Research Journal of Chemistry and Environment

Indexed in SCOPUS, Chemical Abstracts Services, UGC, NAAS and Indian Citation Index etc.

Research Journal of Chemistry and Environment

Vol. 24(9) September 2020

Phytoremediation of Ammoniacal Nitrogen Wastewater using Water Hyacinth (Eichhornia Crassipes)

Ting Winnie Huong Tien, Tan Ivy Ai Wei, Salleh Shanti Faridah and Abdul Wahab Noraziah

Page No. 1-9

Ammoniacal nitrogen (AN) is present in both domestic and industrial wastewater which is one of the main contributors of eutrophication. Phytoremediation is recommended as an alternative solution to treat wastewater with high AN content due to its cost-effective, environmental friendly and sustainable characteristics. In this study, one-factor-at-a-time (OFAT) study was conducted on the parameters influencing the AN removal using water hyacinth.

The variables involved pH (4-10), retention time (2-14 days), initial AN concentration (10-70 mg/L), macrophytes density (5-30 g/L) and salinity (1-5 g NaCl/L) which influenced the AN removal significantly. The highest AN removal of 98.85% was obtained at pH 9, 99.18% at retention time of 14 days, 90.46% at initial AN concentration of 40 mg/L, 84.91% at macrophyte density of 30 g /L and 70.13% at salinity of 1 g NaCl/L respectively. Overall, water hyacinth has demonstrated high potential as the macrophyte for phytoremediation of AN in semiconductor effluent.

Synthesis of biologically active natural product: Camptothecin

Chellapandi T., Jyothi Pon Venkatesh M. and Madhumitha G.

Page No. 10-15

Huge numbers of the medications are being created to avert the sickness. In this study, we have discussed about the synthesis of various derivatives obtained from camptothecin (CPT). Camptothecin is biologically more active because it has heterocyclic structures like five, six membered rings that contain N-hetero atom attached moiety. Anti-cancer, anti-tumor, and cytotoxic behavior of CPT and its derivatives are shortly described. We have focused on various synthesis methods of camptothecin derivatives.

In vitro Anticancer and Antioxidant potential of Essential oil of Zingiber zerumbet (L.) Simth grown in Western Ghats region-South India

Kathirvel Poonkodi, Annadurai Logamadevi, Murugesan Suganthi and Alagumalai Divya

Page No. 16-21

Anticancer and antioxidant potentials of essential oil of Zingiber zerumbet (L.) Simth grown in Western Ghats region-South India were examined. In vitro antioxidant potential was evaluated by DPPH and superoxide radical scavenging methods. Moreover, in vitro anticancer activity against MOLT-3 (T-cell acute lymphoblastic leukemia cancer cell line) using MTT assay was carried out. A total of 20 compounds were present in the essential oil obtained from hydro distillation of Z. zerumbet leaves. The major constituents were Zerumbone (37.44%), Camphor (9.93%), 1, 8 Cineole (9.55%), iso borneal (5.36%) and α-pinene (5.07%).

The in vitro antioxidant results demonstrated that the essential oil of Z.zerumbet showed a concentration dependent antiradical activity by inhibiting DPPH radical with IC50 value of 19.53 µg/ml and showed significant SO inhibiting activity with IC50 being 28.56 µg/ml. Ascorbic acid was used as the standard with IC50 values of 5.45 µg/ml and 12.42 µg/ml for both assays respectively. The essential oil exhibited significant anticancer activity against MOLT-3 cancer cell line with IC50 of 62.5 µg/ml.

Antimicrobial Potential of Some Selected Medicinal Plants Collected from Himachal Pradesh

Sharma Meenakshi and Bharti Dipti

Page No. 22-27

Many natural plants have been employed in various medicinal systems for the treatment and management of different diseases. Antimicrobial screening of eleven medicinal plants namely Cinnamoum verum, Phyllathus emblica, Curcuma longa, Cinnamomum cassia, Calotropis gigantea, Azadirachta indica, Brassica nigra, Mentha laxiflora, Coriandrum sativum, Allium sativum and Zingiber officinale have been carried out against six bacterial strains namely Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, Salmonella typhi, Escherichia coli and Bacillus cereus and three fungal strains Amanita fulva, Aspergillus niger, Aspergillus fumigatus.

