Introduction

Insect pests compete fiercely with people for agricultural resources because they harm and decrease the productivity of most crops1. Vegetative shoots are chewed, stems are eaten, or roots or tubers are consumed by biting insects including locusts, beetles, and Lepidoptera larvae2,3. The moth species Spodoptera littoralis (Boisduval, 1833) belongs to the Noctuidae family and is widely distributed throughout Africa, Mediterranean Europe, and the Middle East4. For many nations, it is well known that the cotton leaf worm causes significant financial losses5. Cotton, potatoes, maize and vegetables are just a few of the highly harmful polyphosphorous plant species that the highly venomous S. littoralis moth feeds on6. It also consumes more than 100 other species. The largest problem facing pesticide research now is likely pesticide resistance. In order to create an effective control strategy for S. littoralis in the future, it is necessary to evaluate various insecticides from various chemical groups with various modes of action as well as some of their combinations7. In an effort to boost the effectiveness of insecticides against S. littoralis while decreasing the amount of pesticides released into the environment, which is important from the perspective of environmental safety, the combination of such bioactive compounds with insecticides was researched8,9,10. In particular, when it comes to pesticides, the majority of urea compounds have a wide range of bioactivities, including insecticidal11, antifungal12, herbicidal13, and antitumor14 effects. In order to improve the insecticidal profile of triazone insecticides and mimic the molecular mechanism of action of pymetrozine and other TRP antagonists, thiourea bridge groups were added. This led to the synthesis of four different novel triazone analogues, which were then studied. For instance the insect growth regulator lufenuron (match), which has a wide range of bioactivity against lepidopteran and coleopteran pests, suppresses the development of chitin, throws off the hormonal balance during the moulting process, and does both. (Fig. 1)15.

Figure 1
figure 1

Chemical structure of Lufenuron (1) and Capsazepine (2).

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In this investigation, we examine how these synthetic IGR-related chemicals affect S. littoralis. This study compares the toxicities of these synthesized compounds and the standard lufenuron against S. littoralis16,17. accordingly, this work was aiming to (1) designing & characterizing of different compounds of poly functional substituted oxopropylthiourea. (2) Investigating their insecticidal effectiveness toward S. littoralis. Our data is measured the first phase in insecticide discovery which it might be appreciated for insecticidal activity companies to enhance novel insecticides toward noctuid moths. These new compounds' insecticidal properties were assessed, and structure–activity connections were examined.

Materials and methods

Chemical compounds and reagents

All synthesized compounds were estimate melting point by a Fisher-John mechanical technique. In our search the instrumentations, chemical compounds & solvents have been acquired from Sigma-Aldrich. The infra-red spectra of the designed products were analyzed employed potassium bromide technique, 1HNMR & 13CNMR were recorded on spectrometer model Bruker Advance 400 MHz. A reference Lufenuron insecticides were acquired from Sigma-Aldrich.

Laboratory bioassay screening

All synthetic oxopropylthiourea derivatives were tested for their insecticidal bioactivity using the industry-standard leaf dip bioassay techniques.18,19,20,21,22,23 preparation of the compound stocks to create 1000 ppm, 0.1 g of compounds 1–10 were dissolved in 5 mL of Dimethyl formamide & combined with 100 mL of distilled H2O. Until usage, the stocks were kept in a refrigerator. The target substances' test results were noted, & the concentrations needed to destroy 50% (LC50) of S. littoralis larvae were calculated. Oxopropylthiourea derivatives were employed in five different concentrations, & 0.1% Tween 80 was employed as a surfactant. Castor bean leaf discs (nine centimeters in diameter) were dipped in the concentration under test for ten seconds, then fed to 2th & 4th larvae, which were roughly the same size and housed in glass jars (five lb). Each action carried out 3 times with ten larvae each. The castor bean leaf has been used in our study, they were collected from the Shandaweel research station geographic area, Sohag governorate, Egypt and we are confirmed that, it is accordance with relevant institutional, national and international guidelines and legislation.

Statistical analysis

The mortality equalized via Abbott's formula24. Calculations of mortality setback line were measurably rummage via probity analysis25. Harmfulness index was strongminded via sun equations26. The mortality results of larval insect were estimated through employing probit analysis through a statistics (LDP-line) equation which estimate the LC50 values with 95% fiducially limits of lower, upper confidence limit and slope.

