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CHAPTER 1

INTRODUCTION

1.1 Introduction

There is no doubt, human activities contribute to pollutions. There are many kinds

of human activity that leads to pollution such as agricultural, commercial and industrial

sector. Pollution occurrences in our environment exist in three forms which are water, soil

and air pollution. Generally, out of the Earth surface, terrestrial part covers 30 % and the

remaining 70 % over is covered by water surface (Chang et al., 2012). As water

dominates the largest portion on Earth, the unsafe and serious water pollution should be

given more attention.

Water pollution has a severe impact on all living organisms, and can harmfully

affect the use of water for drinking, household needs, recreation, fishing and

transportation. There are many causes of water pollution. One of it is the fertilizers that

are discharged from agricultural sector, which contains heavy metal toxic from industrial

sector and sewage from domestic sector (Yang et al., 2012). High chemical content in

fertilizers such as phosphate and nitrogen are able to increase the nutrient level thus


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stimulate the growth ofOscillatoria sp. that is a type of microalgae. Uncontrolled growth

ofOscillatoria sp. will lead to eutrophication occurrence (Cloern et al., 2001).

Eutrophication leads to algae blooms that can bring major problem in freshwater

and marine habitat. This is because the algae may use up all the oxygen in the water thus

resulting in death of many aquatic organisms such as fish that required oxygen to live

(Backer, 2002). Additionally, the bloom of algae could block the sunlight from

photosynthetic aquatic plants under the water surface. Worse come to worst, Oscillatoria

sp. produces toxin that is known as microcystin that lethal to pests, livestock and human

(Huynh et al., 2006)

For this study, several alkoxyl substituted thiourea derivatives that consist of four

difference molecule structure that are compounds 1-4 were used to inhibit the growth of

Oscillatoria sp. For this study, the aim was to investigate that alkoxyl substituted thiourea

derivatives can inhibit the growth of cyanobacteria (Oscillatoria sp.).

1.2 Significance of Study

In condition of warm water with high level of nutrients especially phosphorus,

Oscillatoria sp. produce Harmful Algae Blooms (HAB). This bloom creates surface scum

and has been associated with low levels of dissolved oxygen (


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1.2 Objectives of Study

1) To determine the inhibition effect of several molecules of alkoxyl substituted thiourea

to the growth of cyanobacteria (Oscillatoria sp.)

2) To investigate the inhibition effect of several concentrations of alkoxyl substituted

thioureato the growth of cyanobacteria (Oscillatoria sp.)


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CHAPTER 2

LITERATURE REVIEW

2.1 Water Pollution

One of the most essential and important resources for human beings is water. On the

contrary, when water pollution take place, it can cause harm toward human particularly

and other living things. Kemp (1998) emphasized that pollution is the introduction of

contaminants to the environment that involved physical and biological component of

earth system. Meanwhile, Wang et. al., (2009) stated that contamination can sources from

various ways such as fertilizer factories, urban runoff, automobile emission and mining

operations. These sources release heavy metal, and fertilizer pollutants which affect

water, soil and air. As aquatic ecosystem contains a wide variety of life forms such as

fish, plant and microorganisms that interrelate with each other, water pollution can caused

imbalance and disturbed the ecological system.


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2.3 Cyanobacteria Bloom

Cyanobacteria also formally known as blue-green algae are prokaryotes of huge

importance in many ecological living things and effect water quality and function a great

part in global biogeochemical cycles as mentioned by Rodericket al., (2000). Skulberg et

al., 1993 reported that cyanobacteria form colonies of photosynthetic cells, either in

cluster or connected into filaments and are naturally a problem only when the cell

concentrations become high that produce harmful algal bloom (HAB). This HAB that is

caused by eutrophication that have been reported almost every industrialized nation (Hans

et al., 2001; Joan & Wang., 2008).

