The study was undertaken to assess the in vivo antioxidant efficacy of a boysenberry extract by measuring biomarkers of oxidative damage to protein (carbonyls), lipids (malondialdehyde), and DNA (8-oxo-2'-deoxyguanosine urinary excretion) and plasma antioxidant status (antioxidant capacity, vitamin E) in rats when fed basal diets containing fish and soybean oils, which are likely to generate different levels of oxidative stress. Boysenberry extract was used as the dietary antioxidant. The basal diets (chow, synthetic/soybean oil, or synthetic/fish oil) had significant effects on the biomarkers of oxidative damage and antioxidant status, with rats fed the synthetic/fish oil diet having the lowest levels of oxidative damage and the highest antioxidant status. When boysenberry extract was added to the diet, there was little change in 8-oxo-2'-deoxyguanosine excretion in urine, oxidative damage to proteins decreased, and plasma malondialdehyde either increased or decreased depending on the basal diet. This study showed that boysenberry extract functioned as an in vivo antioxidant and raised the antioxidant status of plasma while decreasing some biomarkers of oxidative damage, but the effect was highly modified by basal diet. Our results are further evidence of complex interactions among dietary antioxidants, background nutritional status as determined by diet, and the biochemical nature of the compartments in which antioxidants function.

The authors assessed the ability of anthocyanins and phenolic fractions of boysenberry and blackcurrant to ameliorate the deleterious effect of the amyloid 25-35 (100 µmol L-1, 24 h) and dopamine (1 mmol L-1, 4 h) on calcium buffering (recovery) of M1 muscarinic receptor-transfected COS-7 cells. Cell viability was also studied. Our results demonstrate that extracts of boysenberry and blackcurrant showed significant protective effect and restored the calcium buffering ability of cells that had been subjected to oxidative stress induced by dopamine and the amyloid 25-35. Blackcurrant polyphenolics showed slightly higher protective effect against dopamine, whereas boysenberry polyphenolics had a higher effect against the amyloid 25-35. In viability studies, all extracts showed significant protective effects against dopamine and amyloid 25-35-induced cytotoxicity.

While there is little evidence uniquely linking berry consumption with lower cancer risk, berries contain high levels of compounds believed to reduce malignant transformation, including the polyphenol flavonoids and anthocyanins. There is strong and convincing evidence that berry extracts and berry phytochemicals modulate biomarkers of DNA damage and indicators of malignant transformation in vitro and in vivo. Data from numerous cell culture and animal models indicate that berry components such as the anthocyanins are potent anticarcinogenic agents and are protective against genomic instability at several sites in the carcinogenic pathway. Anticarcinogenic mechanisms include modulation of carcinogen activation and detoxification, decreased DNA binding of the carcinogen, inhibition of oxidative DNA damage, alteration in cell signalling and malignant transformation and inhibition of cell invasiveness and metastasis. Exactly which berry constituents are cytoprotective remains uncertain and in the majority of in vitro and in vivo studies the concentration of extract or phytochemical employed is non-nutritional. Evidence for an anticarcinogenic effect in human studies is weak.

The objective of this study was to investigate whether anthocyanins and other phenolics present in boysenberries and blackcurrants are effective in protecting cells against the oxidative damage induced by hydrogen peroxide (H2O2). The concentrations of polyphenols used were within the human physiological range. The data showed that SH-SY5Y human neuroblastoma cells were protected against H2O2-induced toxicity by the anthocyanins and phenolic fractions. The concurrent addition of either fractions of these berries with H2O2 significantly inhibited the increase in intracellular reactive oxygen species production.

The female hormone, 17ß-estradiol (E2) is a known risk factor in the development of breast cancer. In this study, female ACI rats were implanted with E2-filled silastic tubes. The rats were provided either a control diet or a diet supplemented with 2.5% powdered mixed berries (1:1 mixture of strawberries, raspberries, blueberries, blackberries and black raspberries), 2.5% blueberries, 2.5% blueberries plus ellagic acid, or ellagic acid. Compared to the control diet, the adduct (cancer-causing enzymes) levels were significantly decreased by the test diets: The P-1 adducts were reduced by >75% with blueberries and >50% each with blueberries plus ellagic acid, and ellagic acid alone. Ellagic acid was more effective (60%) in diminishing the P-2 adducts, followed by blueberries, or blueberries plus ellagic acid (30-40 %). The mixed berries, however showed no change in the adduct levels.

Five types of caneberries (blackberries, marionberries, boysenberries, red raspberries, and black raspberries) were analyzed for antioxidant activity by measuring their oxygen radical absorbance capacity (ORAC). In addition, the berries were analyzed for total phenolics, anthocyanins, procyanidins, and ellagic acid content. All of the berries had high ORAC activity ranging from 24 to 77.2 micromol of Trolox equiv/g of fresh berries. Anthocyanin content ranged from 0.65 to 5.89 mg/g, and phenolics ranged from 4.95 to 9.8 mg/g. Black raspberries had the highest ORAC and anthocyanin and phenolic contents. Only red raspberries had detectable amounts of procyanidin oligomers (monomer, dimers, and trimers). All berries had high levels of ellagic acid (47-90 mg/g), but boysenberries had the highest level prior to hydrolysis. The results from this study indicate that these caneberries were high in antioxidant activity and were rich sources of anthocyanins and phenolics.