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Lamellarins are natural products with a [3,4]-fused pyrrolocoumarin skeleton possessing interesting biological properties. More than 70 members have been isolated from diverse marine organisms, such as sponges, ascidians, mollusks, and tunicates. There is a continuous interest in the synthesis of these compounds. In this review, the synthetic strategies for the synthesis of the title compounds are presented along with their biological properties. Three routes are followed for the synthesis of lamellarins. Initially, pyrrole derivatives are the starting or intermediate compounds, and then they are fused to isoquinoline or a coumarin moiety. Second, isoquinoline is the starting compound fused to an indole moiety. In the last route, coumarins are the starting compounds, which are fused to a pyrrole moiety and an isoquinoline scaffold. The synthesis of isolamellarins, azacoumestans, isoazacoumestans, and analogues is also described. The above synthesis is achieved via metal-catalyzed cross-coupling, [3 + 2] cycloaddition, substitution, and lactonization reactions. The title compounds exhibit cytotoxic, multidrug resistance (MDR), topoisomerase I-targeted antitumor, anti-HIV, antiproliferative, anti-neurodegenerative disease, and anti-inflammatory activities.

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3,4-Fused pyrrolocoumarins, synthetically prepared or naturally occurring, possess interesting biological properties. In this review, the synthetic strategies for the synthesis of the title compounds are presented along with their biological activities. Two routes are followed for that synthesis. In one, the pyrrole ring is formed from coumarin derivatives, such as aminocoumarins or other coumarins. In the other approach, the pyranone moiety is built from an existing pyrrole derivative or through the simultaneous formation of coumarin and pyrrole frameworks. The above syntheses are achieved via 1,3-dipolar cycloaddition reactions, Michael reaction, aza-Claisen rearrangement reactions, multi-component reactions (MCR), as well as metal-catalyzed reactions. Pyrrolocoumarins present cytotoxic, antifungal, antibacterial, α-glucosidase inhibition, antioxidant, lipoxygenase (LOX) inhibition, and fluorescent activities, as well as benzodiazepine receptor ability.

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Pyridocoumarins are a class of synthetic and naturally occurring organic compounds with interesting biological activities. This review focuses on the synthetic strategies for the synthesis of pyridocoumarins and presents the biological properties of those compounds. The synthesis involves the formation of the pyridine ring, at first, from a coumarin derivative, such as aminocoumarins, hydroxycoumarins, or other coumarins. The formation of a pyranone moiety follows from an existing pyridine or piperidine or phenol derivative. For the above syntheses, [4 + 2] cycloaddition reactions, multi-component reactions (MCR), as well as metal-catalyzed reactions, are useful. Pyridocoumarins present anti-cancer, anti-HIV, antimalarial, analgesic, antidiabetic, antibacterial, antifungal, anti-inflammatory, and antioxidant activities.

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Photochemo and photodynamic therapies are minimally invasive approaches for the treatment of cancers and powerful weapons for competing bacterial resistance to antibiotics. Synthetic and naturally occurring quinazolinones are considered privileged anticancer and antibacterial agents, with several of them to have emerged as commercially available drugs. In the present study, applying a single-step green microwave irradiation mediated protocol we have synthesized eleven quinazolinon-4(3H)-ones, from cheap readily available anthranilic acids, in very good yields and purity. These products were irradiated in the presence of pBR322 plasmid DNA under UVB, UVA and visible light. Four of the compounds proved to be very effective DNA photocleavers, at low concentrations, being time and concentration dependent as well as pH independent. Participation of reactive oxygen species was related to the substitution of quinazolinone derivatives. 6-Nitro-quinazolinone in combination with UVA irradiation was found to be in vitro photodestructive for three cell lines; glioblastoma (U87MG and T98G) and mainly melanoma (A-375). Thus, certain appropriately substituted quinazolinones may serve as new lead photosensitizers for the development of promising biotechnological applications and as novel photochemo and photodynamic therapeutics.

