Sucrose esters of aryldihydronaphthalene-type lignans, and antitumor activity of extracts of Moltkiopsis ciliata (Forssk.) aerial parts

One new compound (3f-[(7'R,8'R)-4,4'-dihydroxy-5-methoxy-2,7'-cycloligna-7-en-9-methoxycarbonyl, 9'-carbonyl-O-] -β- D-fructofuranosyl- (2→1)-α- D-glucopyranoside) (Moltkiopsin A) (2) was isolated and identified from the extract of aerial parts of the wild Egyptian plant Moltkiopsis ciliata (Frossk.), family Boraginaceae, for the first time, along with two aryldihydronaphthalene lignans 3f→9':6f→9-[(7'R,8'R)-4,4'- dihydroxy-3,3',5-trimethoxy-2,7'-cycloligna-7-en-9,9'-dicarbonyl]-6g-acetyl-α-D-gluco pyranosyl-(1→2) -β-D-fructofuranoside (Trigonotin A) (1) which was reported for the first time from this plant species and a known compound 3f→9':6f→9-[(7'R,8'R)-4,4'- dihydroxy-3,3',5-trimethoxy-2,7'-cycloligna-7-en-9,9'-dicarbonyl]-α-D-gluco pyranosyl - (1→2)- β-D- fructofuranoside (Trigonotin C) (3). These compounds were separated and purified using different chromatographic techniques and their structures were elucidated by extensive 1D (1H and 13C NMR), and 2D NMR (COSY, HSQC, and HMBC), besides ESI-MS spectral methods. Extracts were screened as antioxidant, antitumor and antibacterial. The different extracts showed moderate to strong antioxidant capacities in DPPH assays. Ethyl acetate, methylene chloride and crude methanol extracts exhibited the most significant free radicals scavenging activity when compared to the standard antioxidant vitamin C. Hexane and butanol fractions showed the highest cytotoxicity against the cancer cell lines HepG2 and MCF-7.

Bioactive compounds from Retama raetam (Forssk.) Webb & Berthel. and their insecticidal activity against cotton pests Aphis gosspyii and Amrasca biguttula

Cotton aphids, Aphis gosspyii and cotton jassids, Amrasca biguttula are destructive piercing sucking pests to many strategic crops, especially cotton, not only in Egypt but also all over the world. Using synthetic pesticides to control these pests led to several deleterious impacts. Natural pesticides can be used as a harmless alternative. Nine compounds were isolated from different fractions of Retama raetam using chromatographic techniques and identified by spectroscopic methods as eugenol (1), alpinumisoflavone (2), licoflavone C (3), ephedroidin (4), anagyrine (5), spartiene (6), genistein-8β-C-glucoside (7), isoprunetin (8) and isoprunetin 7-O-β-D-glucopyranoside (9). The methanol crude extract and its fractions (hexane, chloroform, ethyl acetate and butanol), as well as the isolated compounds were examined against A. gosspyii and A. biguttula as insecticides. The results showed that chloroform fraction was the most potent fraction against A. gosspyii and A. biguttula, with LC50 values of 65.66 and 64.43 ppm, respectively. As well, compounds 1, 5 and 6 were found to be more active, with LC50 values of 69.84, 25.49 and 27.22 ppm for A. gosspyii and 65.17, 24.07 and 24.78 ppm for A. biguttula, respectively. The most potent compounds (1, 5 and 6) exhibited AChE inhibition toward A. gosspyii compared with the control. So, it can be concluded that the isolated compounds eugenol 1, anagyrine 5 and spartiene 6 are the active principles due to their capability to inhibit AchE activity.

Quadrangulosides A-F: new pregnane glycosides from Caralluma quadrangula

The phytochemical investigation of Caralluma quadrangula aerial parts yielded six new pregnane glycosides, quadrangulosides A-F (1-6), in addition to nine known pregnane glycosides and three known flavone glycosides. Structures of isolated phyto-constituents were elucidated via spectroscopic 1D-, 2D-NMR and spectrometric ESI-MS spectra.

Antibacterial and antioxidant activities of a novel enol ether nor-sesquiterpene isolated from Myrtus nivellei Batt. & Trab

Myrtus nivellei is a plant traditionally used to treat diseases including infection of microbial origin. Several M. nivellei Batt. & Trab. extracts (dichloromethane, methanol and ethanol/water) were screened for their activity against 36 microorganisms, including strains resistant to antibiotics. These extracts inhibited on average 15 bacteria strains with minimum inhibition concentrations (MICs) ranging from 0.07 to 1.20 mg/mL. Bioassay guided fractionation was carried out with bioautography on TLC plates using four pathogenic bacteria strains, and following chromatographies (CPC and HPLC) led to the isolation of two novel enol ether nor-cadinane sesquiterpenes from the dichloromethane extract. The major compound (1) showed a strong antibacterial activity. Minimal inhibition concentration and minimal bactericidal concentration (MBC) values were determined against four bacteria: Acinetobacter baumanii, Stenotrophomonas maltophilia, Yersinia pseudotuberculosis and Staphylococcus lugdunensis. The best activity was observed against Acinetobacter baumanii with a MIC value of 9.7 μg/mL. This novel compound was also very active against a Staphylococcus aureus strain resistant to amoxicillin (MIC 19.5 μg/mL). In addition, compound 1 showed a very high antioxidant activity with both DPPH and metal chelate methods.

