Fraxinus Ornus

On the other hand, borohydride reduction of the ketose o-fructose will give a mixture of o-glucitol and its epimer, D-mannitol. A better approach to D-mannitol would be reduction of the aldose D-mannose. o-Glucitol (sorbitol) is found naturally in the ripe berries of the mountain ash (Sorbus aucuparia), but is prepared semi-synthetically from glucose. It is half as sweet as sucrose, is not absorbed orally, and is not readily metabolized in the body. It finds particular use as a sweetener for diabetic products. o-Mannitol also occurs naturally in manna, the exudate of the manna ash Fraxinus ornus. This material has similar characteristics to sorbitol, but is used principally as a diuretic. It is injected intravenously, is eliminated rapidly into the urine, and removes fluid by an osmotic effect. 

Fraxinus ornus L. China Fraxin, aesculin.33 This herb is toxic. Antibacterial, analgesic, anti-inflammatory. 

C. aurantium, Crataegus laevigata, C. monongyna, C. oxyacantha, Cryptotaenia japonica, Datura innoxia, D. metel, D. stramonium, Eleutherocossus senticosus, Ferula assa-foetida, Fraxinus ornus,... 

MANNITOL Mannitol is the active ingredient in the drug Manna, which is the dried juice after incision of the bark of Fraxinus ornus L., family Oleaceae, a small tree which is cultivated in special Sicilian gardens called frassinetti . 

Manna. Dried exudation of Fraxinus ornus L., Oleaceae. Habit. Mediterranean Basin, Asia Minor, Spain, Constit. 40-60% mannitol 10-16% mannotetrose 6 16% mannotriose glucose, mucilage, fraxin. One gram dissolves in 5 ml water, 150 ml 90% alcohol. 

CHEMICAL COMPONENTS OF FRAXINUS ORNUS BARK - STRUCTURE AND BIOLOGICAL ACTIVITY... 

Fraxinus ornus (L.) is a small tree belonging to the Oleaceae family widely found in Bulgaria. Its stem bark is used in the Bulgarian folic medicine for treatment of infected wounds, inflammation, arthritis and dysentery [1,2]. However, the claims of the traditional medicine were not scientifically confirmed, the toxicity of the extract was not examined and the chemical composition of the bark was not completely investigated. 

In order to explain and confirm the biological activities claimed by the traditional medicine, and to search for new biologically active compounds we studied the antimicrobial, antioxidative, immunomodulatory, antiinflammatory, skin-regenerating and antiviral properties of Fraxinus ornus bark extract and its components. In a parallel detailed phytochemical investigation of the extract we isolated and determined the structures of many hydroxycoumarins, secoiridoid glucosides, caffeoyl esters of phenylethanoid glycosides, lignans and other phenolic compounds. 

Previous investigations on bark, flowers and leaves of Fraxinus ornus have shown the presence of the hydroxycoumarins esculin (1), esculetin (2), fraxin (3 ), fraxetin (4), cichoriin (5) and of some phenolic acids [3-6]. The isolation of the flavonoids rutin, quercetin, quercetin-3-glucoside, quercetin-3-galactoside, quercetin-3,7-digalactoside and rhamnetin from leaves and flowers has also been reported [7-9]. 

The bark of Fraxinus ornus was subjected to systematic phytochemical investigation. The isolated compounds and some bark extracts were further investigated for their biological activities. In some cases synthetic derivatives of the natural compounds were prepared and their biological properties studied. 

A characteristic feature of Fraxinus species is the presence of simple hydroxycoumarins having OH or/and OMe groups only in the benzene ring. In Fraxinus ornus we found derivatives of 6,7-dihydroxy-, 6,7,8-trihydroxy- and 5,6,7-trihydroxycoumarins. 

RP- HPLC Analysis of Hydroxycoumarins in Fraxinus ornus Bark Extract... 

In this connection we attempted a reverse phase - high pressure liquid chromatography (RP-HPLC) determination of 11 naturally occurring hydroxycoumarins 1-8 and 11-13 [14]. Conditions were found for best resolution of the standard mixture - mobile phase H20-Me0H, detection at X= 220nm, and appropriate gradient profile and flow rate. These conditions were used for the HPLC analysis of the total extract of Fraxinus ornus bark. 

Secoiridoid glucosides of oleoside (28) type frequently occur in Oleaceae family. Usually, in Fraxinus species they are present as mono- or diesters of p-hydroxyphenylethanol (29) derivatives. Our phytochemical studies on Fraxinus ornus resulted in the isolation of ligstroside (14), oleuropein (18), framoside (19) and of the new compounds ornoside (15), hydroxyornoside (17), hydroxyframoside A (20a) and hydroxyframoside B (20b) [15-17],... 