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Oregano essential oil (EO) enteric release powder was formulated by spray drying feed emulsions stabilized with polysaccharides (PSC) and Eudragit® L100 (PLM). Different modified starches were used in the PSC component. Spray-dried powders were evaluated for particle size and morphology, dynamic packing, flowability, chemical interactions, reconstitution, and gastric protection. Feed emulsions were stable, indicating the good emulsification ability of the PLM/PSC combination. The presence of polymer in the encapsulating wall neutralized electrostatic charges indicating physical attraction, and FTIR spectra showed peaks of both PLM and PSC without significant shifting. Furthermore, the presence of polymer influenced spray drying, resulting in the elimination of surface cavities and the improvement of powder packing and flowability, which was best when the surface-active, low-viscosity sodium octenyl succinate starch was used (angle of repose 42°). When a PLM/PSC ratio of 80/20 was used in the encapsulating wall, the spray-dried product showed negligible re-emulsification and less than 15% release in pH 1.2 medium for 2 h, confirming gastric protection, whereas at pH 6.8, it provided complete re-emulsification and release. In conclusion, (1) polymer-PSC physical interaction promoted the formation of a smoother particle surface and product with improved technological properties, which is important for further processing, and (2) the gastro protective function of Eudragit® L100 was not impaired due to the absence of significant chemical interactions.

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INTRODUCTION: The 1,3-dipolar cycloaddition reactions of nitrile oxides formed in situ (in the presence of NCS and Et3N) from the oximes of (purin-9-yl)acetaldehyde or (coumarinyloxy)acetaldehyde with allyloxycoumarins or 9-allylpurines, respectively resulted in 3,5-disubstituted isoxazolines. The similar reactions of propargyloxycoumarins or 9-propargylpurines led to 3,5-disubstituted isoxazoles by treatment with PIDA and catalytic amount of TFA. METHODS: The new compounds were tested in vitro as antioxidant agents and inhibitors of soybean lipoxygenase LO, AChE and MAO-B. RESULTS: The majority of the compounds showed significant hydroxyl radical scavenging activity. Compounds 4k and 4n presented LO inhibitory activity. CONCLUSION: Compound 13e presents an antioxidant significant profile combining anti-LO, anti-AChE and anti-MAO-B activities.

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AIM: Due to the complex nature of Alzheimer's disease, there is a renewed search for pleiotropic agents. RESULTS: Purine+coumarin hybrids have been synthesized and tested for the potential treatment of Alzheimer's disease. Hybrids 6, 4a-b, 14c and 14e inhibit significantly soybean lipoxygenase, whereas derivatives 14b, c and 20a present antioxidative/lipoxygenase inhibition activities. Cholinesterase (ChE) and monoamino oxidase (MAO) inhibition studies have been carried out. Hybrid 20a is the most potent ChE inhibitor, in the low micromolar range, and selective for hBuChE (IC50 = 4.65 ± 0.23 µM), whereas hybrid 14a is the most potent MAOI, in the low micromolar range, and selective for MAO-B (IC50 = 6.8 ± 0.6 µM). CONCLUSION: The preliminary experimental results point to two selective multitarget lead compounds 20a and 4b.

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9-Substituted (pyrazol-5-yl)methyl- or (2-pyrazolin-5-yl)methyl-9H-purines were synthesized from 9-allyl-6-chloro-9H-purine through the 1,3-dipolar cycloaddition reaction with nitrile imines, prepared in situ from the corresponding hydrazone and NBS/Et3N under MW or from hydrazinoylchloride and Et3N under reflux. The coupling of new 6-chloropurines with amines in H2O under microwaves resulted quantitatively to modified pyrazol-5-yl- or 2-pyrazolin-5-yl adenine homo-N-nucleosides. The new compounds were tested in vitro for their ability to: (i) interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH), (ii) inhibit lipid peroxidation, (iii) inhibit the activity of soybean lipoxygenase, (iv) inhibit in vitro thrombin and for (v) their antiproliferative and cytotoxic activity. Pyrazolines were found to be more potent in vitro. Compound 7a exhibited satisfactory combined antioxidant and anti-lipid peroxidation activity, inhibition of lipoxygenase (89%) and thrombin inhibitory ability, whereas compound 7b exhibited high lipoxygenase inhibitory activity in combination to significant anti-thrombin activity. No compound exhibited a significant cytotoxic activity, while all showed moderate antiproliferative activity.