The effects of various plant extracts on the several bacterial strains were assayed by agar well diffusion method and disc diffusion method. Extract of Cinnamoum verum has been found to be most effective against Bacillus cereus and Aspergillus niger with 40 and 48 mm inhibitory effect respectively. All the plant species have shown the significant antimicrobial potential in the range 2-48 mm. The identification of these medicinal plants as antimicrobial herbs will be helpful in the replacement of some commercialized synthesized antimicrobial drugs.

Swelling Behavior and Antioxidant activity of Poly (N-tert-amylacrylamide - co -Acrylamide / [3-(Methacryloylamino) propyl] trimethylammonium chloride) gold nanocomposite hydrogels

Kayalvizhy E. and Pazhanisamy P.

Page No. 28-38

In the present study, 3-(Methacryloylaminopropyl) trimethylammonium chloride, acrylamide and N-tert-amylacrylamide monomeric unit containing gold nanocomposite hydrogels were synthesized by free radical copolymerization using MBA as cross-linker APS as initiator in methanol/water medium at 600C. The synthesized gold nanocomposite hydrogel was conformed by IR spectroscopy. The SEM analysis indicated that the gold nanocomposite hydrogel exhibited more amorphous and less crystalline in nature. TGA analysis of gold nanocomposite showed double stage decomposition and stability up to 270OC. The swelling behavior of hydrogels increased with increasing amount of MPTMACl content. At higher content of MPTMACl, the swelling rate decreased due to the extent of cross linking occurring during the synthesis of hydrogel. The effect of temperature on swelling increases with increasing temperature up to 30OC and then decreased due to reduction in segmental mobility of polymeric chain at higher temperature.

The gold nanocomposite hydrogel in water follows a non-Fickian diffusion character. In this diffusion, diffusion and relaxation are said to be isochronal effective. Gold nanocomposite hydrogels displayed strong antioxidant activity and it reveals that the hydrogels could have great importance as therapeutic agents.

Electrochemical Reactions at Sacrificial Aluminium Electrode: Synthesis of Aluminium (III) Glycolates and their Coordination Compounds

Bala Kanchan and Singh Baljit

Page No. 39-44

The electrochemical synthesis of parent aluminium(III) glycolates and the coordination complexes supported by nitrogen containing ligands(L) (2,2’-bipyridyl or 1,10-phenanthroline) are reported. These compounds were prepared in good yield using acetonitrile as a solvent in which supporting electrolyte tetrabutylammonium chloride (Bu4NCl) was dissolved and aluminum metal served as the electrode. These electrochemical products have been effectively performed in one-step at room temperature in an h- type divided cell by using an environmentally friendly technique. The products of these reactions were identified by IR spectroscopy, elemental analysis and physical measurements.

Adsorption of Ni (II) ions from aqueous solution using Rice Husk Powder as low cost adsorbent

Choudhari Smita V., Shetye Sugandha S. and Patil Satish D.

Page No. 45-52

Adsorption of Nickel (II) ions from aqueous solution using Rice husk powder as low cost adsorbent is greener way of reducing pollution. Concentrations of Ni(II) beyond acceptable limit 0.02mg/L (according to BIS 2015) may be genotoxic and mutagenic. Present investigations were carried out to optimize contact time and initial metal ion concentration. For adsorbent dose of 0.250 g of RHP , 40 % adsorption of 50 ppm Nickel(II) was observed at room temperature in 30 minutes, with 181.5 rpm and at pH=5 Freundlich adsorption isotherm models (R2 = 0.991) and Langmuir adsorption isotherm model (R2 = 0.983) fit well with high value of regression coefficient nearer to 1. Simple Kinetic models such as Pseudo-first order kinetic model, Pseudo second order kinetic model, Intra particle diffusion Elovich model were employed to determine the adsorption mechanism. Pseudo second and first order kinetic models showed that the chemical adsorption process is dominant. The amount of metal adsorbed at equilibrium qe (theoretical) obtained from Lagergren pseudo -second order kinetic model were found to be nearly the same with the experimental data i.e. 4 mg/g.