Chemical Diversity and Biological Activities of Marine Sponges of the Genus Suberea: A Systematic Review

Marine natural products (MNPs) continue to be in the spotlight in the global drug discovery endeavor. Currently, more than 30,000 structurally diverse secondary metabolites from marine sources have been isolated, making MNPs a profound, renewable source to investigate novel drug compounds. Marine sponges of the genus Suberea (family: Aplysinellidae) are recognized as producers of bromotyrosine derivatives, which are considered distinct chemotaxonomic markers for the marine sponges belonging to the order Verongida. This class of compounds exhibits structural diversity, ranging from simple monomeric molecules to more complex molecular scaffolds, displaying a myriad of biological and pharmacological potentialities. In this review, a comprehensive literature survey covering the period of 1998–2018, focusing on the chemistry and biological/pharmacological activities of marine natural products from marine sponges of the genus Suberea, with special attention to the biogenesis of the different skeletons of halogenated compounds, is presented.

Sucrose diester of aryldihydronaphthalene-type lignans from Echium angustifolium Mill. and their antitumor activity

Four previously undescribed sucrose diester of aryldihydronaphthalene-type lignans, named echiumins A-D, were isolated from the butanol fraction of Echium angustifolium Mill, in addition to a known compound, trigonotin A, which is reported for the first time from the title plant. The structures of isolated compounds were elucidated using spectroscopic methods such as HRESIMS and 1D and 2D NMR spectroscopy. The isolated compounds displayed strong to weak antitumor activity against HepG2 and MCF7 cancer cell lines, with echiumins A and D showed the most potent activity.

Batzella, Crambe and Monanchora: Highly Prolific Marine Sponge Genera Yielding Compounds with Potential Applications for Cancer and Other Therapeutic Areas

Pyrroloquinoline and guanidine-derived alkaloids present distinct groups of marine secondary metabolites with structural diversity that displayed potentialities in biological research. A considerable number of these molecular architectures had been recorded from marine sponges belonging to different marine genera, including Batzella, Crambe, Monanchora, Clathria, Ptilocaulis and New Caledonian starfishes Fromia monilis and Celerina heffernani. In this review, we aim to comprehensively cover the chemodiversity and the bioactivities landmarks centered around the chemical constituents exclusively isolated from these three marine genera including Batzella, Crambe and Monanchora over the period 1981-2017, paying a special attention to the polycyclic guanidinic compounds and their proposed biomimetic landmarks. It is concluded that these marine sponge genera represent a rich source of novel compounds with potential applications for cancer and other therapeutic areas.

Molluscicidal activity of Balanites aegyptiaca against Monacha cartusiana

CONTEXT

Balanites aegyptiaca (L.) Delile (Zygophyllaceae) is a tropical tree that has many folk uses in various countries. The bark extract is used for the control of the fresh water snails that act as intermediary host of Schistosoma.

OBJECTIVE

Study the molluscicidal activity and chemical constituents of seed oil and seed glycosides of B. aegyptiaca against Monacha cartusiana and determine the structure-activity relationship.

MATERIALS AND METHODS

Two bioassay methods (residual film application and the leaf dipping technique) were used to evaluate the toxicity effect of the seed oil and glycosides, in concentrations of 1.000, 0.500, 0.250 and 0.125%. The seed oil was analysed by GC/MS. Acid hydrolysis and chromatographic separation were used to study the seed saponins.

RESULTS

The bioassay of B. aegyptiaca against the land snail, M. cartusiana, indicated the activity of the seed oil and the high activity of the seed saponins. The seed glycosides gave 30.0, 53.3, 73.0 and 73.3% mortality for concentrations of 0.125, 0.250, 0.500 and 1.00%, respectively. The LC(50) values were 0.335 and 0.256%, respectively. The seed oil was analysed by GC/MS. Acid hydrolysis of the seed saponins gave a mixture of diosgenin, yamogenin and 3,5-spirostadiene.

