Medicinal applications of benzoic acid hydrazones synthesized on the basis of steroidal tigogenin

Field of Invention:

In recent years chemical research in the steroid field has gone hand in hand with chemical investigation to develop a wide variety of steroid derivatives, not found in nature, which have specific physiological action and medical application. Small variations in the structure of steroid molecules frequently results in wide variations in the physiological activity and help in search of new drugs with enhanced potency, broader applicability, lower toxicity and fewer undesirable side effects. Steroid therapy is becoming increasingly important in modern medicine, and runs the gamut from preventing abortion to arresting certain cancers, from controlling pregnancy to treating arthritis, and from correcting hormonal abnormality to treating dermatitis. Dexamethasone, a fluorine containing steroid, is used in treating inflammation, the acetylinic derivative of 19-norethisterone exerts control over the menstrual cycle and used as oral contraceptive, and the triketone prednisone finds general application in the field of cortisone therapy.

Steroids include a wide variety of natural products containing the cyclo pentano perhydrophenanthrene ring system present in cholesterol.

OBJECT OF INVENTION

Tuberculosis

The significant increase in the incidence and morbidity from tuberculosis since the start of the 1990' s prompted the World Health Organization t o regard the disease as a worldwide danger. One of the factors leading to the increased incidence is the development of resistance in the Mycobacterium tuberculosis. One in every 20 new cases of TB worldwide is now resistant to two or more drugs. Half a million new cases of MDR-TB and 40,000 new cases of XDR-TB are emerging each year across the globe.110,000 people with MDR-TB die every year from the disease as per the data collected between 2002-2006 on TB patients in 81 countries. There fore the search for new effective antituberculosis compounds has become urgent.

Cancer

Cancer chemotherapy uses compounds that can differentiate to some degree between normal tissue cells and cancer cells. The decision to use a certain anti neoplastic drug depends on type and location of tumor. Therefore it is imperative to keep searching for new compounds.

HIV

HTV infection in humans is now a pandemic. As of January 2006,the joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization ( WHO ) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1,1981 making it one of the most destructive pandemics in recorded history in 2005 alone, AIDS claimed an estimated 2.4-3.3 million lives. About 0.6% of worlds living population is infected with HTV. Antiretroviral reduces both mortality and morbidity of HTV infection, but access to antiretroviral medication is not available in all countries.

PRIOR ART OF THE INVENTION

A number of steroidal compounds with NH2, N-alkyl, N-alkyloxy, N,N-dialkyl etc. substituents in the C- 17 position that exhibit a broad spectrum of biological activity have been synthesized based on tigogenin. Synthesis of 5 α-androstan- 3 β, 17-β-diols were reported as potential anticancer compounds. Novel steroidal isonicotin hydrazones and thiosemicarbazones were reported as potential anti T.B. agents

SOME COPYRIGHT COMPOUNDS

( A ) Formula: C20 H31 N3 S

CA Index Name: Androst-2-en-17-one ( aminothioxomethyl ) hydrazone

Registry No. 487039-91-8

Copyright 2007 American Chemical Society

NH2

(B) Formula: C26 H36 03 S

CA Index Name: Androst-2-en-17-ol, 4-methylbenzenesulphonate

Registry No. 913816-27-0

Copyright 2007 American Chemical Society

(C)Formula: C19H30O

CA Index Name: Androst-2-en-17-ol

Registry No.6699-64-5

Copyright 2007 ACS

(C) Formula: C19H33NO

CA Index Name: 5 β-androstane-3-ol,17-amino-,

Registry No.32911-76-5

Copyright 2007 ACS

REFERENCES l.CamoutisC.,TrafalisD.,Int.New Drugs 2003 21 47

2.Amiranashvili L.,Merlani M.,Menshova N.,Suvorov N.,Bιill.Georg.

Acad.Sci.1998 158(2)2 3.Merlani M.I.,Kemertelidze E.P.,Papadopoulos K.,Menshova N.I., Bioorg

Khim.200430552 [Engl.transl.Russ.J.Bioorg.Chem.200430000].