Synthesis, characterization and biological evaluation of some new chalcones, amino pyrimidines and isoxazoles derivatives incorporating 1, 3, 5-triazine moiety

Shah Bhavna and Pandey Nisha

Page No. 53-61

A series of new amino pyrimidines and isoxazoles derivatives of chalcone incorporating 1, 3, 5-triazine moiety as potential antimicrobial agents was designed, synthesized and characterized by elemental analysis, FTIR and NMR spectral techniques. All the synthesized compounds were screened in vitro against four bacterial strains (Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa) and three fungal strains (Aspergillus niger, Aspergillus clavatus and Candida albicans). The antimicrobial results indicated that some of the compounds showed remarkable activities comparable to the standard drugs.

Removal of organic matter from municipal wastewater using coir

Neena Sunny and Roy M. Thomas

Page No. 62-71

The treatment of waste water has been a challenge throughout the years due to varying waste water characteristics and strict effluent regulations. In the present day scenario, where sustainability and green solution are sought after, biological waste water treatment using eco-friendly materials would definitely provide promising solutions. Coir is abundantly available in Kerala State and the feasibility of using coir as an attached media for treatment of waste water especially removal of organic matter is the focus of the present study.

The study was conducted in a bioreactor fabricated in the laboratory in which coir ropes were submerged to improve the growth of biomass. The effects of hydraulic retention time (HRT) and attached media content in percentage on the performance of the reactor were evaluated based on COD, BOD and TSS value. The experiment was conducted at a constant organic loading rate of 0.45 kg/COD/m3/day. It was concluded that optimum efficiency was obtained at coir filling rate of 3% and hydraulic retention time of 16 hours.

Studies on nickel (II) and mixed nickel (II)-copper (II) complexes of cylindrical macrocycle consisting of four fused cyclen rings

Rastogi Ankur, Anurag and Nayan Ram

Page No. 72-86

Template condensation reactions between 1,2-diaminoethane and 1,1,2,2- tetrachloroethane leading to generation of cylindrical macrocycle 3,6,8,11,13,16, 19,22,24,27,29,32,33,36,37,40-hexadecaazapentacycl o[16.14.4.42,17.07,28.012,23]tetracosane (HDPT, A) under different experimental conditions have been described. The synthesized nickel(II) and mixed nickel(II)–copper(II) complexes [Ni4(HDPT)(H2O)6 Cl2]Cl6.3H2O and [Ni2Cu2(HDPT)(H2O)2Cl2]Cl6. 12H2O and metal-free ligand hydrochloride HDPT.16HCl have been characterized by elemental, conductivity and spectroscopic studies.

The ligand structure of four fused tetraaza [12]-N4 (cyclen) rings is further confirmed by thermodynamic studies in aqueous solution. Macrocyclic effect on stability of MA2+, M2A4+, M3A6+ or M4A8+ (M = Ni2+ or Cu2+) is exhibited by the corresponding stability constant. The stability constant for NiA2+ is about 10 times greater than that for (Ni-cyclen)2+ complex. This enhancement is expected due to additional electron transfer to nickel(II) from uncoordinated donors of less flexible ligand and coordinated H2O molecule trapped in the cavity that forces the nickel(II) ion close to the N-donors atoms. Formation of di, tri and tetrahydroxo complexes ([Ni2A(H2O)2(OH)2]2+, [Ni3A(H2O)3 (OH)3]3+ and [Ni4A(H2O)4(OH)4]4+) in solution shows that 2-4 H2O molecules accommodated in the small spherical cavity through coordinate bonds to metals at axial positions are probably replaced by smaller OH- ions to minimize the crowding.

Pteridophytic diversity of Todgarh-Raoli WildLife Sanctuary, Rajasthan, India

Mourya Rahul and Gena Dilip

Page No. 87-93

Todgarh-Raoli Wildlife Sanctuary (TRWS) in the south central part of Rajasthan spreads over Udaipur, Pali, Ajmer and Rajsamand districts of Rajasthan State and forms a special ecotone between hills of Aravallis and Thar Desert located in the west. The pteridophytes which form a sizeable component of floral resources of Rajasthan are of tremendous academic and medicinal importance. Therefore, to document and find out the present status of these plant species, TRWS of Rajasthan was visited time and again. This area has been found to be quite rich in pteridophytic species. 15 species belonging to 11 genera and six families of pteridophytes have been recorded from the area of this sanctuary of Rajasthan.

