Antidiabetic and Beta cell-protection activities of purple corn anthocyanins.

Antidiabetic and beta cell-protection activities of purple corn anthocyanins (PCA) were examined in pancreatic beta cell culture and db/db mice. Only PCA among several plant anthocyanins and polyphenols showed insulin secretion activity in culture of HIT-T15 cells. PCA had excellent antihyperglycemic activity (in terms of blood glucose level and OGTT) and HbA1c-decreasing activity when compared with glimepiride, a sulfonylurea in db/db mice. In addition, PCA showed efficient protection activity of pancreatic beta cell from cell death in HIT-T15 cell culture and db/db mice. The result showed that PCA had antidiabetic and beta cell-protection activities in pancreatic beta cell culture and db/db mice.

Characterization of Canadian black currant (Ribes nigrum L.) seed oils and residues.

The seeds from five black currant (Ribes nigrum L.) cultivars grown in western Canada were evaluated for their oil content, fatty acid and triacylglycerol (TAG) composition, and tocopherol and phytosterol profiles and contents. Moreover, polyphenolic compounds and antioxidant activity in the seed extracts remaining after oil extraction were determined. Oil contents of black currant seeds ranged from 27 to 33%. The gamma-linolenic acid content varied significantly among the cultivars (from 11% for Ben Conan to 17% for Ben Tirran). Among the 44 TAGs identified, LLalphaLn, alphaLnLgammaLn, and PLgammaLn (where L = linoleoyl, alphaLn = alpha-linolenoyl, gammaLn = gamma-linolenoyl, and P = palmitoyl) were the predominant ones. Black currant seed oil was a good source of tocopherols (1143 mg/100 g of oil on average) and phytosterols (6453 mg/100 g of oil on average). Quercetin-3-glucoside and p-coumaric acid were the main phenolic components in the seed residues. The high concentration of flavonols and phenolic acids was correlated with a high antioxidant activity of seed residue (average ABTS value of 1.5 mM/100 g and DPPH value of 1.2 mM/100 g). The data obtained from this study indicate that Canadian black currant seed oil is a good source of essential fatty acids, tocopherols, and phytosterols. Extraction of phenolic antioxidants from the seed residues even allows the recovery of additional valuable components from the byproduct of fruit processing.

Characterization of Saskatoon berry ( Amelanchier alnifolia Nutt.) seed oil.

The seeds of 17 cultivars of Saskatoon berries ( Amelanchier alnifolia Nutt.) were evaluated for their seed mass, oil content, fatty acid and triacylglycerol (TAG) composition, tocopherol profile, and sterol content. The oil content of the seeds ranged from 9.4% (cv. 'Pasture') to 18.7% (cv. 'Thiessen'). The seed oils contained mainly linoleic acid in the range from 47.3% (cv. 'Success') to 60.1% (cv. 'Lee 3') and oleic acid in the range from 26.3% (cv. 'Lee 3') to 38.1% (cv. 'Success'). The total tocopherol content ranged from 1053 to 1754 mg/kg of oil. alpha-Tocopherol was the major vitamin E compound in all berry seed oils investigated, accounting for 87% of total tocopherols. The predominant sterols were beta-sitosterol, Delta(5)-avenasterol, and campesterol. The sterols content in seed oil ranged from 7357 mg/kg of oil (cv. 'Success') to 15771 mg/kg of oil (cv. 'Lee 3'). Thirteen triacylglycerols (TAG) were identified in seed oils, among which LLL, LLO, LOO, LLP, LOP (L, linoleoyl; O, oleoyl; P, palmitoyl) represented 88% of the total TAG. TAG composition suggests good oxidative stability of the Saskatoon berry seed oil, which could be suitable for food and industrial applications. Moreover, Saskatoon berry seed oil may serve as potential dietary source of tocopherols, sterols, and unsaturated fatty acids.

Evaluation of Saskatoon berry (Amelanchier alnifolia Nutt.) cultivars for their polyphenol content, antioxidant properties, and storage stability.

The polyphenol contents and antioxidant activities were assessed for 17 Saskatoon berry cultivars grown in Canada in fresh and stored fruits at -20 degrees C for 9 months. The Nelson cultivar was the richest in total polyphenol, anthocyanin, and procyanidin contents (801, 382, and 278 mg/100 g fresh weight, respectively). This cultivar was characterized also by the highest antioxidant potential measured with DPPH and ABTS radicals (2.8 and 5.0 mM/100 g FW, respectively). Cultivar-dependent changes in polyphenol content after freezer storage were observed. In the Lee 2 cultivar, significant increases in anthocyanin and flavonol contents occurred, while in the Lee 3 and Martin cultivars considerable decreases were observed. During the freezer storage, the antioxidant activity remained unchanged except for the Smokey which showed to be the most sensitive cultivar during storage. The Nelson and Lee 2 were the most stable cultivars during storage. The high polyphenol content and antioxidant activity of the Nelson cultivar and its good storage stability would make this cultivar the optimal material for fruit growers and food producers.

Survey of bioactive components in Western Canadian berries.

Berries native to Western Canada were analyzed for total anthocyanins, total phenolics, and trolox equivalent antioxidant activity (TEAC). Values ranged from 1.60 to 9.55 mmol trolox equivalent per 100 g fresh mass. Anthocyanin content ranged from 41.6 (in red twinberries) to 1081 mg cyanidin-3-glucoside equivalents per 100 g fresh mass (in honeysuckle fruits). Honeysuckle fruits contained the highest amount of total polyphenols, 1111 mg gallic acid equivalents per 100 g, among analyzed fruits. Additionally, anthocyanins in the investigated berries were identified and characterized by HPLC - electrospray ionization - tandem mass spectrometric method coupled with diode array detection. The number of anthocyanins varied from 4 in saskatoon berries (Amelanchier alnifolia Nutt.) to 20 in bilberries (Vaccinum myrtilloides Michx.). In all the samples analyzed, 6 common anthocyanidins:, cyanidin, delphinidin, pelargonidin, petunidin, peonidin, and malvidin, were found. Half the analyzed berries contained acylated anthocyanins, but a significant amount was found only in bilberries. The analyzed berry seed oils contained high amounts of unsaturated fatty acids (over 90%), but only the golden currant seed oil contained gamma-linolenic acid.