Result & discussion

Synthesis

The reaction of secondary amine 1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid with chloroacetyl chloride in 1,4 dioxane to give 7-[4-(chloroacetyl)piperazin-1-yl]-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, which reacted with ammonium thiocyanate, the vital intermediate 6-fluoro-7-[4-(isothiocyanatocarbonyl)piperazin-1-yl]-4-oxo-1,4-dihydro- quinoline-3-carboxylic acid (1) was synthesized27,28,29,30. Herein, the aimed synthesized products, which named as: 1-Ethyl-6-fluoro-7-(4-(((4-methoxyphenyl)carbamothioyl)glycyl) piperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 2, 1-Ethyl-6-fluoro-7-(4-(((4-hydroxyphenyl)carbamothioyl)glycyl)piperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 3, 7-(4-((Benzylcarbamothioyl) glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 4, 7-(4-((Cyclohexylcarba- mothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 5, 1-Ethyl-6-fluoro-4-oxo-7-(4-((2-phenylhydrazine-1-carbonothioyl) glycyl)piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid 6, 1-Ethyl-6-fluoro-7-(4-((hydrazinecarbonothioyl)glycyl) piperazin-1-yl)-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 7, 7-(4-((2-(2-Cyanoacetyl) hydrazine-1-carbonothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 8, 7-(4-(((2-Ethoxy-2-oxoethyl)carbamothioyl) glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 9 and 7-(4-(((2-Aminoethyl)carbamothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroqui noline-3-carboxylic acid 10 were successfully prepared Fig. 2, the obtained yield is 50−70% through the following steps.

Figure 2
figure 2

Designing of novel oxopropylthiourea derivatives (2–10).

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A solution of component 1 (4 mol) in dry acetone (20 ml), (4 mol) of amine derivatives, (1 mL) conc. HCl and (0.2 gm) anhydrous ZnCl2. The reaction mixture allowed to reflux about 8 h. Cooled and poured to H2O. The crystal product was collection via filtration.

Toxicological effectiveness checking for 2nd larvae

The procedure was carried out in accordance with the published method as part of our ongoing research into bioactive thioura derivatives.30,31 According to Table 1 the result of synthesized target compounds 1–10 were tested against 2nd larvae insect of S. littoralis. The bioefficacy results of tested compounds against the 2nd larvae exhibit from high to low toxicological activity which LC50 values vary from 2.412 to 11.40 ppm in which the LC50 value of a reference lufenuron was 2.295 ppm. Moreover, the LC50 value of compounds 1–10 were 10.738, 3.810, 3.505, 5.943, 11.40, 4.648, 10.922, 2.412, 10.84 and 40.98 ppm respectively, in which lufenuron stander insecticide rate was 2.295 ppm. Consequently, the toxicity of designing product 8 toward second larvae instar insect of Spodoptera littoralis was nearly closed in insecticidal bioactivity than reference lufenuron. These results agree with Bhongade, et al., 2016 who referred that thiourea derivatives exhibited the highest toxic biological activity32.

Table 1 Insecticidal effectiveness of components 1–10 & Lufenuron as reference insecticide toward the 2nd & 4th larvae instar of S. littoralis after 3 days of treatment.
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Toxicological effectiveness checking for adults 4th larvae

After 72 h of treatment, the objective products 1–10 exhibit varying degrees of insecticidal efficacy. Their respective LC50 values for the fourth larvae of S. littoralis were 15.10, 12.78, 10.18, 14.66, 17.68, 13.10, 16.84, 9.531, 16.54, and 16.77 ppm. According of this word, the toxicity of products 2 & 8 toward forth larvae of S. littoralis was nearly lufenuron after seventy two h in which LC50 value of compounds 8 and 3 was 9.531 and 10.18 ppm and lufenuron was 9.079 ppm. On considering the toxicity line and slope we observed that the slope increase in the following order 8 > 3 > 2 > 6 > 4 > 1 > 9 > 7 > 10 > 5, this order revealed that the homologous response of the treated strain of S. littoralis which presented variation in response against of target synthesized products.