As mentioned by Hendrik (1996), heavy metal for example nickel, cobalt, manganese and

iron are vital trace nutrients and frequently added to fertilizers to enhance plant growth.

Unregulated industrial water effluent also released these heavy metals. Furthermore,

numerous of these heavy metals have been designated by the US Environmental

Protection Agency (EPA) as potential threats. The examples of heavy metal that are

targeted by EPA are nickel, cobalt, iron, zinc and manganese. The HAB not only caused

by eutrophication but also the presence of several EPA target metals as reported by

Stephane et al., (2004). However, Thajuddin et al., (2005) stated that heavy metal such as

copper that often used as inhibition agent for the HAB had been resistant and cause the

cyanobacteria to flourish and potentially bloom. Alternative treatment that utiliza heavy

metal to control the growth of HAB must be carried out.


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2.4 Thiourea Derivatives As Antimicrobial Effect

Thiourea derivatives can inhibit the growth of microbial (Saeed et al., 2009). Thiourea is

the molecular structure that substituted oxygen atom in urea by sulfur atom. Koch et al.,

(2002) mentioned that thiourea compounds is classify as one of the precious ligand in

organic chemistry which contains the elements of carbon, sulfur, nitrogen and hydrogen

atoms.

Meanwhile ligand can be distinct as atom, ion, or molecules which have the ability to

donate electrons to the empty vacant metal center as stated by Misseleret al. (2004). In

addition, according to (Ibrahim Baba & Abdul Hamid, 1989) cited in Adibah Izzati

(2012), there are 3 types of ligand such as monodentate, polydentate and ambidentate.

Ligands that have only one donor atoms with only one site of attachment towards metals

is a definition of monodentate ligand. Meanwhile polydentate ligands is a ligands that

have more donor atoms with more site of attachments towards metal. For ligands that

have more than one donor atoms that shows different properties when the metals do

attach to either one of the potential donor atoms are known as ambidentate ligands.

Lange et al. (1996) stated that thiourea able to function as a ligand because the presence

of thiocyanate ion (SCN-), that a type of functional groups in a molecule of thiourea. This

result thiourea to develop into the potential and versatile ligand. This potential and

versatile ligand can be synchronized towards variety of transition metals as bidentate and

monodentate ligand (Tadjarodi et al., 2007).

This brings a lot of research have been reported that thiourea derivatives have worldwide

benefits in many distinct areas such as ability to inhibit the growth of both gram negative

and gram positive of bacteria species (Saeed et al., 2009) and antiviral activity (Karakus


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et al., 2009). Faidallah et al. (2011) mentioned that preliminary biological test of thiourea

compounds show significant response as antimicrobial effect. Besides that, Saeed et al.

(2009) mentioned that thiophene and morpholine from thiourea derivatives contain nitro

group electron withdrawing group on benzothiazole nucleus showed good antimicrobial

activity.


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CHAPTER 3

METHODOLOGY

3.1 Chemicals and Materials

For preparation and inhibitory test of alkoxyl thiourea derivatives to the growth of

cyanobacteria (Oscillatoria sp.), part of chemicals, materials and solvents such as Blue

Green Medium and gauze that were used were commercially purchased from ordinary

supplier. Besides that, the other part of chemicals, materials and solvents such as acetone

and dimethylsulfoxide (DMSO) that were used in this research were obtained from

Department of Biological Sciences and Department of Chemical Sciences, Faculty of

Science and Technology, Universiti Malaysia Terengganu.

Blue Green Medium or also known as BG11 was function in this study as a universal

medium for the culture and maintenance of the cyanobacteria. The composition of this

medium were sodium nitrate, dipotassium hydrogen phosphate, magnesium sulphate,

calcium chloride dihydrate, sodium carbonate, disodium magnesium EDTA, citric acid

and ferric ammonium citrate. This all inclusive medium was purchased from Sigma

Aldrich. This medium was stored below 8C and protected from direct light.


