*Corresponding Author:
S. P. Deshmukh
P. G. Department of chemistry, Shri shivaji college, Akola - 444 001, India
E-mail: [email protected]
Date of Submission 25 October 2005
Date of Revision 14 July 2006
Date of Acceptance 10 April 2007
Indian J Pharm Sci, 2007, 69 (2): 295-298  

Abstract

A series of novel thiolactosides like S -hepta- O -acetyllactosyl-1-arylisothiocarbamides (1a-g) and hepta- O -acetyl lactosyl arydithiocarbamates (2a-g) were prepared by the interaction of hepta- O -acetyl lactosyl bromide with arylthiocarbamides and ammonium aryldithiocarbamates respectively. Similarly (hepta- O -acetyl lactosyl)-1,5-disubstituted-2-isothiobiurets (3a-g) 1,5-disubstituted-2,4-isodithiobiurets (4a-g) and-1,2,4-thiadiazolines (5a-g) were synthesized by the interaction of (1a-g) with phenyl isocyanate, phenyl isothiocyonate and S -chloro- N -phenyl isothiocarbamoyl chloride respectively. The compounds 3-Aryl-2,6-diphenylimino 4-S-hepta- O -acetyl lactosyl-2,3dihydro-1,3,5-thiadiazines hydrochlorides (6a-g) were prepared by the interaction of (4a-g) with phenyl isocyanodichloride. In the present investigation activities of these thiolactosides against pathogenic bacteria and fungi such as E. coli, S. aureus, P. vulgaris, Salmonella typhi, Candida guilliermondii and A. niger are discussed.

Thiolactosides are those compounds in which lactosyl group or its derivatives are attached to the sulphur of the sulphur containing compounds. This class of compounds has several applications in industries, medicinal chemistry and in many other ways [1,2]. Literature survey revealed that the heterocyclic derivatives of sugars possess antibacterial and antitumor activity [3]. Benzothiazole derivatives found to exhibit anticancer, antiHIV and antimalerial activity [4-8]. With this end in view, we recently reported the synthesis of several thiolactosides [9-12] Scheme-1. In the present investigation, activities of these thiolactosides against pathogenic bacteria and fungi such as E. coli, S. aureus, P. vulgaris, Salmonella typhi, Candida guilliermondii and A. niger are reported.

Figure

Scheme 1: Synthesis of several thiolactosides R = a) Phenyl, b) O-CI-phenyl, c) m-CI-phenyl, d) p-el-phenyl, e) o tolyl, f) m-tolyl, g) p-tolyl and ph = Phenyl

Melting points were determined on an electrothermal melting point apparatus and were uncorrected. The structures of the synthesized compounds were elucidated on the basis of elemental analysis and IR [13-16], 1H NMR [14-19] and Mass [20-22] spectral studies (Table-1). IR spectra were recorded in KBr on a FT IR PerkinElmer (4000 450 cm-1) spectrophotometer. 1HNMR spectra are run on Brucker DRX 300 instrument operating at 300 MHz using CDCl3 solution with TMS as internal standard and mass spectra on Jeol SX 102 FAB instrument.

Comp Mol. Formula IR(KBr) cm-1 1HNMR (ppm) Mass (m/z)
1a C33H42O17N2S 3350, 2970,1751, 1635,
1439, 1229, 1050, 758
d7. 6-6.8 (m, 5H, Ar), d 5.6-5.3 (2H, s, HN) d 5.3
-3.4 (m, 14H, lactose), δ 2.1-1.9 (m, 21H, 7 OAc)
(M++1)771, 619, 313, 169,127, 109
1b C33H41O17N2SCl 3348,2965,1751,1636
1437,1229,1051,759
δ 7.5-7.0 (m, 5H, Ar), δ 6.5-6.1 (2H, s, NH), δ
5.4-3.8 (m,14H, lactose), δ 2.1-1.9 (m, 21H, 7OAc)
(M++1) 805, 619, 331, 229, 169, 127,109
1e C34H44O17N2S 3458, 2969, 1751, 1642, 1437, 1228, 1050, 755 δ 7.2-6.9 (m, 14H, Ar), δ 5.3-5.2 (2H, s, NH), δ 5.2-3.7(m,14H, lactose), δ 2.2-1.9 (m, 21H, 7OAc) (M++1) 785, 619, 331,229,169,127, 109
2a C33H41O17NS2 3408,2964,1753, 1443, 1229, 1172, 1052, 760 δ 7.9-7.1(m, 5H, Ar), δ 6.8-6.6 (H, s, NH), δ 
5.4-3.6 (m, 14H, lactose), δ 2.1-1.9 (m, 21H, 7OAc)
(M+)787,619,331,
229,169,127, 109
2d C33H40O17NS2Cl 3426,2972,1754,1448,
1228,1173,1053,771
δ 8.0-7.1 (m, 4H, Ar), δ 6.5 (H, s, NH), δ 5.5-3.4
(m, 14H, lactose), δ 2.2-1.9 (m, 21H, 7OAc)
(M+) 21,620,331,
229,169,127,109
2f C34H43O17NS2 3374,2944,1752,1435,
1229,1171,1050,738 
δ 7.3-7.0 (m, 4H, Ar), δ 6.6-6.4 (H, s, NH), δ 
5.4-3.7 (m, 14H , lactose), δ 2.1-1.8(m, 21H, 7OAc)
(M++1) 801, 619, 331, 229,169, 127,109
3a C40H47O18N3S 3414,3000,752,1601,
1441,1227,1053,756
δ 7.8-7.0 (m, 10H, Ar), δ 5.8-5.2 (2H, s, NH),
δ 4.8-3.4 (m, 14H,lactose), δ 2.1-1.8 (m, 21H, 7OAc)
(M++1) 890, 619, 331,
229, 169, 127, 109 
3b C40H46O18N3SCl 3465,3000,1752,1633,
1443,1228,1052,756
δ 7.8-6.8 (m, 9H, Ar), δ 5.5-5.3 (2H, s, NH), δ
5.3-3.4 (m, 4H, lactose), δ 2.2-1.8 (m, 21H, 7OAc)
(M++1) 924, 619, 331,
229, 169, 127,109
3e C41H49O18N3S 3350,3000,1754,1630, 1444,1226,1049,750 δ 7.8-6.8 (m, 9H, Ar), δ 5.5-5.3 (2H, s, NH), δ 
5.3-3.4 (m,14H,lactose), δ 2.2-1.9 (m,21H,7OAc)
(M++2) 905, 619, 331,229, 169, 127,109
4a C34H44O17N2S 3458,2969,1751,1642, 1437,1228,1050,755 δ 7.5-6.9 (m,10H, Ar), δ 4.7-4.4 (2H, s, NH), δ
4.3-3.0 (m,14H, lactose), δ 2.2-1.9 (m, 21H, 7OAc)
(M++1) 905, 619, 331,229, 169, 127,109