Biological studies

According the reported method to determinates the biological characteristics of the thiourea derivatives such larval and pupal duration, pupal weight, the percentage of normal, malformed pupae, and adult emergency, as well as the percentage of fecundity and egg hatchability, were assessed for the latent effects of the investigated component32. Activity of the synthetic target components 2, 3, 4, 6 and 8 under test on some biological characteristics of S. littoralis. Recently molted fourth instar larvae of S. littoralis were fed caster bean leaves treated with LC25 concentrations of the most poisonous Oxopropylthiourea derivatives 2, 3, 4, 6 and 8 for 48 h before being switched to untreated leaves until pupation as part of an investigation into the biological characteristics of the species. Tables 2 and 3 present the findings after recording the key biological characteristics.

Table 2 The biological characteristics of a laboratory strain of fourth-instar larvae of S. littoralis (Boisd.) were affected by the very poisonous, recently synthesized compounds 2, 3, 4, 6 and 8 at their LC25 values.
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Table 3 The influences of the greatly toxic novelty designing components 2, 3, 4, 6 and 8 at their LC25 values on the fecundity, fertility & adult longevity for S. littoralis (Boisd.) laboratory strain larvae that survived the fourth instar.
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Larval and pupal duration

According to the data as shown in Table 2, all of the checked chemicals considerably increased the larval duration, which was 8 (18.61 days), 3 (16.35 days), 2 (14.56 days), 6 (11.95 days), and 4 (14.65 days, respectively, according to control in (9.55 days). oppositely, the checked components reduced the pupal period with significantly different results from one another, tabulating as 8 (11.32 days) and 3 (13.56 days), while 2, 6, and 4 had no significantly different results from one another, tabulating as 14.20, 15.33, and 16.85 days, respectively, compared to the larvae that were not treated (17.34 days).

Pupal weight

According to result tabularized shown in Table 2, the pupal weight trended in the same direction. The checked components all significantly decreased pupal weight, with 8 being the most effective, recording (263.72 mg), followed by 3, 2, 6, and 4 at 272.14, 281.60, 286.15, and 395.14, respectively, in comparison to the control pupal weight of 298.0 mg. As shown in Fig. 3, the malformations in S. littoralis caused by examined products. Pupae with a larval head, larval legs, and small, deformed wings; non-developed wings, and vestiges of larval prolegs. (B) Regular pupae (the control).

Figure 3
figure 3

(A) Morphological malformations of S. littoralis (Boisd.) affected through checked products. (Pupae with larval head, larval legs and shortened malformed wings; non developed wings & remnants of larval prolegs). (B) Normal pupae (control).

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% of Normal, deformed pupae & adult emergency

The findings in Table 2, revealed that components were responsible for the latent effects 8, 3, 2, 6 and 4 were the most effective, recording (36.56, 72.51, 81.25, 90.25 and 94.68%), (13.23, 15.62, 7.65, 5.65 and 3.23%) and (73.35, 65.23, 68.31, 80.24 and 89.61%), respectively, associated to the control moiety (95.21, 3.20, 93.41%) to corresponding percentages of healthy pupae, malformed pupae, and adult emergence.

% of Fecundity and egg hatchability

Concerning to the results characterized of Table 3, the amount of eggs per female, the fecundity rate, and the hatchability rate, it was experiential that compounds 8 and 3 have been a markedly noteworthy diminution in the mean numbers of eggs laid via adult of females (fecundity), In the other hand, after treatment of the parent fourth instar larvae, eggs hatchability (fertility) was abruptly reduced in the offspring generation, with 8 recording 702.39 eggs per female, 22.8 fecundity, and 42.36% eggs hatchability, followed by 3 (956.33 eggs per female, 42.65 fecundity, and 50.25% eggs hatchability), in contrast to the control group (2915.55 eggs per female, 100 fecundity, and The least productive was number two (1320.23 eggs per female, 65.35 fecundity, and 66.15% fertility), while compound 6 exhibited (1918.69eggs/female, 79.23% fecundity & 75.23% fertility) & 4 exhibited (2623.56 eggs/female, 82.15 fecundity and 86.51% fertility).