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Cross metathesis (CM) of 9-butenylpurines with 4-butenyloxycoumarin in the presence of Grubbs 2nd generation catalyst under MW irradiation resulted to conjugated compounds containing homo-N-nucleosides and coumarins. Analogous derivatives received by the CM reaction of 9-butenyl-6-piperidinylpurine with 6- or 7-butenyloxycoumarins, allyloxycoumarins or coumarinyl acrylate. These compounds were tested in vitro for their antioxidant activity and they present significant scavenging activity. The presence of a pentenyloxy moiety, the attachment position on coumarin ring as well as a purine homo-N-nucleoside group are considered as important structural features.

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The allylation of aminocoumarins in the presence of excess of anhydrous K(2)CO(3) and allyl bromide to diallylaminocoumarins is described. The Ring Closing Metathesis reaction of the later with the Grubbs' 1rst generation catalyst under reflux or MW irradiation has resulted mainly to (2,5-dihydro-1H-pyrrol-1-yl)coumarins and (1H-pyrrol-1-yl)coumarins. The new compounds were tested in vitro for their ability: (i) to interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical, (ii) to inhibit lipid peroxidation, (iii) to scavenge the superoxide anion, (iv) to inhibit the activity of soybean lipoxygenase LO and (v) to scavenge hydroxyl radicals. Most of them were found to be potent lipid peroxidation inhibitors in vitro. The majority of the compounds showed significant hydroxyl radical scavenging activity. Compounds 11a and 12c presenting higher LO inhibitory activity as well as compound 17 were found to present a promising antioxidant and LO inhibitory profile.

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Some fused dihydrooxepino[f]-, [g]-, and [h]coumarins were obtained from the ring-closing metathesis of the corresponding o-allyl-allyloxycoumarins under the treatment with the first generation Grubbs' catalyst. These compounds were tested in vitro for their antioxidant activity, and they present significant scavenging activity. They were also showed to inhibit in vitro soybean lipoxygenase.

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We describe herein a convenient straightforward synthesis of 5-amino-substituted 1,2,4-oxadiazoles, upon the reactions of amidoximes with carbodiimides, as well as their further derivatization to acetamides, in good yields. Most of the compounds exhibited in general low interaction with the stable radical 1,1-diphenyl-2-picryl-hydrazyl. Compounds 32 and 39 inhibited significantly soybean lipoxygenase. Selected compounds were screened for their in vivo anti-inflammatory activity using the carrageenin paw edema model and showed significant anti-inflammatory activity (26, 51%). The ability of the compounds to release NO in the presence of a thiol factor has been also investigated.

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9-(3-Mesityl-4,5-dihydroisoxazol-5-yl) homo-N-nucleosides were prepared from the 1,3-dipolar cycloaddition reactions of mesityl nitrile oxide with 9-allyl derivatives of 6-chloropurine, 6-piperidinylpurine, 6-morpholinylpurine, 6-pyrrolidinylpurine, and 6-N,N-dibenzoyladenine. The new compounds were tested in vitro for their ability: (i) to interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical, (ii) to inhibit lipid peroxidation, (iii) to scavenge the superoxide anion, (iv) to inhibit the activity of soybean lipoxygenase, and (v) to inhibit in vitro thrombin. Most of them found to be potent thrombin inhibitors and to inhibit in vitro lipid peroxidation. The majority of the compounds showed significant lipoxygenase inhibitory activity.