DISCUSSION AND CONCLUSION

To study the structure-activity relationship, a triterpenoidal saponin and a triterpenoidal saponins rich extract (of Zygophyllum coccenum) were proven to be inactive. Thus, the activity is associated with the steroidal, not triterpenoidal saponins. Moreover, a spirostane aglycone without sugar moiety, was found to be inactive and attained the activity by glycosidation.

A novel podophyllotoxin lignan from Justicia heterocarpa

Chromatographic separation of the extract of Justicia heterocarpa T. ANDERS. afforded, in addition to known fatty acids, terpenoids and steroids, a new podophyllotoxin lignan. Structures were elucidated by spectroscopic methods, and the structure of the new lignan was confirmed by single crystal X-ray diffraction studies, which have shown that there is a H-bonding stabilized dimer.

Two new naphthalene and anthraquinone derivatives from Asphodelus tenuifolius

Chromatographic separation of an ethanolic extract of rhizomes of Asphodelus tenuifolius Cav. (Asphodelaceae) yielded in addition to beta-sitosterol, stigmasterol and two anthraquinone derivatives, 1,8-dimethoxynaphthalene as well as two new naphthalene derivatives. The new compounds were identified as 2-acetyl-8-methoxy-3-methyl-1-naphthol and 2-acetyl-1,8-dimethoxy-3-methylnaphthalene. The separated compounds were identified on the basis of IR, MS, 1H and 13C NMR data.

Chemistry of the Genus Plectranthus

This review presents the phytochemical constituents of the genus Plectranthus reported up to 1999. Only a tetrameric derivative of caffeic acid was isolated from P. japonicus, but a group of long-chain alkylphenols, of possible taxonomic significance in the genus, was also isolated. As a genus of the subfamily Nepetoideae, Plectranthus is free from iridoid glycosides and rich in essential oil (i.e. > 0.5% volatile oil on a dry weight basis). Diterpenoids are the more common secondary metabolites in Plectranthus. The majority of them are highly modified abietanoids. This seems to be similar to the pattern of diterpenoids observed for Salvia, but no clerodane diterpenoids were found in Plectranthus.

New clerodane diterpenoid and flavonol-3-methyl ethers from Dodonaea viscosa

Chromatographic separation of the extract of the aerial parts of Dodonaea viscosa L. (family Sapindaceae) afforded beta-sitosterol, stigmasterol, the flavone acacetin-7-methyl ether, the flavonol-3-methyl ethers 4',5,7-trihydroxy-3,6-dimethoxyflavone and penduletin, as well as a new clerodane diterpenoid which was identified by spectral means as 15,16-epoxy-5,9-diepicleroda-3,13(16),14-trien-20,19-olide.

Stilbenes and a New Acetophenone Derivative from Scirpus holoschoenus

Separation of the extract of the tubers of Scirpus holoschoenus L. (family Cyperaceae), a species easily confused with Juncus plants, afforded 2-prenyl-3,5,4'-trimethoxystilbene, 2-prenyl-3-hydroxy-5,4'-dimethoxystilbene, 2-prenyl-3,4'-dihydroxy-5-methoxy-stilbene and 3,5,4'-trimethoxystilbene, in addition to a new acetophenone derivative. The isolated compounds were identified on the basis of spectral measurements.

New stilbene carboxylic acid from Convolvulus hystrix

Convolvulus hystrix Vahl. (family Convolvulaceae) is a common wild plant growing in the kingdom of Saudi Arabia. It is used in traditional medicine. Our study resulted in the isolation and structural elucidation of ten natural products from which a stilbene carboxylic acid was isolated for the first time as a new natural product. The isolated products are mainly shikimates in addition to two sterols; beta-sitosterol and stigmasterol, as well as one triterpenoid, oleanolic acid. The shikimate products are vanillin, vanillic acid, syringic acid, ferulic acid, isoferulic acid, isoscopoletin and the new stilbene derivative. The structures were elucidated on the basis of spectral data from 400 MHz 1H NMR, MS, IR and UV. The biogenesis of the new stilbene is discussed.

Two novel flavans from Cyperus conglomeratus

Separation of the extract of the underground tubers of Cyperus conglomeratus Rottb. (family Cyperaceae) afforded, in addition to known compounds, two novel flavans, which were identified, by one and two dimensional NMR, MS and IR spectra, as 5-hydroxy-7,3',5'-trimethoxyflavan and 5,7-dihydroxy-3',5'-dimethoxy-6-prenylflavan.

1,3-Dimethylpyrimidoheterocycles as antibacterial agents

1,3-Dimethylbarbituric acid was used as a versatile precursor for the preparation of annelated pyranopyrimidines 2 and 3a-c besides pyrrolopyrimidine 12. The isolated pyrazolopyrimidines 8a-c and 10 and fused pyrazolopyrimidines 14a-d were also synthesized. In addition the new obtained pyrimidoheterocycles were subjected to bacterial testings.