Structure-action relationship (SAR)

Herein, the creation of novel, bioactive, polyfunctional substituted oxopropylthiourea compounds was deemed useful. By using a computerised regression analysis programme and confirming the toxicity value in Table 1 and Fig. 4, the median lethal concentration (LC50) & slope values of the targeted components were determined & expressed as parts per million (ppm). The insecticidal efficiency of the designed components (1–10) were compared with lufenuron teword S. littoralis, in which second instar larvae of S. littarolis are characterized via black lines & forth instar larvae of S. littoralis are signified via red lines after 3 days of treatment (Fig. 5). In this section the structure-action relationship was recognized component 8 is more performance toward 2nd & 4th larvae instar of S. littoralis insect than the other oxopropylthioureas. The high activity of product 8 this is occurrence of fluorophenyl, cyanoacetamide & carboxalic acid group in its structure. Existence of fluorophenyl & carbonitrile groups in this component which considered as an electron-withdrawing groups increase its effectiveness than the other oxopropylthioureas derivatives compared to the reference insecticide. Also, the product 3 gave high effective may be because of the existence of the fluorophenyl p-hydroxy phenyl, carboxalic acid group and piprazin moiety in its chemical structure. In addition to, the insecticidal activity of compound 2 showed higher toxicity might be because of the existence of fluorophenyl, p-methoxyphenyl, carboxalic acid group & piprazin group in its configuration. Finally, compound 8 is higher in toxicity than that of compound 3, 2, 4 & this because of the existence of fluorophenyl & cyanoacetamide in its building.

Figure 4
figure 4

Insecticidal effectiveness of selective products 1–10 and lufenuron as reference insecticide for the 2nd & 4th larvae instar of S. littoralis.

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Figure 5
figure 5

Insecticidal effectiveness of products 1–10 toward the 2nd & 4th larvae instar of S. littoralis.

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Conclusion

In a continuation of our previous studies on searching a bout bioactive compounds, we reported here on the insecticidal activity of some oxopropylthiourea derivatives. The reaction mixture of 6-fluoro-7-[4-(isothiocyanatocarbonyl)piperazin-1-yl]-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (1) in dry acetone, amine derivatives, conc. HCl and anhydrous ZnCl2 were allowed to reflux about 8 h. The crystal product was collection via filtration. On concerning the data that presented in Table 1 and illustrated in Figs. 4 and 5 which represented the insecticidal activity of novel oxopropylthiourea derivatives containing fluorophenyl and cyanoacetamide, we deduced that compound 8 is more efficacious toward second and forth S. littoralis larvae than the other oxopropylthioureas. The present data proved that values of LC50 of the most effected synthesized compound 8 was 2.412 ppm in which LC50 for commercial lufenuron was 2.295 ppm. On considering the toxicity line and slope we observed that the slope increase in the following order 8 > 3 > 2 > 6 > 4 > 1 > 9 > 7 > 10 > 5, this order revealed that the homologous response of the treated strain of S. littoralis which presented variation in response against of target synthesized products. Additionally, in an effort to marginally enhance insecticidal compounds, evaluation of the latent effects of the examined components on several biological parameters, including adult longevity, pupal weight, proportion of normal, deformed pupae, & adult emergency, fecundity, & egg hatchability, was carried out. The high in effectiveness of component 8 may be because of the existence of fluorophenyl, cyanoacetamide and carboxalic acid group in their chemical structure. When compared to other oxopropylthioureas derivatives and the commercial lufenuron insecticide, the fluorophenyl and carbonitrile groups, which are thought of as electron-withdrawing groups, boost its efficiency.

Experimental

General method for preparing of oxopropylthiourea derivatives 2–10

A solution of target compound 1 (4 mmol) in dry acetone (20 mL), (4 mmol) of amine derivatives, (1 mL) conc. HCl and (0.2gm) anhydrous ZnCl2. For roughly 8 h, the reaction mixture was refluxed while being stirred. Ice-cold water was added once then the reaction had been cooled. After being filtered, the solid product was collected and dried.

