Non-flavonoid phenolics from Averrhoa carambola fresh fruit

The fruit of Averrhoa carambola L. (Oxalidaceae) is a commercially important fruit. Our study on the chemical constituents present in the fresh sweet fruit led to the isolation of eleven non-flavonoid phenolic compounds. Their structures were identified by analyses of spectroscopic data. They were two new alkyl phenol diglucosides, carambolasides K ( 1 ) and L ( 2 ), four phenylpropanoids, (+)-isolariciresinol 9- O -β- d -glucoside ( 3 ), (+)-lyoniresinol 9- O -β- d -glucoside ( 4 ), (−)-lyoniresinol 9- O -β- d -glucoside ( 5 ), and 1- O -feruloyl-β- d -glucose ( 6 ), three benzoic acids, protocatechuic acid ( 7 ), 1- O -vanilloyl-β- d -glucose ( 8 ), and tecomin ( 9 ), a simple phenol, koaburaside ( 10 ), and a naphthoquinone, (+)-cryptosporin ( 11 ). All of them were reported from A. carambola fruit for the first time. Compounds 1 – 8 and 10 showed 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation scavenging activity comparable to l -ascorbic acid, while compounds 3 , 5 , and 7 exhibited potent ferric reducing antioxidant power (FRAP). In addition, compounds 6 and 11 demonstrated weak porcine pancreatic lipase inhibitory activity.