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Four types chemicals of alkoxyl substituted thiourea derivatives such as compounds 1-4

were obtained from Chemical Science Department, Faculty of Science and Technology,

Universiti Malaysia Terengganu. Meanwhile, solvent such as dimethylsulfoxide (DMSO)

and acetone were obtained from Department of Biological Sciences and Department of

Chemical Sciences, Faculty of Science and Technology, Universiti Malaysia Terengganu.

All related chemicals and solvent were carried out in very intensive care in laminar flow.

3.2 Apparatus

The apparatus and glassware that were used in this study were phytoplankton net,

inoculum loop, plastic bottle, conical flask with different sizes (100 ml, 150 ml, 500 ml

and 3000 ml), petri dishes, filter funnel, spectrophotometer, parafilm, microscope,

freezer, incubator, air-pump, centrifuge, filter paper, parafilm, gauze, micropipette with

different sizes (10 mL, 20 mL, 100 mL, 1000 mL and 5000 mL), vials, dropper, cotton

swap, beaker with different sizes (50 mL, 100 mL, 250 mL and 500 mL) and centrifuge

tube.

3.3 General Procedure

Cyanobacteria from Oscillatoria sp. was sampled in a pond at Universiti Malaysia

Terengganu. Then, the cyanobacteria was further isolated and identified under the

microscope. Then, the cyanobacteria was cultured in petri dish to grow. Subsequently, the

cyanobacteria was mass culture in the flask to prepared enough numbers for inhibition

treatment.


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Then, four several molecule structure of compounds 1-4 were diluted from the powder to

become liquid. Next, the cyanobacteria was treated by the compounds. Afterward, the

process extraction chlorophyll-A was done and the percentage of inhibition was counted

by using formula.


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Figure 3.1: Flow chart of general procedure approach

Sampling ofcyanobacteria

(Oscillatoria sp.)

Cultured ofcyanobacteria

(Oscillatoria sp.)

Inhibitory test ofalkoxyl substituted

thioureaderivatives to the

growth ofcyanobacteria

(Oscillatoria sp.)

Extraction ofchlorophyll a and

inhibitionpercentage was

calculated byusing formula.


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3.4 Study Sites

Sampling was conducted in a channel

Malaysia Terengganu (UMT). UMT located in the Kuala Terengganu, Terengganu and

strategically located on the shoreline of Terengganu facing South China Sea (Figure 3.1)

UMT originally founded as Centre for Fisheries and Marine Science. Later, in 1999, it

was renamed as Universiti Putra Malaysia Terengganu (UPMT) before turned into

College of Science and Technology Malaysia (KUSTEM) in June 2001. Subsequently it

was approved by Malaysian goverment to rename KUSTEM to UMT in 2007.

Figure 3.2 Satelite image showing study site in Universiti Malaysia Terengganu note that

the yellow star indicate the sampling site


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3.5 Field Sampling

Cyanobacteria (Oscillatoria sp.) was collected from channel as in the area of Universiti

Malaysia Terengganu beside the building of Research Management Inovation Centre

(RMIC) in early October 2012 (Figure 3.2). Oscillatoria sp. was determined by the

characteristics that tend to float underwater and appear green in colour. Oscillatoria sp.

was collected by using 25 m phytoplankton net (Saeed et al., 2009). Then the sample

was placed inside labeled plastic bottle. The labeled plastic bottle with the sample was

brought back to the laboratory for further identifying and isolation procedure.

Figure 3.3: Photo of the channel where the samples of Cyanobacteria (Oscillatoria sp.)

was collected


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3.6 Identification and Isolation ofOscillatoriasp.

The identification of Oscillatoria sp. was made based on the identification key of

freshwater algae (Presscott et al., 1999). Oscillatoria sp. was identified under compound

microscope as shown in the Figure 3.3. Then, the identified colony ofOscillatoria sp. was

transferred and isolate onto sterile BG-11 media by using inoculum loop. The media was

remained up to 10 days in order to obtain pure culture ofOscillatoria sp.