Tanahashi and co-authors [18] postulated that insularoside (15) is biosynthesized by oxidative C-0 coupling of the two p-hydroxyphenethyl moieties from framoside (19) found at that time in Fraxinus formosana [24]. The presence of 15, hydroxyframoside A (20a) and framoside (19) in Fraxinus ornus is in support of their postulate. However, the cooccurrence of 15 and omosol (30) in Fraxinus ornus allows to speculate that 30 could be also involved in the biosynthesis of insularoside (15). 

Our investigations revealed the presence of calceolarioside B (23) in Fraxinus ornus leaves [28] and of six caffeic acid esters of PhGs in the polar part of the EtOH extract of the bark [29]. Five of them were identified as the known 2-(4-hydroxyphenyl)-ethyl-(6-0-caffeoyl)-p-D-glucopyranoside (22), calceolarioside B (23), verbascoside (24), isoacteoside (25) and lugrandoside (26). The occurrence of 22 and 26 in Oleaceae has not been reported so far. 

Antimicrobial Properties of Hydroxycoumarins, Secoiridoids, Phenylethanoids and Fraxinus ornus Bark Extracts... 

The weak bacteriostatic effect of ethanolic extracts of Fraxinus ornus bark against Staphylococcus aureus has been reported [31]. The antimicrobial properties of the natural dihydroxycoumarins esculin (1), esculetin (2) and daphnetin have been also investigated using different test systems [32]. However, there was no detailed investigation on the antimicrobial activity of Fraxinus ornus extract and the compounds responsible for have not been identified. 

We studied the antimicrobial properties [33] of three Fraxinus ornus bark extracts and their main components 1-4 against Staphylococcus aureus, Candida species, Escherichia coli and Pseudomonas aeruginosa using the procedure of Heiss [34]. Evaluation of microbial growth on the contact surface was performed by measuring the Contact Growth Index (CGI). The crude extract (extract A) of the bark was separated into... 

This gave us a reason to study and compare [35] the antimicrobial properties of a series of Fraxinus ornus bark constituents - the hydroxycoumarins 1-4, 6-7, 11-12, and acetates 2a and 4a the secoiridoids 14, 14a, 15, 15a, and the tyrosol derivatives 29 and 30 applying the method described by Bankova et al. [36]. In this case the antibacterial properties of the studied compounds were also dependable on their structure and substitution (Table 8). 

The MIC of the acetates esculetin 2Ac (2a) and fraxetin 2Ac (4a ) were found to be equal to those of the parent compounds 2 and 4. Most probably, acetylation of the phenolic OH does not alter the antibacterial activity of the hydroxycoumarins. Compounds 4 and 4a are the most potent inhibitors of S. aureus among the tested Fraxinus ornus components. 

We investigated the skin regenerating properties of esculin (1) and Fraxinus ornus bark extract on male white Wistar rats having standard oval wounds [41]. The rats were divided into four groups of 6 animals and treated as follows ... 

These investigations have shown that the alcoholic extract and esculin obtained from Fraxinus ornus bark exercise moderate skin regenerating effects, no toxicity or local irritation being observed. The experimental results are in line with the antimicrobial properties of the extract and its constituents, and with the use of the bark in the traditional medicine for wound treatment and against inflammation. 

Antioxidative Action of the Ethanolic Extract and some Hydroxycoumarins from Fraxinus ornus Bark... 

In the literature there was no information about the antioxidative action of Fraxinus ornus extract and the data on hydroxycoumarins were scarce [44]. 

The parameters F and ORR for TGL and TGSO oxidation in the presence of 0.05 and 0.10% ethanolic extracts of Fraxinus ornus bark are presented in Table 11. The data indicate that the ethanolic extract of Fraxinus ornus bark has a pronounced antioxidative activity during the oxidation of both lipid substrates. This activity is commensurate with the inhibiting effect of the same concentration of butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) during TGL oxidation [46]. 

Table 11. Stabilization Factor F and Oxidation Rate Ratio ORR for the Inhibited Oxidation of TGL and TGSO at 100°C in the Presence of Ethanolic Extract, Esculetin (2) and Fraxetin (4) from Fraxinus ornus bark...

TLC analysis of the antioxidatively acting compounds [48] in the ethanolic extract from Fraxinus ornus bark revealed the presence of additional antioxidative acting compounds. Among them calceolarioside B (23) demonstrated a significant activity. Most probably, caffeic acid (16) and the caffeoyl esters of phenylethanoid glycosides 22, 24-27 also contribute to the antioxidative properties of the extract. 

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