INVENTION IN DETAIL

Steroidal sapogenin-tigogenin was proposed as starting material for synthesizing 5α-series. Tigogenin is isolated from the plant Yucca gloriosa, which is cultivated in Georgia [I]. We developed a synthetic scheme for acetate eoiandrosterone based on tigogenin (1) that involves conversion of 1 to pregnenolone acetate (2), of 2 to epiandrosterone acetate. For conversion of 1 to 2, we chose oxidative dehydration using TiCH as catalyst. The yield of 2 from 1 was 69.5% [2]. Compound 2 was converted to epiandrosterone acetate using the Schmidt-Thome method [3], according to which pregnenolone acetate oxime (3) underwent Beckmann rearrangement by POCl ₃ in pyridine. Acid hydrolysis of intermediate 17-acetylamino derivative 4 gave epiandrosterone acetate (5) in 65% yield [4].

3β-Acetoxy-5α-pregn-16-en-20-one (2). A mixture of 1 (50 g, 120.0 mmol), (CH ₃ CO) ₂ O (150 mL), and C ₅ H ₅ N (10 mL) was boiled for 1 h, cooled to 100 ⁰ C, stirred, treated with TiCl ₄ (2.5 g, 13.16 mmol) in (CH ₃ CO) ₂ O (2.5 mL), boiled an additional 2 h, cooled to 40°C, treated gradually with CHsCOONa (10 g) dissolved in water (25 mL), stirred 20 min, cooled to room temperature, poured into CH ₃ COCH ₃ (220 mL) and CH ₃ COOH (220 mL), oxidized by addition of CrO ₃ (15 g)

in water (7.5 mL) at 15-18°C, stirred an additional hour, treated with isopropanol (7.5 mL), gradually heated to distill off acetone and reach a temperature of 115-117°C, boiled for 1.5 h, cooled to room temperature, and treated with water (425 mL). The resulting precipitate was filtered off, washed with water, and recrystallized from methanokacetone (3:1) to afford 2 (29 g, 69.5%), mp 158-162°C, lit. mp 158-162°C [2].

5α-Pregn-16-en-3β-ol-20-one Acetate Oxime (3). A mixture of 2 (2.5 g, 6.97 mmol), NH ₂ OH HCl (0.55 g, 7.91 mmol), and dry C ₅ H ₅ N (12 mL) was heated at 65-68°C for 2 h, cooled to room temperature, treated with water (45 mL), and stirred for 30 min. The resulting precipitate was filtered off and washed with water to afford 3 (2.5 g, 98.07%), mp 196-198°C, lit. mp 195.5-98.5°C [4].

3β-Acetoxy-5α-androstan-17-one (5). A mixture of 3 (1 g, 2.67 mmol), dry C ₅ H ₅ N (3.2 mL), and dry CH ₃ COCH ₃ (3.2 mL) at 18-20°C was treated with POC13 (1.2 mL), stirred for 30 min, cooled to -5 ⁰ C, treated with dilute HCl (1:1 with water, 28 mL), stirred for 30 min, and treated with water until neutral. The resulting precipitate was filtered off and washed with water to afford crude product (0.83 g) that was chromatographed over a column of silica gel (L 100-160) with elution by

low-boiling petroleum etheπether (20:1) to afford 5 (0.58 g, 65%), mp 111-113°C, lit. mp 111-13°C [4].

3β-hydroxy-5α-androstan-17-one (6). A mixture of 5 (1 g, 3.00mmol), NaOH 0.12g (3.44 mmol) in methanol was refluxed for 10 min, cooled to room temperature and treated with water. The resulting precipitate was filtered off and washed with water to afford crude product 6 (0.82 g, 95%)

5α-androstan-3,17-dione (7). To the mixture of 6 (5g, 17.2 mmol) and 75 ml acetone at room temperature 1.5 ml of Jones reagent (CrO ₃ , H ₂ SO ₄ , H ₂ O) was added by drops. After the reaction was completed, NaOH was added, liquid phase was separated and then 90 ml water was added. The resulting precipitate was filtered off to afford product 7 (4.72 g, 94%). M.p. 134-137°C.