Figure 3.3: Process of identification and isolation ofOscillatoria sp. by using compound

microscope


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3.7 Mass Culture ofOscillatoriasp.

The pure cultured Oscillatoria sp. colony was cultured by using BG-11 liquid media in

3000 ml conical flask. The flask was sterilized by being autoclaved it at 126 C for 20

minute and with pressure 1 atm. Then the cultures as shown in Figure 3.5 was incubated

and maintained at 25 C under continuous illumination of cool fluorescent light (Zhang et

al., 2011). It was left in 10 days for optimum growth to provide optimum rate for

inhibition test.

Figure 3.5: Mass Culture ofOscillatoria sp.


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3.8 Inhibition test of alkoxyl substituted thiourea on the Oscillatoria sp.

In the exponential growth of 10 days, 27 ml ofOscillatoria sp. cultivation was harvested

and transferred into 100 ml conical flask. 3 ml each of four different types of alkoxyl

substituted thiourea which has concentration 10 g/mL, 12 g/mL, 14 g/mL, 16 g/mL,

18 g/mL and 20 g/mL was added into each of the conical flask. The controlled system

without treatment of alkoxyl substituted thiourea derivatives also were set up. Each

treatment was conducted in triplicate.

Figure 3.5: Inhibition test of alkoxyl thiourea derivatives to the growth of cyanobacteria

(Oscillatoria sp.)


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3.9 Chlorophyll a extraction and the calculation of inhibition test.

The treatment and controlled of the inhibition test were filtered with 0.45 m whatman

filter paper. Then, the filter paper washed in 5 to 10 mL of 100% acetone in a centrifuge

tube with glass rod. Next, there were sealed with aluminium foil and left 24 hour in the

dark conditions in 4 C. Later, the blank filter paper also washed with 100% acetone. On

the following days, the centrifuge tube was centrifuged at 3000 rpm for 10 minutes. The

absorbance of supernatant was measured at 665 nm, 645 nm and 630 nm. Next, the

chlorophyll a content was calculated by using the formula as shown as below. Then, the

inhibition percentage of alkoxyl thiourea substituted derivatives to the growth of

cyanobacteria (Oscillatoria sp.) was calculated by using formula that shown in Figure

3.7.

Chlorophyll a, Chl-a (mg/m) = (Ca x Va) / Vc

Where Ca = 11.6 x OD665 - 1.31 x OD645 - 0.14 x OD630

Va= Volume of acetone (mL) used for extraction

Vc= Volume of culture (L)

The formula to calculate the chlorophyll-a content

Inhibition Percentage = [(Control - Treatment) / Control] x 100%

The formula to calculate the inhibition percentage of alkoxyl thiourea substituted

derivatives to the growth of cyanobacteria (Oscillatoria sp.)


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CHAPTER 4

RESULTS

4.1 Sampling ofOscillatoriasp.

Oscillatoria sp. was sampling as shown in Figure 4.1. The physical appearance of

Oscillatoria sp. that was green scum expose in the water surroundings help the process of

sampling. The specimen was further identified under the microscope in the laboratory.

Under observation of microscope, it was easily to determine by the similarities of its

shape that is filamentous and non-differentiated as shown in Figure 4.2.

Figure 4.1: Sampling ofOscillatoria sp.


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Figure 4.2: Successfull identification ofOscillatoria sp. under the microscope

4.2 Culture ofOscillatoriasp.

The process of cultured of Oscillatoria sp. was continued after the process of

identification and isolation done. It was successfully cultured in agar plate that containing

BG-11 agar medium to obtain pure cultured of Oscillatoria sp. as shown in Figure 4.3.

After that, it was successfully propagate in 10 day by mass cultured it using BG-11 liquid

medium.

