited antifungal activity against Candida albicans with inhibition diameters of 20.5 and 18.0 mm, respectively. Moreover, compound 2 also displayed the most potent preferential cytotoxicity against MCF-7, while compound 1 displayed relatively mild activity against HCT-116 with IC50 values of 2.18 and 5.23 µM, respectively, compared to the drug control, paclitaxel.

Halo-phenolic metabolites and their in vitro antioxidant and cytotoxic activities from the Red Sea alga Avrainvillea amadelpha.

From the green alga Avrainvillea amadelpha, two new naturally halo-benzaldehyde derivatives were isolated by various chromatographic methods along with 10 known metabolites of bromophenols, sulfonoglycolipid, and steroids. Based on the 1D and 2D NMR spectra as well as on MS data, the structures of the new compounds were identified as 5-bromo-2-(3-bromo-4-hydroxybenzyl)-3,4-dihydroxybenzaldehyde named avrainvilleal (1), and 3-iodo-4-hydroxy-benzaldehyde (2). Using SRB assay, both compounds showed mild and weak cytotoxic activity against HeLa and MCF-7 cancer cell lines, compared to the good activity of their extract (IC50 values 3.1 and 4.3 µg/mL, respectively). However, avrainvilleal (1) displayed an effective scavenged DPPH radical activity with IC50 value 3.5 µM, compared to the antioxidant quercetin with IC50 value 1.5 µM.

In vitro antioxidant and antiproliferative activities of flavonoids from Ailanthus excelsa (Roxb.) (Simaroubaceae) leaves.

The present study aimed to investigate the chemical composition, and the antioxidant and antiproliferative activities of Ailanthus excelsa, a plant used in Egyptian traditional medicine. Chromatographic separation of a methanol extract of A. excelsa leaves yielded four flavones, namely apigenin (1), apigenin 7-O-beta-glucoside (2), luteolin (3), and luteolin 7-O-beta-glucoside (4), and seven flavonols, namely kaempferol (5), kaempferol 3-O-alpha-arabinoside (6), kaempferol 3-O-beta-galactoside (7), quercetin (8), quercetin 3-O-alpha-arabinoside (9), quercetin 3-O-beta-galactoside (10), and quercetin 3-O-rutinoside (11). The A. excelsa extract tested in different in vitro systems (DPPH and FRAP assays) showed significant antioxidant activity. The potential antiproliferative activity of the A. excelsa extract and isolated flavonoids against five human cancer cell lines such as ACHN, COR-L23, A375, C32, and A549 was investigated in vitro by the SRB assay in comparison with one normal cell line, 142BR. The extract exhibited the highest inhibitory activity against C32 cells with an IC50 value of 36.5 microg ml(-1). Interesting activity against COR-L23 was found with 10 (IC50 value of 3.2 microg ml(-1)). Compounds 1 and 3 inhibited cell growth in both amelanotic melanoma and malignant melanoma cells.

Rotenoid and isoflavone metabolites from an antioxidant seed extract of Dalbergia lanceolaria subsp. paniculata (roxb.) thoth.

A new rotenoid named 12-O-methylrotenolol along with five known rotenoid and isoflavone metabolites were isolated from the seeds of Dalbergia lanceolaria subsp. paniculata, collected from Egypt. The structures of these compounds were identified by physical and spectroscopic data measurements ([α]D, UV, 1D- and 2D-NMR and MS). The methanol extract of the seeds exhibited strong antioxidant activity with IC50 value 0.7 µg/µl against DPPH radical, in respect to quercetin as antioxidant reference (IC50 1.5 µM), while the tested compounds from this extract showed weak activities with IC50 values ranged from 19.6 to 33.0 µM.

Mansouramycins A-D, cytotoxic isoquinolinequinones from a marine streptomycete.

Chemical screening of the ethyl acetate extract from the marine-derived Streptomyces sp. isolate Mei37 resulted in five isoquinolinequinones, four new derivatives, mansouramycin A-D (1, 3-5), and the known 3-methyl-7-(methylamino)-5,8-isoquinolinedione (2). Their structures were elucidated by NMR and MS techniques and by comparison with related compounds. Cytotoxicity profiling of the mansouramycins in a panel of up to 36 tumor cell lines indicated significant cytotoxicity of several derivatives, with pronounced selectivity for non-small cell lung cancer, breast cancer, melanoma, and prostate cancer cells.

Inhibition of the initiation stage of carcinogenesis by Salvia disermas constituents.