PREPARATION OF NOVEL BENZOIC ACID HYDRAZONES Bis- {3-brom benzoic acid [( SαVandrostaiiO.π-ylidenell-hvdrazide

Bis-m-brombenzoic acid hydrazone of 5a-androstane-3,17-dione. A mixture of 5a- androstane-3,17-dione (1 g, 3.46 mmol), m-brombenzoic acid hydrazide (1.49 g, 6.93 mmol) and acetic acid (1 ml) in ethanol (10 ml) was refluxed for 2 h and cooled to room temperature. The precipitated solid was filtered, washed with water, and recrystallized from ethanol to give desired hydrazone; yield 93%; mp 165-167°C Structural Formula ( I )

IR (KBr, cm ^'1 ): 3475 (NH), 1700 (NHC=O), 1643 (C=N), 1550 (aromatic ring),

¹ H NMR (500MHz, CDCl ₃ ), δ : 0.83 (3H, s, C18-H3), 0.90 (3H, s, 19-CH3), 7.64-7.89 (1OH, m, aromatic protons), 8.17 (IH, br s, NH), 8.31 (IH, br s, NH)

¹³ C NMR(500MHz, CDCl ₃ ), δ :11,11(CH ₃ ), 16.95(CH ₃ ), 122.91-150.1 l(aromatic ring) 161.21

(C=N), 162,22 (C=N), 171.22(C=O)

Bis nitrobenzoic acid f( 5α)-androstan-3,17-ylideneU-hydrazide

Bis-m-nitrobenzoic acid hydrazone of 5a-androstane-3,17-dione. A mixture of 5a- androstane-3,17-dione (I g, 3.46 mmol), m-nitrobenzoic acid hydrazide (1.25 g, 6.93 mmol) and acetic acid (1 ml) in ethanol (10 ml) was refluxed for 2 h and cooled to room temperature. The precipitated solid was filtered, washed with water, and recrystallized from ethanol to give desired hydrazone; yield 90%; mp 202.-205 ⁰ C Structural Formula ( II )

IR (KBr, cm ¹ ): 3484 (NH), 1700 (NHC=O), 1639 (C=N), 1528 (aromatic ring),

¹ H NMR (500MHz, CDCl ₃ ), δ : 0.83 (3H, s, C18-H3), 0.90 (3H, s, 19-CH3), 7.64-7.89 (1OH, m, aromatic protons), 8.17 (IH, br s, NH), 8.31 (IH, br s, NH)

¹³ C NMR(500MHz, CDCl ₃ ), δ :11,23(CH ₃ ), 17.26 CH ₃ ), 122.91-147.1 l(aromatic ring), 161.21

(C=N), 162,22 (C=N), 176.22(C=O)

3-Nitrobenzoic acid [(3a, 5a)-3-hydroxyandrostan-17-yIidene]-hydrazide

/M-nitrobenzoic acid hydrazone of Sα-hydroxy-Sα-androstan-π-one. A mixture of 3α-hydroxy-5α-androstan-17-one (lOOmg, 0.34 mmol), m-nitrobenzoic acid hydrazide (0.74mg, 0.41 mmol) and acetic acid (1 ml) in ethanol (5 ml) was refluxed for 12 h and cooled to room temperature. The precipitated solid was filtered, washed with water, and recrystallized from ethanol to give desired hydrazone; yield 85%; mp 305.-07 ⁰ C

References

1. E. P. Kemertelidze and T. A. Pkheidze, Khim-Farm. Zh, 6, 44 (1972).

2. L. K. Kavtaradze, R. I. Dabrundashvili, N. I. Men'shova, N. A. Korzinkina, and E. P. Kemertelidze, Soobshch. Akad. Nauk Gruz. SSR, 132, No. 3, 537 (1988).

3. J. Schmidt-Thome, Chem. Ber., 88, 895 (1955).

4. N. I. Men'shova, N. A. Korzinkina, E. P. Kemertelidze, N. Sh. Nadaraia, M. G. Davitishvili, L. I. Lishcheta, and V. S. Grosheva, Sb. Nauchn. Tr. VNIKhFi im. S. Ordzhonikidze, 10, 83 (1982).