4.3 Inhibition Effect of Six Different Concentration of Compound 1 to the growth of

Cyanobacteria (Oscillatoriasp.)

Figure 4.4 showed the inhibition effects of six different concentration of compound 1 on

the growth of cyanobacteria (Oscillatoria sp.) Based on this result, there was an

increasing of inhibition percentage along together with the increasing of the treatment

concentrations from 10 g/mL until the optimum treatment concentrations that was at


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18g/mL. However, the 20 g/mL treatment showed decreasing in the inhibition

percentage towards the growth of cyanobacteria (Oscillatoria sp.). Treatment

concentration of 18 g/mL showed highest inhibition percentage that was 69.43 % while

the lowest inhibition percentage was 27.7 % with at 20 g/mL treatment concentration.

Figure 4.4: Inhibition effect of six different concentration of compound 1 to the growth of

cyanobacteria (Oscillatoria sp.)



Figure 4.5 shows that the inhibition percentage increased proportionally towards the

treatment concentration of 16 g/mL. However, for the treatment of compound 2, at 18

g/mL and 20 g/mL of concentration, the inhibition percentage decreased. The highest

inhibition percentage was 58.4 % at 16 g/mL of treatment concentration. In contrast, the

0

10

20

30

40

50

60

70

80

10 12 14 16 18 20

InhibitionPer

centage(%)

Concentration (g/mL)

Compounds 1


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lowest inhibition percentage was recorded at 20 g/mL treatment concentration which

was 33.43 %.





Figure 4.6 shows the inhibition effects of six different concentration of compounds 3 on

the growth of cyanobacteria (Oscillatoria sp.). Based on this result, there was anincreasing of inhibition percentage along together with the increasing of the treatment

concentrations from 10 g/mL until the optimum treatment concentrations that was at

14g/mL. However at the 16 g/mL, 18 g/mL and 20 g/mL treatment concentration

showed decreasing in the inhibition percentage towards the growth of cyanobacteria

(Oscillatoria sp.). Treatment concentration of 14 g/mL showed highest inhibition

0

10

20

30

40

50

60

70

10 12 14 16 18 20

InhibitionPercentage(%)


Compounds 2


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percentage that was 50.53 %. Meanwhile the lowest inhibition percentage recorded at 20

g/mL treatment concentration which was 37.73 %.





Figure 4.7 shows that the inhibition percentage increased proportionally towards the

treatment concentration of 14 g/mL. However, for the treatment of compound 4, at 16

g/mL, 18 g/mL and 20 g/mL of concentration, the inhibition percentage decreased.

The highest inhibition percentage was 63.17 % at 14 g/mL of treatment concentration.

In contrast, the lowest inhibition percentage was recorded at 20 g/mL treatment

concentration which was 35.5 %.

0

10

20

30

40

50

60

10 12 14 16 18 20

In

hibitionPercentage(%)


Compound 3


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4.7 Inhibition Effect of Four Different Compounds to the growth of Cyanobacteria

(Oscillatoriasp.)

Figure 4.8 shows the inhibition effect of four different compounds to the growth of

Cyanobacteria (Oscillatoria sp.). The result showed there were increasing trend of towardtreatment concentration of 14 g/mL, 16 g/mL and 18 g/mL in each compounds.

However all compound shows decreasing inhibition percentage at 20 g/mL. At 10

g/mL, compound 1 shows the highest inhibition percentage that was 38.63 percent while

compound 4 shows the lowest inhibition percentage that was 35.5 %.

0

10

20

30

40

50

60

70

10 12 14 16 18 20

InhibitionPercentage(%)


Compounds 4


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Treatment concentrations at 12 g/mL shows that compound 4 recorded the highest

inhibition percentage at the concentration that was 48.57 % while compound 2 record the

lowest inhibition percentage that was 38.27 %. The highest inhibition percentage fortreatment concentration at 14 g/mL record by compound 4 which was 63.17 % whereas

compound 2 shows the lowest inhibition percentage that was 42.1 %. At 16 g/mL of

treatment concentration, compound 2 recorded the highest inhibition percentage that was

58.4 % while the lowest inhibition percentage recorded by compounds 3 which was 40.27

%.

