4. Concluding remarks

described as a regulator of vascular tones in the cardiovascular system. Beyond this function it can prevent platelet activation, limit leukocyte adhesion to the endothelium, and regulate myocardial contractility, and it is involved in immune system

0.049

77.19

Compd. EC50 (mg/ml) Ia >>1 Ib >>1 IIa >>1 IIb >>1 IIIa 0.176 IVa 0.627 IVb 1.02 Va >>1 Vb >1

Despite the possible beneficial effects of NO, it also contributes to oxidative damage. In general, the overwhelming production of NO contributes to the pathogenesis of both acute and chronic inflammatory processes, and NO has been recognized as one of the main signaling molecules involved in these processes [23, 40]. Therefore, compounds that act like nitric oxide inhibitors have beneficial effects. The NO inhibition assay is based on the diazotization of sulfanilic acid at acid pH by nitric oxide. The reaction product is subsequently coupled stoichiometrically with N-(1-naphthyl)ethylenediamine, forming a colored azo compound which is

0.5 ml of the tested coumarin derivative solution, as well as ascorbic acid (standard compound), was taken in separate tubes, and 2.0 ml of sodium nitroprusside

Compd. NO inhibition (%) Ia 15.2 Ib 19.8 IIa 12.11 IIb 14.7 IIIa 22.8 IIIb 55.5 IVa 28.45 IVb 29.44 Va 22.6 Vb 26

measured spectrophotometrically at a peak absorbance of 548 nm [36].

reactions.

Ascorbic acid 50 mg/ml

NO inhibition activity of compounds I–V.

Table 17.

152

Table 16.

Ascorbic acid 1 mg/ml

The calculated values of EC50.

Phytochemicals in Human Health

We have synthesized some coumarin derivatives starting from 4-methyl-7 hydroxycoumarin with antimicrobial and antioxidant activities to different reaction steps. The IR and NMR spectra of the synthesized compounds were in accordance with the assigned structures. All the synthesized compounds were very active against S. aureus ATCC 25923, and they exhibited excellent antibacterial activity against S. lutea. The presence of the methyl group attached to the coumarin ring in the fourth position had a positive influence on the anti-Pseudomonas ATCC 27853 potential of the compounds, all the tested 4-propyl-coumarin derivatives being inactive. Against the investigated Candida strains, all tested compounds were found to be very active. The introduction of the sulfur atom appeared to be correlated with a good anti-Candida activity. The most active DPPH free radical scavengers were the coumarin hydrazide derivatives, the activities of these being similar to that of the standard. The reducing power of the tested compounds was modest, and only the hydrazide derivatives were moderately active. Most of the investigated compounds were moderate NO inhibitors.

The interest in the synthesis of coumarin derivatives has been gaining importance over the last decades, reflecting the importance of such compounds in both medical and chemical research. Future goals for this field of research include the discovery, synthesis, and development of compounds which display increased potency, as well as fueling structure–activity relationship studies aimed at understanding the modes of action of the most biologically active members of these classes of products.

Although coumarin is a simple molecule and many of its derivatives have been known for more than a century, it continues to maintain the interest of researchers being a plentiful source of potential drug candidate because of their significant therapeutic potential.