Of these, seven pteridophytic species namely; Equisetum ramosissimum Desf. Subsp. ramosissimum Hauke, Adiantum caudatum L., Azolla pinnata R. Br. Sub sp. asiatica, Marsilea minuta L., Ceratopteris thalictroides (L.) Brong., Negripteris scioana (Chiov.) Pich. Ser. and Ophioglossum petiolatum Hook. have been recorded from this locality. Asplenium pumilum Sw. Var. Hymenophylloides Fee. And Christella dentata (Forsk.) Holttum recorded by earlier workers could not be relocated despite a keen and thorough search of the localities reported by earlier workers. Dense population of Pteris vittata L. and Equisetum ramosissimum Desf. Subsp. ramosissmum Hauke has been recorded at several localities in the sanctuary area which is rarely seen in other parts of the state. Adiantum is represented by four species, Aleuritopteris by two and rest of the genera are represented by single species.

Analysis of external mass transfer on the degradation of Reactive black 5 using immobilized Trametes hirsuta in packed bed reactor

Rengadurai S., Preetha B., Vivekanandan B. and Elavarasan P.

Page No. 94-100

Biological degradation of Reactive black5(RB5) dye was carried in up-flow mode in packed bed reactor with white rot fungus Trametes hirsuta immobilized on Na-alginate beads and the beads were packed in the packed bed reactor. The kinetic parameters and mass transfer coefficients were calculated at different flow rates (0.026cm3/s, 0.057 cm3/s, 0.102 cm3/s, 0.204 cm3/s and 0.408 cm3/s), size of bead (0.2cm,0.5cm and 0.8cm) and initial concentration of RB5(55mg/l, 110mg/l, 165mg/l and 220mg/l).

The external mass transfer correlation was found to be jD = K(Re')n-1 generated with different values of 'K' as 1.51, 1.43 and 1.34.The external mass transfer correlation value of ‘(n− 1)’ was found to be –0.28 for all 'K' value.

Determination of atorvastatin calcium by quenching of tyrosine fluorescence

Mote U.S.

Page No. 101-104

A novel method for the quantitative determination of atorvastatin calcium based on the fluorescence quenching of tyrosine by atorvastatin calcium in aqueous solution was proposed. The method is simple, rapid, specific and highly sensitive because the fluorescence quenching is the sensitive and selective phenomenon and depends on the nature of fluorophore and quencher. The fluorescence of tyrosine is quenched by addition of atorvastatin calcium.

The quenching process is studied by Stern-Volmer equation. Under the optimal conditions, the Stern–Volmer calibration plot of F0/F against concentration of atorvastatin calcium was linear in the range of 2.5 µmolL-1 to 20.00 µmolL-1 with a correlation coefficient of 0.9890. The limit of detection was 5.1495 µmolL-1. The method was satisfactorily applied to the direct determination of atorvastatin calcium in pharmaceutical formulations.

Cross Aldol Condensation of D – Glyceraldehyde with Cyclohexanone in aqueous micellar media using L-Proline as Catalyst: A Green approach

Biswas Satyajit

Page No. 105-111

L - Proline catalyzed C-C bond formation reaction is of great interest in organic compound synthesis. Aldol condensation reaction is well established special type of C-C bond formation reaction. Due to low solubility of organic compounds, it is very difficult to achieve the aldol condensation reaction in water. Herein, in this research, we established how the combined proline–surfactant organocatalysis promotes the cross aldol condensation reaction in water with high yield and with high purity. In the emerging field of chemical biology, chemical tools to study biological system, aqueous organic chemistry are very much essential. We investigated the amino acid catalyzed cross aldol condensation reaction of D - glyceraldehyde with cyclohexanone in aqueous anionic micellar media at room temperature. Reaction yields and purity of the product were observed to be greater than that of the corresponding reaction in any other organic solvents.

Initially the aldol reaction of D- glyceraldehyde with cyclohexanone in aqueous media in the absence of surfactant is studied by mixing 20 mM of cyclohexanone, 5 mM of glyceraldehyde and 20 mol% of proline in water. After seven days at 35o C, the anticipated aldol product was obtained in very low amount. When a surfactant SDS (20 mol %) is added to the reaction medium, above 80% yield of aldol product was obtained in only 18 hr. The above result proves that anionic surfactant Sodium Dodecyl Sulfate (SDS) plays important roles in the reaction. The reaction progress is monitored by thin layer chromatographic (TLC) and the isolated product is characterized by melting point, FTIR, Mass spectroscopy and finally by H1NMR spectroscopic technique. The use of biogenic L – proline as the catalyst and the aqueous conditions make this method very attractive. The reaction takes place in the emulsion media which assemble both hydrophobic aldehyde and ketone.