The highest inhibition percentage that recorded at 18 g/mL of treatment concentration

was compound 1 which was 69.43 % while compound 3 shows the lowest inhibition

percentage that was 38.1 %. Meanwhile at the treatment concentration of 20 g/mL,

compound 4 shows the highest inhibition percentage that was 39.3 % while compound 1

shows the lowest inhibition percentage that was 27.7 %. In general, compound 1

exhibited the highest inhibition percentage between the compounds and concentrations

that was at 18 g/mL treatment concentration while compound 1 also was the compound

with had lowest inhibition percentage between all the compound and concentrations that

was at 20 g/mL.

Besides that, statistical analysis had been done to this result. Two-way analysis of

variance (ANOVA) test had been select to analyse this data. This is because in this study

two independent variable; structure and concentration had been study. This two way

ANOVA is the best analysis used when there are more than one independent variable.

The two way ANOVA not only function to determine the main effect of contributions of

each independent variable but it is also identified if there significant interaction effect

between the independent variable had been choose as shown in Appendix A.


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The analysis using two way ANOVA shows that, there was a significant difference

between all concentration treatment (ANOVA, p


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Table 4.1: Highest values inhibition percentage and highest concentration of each

compounds

Compounds Highest Inhibition(%) Highest Concentration(g/mL)

1 69.40 18

2 58.40 16

3 50.53 14

4 63.17 14


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CHAPTER 5

DISCUSSION

5.1 Sampling

The sampling site was chosen because it is ideal since it is close to UMT, low cost of

transport and has a disturbed environment. Besides that, the output of the study can be

used by the future developer to consider any environmental friendly development. In

addition, the data collection was carried out in the monsoon season. There are several

problems during the sampling in monsoon season such as fast moving water, precipitation

of soil that entered the phytoplankton net and difficulties to find Oscillatoria Sp.

However all the sampling task was successfully done.

5.2 Inhibition Effect of Alkoxyl Substituted Thiourea Derivatives To The Growth of

Cyanobacteria

In this study, compounds 1-4 of alkoxyl substituted thiourea derivatives were proven to

inhibit the growth of cyanobacteria (Oscillatoria sp.). As mentioned by Francoise et al.,(1998), molecular studies of cyanobacteria much similar to that of other bacteria such as

lactose based expression in E. coli and vanillate based expression in Caulobacter

crescentus (C. crescentus). The vanillate is the byproduct of the saprotrophic digestion of

plant lignin. In addition, cyanobacteria is gram positive prokaryotes. The inhibition result


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was supported by research had been done by Golan et al. (2008) state that the simply coat

of murein make a sample easy to penetrate into it.

Furthermore, the result inhibition effect of alkoxyl substituted thiourea also was furthersupported by a study which had been done by Zhong et al. (2008). This study found that

chitosan-thiourea derivatives have inhibition effect towards gram-positive and negative

bacteria. Besides that the study found that the presence of potential functional groups

C=S, NH and C=O in their derivatives had caused the inhibition effect to the bacteria.

Additionally, Lange et al. (1996) found that molecule of thiourea contains thiocyanate ion

(SCN-), a type of functional groups which makes thiourea able to act a ligand. This result

of thiourea molecule as potential and versatile ligand as mentioned by Tadjarodi et al.

(2007). This ligand makes the compounds 1-4 become suitable to become anti-algae

product because the properties of ligand that can be easily degraded compare to other

current anti-algae product such copper that types of heavy metal that cannot be degraded

and in long times will affect lethal to living things.