4b C34H44O17N2S 3458,2969,1751,1642,1437,
1228,1050, 755
δ 7.5-7.2 (m, 9H, Ar), δ 5.1-4.9 (2H, d, NH), δ
4.9-2.4 (m,14H, lactose), δ 2.2-1.9 (m,21H,7OAc)
(M++1) 939, 619, 331,
229, 169, 127,109 
4e C34H44O17N2S 3458,2969,1751,1642,1437,1228,1050,755 δ 7.2-6.9 (m, 9H, Ar), δ 5.3-5.2 (2H, d, NH), δ
5.2-3.7 (m, 14H, lactose), δ 2.2-1.9 (m, 21H, 7OAc)
(M++1) 919, 619, 331, 229, 169, 127,109
5a C47H51O17N4S2Cl 2982, 1750, 1597, 1493, 1231, 1054, 757 δ 7.6-7.2 (m, 9H, Ar), δ 5.3-3.8 (m, 14H, lactose), δ 2.1-1.9 (m, 21H, 7OAc) (M+) 1042, 619, 331, 229, 169, 127,109
5d C47H50O17N4S2Cl2 2974, 1749, 1598, 1542, 1231, 1054, 757 δ 7.3-6.9 (m, 9H, Ar), δ 5.3-3.8 (m, 14H, lactose), δ 2.1-1.9 (m, 21H, 7OAc) (M+) 1076, 619, 331,229, 169, 127, 109
5g C48H53O17N4S2Cl 2928, 1749, 1596, 1512, 1230, 1052, 757 δ 7.6-6.9 (m, 9H, Ar), δ 5.3-3.8 (m, 14H, lactose), δ 2.1-1.9 (m, 21H, 7OAc) (M+) 1056, 619, 331, 229, 169, 127, 109

Table 1: Characterisation data of thiolactosides (1-5) (A-G)

Solutions of hepta-O-acetyl lactosyl bromide and arylthiocarbamides in isopropyl alcohol were kept at room temperature for 18 h. It was mixed with distilled water and basified with aqueous ammonia to yield a sticky mass. The sticky mass was purified with ethanol-water furnished a granular solids of S-hepta-O-acetyl lactosyl-1-arylisothiocarbamides (1a -g) [9].

Solutions of hepta-O-acetyl lactosyl bromide and ammonium arydithiocarbamates in isopropyl alcohol were kept at room temperature for 18 h. Upon adding distilled water, a sticky mass was separated. The sticky mass was purified with ethanol-water to give hepta-O-acetyl lactosyl arydithiocarbamates [10] (2a-g).

An equimolar (0.0025 mol) mixture of S-hepta-O-acetyl lactosyl-1-arylisothiocarbamides (1a-g) and phenyl isocyanate in dry benzene was kept at room temperature for 24 h. The benzene was distilled off. The sticky mass thus obtained was triturated several times with petroleum ether to obtain S-hepta-O-acetyl lactosyl-1-aryl-5-phenyl-2-isothiobiurets [11] in the form of granular solids (3a-g).

