Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Pharmacognosy

Averrhoa carambola L. is a tropical tree with edible fruits that grows at different climatic conditions. Despite its nutritive value and reported health benefits, it is a controversial plant owing to its fruits rich oxalate content.The present study aimed at investigating aroma and nutrient primary metabolites distribution in A. carambola fruits grown in Indonesia, Malaysia (its endemic origin) versus Egypt, and at different ripening stages.Two techniques were employed to assess for volatile and non-volatile metabolites including headspace solid-phase micro-extraction (HS-SPME) coupled to gas chromatography mass-spectrometry (GC-MS) and GC-MS post silylation, respectively. 24Volatiles were detected, with esters amounting for the major class in Egyptian fruits at ca. 66%, with methyl caproate as the major component. Primary metabolites profiling led to the identification of 117 metabolites viz. sugars, polyols and organic acids. Fructose (38{u2013}48%) and glucose (21{u2013}25%) predominated sugar compositions in ripe fruits, whereas sorbitol was the major sugar alcohol (2.4{u2013}10.5%) in ripe fruits as well. Oxalic acid, an anti-nutrient with potential health risks, was the major organic acid detected in all fruits (1.7{u2013}2.7%), except the Malaysian one (0.07%). Further objective of this study was to investigate the use of its plant parts (leaves & fruits) cultivated in Egypt forthe treatment of obesity as extracts and its isolated compounds.The effect of the total MeOHextracts of leaf and fruit on high-fat diet induced obesity in rats was evaluated in vivo. Results revealed thatboth extracts exhibited potential anti-obese activity in comparison to Orly as a reference drug. To pinpoint for the active agents in A. carambolaleaf extract cultivated in Egypt as an anti-obese and antidiabetic agents,a detailed phytochemical study was adopted. 14 compounds were isolated including 3 new dihydrochalcone glycosides & 1 flavonoid glycoside. The isolated compounds were comparatively assessed for their antidiabetic and cytotoxic activities. Structure-activity relationship (SAR) was adopted to determine the effect of substitution pattern on biological effects

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