Phytochemical studies of an ethanolic extract of the aerial parts of Salvia disermas resulted in the isolation of seven known compounds, rosmarinic (1) and caffeic (2) acids, salvigenin (3), luteolin (4), luteolin 7-O-beta-arabinoside (5), luteolin 7-O-beta-glucoside (6), and ocotillol II (7). The initiation stage of carcinogenesis is triggered by activation of procarcinogens by phase I enzymes, such as cytochrome P-450 1A, and oxidative stress that leads to DNA damage. The initiation stage is countered by phase II detoxification enzymes such as glutathione S-transferases (GST), quinine reductase (QR), epoxide hydrolase (mEH) besides conjugation with thiols. We aimed to investigate the cancer chemopreventive and tumour anti-initiating activity of the ethanolic extract of the aerial parts of Salvia disermas and its constituents. The S. disermas extract was a promising inhibitor of CYP1A activity, inducer of GST, QR, and mEH activities, enhancer of thiol content, radical scavenger, and inhibitor of DNA damage. On the other hand, 3 was an enhancer of thiol content and QR activity, while 4 was an inhibitor of CYP1A activity, inducer of QR activity, and radical scavenger of ROO*, and 5 was an inducer of GST activity and inhibitor of DNA damage. The present study indicated that the ethanolic extract of S. disermas and 4 are promising anti-initiating and multipotent blocking agents.

Antioxidant and antiproliferative activity of Diospyros lotus L. extract and isolated compounds.

The object of the study was to determine the chemical composition of Diospyros lotus L. extract and their antioxidant and antiproliferative properties. Eight compounds were isolated from D. lotus and identified as gallic acid, methylgallate, ellagic acid, kaempferol, quercetin,myricetin, myricetin 3-O-beta-glucuronide, and myricetin-3-O-alpha-rhamnoside. D. lotus extract tested in different in vitro systems (DPPH, ABTS, FRAP, and Fe2+ chelating activity assay) showed significant antioxidant activity. The potential antiproliferative properties of D. lotus extract and isolated compounds against nine human cancer cell lines such as COR-L23, CaCo-2, C32, ACHN, A375, A549, Huh-7D12, MCF-7, and LNCaP were investigated in vitro by SRB assay. D. lotus extract demonstrated the highest inhibitory activity against COR-L23 with an IC50 value of 12.2 microg/ml. Among identified hydrolysable tannins, ellagic acid evidenced strong antiproliferative activity against both C32 and A375 cells with IC50 values of 0.8 and 4.1 microg/ml, respectively. Interesting results were observed, also, with gallic acid that showed the highest cytotoxic activity against CaCo-2 (IC(50) 2.6 microg/ml). Overall, the results of this study suggest that D. lotus displays a good antioxidant activity and has antiproliferative effects. Both activities are related to identified phenolic compounds.

In vitro inhibition of Hepatitis C virus protease and antioxidant by flavonoid glycosides from the Saudi costal plant Sarcocornia fruticosa.

A new flavonol triglycoside, rhamnazin 3-O-2G-rhamnorutinoside or rhamnazin 3-O-(2″,6″-O-α-di-rhamnosyl)-ß-glucoside (1) was isolated along with known flavonols, rhamnazin 3-O-rutinoside (2), rhamnazin 3-O-(6″-O-α-rhamnosyl)-ß-galactoside (3), isorhamnetin 3-O-(6″-O-α-rhamnosyl)-ß-galactoside (4), isorhamnetin 3-O-(2″,6″-O-α-di-rhamnosyl)-ß-galactoside (5), and isorhamnetin (6), and allantoin (7) from the aqueous methanol extract of Sarcocornia fruticosa leaves. Spectral analyses (UV, MS, and NMR) and acid hydrolysis were used to determine the structures. These compounds in this study except 6 were reported for the first time from the genus Sarcocornia. The extract and flavonol glycosides (1-5) were evaluated for antioxidant and inhibition of HCV protease enzyme. Rhamnazin triglycoside (1) was shown to have a potent HCV protease inhibitor with IC50 value 8.9 µM, while isorhamnetin di- and triglycosides (4 and 5) were effectively scavenged DPPH radicals with IC50 values 3.8 and 4.3 µM, respectively.

Novel bioactive metabolites from a marine derived bacterium Nocardia sp. ALAA 2000.

Extracts of the Egyptian marine actinomycete, Nocardia sp. ALAA 2000, were found to be highly bioactive. It was isolated from the marine red alga Laurenica spectabilis collected off the Ras-Gharib coast of the Red Sea, Egypt. According to detailed identification studies, the strain was classified as a member of the genus Nocardia. The cultivation and chemical analysis of this species yielded four structurally related compounds namely, chrysophanol 8-methyl ether (1), asphodelin; 4,7'-bichrysophanol (2) and justicidin B (3), in addition to a novel bioactive compound ayamycin; 1,1-dichloro-4-ethyl-5-(4-nitro-phenyl)-hexan-2-one (4) which is unique in contain both chlorination and a rarely observed nitro group. The compounds were isolated by a series of chromatographic steps and their structures of 1approximately 3 secured by detailed spectroscopic analysis of the MS and NMR data whereas that of 4 was elucidated by single crystal X-ray diffraction studies. These compounds displayed different potent antimicrobial activity against both Gram-positive and Gram-negative bacteria as well as fungi with MIC ranging from 0.1 to 10 microg/ml.