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Background: The synthesis and biological evaluation of 1,4-naphthoquinone derivatives are of great interest since these compounds exhibit strong antibacterial, antifungal, antimalarial, and anticancer activities. The electronic properties of naphthoquinones are usually modulated by attaching functional groups containing nitrogen, oxygen, and sulfur atoms, which tune their biological potency and selectivity. Methods: A series of 13 amino acid 1,4-naphthoquinone derivatives was synthesized under assisted microwave and ultrasound conditions. The antibacterial activity of compounds was tested against American Type Culture Collection (ATCC): Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis, as well as 2 multidrug resistant pathogens: E. coli and S. aureus from clinical isolated. Minimal inhibitory concentration (MIC) was determined using the broth microdilution method. Results: MIC of derivatives 4–11, 14, and 16 showed antimicrobial activity against Gram-positive and Gram-negative bacteria. Antimicrobial activities of the compounds 4–8 and 14 were ≤MIC 24.7 μg mL−1 against all the reference strains; even more, compound 6 showed the most potent activity with an MIC of 3.9 μg mL−1 on S. aureus. On the clinical isolated, the compounds 7, 8, and 14 showed an MIC of 49.7 and 24.7 μg mL−1 against S. aureus and E. coli, respectively. About ADME properties and Osiris analysis, the compounds 4–16 presented high gastrointestinal absorption and good characteristics for oral bioavailability, and compound 14 was the less toxic. Conclusion: Amino acid 1,4-naphthoquinone derivatives showed good in vitro antibacterial activity against clinical strains, and modifications on C-3 with a chloride atom enhanced the efficiency against the same pathogens.

The hydantoin moiety is found in several bioactive compounds with important pharmacological properties such as antimicrobial, antifungal, anti-androgens, anticancer and the historical action anticonvulsant. Because of these reasons, the synthesis of these compounds and their derivatives is important to review considering the philosophy of the green chemistry. In this review, we present the actual importance in the green synthesis of hydantoins and their derivatives using green methods, such as microwave and ultrasound irradiation, ionic liquids, solid-phase and solvent-free synthesis. Finally, several green protocols reported have been discussed.

1,4−naftoquinone (NQ) molecules have been extensively evaluated as potent antibacterial compounds; however, their use is limited, since they have low water solubility and exhibit toxicities in healthy eukaryotic cells. A possible path to overcoming these challenges is the use of particulate vehicles, such as SBA-15, which is a biocompatible and biodegradable mesoporous silica material, that may enhance drug delivery and decrease dosages. In this work, an isotherm model-based adsorption of three NQs into SBA-15 microparticles was evaluated. Interactions between NQs and SBA-15 microparticles were modeled at the B3LYP/6-31+G(d,p) level of theory to understand the nature of such interactions. The results demonstrated that the adsorption of NQ, 2NQ, and 5NQ into SBA-15 fit the Freundlich adsorption model. According to theorical studies, physisorption is mediated by hydrogen bonds, while the most stable interactions occur between the carbonyl group of NQ and silica surfaces. Both experimental and theoretical results contribute to a deeper understanding of the use of SBA-15 or similar particles as nanovehicles in such a way that NQs can be modified in carbonyl or C3 to enhance adsorptions. The theoretical and experimental results were in accordance and contribute to a deeper understanding of how interactions between NQ-type molecules and SiO2 materials occur.

Mannich bases are formed in a noncatalytic multicomponent reaction, which is promoted by ultrasound irradiation. The procedure avoids the use of toxic solvents, catalyst, and purification, generating the desired compounds in excellent yields and short reaction times.

Pecan nut (Carya illinoensis K.) is an economically important tree due to the fruit that it produces. It has been reported that extracts of some parts of the tree, like the leaves, husk, and shell of the fruit, has antimicrobial properties. Because of this it is possible to develop a green technology to extract natural antimicrobial agents such as polyphenols that has potential application in food industries as antimicrobials that permits substitute synthetic antimicrobials for natural ones. Leaves, husk, and shell of pecan nut were collected by a community in Parras de la Fuente, Coahuila, Mexico, and phenolic extracts were obtained by water heating, ohmic heating, and microwave at 40°C, 60°C, and 80°C, respectively, by 20 min for each sample. Obtained extracts were tested against Escherichia coli and Staphylococcus aureus. Present work demonstrates that extracts obtained by green technologies (ohmic and microwave) are more effective to inhibit growth of E. coli and S. aureus.

Several synthetic and natural naphthoquinone derivatives have been associated with antifungal activity. Candida albicans is a fungus that is known to exist in the normal human flora, but under certain conditions it can cause mild to fatal infections. Its pathogenicity has been associated with fungus conversion from cellular yeast to filamentous form Y–M. Inhibition of this process by several anilino-, dianilino-, phenoxy-, and diphenoxy-1,4-naphthoquinones was investigated in order to find some correlation between structure, redox properties and biological activity.