Eriodictyol imparting Cardioprotection and lipid modulation in isoproterenol-induced myocardial infarcted rats

Preethi Rajesh and Manju V.

Page No. 112-119

The study was designed to evaluate the cardioprotective potential of eriodictyol on cardiac myocytes caused due to isoproterenol (ISO) induced myocardial infarction (MI) in albino male wistar rats and its possible effects in lipid metabolism. Myocardial Infarction was induced by subcutaneous injection of isoproterenol, 85 mg/Kg body weight in two doses at an interval of 24 hrs after treatment period of 45 days with eriodictyol 200mg per kg body weight through intragastric intubation. The standard drug metoprolol succinate was administered at a dosage of 2.5mg per kg body weight for 45 days followed by ISO induced myocardial infarction.

The study showed significant increase in the levels of triacylglycerol, cholesterol, free fatty acids both in plasma and heart tissue with considerable decrease in the levels of phospholipids in ISO induced myocardial infracted rats. The oral administration of eriodictyol showed significant decrease in total lipids with significant increase in the levels of phospholipids. The results also showed considerable increase in HDL and improvement in the hemodynamic parameters with considerable decrease in the LDL levels on pretreatment with eriodictyol. The results indicate that the oral administration of metoprolol succinate also modulates the lipid metabolism of the ISO induced myocardial infracted rats.

Degradation of Rhodamine-B Dye by Electrochemical Method

Ratanesh Kumar, Wagh P.B., Joshi K.D., Manmohan Kumar and Kaushik T.C.

Page No. 120-124

Rhodamine-B is one of the major contaminant in the effluents generated from the textile industries and represents one of the most problematic groups of non-biodegradable effluent. It can be easily identified by the human eye. Rhodamine-B effluent needs to be treated effectively to avoid its adverse impact on human beings and environment. In the present work, a process is demonstrated using electrolytic method for its degradation. Electrochemical removals of colour and organic load from solutions containing Rhodamine-B are performed using a platinum electrode. The detailed studies on the influence of strong electrolyte (0.02 M to 0.12M), pH (2 to 9), applied potential (6 to 24 V) and concentration of oxidizer (5 to 30 mM) etc. have been carried out in the present study.

It has been found that 50 ppm Rhodamine-B solution is successfully degraded to a safe discharge limit of ≤ 1 ppm at optimal value of pH = 3, [NaCl] = 0.10M, [H2O2] = 20mM and applied potential = 12V. The treated Rhodamine-B solution has been analyzed by UV-Visible Spectrophotometer and Total Organic Carbon (TOC) analyzer.

Fe-doped Manganese Dioxide films for supercapacitors

Tsagareli Giorgi, Makhatadze Shota, Soselia Marina and Maisuradze Nino

Page No. 125-130

The effect of the presence of Fe (II) or Fe (III) ions in solutions for obtaining thin films of manganese dioxide (MD) on their capacitive properties has been studied by the cyclic voltammetry. Optimal conditions of electrochemical method of producing films on a platinum anode have been established. Incorporation of iron ions in the crystal lattice of MD increased the capacity of the film and improved appearance of cyclic voltammogram which approached a rectangular shape. Films with the thickness up to ~150 nm after 1000 cycles lost about 10% of capacitance and retained their shape whereas for thicker films capacitive properties noticeably deteriorated.

It was shown that Fe (II) ions were chemisorbed and Fe (III) ions were adsorbed without charge transfer on the surface of the MD and thus were incorporated in its structure. At the same time, the capacity of MD films obtained in the presence of Fe (III) ions increased compared to films obtained in solutions containing Fe (II) ions. The capacity of the ~50 nm film obtained in the presence of Fe (III) ions, at 20th CV cycle was equal to 460 F/g.

Green mediated synthesis and characterisation of dysprosium doped cadmium oxide nano particles

Shivananjaiah H.N. and Sailaja Kumari K. P.