Meanwhile inhibition percentage of alkoxyl substituted thiourea derivatives towards the

growth of cyanobacteria (Oscillatoria sp.) was measured based on extraction of

chlorophyll a. The measurement based on extraction of chlorophyll a because

cyanobacteria are photosynthetic can manufacture their own food. In addition,

cyanobacteria derived their name from bluish pigment phycocyanin which function to

capture light for photosynthesis. Furthermore, chlorophyll a contain in cyanobacteria is

the same photosynthetic pigment that plant use. Inhibition of alkoxyl substituted thiourea

derivatives towards chlorophyll a of cyanobacteria would disturb photosynthetic process

which result in the low efficiency food production for cyanobacteria and as a

consequence, it will die.


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As the result of this study show different patterns of inhibition effect for each molecule

structure and concentration, it can be explained by the presence of a conjugated cyclic

system which is stabilized by resonance is called an aromatic system. Besides that,

benzene is one of the examples of conjugated six-membered. This supported by the result

of this study thatfour different compounds of aromatic system produce different patterns

of inhibition effect particularly caused by delocalization of electron.


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CHAPTER 6

CONCLUSION AND RECOMMENDATION

6.1 Conclusion

Cyanobacteria bloom does cause various side effects to the environment such as become

lethal to living things. Current method to threat it such as by using copper and silver

nanoparticle have many disadvantage such as high cost and not easily decompose. Thus,

alternative treatment must be find. In this study, alkoxyl thiourea substituted derivatives

are very well-known compounds as versatile ligands that easily decompose was used totreat the cyanobacteria bloom. This types of thiourea have proven to be very functional in

numerous application particularly in environmental in order to develop new sources

energy from different reaction of thiourea derivatives. This is because thiourea is a very

versatile ligand because of its ability to provide huge number bonding potential towards

metals metal centers. However, there are four compounds of alkoxyl thiourea derivatives

substituted that have fully tested to apply as anti-algae agents through the reaction with

the cyanobacteria (Oscillatoria sp.) in this study.

Furthermore all the treatment compounds demonstrate positive result towards inhibit the

growth of cyanobacteria (Oscillatoria sp.). Compound 1 has highest inhibition percentage

towads the growth of cyanobacteria (Oscillatoria sp.) followed by compound 4, 2 and 3


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respectively. All treatment concentration shows increase pattern of inhibition toward the

growth of cyanobacteria (Oscillatoria sp.) until treatment concentration of 14 g/mL for

both compounds 3 and 4,however for compounds 1 and 2, it shows different increasing

pattern of inhibition towards the growth of cyanobacteria (Oscillatoria sp.) that are until

treatment concentration of 18 g/mL and 16 g/mL respectively. In conclusion,

compounds 1-4 has high potential to be further developed as anti-algae product but all the

compounds need further studying in efficiency dosage, environmental effect and clinical

effect before it can be used as antialgae product for treatment of cyanobacteria

(Oscillatoria sp.) bloom.

6.2 Recommendation

Alkoxyl substituted thiourea derivatives are very interesting molecules as thus give a

many advantages towards various field of applications. For future studies on this thiourea,

the side effect of this chemical on the environment should be further investigated. Besides

that, further studies on the efficient dosage must be done to know the best dosage of

treatment.

Besides that, this thiourea system can be also substituted by other novel thiourea

derivatives such as thiourea derivatives of metal complexes with various transition metals

such as nickel and copper which prove that have tremendous biological activity. The

presence of unpaired electrons at oxygen atoms make it easy to gives good yields of

products.

Next, the antialgae properties of 1-4 can also be tested using various types of

cyanobacteria such as Nostoc, Microcystis and Anabaena. Besides that, compounds 1-4

can also be tested towards other biological species like viruses and protozoa.


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Alkoxyl thiourea substituted derivatives will be great future system because it have large

prospect to be developed such as in renewable energy, catalyst, electricity and electronic

devices and biomedical. This prospect comes with the fully packaged of this alkoxyl

thiourea substituted derivatives that low cost.


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