Invertases or β-d-fructofuranosidases are used to hydrolyze sucrose and polysaccharides, which have the same type of β-d-fructofuranosyl bond, to obtain fructose and glucose as final products. These enzymes are also able to perform this reaction in the reverse direction. The resulting mixture of the fructose and glucose is referred as “inverted sugar” because of the inversion of its optical property from the positive rotation to the negative rotation. Invertases are important in the food industry, especially in confectionery, as a catalytic agent in obtaining an artificial sweetener. Thus, it is used for the preparation of formulas that prevent crystallization of certain sweet preparations, employing in the chocolate industry. In some syrup, it is also employed to increase its sweetening properties such as manufacturing of soft caramel fillings. The most common form of this inverted sugar is honey, which is a supersaturated mixture of glucose and fructose. In addition, invertases are able to synthesize fructooligosaccharides through fructotransferase where sucrose is presented in high concentrations. The fructooligosaccharides are associated to improve human health. Invertases are produced by plants, bees, and microorganisms. But, the filamentous fungi belonging to the Aspergillus genus and yeast such as Saccharomyces cerevisiae and Candida utilis are the most prominent organisms used for invertase production. The purpose of this chapter is to compile results of recent advances on invertase including its production, application, and molecular characterization.

Several novel 2-(fluoroanilino)-3-(2,4-dinitroanilino) derivatives of 1,4-naphthoquinone have been synthesized in good to excellent yields. First, 2-chloro-3-(2,4-dinitroanilino)-1,4-naphthoquinone was prepared in two steps beginning with the reaction of 2,3-dichloro-1,4-naphthoquinone with aniline in the presence of a Lewis acid (CeCl ·7H O). The resulting 2-(anilino)-1,4-naphthoquinone was then nitrated. The strong electron withdrawing effect of the 2,4-dinitroanilino substituent on the naphthoquinone framework facilitated the displacement of the second chlorine atom by a variety of weakly nucleophilic fluoro-substituted anilines under reflux conditions. 3 2

Mannich bases are formed in a non-catalytic multicomponent reaction, which is promoted by ultrasound irradiation. The procedure avoid the use of toxic solvents, catalyst and purification, generating the desired compounds in excellent yields and short reaction times.

The strong electron withdrawing nature of the 2,4-dinitroanilines in substrate (I) allows the displacement of chlorine by weak nucleophilic anilines to give the title products (III).

Citrus peels are underutilized in the processing industry and are commonly considered as waste as their chemical composition varies. However, it is possible to recover some value-added products, one of them being essential oil, which is widely used in the food industry. Due to the current increase in global demand for citrus essential oils, it is necessary to implement processes directed to the maximum recovery of oil from waste peels. Numerous efforts have been made without achieving significant improvements in yields. In this work, enzymatic pretreatments of orange, lemon, and grapefruit peels were applied to achieve increased yields of essential oil extracted by hydro-distillation. In two of the sources it was possible to increase the essential oil yield from two to six times. Moreover, a significant amount of fermentable sugars which can be used in the production of certain other compounds of interest through fermentation was obtained.

The preparation of novel 2-(fluoroanilino)-1,4-naphthoquinones is presented. It takes place under mild conditions by reacting the corresponding fluoroaniline and 1,4-naphthoquinone in the presence of a Lewis acid catalyst with strong oxidation properties such as CeCl3·7H2O. This preparation was also investigated under microwave irradiation. All 1,4-naphthoquinone derivatives were characterized by UV–Vis, IR, 1H and 19F NMR, MS and cyclic voltammetry, to investigate the effect of the fluoro-substituents on their electronic properties.

The influence of catalysts on the addition of methoxy- and fluoroanilines with 1,4-naphthoquinone to give methoxy- and fluoro-substituted 2-(anilino)-1,4-naphthoquinones was investigated. In the absence of a catalyst, this reaction requires long times and low yields of the anilino derivatives are obtained accompanied with the formation of several secondary products. Excellent yields were obtained with a catalytic amount of a Lewis acid with strong oxidation properties such as CeCl3 or FeCl3. Excellent yields were also obtained when the reaction was performed with a Bronsted acid/oxidant mixture such as AcOH/Cu(OAc)2. This addition reaction was also investigated using microwave irradiation. A discussion on reaction conditions and mechanism is presented. The 1H and 13C NMR data of all the derivatives were analyzed and assigned using two dimensional 1H–13C gHSQC and gHMBC NMR experiments. The effect of fluorine substitution on redox and NMR properties was also investigated.

ObjectiveTo determine the extraction suitable conditions of total phenolic content (TPC) by heat–reflux system, antioxidant activities and HPLC characterization of the aqueous–ethanolic extracts of Jatropha dioica (J. dioica) (Dragon's blood), Flourensia cernua (F. cernua) (Tar bush), Eucalyptus camaldulensis (E. camaldulensis) (Eucalyptus) and Turnera diffusa (T. diffusa) (Damiana).MethodsTPC was evaluated by the well–known colorimetric assay using Folin–Ciocalteu reagent. The antioxidant activities were assayed by three methods based on scavenging of DPPH, ABTS and by lipid oxidation inhibition. The chemical composition of the extracts obtained was subject to HPLC analysis.ResultsTPC in the plant extracts ranged from 2.3 to 14.12 mg gallic acid equivalents/g for J. dioica and E. camaldulensis, respectively. The plant extracts of F. cernua, E. camaldulensis and T. diffusa showed similar strong antioxidant activities on scavenging of DPPH and lipid oxidation inhibition. In contrast, J. dioica extracts had lowest potential antioxidant in three assays used. HPLC assay showed the presence of several phenolic compounds in the extracts used.ConclusionsThe results obtained suggest that F. cernua, E. camaldulensis and T. diffusa are potential sources to obtain bioactive phenolic compounds with high antioxidant properties which can be used in the factories as antioxidant agents or for treatments in diseases.