Page No. 131-135

Dysprosium-doped CdO nanoparticles [Cd1−xDyxO] were studied to enhance and control their multifunctional properties for various optoelectronic or magneto electrical properties. After synthesizing well-defined Dy-doped CdO nanoparticles by combustion route using Euphorbia Milli latex as reducing agent, the optical and magnetic characteristics of synthesized nanoparticles were analysed. Formation of cubic structured Dy-doped CdO nanoparticles was recognized by PXRD studies and morphology by transmission electron microscopy (TEM).

The effect of increase in dopant concentration on the band gap was confirmed by UV-Vis spectra. FTIR studies confirmed the purity of the sample. In magnetic studies, room-temperature ferromagnetism (RTFM) behaviour was observed.

Biodegradation of Dioxin and Furan from Sludge Wastewater Treatment of Pulp Industry by Phanerochaete chrysosporium

Henggar Hardiani and Teddy Kardiansyah

Page No. 136-145

The chlorinated organic compounds in the wastewater are formed from the bleaching process in pulping. These compounds are dioxins and furans known to be toxic and carcinogenic and persistent environmental pollutants with bio-accumulative properties and provide a risk of adverse effects on human health and the environment. Beside that they have the potential to migrate through soil, water and air. Disposal of sludge from WWTP by open dumping has the potential to cause environmental problems such as soil pollution, groundwater and surface water. Because of the toxicity of dioxins, how to remove dioxins from polluted environments is one of the most challenging problems in environmental technology. This research aims to determine the potential of Phanerochaete chrysosporium fungi to be able to degrade dioxins and furans. The characteristics of waste sludge from WWTP contains high EOX compounds of 957.0 µg/g, organic content of 83.89%; 2.3.7.8-Tetrachlorodibenzodioxin is <0.0011 µg/g; Octachlorodibenzodioxin 0.2 µg/g; and Octachlorodibenzofuran around of 0.25 µg/g.

The experiment was conducted for incubation at 27 days with observed parameters as temperature, pH, humidity and analysis of dioxin and furans content. The optimal conditions for the degradation of dioxin and furan compounds by the fungus P. chrysosporium are pH 6-9, the water content is 50% -60% and the temperature is 30-70oC. The incubation period of 27 days showed that P. chrysosporium could degrade 2,3,7,8-Tetrachlorodibenzodioxin by 48.67%; while 1,2,3,4,6,7,8-Heptachloro-dibenzo-dioxin is 31.82% and Octachlorodibenzodioxin is 33.33%, 2,3,7,8-Tetrachloro-dibenzo-furan by 35.82% and Octachlorodibenzofuran by 40%.

Freshwater larval digenetic trematode parasites in India: an epitomised review

Choubisa Shanti Lal and Jaroli Vishvajeet

Page No. 146-156

It is well documented that various developmental larval stages of digenetic trematode parasites of vertebrates including humans and domestic animals such as sporocyst, redia and cercaria generally develop in their intermediate aquatic snail hosts. In India, both common and rare forms of these trematode larvae have been reported from diverse freshwater snail species inhabiting various lentic and lotic habitats of different geographical provinces. However, most of the studies have been conducted so far on their taxonomy, seasonal occurrence or infection and behaviors.

Nevertheless, some excellent and original research works on their certain biology such as mode of feeding (nutrition), digestion, neuroanatomy, histopathology, parasitic castration, host-specificity etc. have also been done. Besides these studies, for the first time in-vitro culture up to juvenile stage of trematode larvae has also been successfully done in India. In the present communication, the basic and significant research works done so far on biology of freshwater larval trematode parasites in India have been briefly and critically reviewed.

Comprehensive Review on synthesis and pharmaceutical applications of substituted 1,3,4-oxadiazole

Santhanalakshmi K., Jacquline Rosy P. and Muthukumar S.

Page No. 157-170

Among heterocyclic compounds, 1,3,4-oxadiazole has become an important one in the development of new drugs. Compounds comprising 1,3,4-oxadiazole nuclei show broad spectrum of pharmaceutical applications which include antibacterial, antifungal, analgesic, anti-inflammatory, antiviral, anticancer, antidepressant, anticonvulsant, and anti-diabetic properties. The capability of 1,3,4-oxadiazole heterocyclic compounds to undergo various chemical reactions has made them important because of their enormous biological potential.