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Angular [7,8]-fused coumarins were obtained from the reaction of [2,3]-fused phenols with DMAD and PPh(3), while linear [6,7]-fused coumarins were formed from the analogous reaction of [3,4]-fused phenols with DMAD and PPh(3). These compounds were tested in vitro for antioxidant activity and they found to present significant scavenging activity. In parallel, these new compounds were evaluated in vivo for anti-inflammatory activity and they found to inhibit the carrageenin-induced paw edema (34-65%). Although their interaction with the free stable radical DPPH was low, the methyl 2,2-dimethyl-8-oxo-3,8-dihydro-2H-furo[2,3-h]chromene-6-carboxylate was the most potent (65%) in the in vivo experiment. The later seems to be a potent soybean Lipoxygenase inhibitor and does not acquire gastrointestinal toxicity.

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Substituted hydroxycoumarins and 7- or 8-hydroxybenzo[f]coumarins were prepared by the treatment of phenols and naphthalenediols, respectively, with malic acid and H(2)SO(4) under microwave irradiation. 7- or 8-Hydroxybenzo[f]coumarins and 6-hydroxybenzo[h]coumarin were synthesized by the reaction of naphthalenediols with ethylpropiolate in the presence of ZnCl(2) in refluxing dioxane. The compounds were tested in vitro for their ability: (i) to interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical, (ii) to inhibit lipid peroxidation, (iii) to scavenge the superoxide anion, (iv) to inhibit the activity of soybean lipoxygenase and (v) to inhibit in vivo the carrageenin-induced rat paw edema. Most of them are potent superoxide anion scavengers and inhibit in vitro lipid peroxidation. The majority of the compounds did not show high lipoxygenase inhibitory activity. No differences were observed between biological responses of hydroxycoumarins and hydroxybenzocoumarins. Compound 3i was found to present a promising antioxidant profile.

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Angular pyrrolocoumarins were synthesized from the reaction of 4-hydroxyindole or 5-hydroxyindole with DMAD and PPh(3) and were tested for anti-inflammatory and antioxidant activity. These compounds significantly inhibited the carrageenin-induced paw edema (60.5%-73.4%) and have important scavenging activity. Although their interaction with the free stable radical DPPH is not high, compound 9 is the most potent (73.4%) in the in vivo experiment. Compound 7 seems to be a potent LOX inhibitor. An attempt was made to correlate the biological results with their structural characteristics and physicochemical parameters.

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Several natural products with a coumarinic moiety have been reported to have multiple biological activities. It is to be expected that, in a similar way to isomeric flavonoids, coumarins might affect the formation and scavenging of reactive oxygen species (ROS) and influence processes involving free radical-mediated injury. Coumarin can reduce tissue edema and inflammation. Moreover coumarin and its 7-hydroxy-derivative inhibit prostaglandin biosynthesis, which involves fatty acid hydroperoxy intermediates. Natural products like esculetin, fraxetin, daphnetin and other related coumarin derivatives are recognised as inhibitors not only of the lipoxygenase and cycloxygenase enzymic systems, but also of the neutrophil-dependent superoxide anion generation. Due to the unquestionable importance of coumarin derivatives considerable efforts have been made by several investigators, to prepare new compounds bearing single substituents, or more complicated systems, including heterocyclic rings mainly at 3-, 4- and/or 7-positions. In this review we shall deal with naturally occurring or synthetically derived coumarin derivatives, which possess anti-inflammatory as well as antioxidant activities.

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Treatment of 3-hydroxy-beta-lapachone 4 with ylide 5 gave the coumarin derivative 7a, which was transformed to compounds 10-14. Compound 14 was then transformed to benzo[f]seselin 15 as well as to benzo[l]khellactones 16, 18 from which the title compounds 17, 19(I), 19(II), 20, 21(I) and 21(II) were prepared. All the tested compounds were found to interact with DPPH in a concentration and time dependent manner. All the tested compounds highly inhibited the soybean lipoxygenase, whereas compounds 12, 17 and 19(II) highly compete with DMSO for (*)OH. Compounds 7a, 7b, 12 and 17 induced at 48.7-58.9% protection against carrageenin induced rat paw edema.

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