Designing, synthesis of selective and high-affinity chalcone-

benzothiazole hybrids as Brugia malayi thymidylate kinase

inhibitors: in vitro validation and docking studies

Koneni V. Sashidhara‡, *, Srinivasa Rao Avula‡, Pawan Kumar Doharey§, L. Ravithej Singh‡,

Vishal M. Balaramnavarψ,‡, Jyoti Gupta#, Shailja Misra-Bhattacharya#, Sushma Rathaur▲,

Anil K. Saxena‡, Jitendra Kumar Saxena§ *

‡Medicinal and Process Chemistry Division, §Biochemistry Division, #Parasitology Divion, CSIR-Central Drug

Research Institute, BS-10/1, Sector 10, Jankipuram extension, Sitapur Road, Lucknow 226031, India.

▲Department of Biochemistry, Banaras Hindu University, Varanasi 221005, India. ψPresent Address- Dept. of

Pharmaceutical Chemistry, Global Institute of Pharmaceutical Education and Research, Kashipur,

Uttarakhand, 244713, India.

*Corresponding author. Tel.: +91 9919317940; Fax: +91-522-2628493.

Email: kv_sashidhara@cdri.res.in, sashidhar123@gmail.com (Dr. K. V. Sashidhara)

All reagents were commercial and were used without further purification.

Chromatography was carried on silica gel (60-120 and 100-200 mesh). All

reactions were monitored by thin-layer chromatography (TLC), silica gel plates

with fluorescence F254 were used. Melting points were taken in open capillaries

on Complab melting point apparatus and are presented uncorrected. Infrared

spectra were recorded on a Perkin-Elmer FT-IR RXI spectrophotometer. 1H

NMR and 13C NMR spectra were recorded using Bruker Supercon Magnet

DRX-300 spectrometer (operating at 400 MHz, 300 MHz for 1H and 75 MHz

for 13C) using CDCl3 and DMSO-d6 as solvent and tetramethylsilane (TMS) as

internal standard. Chemical shifts are reported in parts per million and

multiplicity(s = singlet, brs = broad singlet, d = doublet, brd = broad doublet, dd

1

= double doublet, t = triplet, q = quartet, m = multiplet). Electro spray ionization

mass spectra (ESIMS) were recorded on Thermo Lcq Advantage Max-IT. High

resolution mass spectra (HRMS) were recorded on 6520 Agilent Q Tof LC

MS/MS (Accurate mass).

1H NMR of compound 33 at 400 MHz (DMSO-d6)

2

13C NMR of compound 33 at 100 MHz (DMSO-d6)

1H NMR of compound 34 at 400 MHz (DMSO-d6)

3

13C NMR of compound 34 at 100 MHz (DMSO-d6)

1H NMR of compound 35 at 400 MHz (DMSO-d6)

4

13C NMR of compound 35 at 100 MHz (DMSO-d6)

1H NMR of compound 36 at 400 MHz (DMSO-d6)

5

13C NMR of

compound 36 at 100 MHz (DMSO-d6)

1H NMR of compound 37 at 400 MHz (DMSO-d6)

6

13C NMR of compound 37 at 100 MHz (DMSO-d6)

1H NMR of compound 38 at 400 MHz (DMSO-d6)

7

13C NMR of compound 38 at 75 MHz (DMSO-d6)

1H NMR of compound 39 at 400 MHz (DMSO-d6)

8

13C NMR of compound 39 at 100 MHz (DMSO-d6)

1H NMR of compound 40 at 400 MHz (DMSO-d6)

9

13C NMR of compound 40 at 75 MHz (DMSO-d6)

1H NMR of compound 41 at 400 MHz (DMSO-d6)

10

13C NMR of compound 41 at 75 MHz (DMSO-d6)

1H NMR of

compound 42 at 400 MHz (DMSO-d6)

11

13C NMR of compound 42 at 75 MHz (DMSO-d6)

1H NMR of compound 43 at 400 MHz (DMSO-d6)

12

13C NMR of compound 43 at 100 MHz (DMSO-d6)

1H NMR of compound 44 at 400 MHz (DMSO-d6)

13

13C NMR of compound 44 at 75 MHz (DMSO-d6)

1H NMR of compound 45 at 500 MHz (DMSO-d6)

14

1H NMR of compound 46 at 400 MHz (DMSO-d6)

13C NMR of compound 46 at 75 MHz (DMSO-d6)

15

1H NMR of compound 47 at 400 MHz (DMSO-d6)

Figure 1. A linear regression graph between docking scores and ki values.

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Figure 2. Intermolecular interactions between compound 39 and BmTMK

a) b)

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c) d)

Figure 3. The molecular interactions of compounds 34 and 42 with BmTMK binding site are shown in a and b respectively, whereas the comparative binding site interactions of molecule 34 and 42 with human thymidylate kinase enzyme (PDB 1E2D) are shown in c and d respectively.

Table 1: The predicted physicochemical & toxicity of the most active compounds.

S.

No.

ADME

T_BBB

_Level

ADMET_Hepatotox

icity_Probability

ADMET_CYP2

D6_Probability

ADMET_P

PB_Level

ADMET_

AlogP98

34 4 0.576 0.257 2 5.667

42 4 0.913 0.178 2 6.976

18