Condensation of S-hepta-O-acetyl lactosyl-1-arylisothiocarbamides (1a-g) with phenyl isothiocyanate in benzene was carried out for 9 h. The benzene was distilled off. The sticky mass obtained when triturated several times with petroleum ether furnished S-hepta-O-acetyl lactosyl-1-aryl-5-phenyl-2,4-isodithiobiurets [11] as granular solids (4a-g).

Condensation of an equimolar (0.0025 mol) mixture of S-hepta-O-acetyl lactosyl-1,5-disubstituted-2,4-isodithiobiurets (4a-g) and phenyl isocyanodichloride in chloroform was carried out for 2.5 h. The excess of chloroform was distilled off. The sticky mass obtained was triturated with petroleum ether to separate 3-aryl-2,6-diphenylimino-4-S-hepta-O-acetyl lactosyl-2,3-dihydro-1,3,5-thiadiazine hydrochlorides [12] as granular solids (5a-g).

All the compounds have been screened for both antibacterial and antifungal activity using cup plate agar diffusion method [23,24] by measuring the inhibition zone in mm. the compounds were taken at a concentration of 1 mg/ml using dimethyl formamide (DMF) as solvent. Amikacin (100 μg/ml) was used as a standard for antibacterial activity and fluconazole (100 μg/ml) as a standard for antifungal activity. The compounds were screened for antibacterial activity against Escherichia coli, Staphylococcus aureus, Proteus vulgaris, and Salmonella typhi in nutrient agar medium and for antifungal activity against Candida guilliermondii and Microsporum in potato dextrose agar medium. These sterilized agar media were poured in to Petri dishes and allowed to solidify. On the surface of the media microbial suspensions were spread with the help of sterlized triangular loop. A stainless steel cylinder of 8 mm diameter (pre-sterlized) was used to bore the cavities. In to these wells were added 0.1 ml portions of the test compounds in solvent. The drug solution was allowed to diffuse for about an hour into the medium. The plates were incubated at 37o for 24 h and 30o for 48 h for antibacterial and antifungal activities, respectively. The zone of inhibition observed around the cups after respective incubation was measured. The results are presented in Table 2.

Compound No. MP0 Antibacterial** Antifungal**
    E. c S. a P. v S. t C. g A. n
1a 121 17 14 18 19 21 18
1b 140-42 18 15 17 22 18 21
1c 120 18 17 15 20 18 17
1d 126 17 15 15 20 20 19
1e 134-35 19 14 14 18 18 22
1f 127 20 14 15 18 20 19
1g 145 22 15 16 20 18 20
2a 115-18 16 13 16 13 22 18
2c 85-87 18 20 18 22 19 19
2d 145-47 16 18 14 21 21 21
2e 122-23 15 13 14 19 19 21
2f 109-10 18 15 17 21 20 19
2g 136-38 17 14 15 22 16 20
3a 163-65 13 16 16 17 18 20
3b 148-49 - 15 19 19 19 25
3c 136-37 15 18 20 18 20 22
3d 165-67 17 17 19 17 20 20
3e 152-55 16 16 22 16 20 22
3f 143-44 17 15 19 ­ 22 22
3g 160-62 18 14 15 18 18 18
4a 142-45 17 15 16 18 21 18
4b 153-54 16 15 19 17 20 20
4c 130-32 18 16 20 16 22 20
4d 135 19 14 21 17 20 19
4e 123-25 17 13 20 20 19 17
4f 164-65 17 - 17 19 19 16
4g 160-62 21 - 18 18 19 24
5a 175-77 18 16 18 19 21 24
5b 150-51 16 14 18 17 20 18
5c 170-72 16 13 20 18 21 20
5d 161-62 16 14 18 19 20 23
5e 158-60 17 15 17 20 24 20
5f 163-64 16 15 18 19 20 18
5g 182-84 18 15 17 20 20 20
Amikacin  --  19 23 21 24 - -
Fluconazole  - - ­   25 26
DMF  -  - - -   - -

Table 2: Antimicrobial activities of thiolactosides (1-5) (a-g)

It has been observed that some of these compounds exhibited interesting microbial activities. 1b, 2c, 2d, 2f and 2g exhibited most significant activity against Salmonella. 1g and 4g inhibited E. coli while 3e, 4d inhibited S. aureus and P. vulgaris, respectively. All other compounds exhibited low to moderate activity (Table 2).

The results of antifungal activity are also tabulated in Table 1. 2a, 3f, 4c, and 5e are effective towards Candida guilliermondii while other exhibited moderate to low activity. 1e, 3b, 3e, 3f, 4g, 5a and 5d are effective against Microsporum while others exhibited moderate to low activity (Table 2).

Thus, the novel thiolactosides synthesized, exhibits comparable antibacterial and antifungal activities against the organisms tested. The method adopted in this investigation is simple, efficient, inexpensive, and is useful in synthesizing pharmacologically important molecules..

Acknowledgements

The authors thank Dr. S. G. Bhadange, Principal, Shri Shivaji College, Akola and Dr. P. R. Rajput, Principal, Shankarlal Khandelwal College, Akola for providing laboratory facilities.

References