Chemical Constituents Of Hulls Of Nephelium Lappaceum L. And Punica Granatum L. And Their Anti-FAS Activities

The animal Fatty acid synthase (EC2.3.1.85, ab. FAS) is a key metabolic enzyme catalyzing the de novo synthesis of long chain saturated fatty acids from acetyl-CoA and malonyl-CoA in the presence of the reducing substrate NADPH. Natural inhibitors of fatty acid synthase (FAS) are emerging as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Nephelium lappaceum L. and Punica granatum L.led to the isolation of53compounds (1-53) mainly including flavonoids and oleane-type triterpene oligoglycosides, in which all of the compounds were isolated from Nephelium lappaceum L. for the first time and compounds17,23,24and26were new products. All of the compounds were separated by column chromatography (siliga gel, sephadex LH-20, RP-18, RP-8) and identified on the basic of extensive spectroscopic methods. Comparing with the known FAS inhibitor EGCG (IC50=51.97uM), these isolates exhibit inhibitory activity of FAS with the IC50values ranging from6.69to173.1μM. The study indicates that the hulls of Nephelium lappaceum L and Punica granatum L. could be considered as potential sources of promising FAS inhibitors, as and need not simply be discarded.Nephelium lappaceum L., commonly known as "rambutan", is a tropical fruit of the Sapindaceae family. Native to Southeast Asia, rambutan is cultivated for its fruit and sold commercially. The seeds are bitter and narcotic, with the roots used for treating fevers, the leaves as poultices, and the bark as an astringent. The hull of rambutan, which is normally discarded, was found to contain extremely high antioxidant and antibacterial activities. Compouds isolotied from hulls of Nephelium lappaceum L. are identified as pyrocatechol (1), l-methoxy-4-methylbenzene (2), ethyl gallate (3),3-(3,4-dimethoxyphenyl)-2-propenal (4), isocopoletin (5),3,4-dihydroxy-5-methoxybenzaldehyde (6), ergosterol (7), hedragenin (8), dihydrokaempferol (9), kaempferol (10), kaempferol-3-/β-D-(6-O-trans-p-coumaroyl)-glucopyranoside (11), kaempferol-3-a-L-ramnopyranoside (12), kaempferol3-0-(6-O-caffeoyl)-/β-D-glucopyranoside (13), atroside (14),3-0-[6’-O-n-acyl-β-D- glucosyl]-22-dehydroclerosterol (15), sitosterol (16), hederagenin3-0-(3-0-acetyl-β-D-xylopyranosyl)(1â†'3)-α-L-arabinopyranoside (17*), hederagenin3-O-(4-O-acetyl-a-L-arabinopyranosyl)(1â†'3)-a-L-rhamnopyranosyl(1â†'>2)-α-L-arabinopyranos ide (18), hederagenin3-O-(3-O-acetyl-β-D-xylopyranoside)(1â†'3)-α-L-rhamnopyranosyl(1â†'2)-α-L-arabinopyranoside (19), hederagenin3-O-(α-L-arabinopyranosyl)(1â†'3)-α-L-rhamnopyranosyl(1â†'2)-a-L-arabinopyranoside (20), hederagenin3-O-(β-D-glucopyranosyl)(1â†'3)-a-L-rhamnopyranosyl(1â†'4)-β-D-xylopyranoside (21), hederagenin3-O-(a-L-rhamnopyranosyl)(1â†'2)-a-L-arabinopyranoside (22), hederagenin-3-O-(2,3-di-6)-acetyl-a-L-arabinofuranosyl)(1â†'3)[a-L-rhamnopyranosyl(1â†'2)]-β-L-arabinopyranoside (23*), hederagenin3-O-(3-O-acetyl-a-L-arabinofuranosyl(1â†'3)[a-L-rhamnopyranosyl(1â†'2)]-β-L-arabi nopyranoside (24*), hederagenin3-O-(a-L-arabinofuranosyl)(1â†'3)[a-L-rhamnopyranosyl(1â†'2)]-β-L-arabinopyranoside (25).Pomegranate (Punica granatum L.) belongs to Punicaceae family, whose peel could be used for treating chronic diarrhea, lingering dysentery, hemafecia and enterozoic abdominalgia. Compouds isolotied from hulls of Punica granatum L. are identified as*punicaone (26), oleanic acid (27),1β-hydroxy-3-keto-olean-12-en-28-oic acid (28), lantanolic acid (29), lantic acid (30),30,24-dihydroxyurs-12-en-28-oic acid (31), lupeol (32), betulinic acid (33), betulin (34), friedelin (35), catechin (36), epigallocatechin (37),3’,4’,5’,7-tetra-O-methyl-(-)-epigallocatechin (38), penta-O-methylepigallocatechin (39),3’,4’,5’,5,7-penta-O-methyl-(-)-gallocatechin (40), sesamin (41),4-hydroxy sesamin (42), gallic acid (43),8-(3,5-dihydroxyphenyl)-1-propyloctyl2,4-dihydroxy-6-undecylbenzoate (44), βsitosterol (45),β-sitosteryl acetate (46),24-epiergosterol (47), borneol (48), flavogallonic acid (49),(R)-dimethyl malate (50), tetradecanoic acid,2,3-dihydroxypropyl ester (51),1-oleoyl-sn-glycerol (52), nonadecan-1-ol (53).