1-Ethyl-6-fluoro-7-(4-(((4-methoxyphenyl)carbamothioyl)glycyl)piperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 2

Pale yellow precipitate, Yield (60%). Mp 0.290–292 °C. FT IR (KBr) max cm−1: 3409 (OH, st), 3315, 3262 (NH), 3057 (CH-arom.) 2986–2835 (CH2, CH3, st), 1683 (C=O carboxylic), 1646 (C=O amide, st) and 1628 (C=C, st). 1H-NMR (ppm) 15.21 (s, 1H, COOH), 9.62(1H,NH), 8.95 (s, 1H, H-2 of quinolone); 8.38–7.93(m, 4H, arom.), 7.91(d, JH-F = 13 Hz, 1H, 5H of quinolone); 7.11 (d, JH-F = 7.5 Hz, 1H, 9H of quinolone); 6.11(1H, NH), 4.91 (s, 2H, CH2-CO), 4.60 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.91 (s, 3H, OCH3), 3.76 (b, 2H, piperazine), 3.68 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.43 (t, JH-H = 7 Hz, 3H, –Me). 13CNMR (DMSO-d6), δ ppm: 176.62, 166.59, 149.17, 145.80, 144.01, 137.37, 107.03, 56.50, 49.90, 45.96, 19.14, 14.54. Anal. for C26H28FN5O5S (541.5) Calcd./found: C: 57.66/57.58, H: 5.21/5.19 and N: 12.93/12.91%.

1-Ethyl-6-fluoro-7-(4-(((4-hydroxyphenyl)carbamothioyl)glycyl)piperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 3

Pale yellow precipitate, Yield (66%). Mp 0.298–300 °C. FT IR (KBr) max cm−1: 3408 (OH, st), 3314(OH), 3262, 3190 (NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1682 (C=O carboxylic), 1663 (C=O amide, st) and 1622 (C=C, st). 1H-NMR (ppm) 15.31 (s, 1H, COOH), 9.61 (s, 1H, NH), 9.60 (s, 1H, OH), 8.95 (s, 1H, 8H of quinolone); 8.38–7.93 (m, 4H, arom.), 7.91 (d, JH-F = 13 Hz, 1H, H-5 of quinolone); 7.21 (d, JH-F = 7.5 Hz, 1H, 8H of quinolone); 6.11(1H, NH), 4.91 (s, 2H , CH2–CO), 4.60 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.76 (b, 2H, piperazine), 3.68 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.44 (t, JH-H = 7 Hz, 3H, -Me). 13CNMR (DMSO-d6), δ ppm: 177.19, 167.34, 166.94, 154.59, 152.16, 148.94, 145.63, 137.39, 119.98, 112.09, 107.61, 106.19, 56.79, 49.86, 45.63, 31.93, 19.50, 14.80. Anal. for C25H26FN5O5S (527.5) Calcd./found: C: 56.92/56.90, H: 4.97/4.95 and N: 13.27/13.25%.

7-(4-((Benzylcarbamothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 4

Pale yellow precipitate, Yield (60%). Mp 0.208–210 °C. FT IR (KBr) max cm−1: 3409 (OH, st), 3314, 3262(2NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1682 (C=O carboxylic), 1664 (C=O amide, st) and 1626 (C=C, st). 1H-NMR (ppm) 15.26 (s, 1H, COOH), 10.70 (s, 1H, NH), 8.94 (s, 1H, 2H of quinolone); 8.38–7.93(m, 4H, Harom.), 7.91(d, JH-F = 13 Hz, 1H, 5H of quinolone); 7.21 (d, JH-F = 7.5 Hz, 1H, 8H of quinolone); 6.11(1H,NH), 4.91(s, 2H, CH2-benz,),4.58 (s, 2H, CH2–), 4.60 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.76 (b, 2H, piperazine), 3.68 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.44 (t, JH-H = 7 Hz, 3H, –Me). 13CNMR (DMSO-d6), δ ppm: 177.19, 167.34, 166.49, 154.59, 152.35, 145.94, 145.63, 137.39, 119.98, 112.09, 107.61, 106.19, 56.79, 50.01, 49.86, 45.63, 31.93, 19.50, 14.80. Anal. for C25H26FN5O5S (525.5) Calcd./found: C: 59.41/59.39, H: 5.73/5.70 and N: 13.32/13.29%.

