الفهرس 
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Abstract
The work presented in this thesis is furtherphytochemical investigations of the ornamental coral plants, Erythrina caffraThunb. and Erythrina lysistemonHutch. (family Fabaceae) as representatives of Erythrinaspecies cultivated in Egypt.
In this thesis, the investigation of the root bark composition of Erythrina lysistemon as well as the flower and seed composition of Erythrina caffra, the African coral tree, are reported, in addition to the investigation of selected isolated polyphenolics for their antiangiogenic activity, anti-MRSA activity, and anti-SARS-CoV2properties and selected alkaloids for their anticholinesterase activityand antioxidant activity.
Flavonoids isolated from the genus from 2014-2020 and all the isolated alkaloids until now were reviewed. Structure activity relationship of pterocarpans for different activities was concluded. All the ocular antiangiogenic natural promising compounds up to now were also reviewed.
The genus Erythrina is one of several genera of the Fabaceae family.
<The origin of the name Erythrina comes from the Greek word “erythros” which means red, referring to the bright red flowers of the trees of the genus. Over 130 species belong to the genus Erythrina, with less than 40 species having been widely studied, and they are distributed in tropical and subtropical regions of the world.
This genus has attracted attention for its broad spectrum of physiological activities and its rich polyphenolic and alkaloidcontent. Up to now, the Erythrinagenus is the only plant resourcethat contains pterocarpans and alkaloids at the same time.
More than 370 flavonoids and 120 alkaloids have been isolated from the genusErythrina.
<Erythrina caffraand Erythrina lysistemonare cultivated in Egypt as ornamental plants.
<Erythrina lysistemonHutch., commonly known as the common coral tree, is a deciduous tree, growing up to 12 m tall with a spreading crown and brilliant red flowers. It is used traditionally to treat various ailments including menopausal complaints, earache, wounds, abscesses and arthritis.
< Erythrina caffra is a medium-sized to large deciduous subtropical tree, indigenous to South Africa. It is often cultivated as an ornamental, street, and park tree in drier areas to provide shade and improve soil quality by fixing nitrogen for other tree crops. The flower has a short, broad, standard petal, the lower half of which curves upward to expose the stamens, which give the flower a bewhiskered appearance. Recently, polyphenolics and alkaloids isolated from thetwo species showedremarkable activity against variety of diseases.
< These results stimulated further phytochemical investigation of Erythrinaspecies cultivated in Egypt and exploring possible biological activities of their constituents.
< The CH2Cl2extract of the root barkof Erythrina lysistemon yielded twenty-four phenolic compounds, including seventeen pterocarpans, two isoflavanones, one flavanone, twoisoflavans, one 2-arylbenzofuran and an isoflava-3-ene. Eleven compounds,erythrabyssin II (ELP-2), phaseollidin (ELP-3), eryzerin C (ELP-5), eriotrichin B (bidwillon A) (ELP-6), erybraedin B (ELP-10), eryvarin L vignafuran (ELP-15), eryvarin k (ELP-16), eryvarin H (ELP-17), eryvarin C (ELP-18), orientanol E (ELP-21) and 8-methoxyneorautenol (ELP-23)have been reportedfor the first time in the species, nine pterocarpans (ELP-7, ELP-8, ELP-9, ELP-11, ELP-12, ELP-13, ELP-14, ELP-19 and ELP-20) are reported here for the first time in nature and four compounds, erybraedin A (ELP-1) phaseollin (ELP-4), abyssinone-V-4’-O-methyl ether (ELP-24), eryvarin D (ELP-22), have been reported previously. Table 23summarises the isolated polyphenolic compounds (ELP-1-ELP-24) and their reported biological activity.
Flavonoidsandis oflavonoidsarepromisingcandidatesfortheinhibitionofocularangiogenesis.Up to now, there are no approved small molecule drugs targeting pathological 297angiogenesis in the eye.
New specific and small molecule drugs are needed to supplement the existing ones especially that the available biologics have limitations and can result in severe side effects. Reviewing literature,thepterocarpanskeletonhasnotbeentestedbeforefortheinhibitionofocularangiogenesis.FlavonoidsELP-5andELP-6andpterocarpansELP-1,ELP-4,ELP-9,ELP-20andELP-22,isolatedingoodquantities,were investigatedfortheiranti-proliferativeactivitiesagainsthumanretinalendothelialcells(HRECs),arelevanttissuespecificcelltype.
Sevencompounds(ELP-1,ELP-2,ELP-4,ELP-5,ELP-6,ELP-20andELP-22)showedanti-proliferativeeffectsonHRECtubulegrowthatlowmicromolarconcentrationsinadosedependentmannerandtwopterocarpans(ELP-3,ELP-9),showedanegligibleeffectoncellproliferation.
The activecompoundsshowedselectivityforblockingHRECproliferationoveranon-relevantocularcellline, humanretinalpigmentedepithelialcells(ARPE-19)aswell.
TheantiangiogeniceffectoftheactivecompoundswasinvestigatedfortheinhibitionofHRECstoformtubules.
All compound sthatreduced the proliferation of HRECs in the low micromolar range (ELP-1,ELP-2,ELP-4-ELP-6,ELP-20,ELP-22),showedadosedependentblockadeofthisproperty.
Structureactivityrelationshipfortheantiangiogenicactivityofthepolyphenolicswasconcludedinthis work.
Inaddition,the activity of fourteen polyphenolics isolated in good quantities were investigated against methicillin resistant staphylococcus aureus (MRSA).
All compounds showed significant activity against MRSA except for ELP-14 and ELP-16 with high MIC values of 16.89 μg/ml and 25.00 μg/ml, respectively.Compound ELP-8 showed the highest activity with MI Cvalue of 1.72 μg/ml followed by ELP-21 with MIC value of 3.13 μg/ml.
The identified compounds were also subjected to molecular docking against three proven protein targets in SARS-CoV-2 in the contribution to the active search for potent natural compounds possessing anti-SARS-CoV2 properties.
The results showed that some of the identified compounds might act as potential anti-SARS-CoV-2 leads for further in vitro and in vivo studie