Study On The Synthesis And Pharmacological Evaluation Of Hesperidin Derivatives

Hesperidin, a rutinoside of hesperetin, is a dihydroflavonoid derivative. It is present in fruit, leaves and in the bark of orange and other citrus species. Hesperedin has shown a broad range of biological activities, including antitumor, antivirus, antioxidant, antiallergic, anti-inflammatory, hypotensive effects. As a result of its safety and non-toxic side effects, taking hesperidin as a lead compound to modificate its stucture by the method of computer-aided drug design for the development of some novel active substances, has become a hot topic in this field. In this study, the method of receptor-based drug design had been chosen, Angiotensin-converting enzyme (ACE) was selected as the receptor, hesperidin derivatives as the ligands to coupling with ACE-receptor by the technique of molecular docking. According to the pretest results, the hesperidin derivatives had been synthesized and their inhibitory activities on ACE in vitro were studied to confirm furtherly. At the same time, the other pharmacological effects of the derivatives had also been screened by the lead compound hesperidin owning. The special research was as follow:1. Synthesis and structures confirmation of hesperidin derivativesAs a lead compound of hesperidin, hesperetin, methyl-hespereridin and methyl-hespereretin had been prepared by acid-catalyed hydrolysis and methylized reaction, and then by the esterified and etherified reaction, the ester and the ether derivatives of hesperetin and methyl-hespereretin had been synthesized. The spectral data of UV, IR, 1H NMR and MS confirmed the structures of the synthesized compounds.2. Antimicrobial activities of hesperetin-7-alkyl etherAntimicrobial activities of hesperetin-7-alkyl ether on 5 patheogenic microorga-nisms were studied with the methods of agar well diffusion and 2-fold serial dilution test.5 patheogenic microorganisms used for the antimicrobial assay were Gram-positive (G+) bacteria viz. Bacillus subtilis, Staphylococcus aureus, Gram-negative (G-) bacteria viz. Proteus vulgaris, Escherichia coli and a fungus viz. Candida albicans, respectively. The result indicated hesperetin-7-alkyl ether derivatives had the antibacterial effects none antifungal effects at the concentration of 400μg/mL. The average diameter of the inhi- bitory zone with 4 bacterial strains was from 1.5 to 3.9 mm. Compared with hesperidin and hesperetin, The antibacterial effects of hesperetin-7-alkyl ether derivatives were become stronger as the enlongating of the length of carbon chain (Cn= 12), hesperetin- 7-N-dodecyl ether showed the highest antibacterial activity (MIC= 6.25μg/mL) among all the compounds.3. Antioxidant and anti-inflammatory effects of methyl-hespereretin-7-alkyl ether derivativesThe antioxidant activities of methyl-hespereretin-7-alkyl ether derivatives were studied with the in vitro screening effects on superoxide anion radical (O2·-) and hydroxyl radical (OH), the in vivo inhibitory effects on nitric oxide released by microphage, and the influence on the concentration of Malondialdehyde (MDA) and Superoxide dismutase (SOD) in the serum of Freund's complete adjuvant (FCA) induced arthritic mice. The anti-inflammatory activities of methyl-hespereretin-7-alkyl ether derivatives were studied with the inhibitory effects on FCA induced mouse paw edema, the influence on the concentration of COX-2, PGE2 in the serum of the arthritic mice and acetic acid induced capillary permeability in mice. The result showed methyl-hespereretin-7-n-octyl ether had good antioxidant and anti-inflammatory activities.4. Influence of methyl-hespereretin-7-alkyl ether derivatives on the inhibitory effects of atropine sulfate-induced gastric emptying and small intestinal propulsive in miceGastric residual rate and small intestinal propulsive rate had served as the main parameters, the antagonistic action of methyl-hespereretin-7-n-octyl ether on the inhibitory effects of atropine sulfate-induced gastric emptying and small intestinal pro-pulsive in mice were studied, the conclusion indicated the gastric rate and small intes- tinal propulsive rate of methyl-hespereridin separately was 39.9% and 52.75%, methyl-hesperidin had the significantly antagonistic action.5. Inhibitory effects of hesperidin derivatives on Angiotensin-converting enzymeWith ACE as the receptor, the ligands of hesperidin derivatives were synthesized under the method of molecular docking and their structures were confirmed, at the same time, the relationship between the structures of the synthesized compounds and the inhi-bitory activities on ACE had also been studied. The result had indicated that the inhibi-tory activities of hesperidin on ACE were different between the predict evaluation and the practical measurement, the inhibitory rate of hesperetin-7-n-hexadecyl ether and methyl-hespereretin-7-n-dodecyl ether on ACE individually was 50.96% and 43.04%, they had the significantly inhibitory effects on ACE. In hesperetin ether/ester derivatives and in methyl-hespereretin ether/ester derivatives, the conclusion also indicated ester derivatives and the introduction of phenyl group in ether could decrease the inhibitory effect on ACE. The inhibitory rate of methyl- hespereretin- 7-n-butyl ether and methyl-hespereretin-7-(1"-bromo)-N-butyl ether was 34.47% and 36.88%, respectively, it indicated that the introduction of halogen didn't improve the inhibitory activity on ACE, the result was correspondent with the prediction.