7-(4-((Cyclohexylcarbamothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 5

Pale yellow precipitate, Yield (60%). Mp > 300 °C. FT IR (KBr) cm−1: 3408 (OH, st), 3315, 3264(2NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1681 (C=O carboxylic), 1663 (C=O amide, st) and 1626 (C=C, st). 1H-NMR (ppm) 15.26 (s, 1H, COOH), 8.94 (s, 1H, H-2 of quinolone); 8.38–7.93(m, 4H, arom.), 7.91(d, JH-F = 13 Hz, 1H, 5H of quinolone); 6.55 (s, 1H, NH) 7.21 (d, JH-F = 7.5 Hz, 1H, 8H of quinolone); 5.10 (s, 2H, CH2CO,), 4.58 (s,2H, CH2–), 4.60 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.76 (b, 2H, piperazine), 3.82 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.80–1.27 (m,13H,cyclohexyl + -Me). 13CNMR (DMSO-d6), δ ppm: 177.29, 167.37, 167.05, 163.31, 145.94, 137.37, 119.52, 117.42, 112.32, 107.23, 56.27, 49.38, 45.41, 31.92, 23.91, 18.64, 14.77. Anal. for C25H32FN5O4S (517.6) Calcd./found: C: 58.01/58.00, H: 6.23/6.20 and N: 13.53/13.51%.

1-Ethyl-6-fluoro-4-oxo-7-(4-((2-phenylhydrazine-1-carbonothioyl)glycyl)piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid 6

Pale brown precipitate, Yield (70%). Mp . 220–222 °C. FT IR (KBr) cm−1: 3409 (OH, st), 3314, 3261, 3190(3NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1683 (C=O carboxylic), 1663 (C=O amide, st) and 1627 (C=C, st). 1H-NMR (ppm) 15.26 (s, 1H, COOH), 10.20 (s,1H,NH), 8.89 (s, 1H, 2H of quinolone); 8.53–7.95 (m, 4H, Harom.), 7.91(d, JH-F = 13 Hz, 1H, H-5 of quinolone); 7.21 (d, JH-F = 7.5 Hz, 1H, H-8 of quinolone); 6.11(s, 1H, NH), 4.91(s, 2H, CH2CO,),4.58 (s,2H , CH2-), 4.60 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.76 (b, 2H, piperazine), 3.82 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.44 (t, JH-H = 7 Hz, 3H, –Me). 13CNMR (DMSO-d6), δ ppm: 176.88, 166.89, 157.00, 149.29, 137.76, 126.37, 118.51, 111.94, 108.22, 106.77, 56.51, 49.88, 19.13, 14.69. Anal. for C25H27FN6O4S (526.5) Calcd./found: C: 57.02/57.00, H: 5.17/5.15 and N: 15.96/15.94%.

1-Ethyl-6-fluoro-7-(4-((hydrazinecarbonothioyl)glycyl)piperazin-1-yl)-4-oxo-1,4-dihydroquino-line-3-carboxylic acid 7

Pale yellow precipitate, Yield (50%). Mp. 250–252 °C. FT IR (KBr) cm−1: 3408 (OH, st), 3314, 3263, 3190 (NH2, NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1681 (C=O carboxylic), 1664 (C=O amide, st) and 1627 (C=C, st). 1H-NMR (ppm) 15.21 (s, 1H, COOH), 8.95 (s, 1H, H-2 of quinolone); 8.00 (d, JH-F = 13 Hz, 1H, 5H of quinolone); 7.57 (d, JH-F = 7.5 Hz, 1H, H-8 of quinolone);7.27, 7.22(d, 2H, 2NH), 6.11(s, 2H, NH2), 4.62(s, 2H, CH2CO,),4.58 (s,2H, CH2–),3.76 (b, 2H, piperazine), 3.82 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 1.44 (t, JH-H = 7 Hz, 3H, -Me). 13CNMR (DMSO-d6), δ ppm: 176.34, 167.81, 166.18, 148.78, 137.42, 119.93, 112.02, 108.13, 106.40, 56.82, 47.64, 31.93, 18.58, 14.80. Anal. for C19H23FN6O4S (487.1) Calcd./found: C: 50.66/50.64, H: 5.15/5.12 and N: 18.66/18.64%.

