Mini-Reviews in Organic Chemistry - Volume 13, Issue 6, 2016

Some bryophyte species often dominate plant communities by forming large monospecific mats. The potential mechanisms for this domination are considered to be disturbing light and moisture availability, creating physical barriers which prevent seeds from reaching the soil by the bryophyte mats, and allelopathy of bryophytes. However, allelopathy of bryophytes for the domination is most controversial. This review provides a short overview of allelopathic chemical interaction of bryophyte with vascular plants. The bryophytes contain a variety of secondary metabolites and some of those compounds are secreted from the bryophytes into the rhizosphere soil and act as allelopathic agents. However, only small number of compounds have been evaluated their allelopathic potential. Of those compounds, momilactones and 3-hydroxy-β-ionone were found to secret into surrounding environments from moss species Hypnum plumaeforme and Rhynchostegium pallidifolium, respectively, at phytotoxic levels and inhibited growth of several vascular plants nearby. Those compounds may work as allelopathic substances which contribute to the formation of the monospecific mats of H. plumaeforme and R. pallidifolium by inhibiting the growth of vascular plants in the local ecosystems. Therefore, allelopathic chemical interaction of the bryophytes with vascular plants may play an important role in the establishment of the monospecific mats.

Laccases are copper containing oxidases and one of the most promising enzymes of the oxidoreductase group. They are renowned due to their unique properties and functions in the biotechnological field and are involved in various promising applications in different areas of chemistry like synthetic chemistry, food chemistry, hormonal chemistry, carbohydrate chemistry, biosensor development etc. Furthermore, laccases have shown their presence in the field of medicinal chemistry which is an emerging field for their application. They have fabulous roles in the developments of antibiotics, anticancer drugs, antifungal drugs, melanin synthesis, prostaglandin production, sedatives and in detoxifying the toxic compounds etc. In the in-situ generation of iodine, generation of bacteria/spores free surface, development of hair dyes, malodour removal, prevention/treatment of dermatitis, reduction of allergenicity, deodorants, diaper and many more products preparation, laccases have potent roles. This review has been written in order to discuss various medicinal roles of laccases, collect useful information and dig out the prospective promising inferences for their future applicability. Astonishingly, there are not any significant and prevalent reviews utterly focused on the importance of laccases in pharmaceutical chemistry that can demonstrate their efficacious roles in this area. In this context, this review will be strongly helpful in providing the latest and updated research information on medicine based laccases and their future prospective roles in pharmaceutical field. This review discusses the significances of laccases in medicinal chemistry and those laccase catalysed syntheses having no medicinal activities are not entertained.

Polycyclic aromatic hydrocarbons (PAHs) gain more attention from the researchers all over the world as compared to other air pollutants due to their carcinogenic, mutagenic and teratogenic nature to humans. The association of PAHs with the fine fraction of particulate matter is of significant importance in terms of persistence in the atmosphere, where they can undergo chemical reactions and also be transported to a long distance. In present study we reviewed the ambient concentrations of PAHs in India and South Korea from the published papers since 2012. From this study it is clear that the Indian people are exposing high amounts of PAHs than Koreans. For example, the highest concentration of Benzo[a]pyrene (carcinogen to humans) reported in Korea is 3.46 ng/m3 where as in India it is 1189 ng/m3. In this study, we tabulated and discussed the analytical parameters evaluated in the determination of atmospheric PAHs, such as sampling period, sampling device, extraction method, analytical instrument used and QA/QC measurements.

Mycotoxins are chemical compounds produced by pathogenic molds that are toxic and cause diseases such as cancer and immune suppression. Alternariol (AOH), is well reported a type of mycotoxin, which is produced by Alternaria species. It is widely distributed in cereal based foods and fruits. Environmental conditions related to storage of food and cereals are main factors that are responsible for the presence of mycotoxins. Besides temperate zones, mycotoxins are frequently found in hot and humid areas that are more favourable for the growth of mold species. Generally, mycotoxins are directly ingested in the body but sometimes spore inhalation or skin contact can also be a route. Mycotoxicoses are disorders which are caused by the exposure to mycotoxins. It is difficult to control intrinsic and extrinsic factors such as strain variation, fungal strain specificity, instability of toxigenic properties. As mycotoxins have ability to induce DNA damage, modulate antioxidant capacity and mitigate macrophage phenotype and inflammatory responses, therefore, they pose acute effects on humans. Although efforts have been carried out internationally to control mycotoxins, practical measures are yet to be executed. Taken together, this communication highlights and showcases the toxicological impacts of Alternariol secreted by Alternaria alternata on the human health.

Oxidation of different groups of organic compounds, with hydrogen peroxide by non-heavymetal containing low-molecular-weight compounds is reviewed. Since hydrogen peroxide is inactive toward most of the organic substrates, catalytic in situ activation of the terminal oxidant is necessary. The bases, acids, iodine and bromine, selenium compounds, flavines, triazines, amines, N-oxides, thioureas, nitriles and ketones, aluminium compounds and carbon materials are representative catalysts. They are involved in oxygen and electron transfer processes whose mechanisms are briefly discussed. Their applications in practical synthesis for the oxidative transformations of different organic compounds are indicated.

Background: Quinoline and 1,2,3-triazoles have attracted increasing attention due to their significant biological activities. Combination of these two scaffolds in one single molecule, quinolinebased 1,2,3-triazoles, gives an excellent opportunity to create new structurally diverse drug-like molecules with potent biological properties. Synthesis of these molecular hybrids has become available from a recently developed copper-catalyzed azide-alkyne cycloaddition methodology. Objective: The aim of the present review is to summarize the recent developments in Cu-catalyzed azide- alkyne cycloaddition reactions for the synthesis of functionalized quinoline-based 1,2,3-triazoles. Method: The discussion was organized according to structural criteria and functional role of the triazole ring connected to quinoline derivatives. The quinoline-based 1,2,3-triazoles obtained through azidealkyne cycloaddition methodology were classified in two general groups: quinoline-based triazoles, in which 1,2,3-triazole ring acts as pharmacophore and triazoles containing quinoline and other heterocycles, in which 1,2,3-triazole ring acts as linker. Both of these groups are based on triazole structures of type 1 (1-(quinolinyl)-1,2,3-triazoles) and type 2 (4-(quinolinyl)-1,2,3-triazoles). Results: Recent studies (112 references) on the functionalization of quinoline derivatives by 1,2,3- triazole incorporation have been discussed providing reaction conditions of organoazides and alkyne derivatives and biological activity of the obtained quinoline-based 1,2,3-triazoles. Additionally, various recent advancements in the synthetic aspects of the copper-catalyzed azide-alkyne cycloaddition have been briefly analyzed. Conclusion: This information should furnish a fresh insight for organic chemists in the design of novel bioactive molecules that contain the triazole and quinoline skeletons. It can be expected that efficient, original preparative methods for new biological materials based on quinoline-triazole structures will be reported in the near future.