7-(4-((2-(2-Cyanoacetyl)hydrazine-1-carbonothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 8

Yellow precipitate, Yielding compound (50%). Melting point. > 300 °C. FT IR (KBr) max cm−1: 3414 (OH, st), 3400–3190 (3NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 2088(CN), 1708 (CO carboxylic), 1661 (CO amide, st) and 1628 (C=C, st). 1H-NMR (ppm) 15.21 (s, 1H, COOH), 9.13(s,1H,NH), 8.95 (s, 1H, H-2 of quinolone); 7.99(d, JH-F = 13 Hz, 1H, H-5 of quinolone); 7.69 (d, JH-F = 7.5 Hz, 1H, H-8 of quinolone);7.64(s, 2H, 2NH), 7.22(s 1H, 1NH), 4.62(s, 2H, CH2CO,), 4.16 (s, 2H, CH2-),3.75 (b, 2H, piperazine), 3.82 (b, 2H, piperazine), 3.41(b, 4H, piperazine); 2.89 (s,2H,CH2CN), 1.43 (t, JH-H = 7 Hz, 3H, -Me). 13CNMR (DMSO-d6), δ ppm: 178.62, 167.68, 166.46, 151.28, 149.48, 145.33, 137.73, 120.55, 111.91, 110.42, 106.24, 56.77, 49.57, 47.98, 42.90, 31.23, 19.10, 14.91. Anal. for C22H24FN7O5S (517.5) Calcd./found: C: 51.06/51.04, H: 4.67/4.65 and N: 18.95/18.92%.

7-(4-(((2-Ethoxy-2-oxoethyl)carbamothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 9

Yellow precipitate, Yield (53%). Mp > 300 °C. FT IR (KBr) cm−1: 3410 (OH, st), 3400–3190 (2NH), 3053 (CH-arom.) 2986–2835 (CH2, CH3, st), 1703 (C=O ester), 1690C=O, acid, st), (1662 (C=O amide, st) and 1628 (C=C, st ). 1H-NMR (ppm) 15.24 (s, 1H, COOH), 9.20(s,1H,NH), 8.95 (s, 1H, H-2 of quinolone); 8.43(d, JH-F = 13 Hz, 1H, 5H of quinolone); 7.96 (d, JH-F = 7.5 Hz, 1H, H-8 of quinolone); 7.28(s, 1H, NH), 5.09(q,2H, CH2-ester), 4.60–4.28(m, 4H, 2CH2,),4.25 (s,2H,CH2-),3.75 (b, 2H, piperazine), 3.82 (b, 2H, piperazine), 3.41(broad, 4H, piperazine); 1.95–187(t, 3H, CH3 ester), 1.43–1.35 (t, JH-H = 7 Hz, 3H, –CH3). 13CNMR (DMSO-d6), δ ppm: 177.14, 166.70, 154.32 152.56, 149.56, 139.35, 128.66, 117.57, 108.27, 106.56, 57.97, 49.26, 47.14, 42.88, 29.01, 25.72, 15.27. Anal. for C23H28FN5O6S (521.5) Calcd./found: C: 52.97/52.94, H: 5.41/5.40 and N: 13.43/13.40%.

7-(4-(((2-Aminoethyl)carbamothioyl)glycyl)piperazin-1-yl)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 10

Pale yellow precipitate, Yield (60%). Mp 0.270 °C. FT IR (KBr) cm−1: 3421 (OH, st), 3057 (CH–arom.) 2986–2835 (CH2, CH3, st), 1693 (C=O carboxylic), 1646 (C=O amide, st) and 1628 (C=C, st). 1H-NMR (ppm) 15.20 (s, 1H, COOH), 9.45(s,1H,NH),8.95 (s, 1H, H-2 of quinolone); 7.97(d, JH-F = 13 Hz, 1H, 5H of quinolone); 7.90 (d, JH-F = 7.5 Hz, 1H, H-8 of quinolone); 4.63 (q, JH-H = 7 Hz, 2H, –CH2–CH3), 3.76 (b, 2H, piperazine), 3.67 (b, 2H, piperazine), 3.41 (b, 4H, piperazine); 2.74 (s,1H, NH), 1.43 (t, JH–H = 7 Hz, 3H, –CH3). 13CNMR (DMSO-d6), δ ppm: 176.68, 166.45, 151.28, 149.48, 145.33, 137.73, 120.95, 111.91, 107.74, 107.42, 107.34, 56.77, 42.90, 31.23, 19.10, 14.91. Anal. for C40H46F2N10O8S2 (896.9) Calcd./found: C: 53.56/53.54, H: 5.17/5.15 and N: 15.62/15.61% (Supplementary information 1) .