Nanopolyphenols : a review of their encapsulation and anti-diabetic effects

Polyphenols are believed to possess numerous health benefits and can be grouped as phenolic acids, flavonoids or non-flavonoids. Research involving the synthesis of nanopolyphenols has attracted interest in the areas of functional food, nutraceutical and pharmaceutical development. This is in an effort to overcome current challenges which limit the application of polyphenols such as their rapid elimination, low water-solubility, instability at low pH, and their particle size. In the synthesis of nanopolyphenols, the type of nanocarrier used, the nanoencapsulation technique employed and the type of polymers that constitute the drug delivery system are crucial. For this review, all mentioned factors which can influence the therapeutic efficacy of nanopolyphenols were assessed. Their efficacy as anti-diabetic agents was also evaluated in 33 publications. Among these were phenolic acid (1), flavonoids (13), non-flavonoids (17) and polyphenol-rich extracts (2). The most researched polyphenols were quercetin and curcumin. Nanoparticles were the main nanocarrier and the size of the nanopolyphenols ranged from 15 to 333 nm with encapsulation efficiency and drug loading capacities of 56-97.7% and 4.2-53.2%, respectively. The quantity of nanomaterial administered orally ranged from 1 to 300 mg/kg/day with study durations of 1-70 days. Most studies compared the effect of the nanopolyphenol to its free-form and, in all but three cases, significantly greater effects of the former were reported. Assessment of the polyphenol to understand its properties and the subsequent synthesis of its nanoencapsulated form using suitable nanocarriers, polymers and encapsulation techniques can result in effective therapeutic agents for the treatment of diabetes

Medical and pharmacokinetic effects of nanopolyphenols : A systematic review of clinical trials

A significant percentage of the population has been turning to herbal remedies either as a sole treatment option or in combination with other drugs. Efforts to increase the production of therapeutic remedies from these scaffolds have therefore amplified. A fundamental aim when developing new drugs is to develop drugs that have virtually no or less adverse effects than those currently available while being efficacious. Several approaches have been undertaken to use nanotechnology to develop nanoencapsulated polyphenols for use in therapeutics in an attempt to improve their physicochemical properties, bioavailability, and efficacy. This review covers the types of nanopolyphenols that have been evaluated in clinical trials against various medical conditions and their outcomes. Medical conditions covered include cardiometabolic diseases, inflammatory diseases, and cancer and in almost all instances the nanoencapsulated polyphenol produced a positive outcome. Similar outcomes were also reported for pharmacokinetic analyses.

Chemical and Sensory Characterisation of Two Rubus rosifolius (Red Raspberry) Varieties

Raspberries are economically important fruits, being highly valued for their taste and medicinal properties. Prior to our recent finding, the occurrence of different varieties of Rubus rosifolius growing in Jamaica had not been previously reported. Upon close observation of the plants, differences in various physical features pointed to the existence of two distinct plant morphotypes, which were described as Red “R” and Wine Red “WR.” With an aim to determine which variety may be more favourable for value-added food production, we undertook their physicochemical and sensory analysis. This characterisation led to the rationalisation of the differences in the perceived sensory properties of these biologically active fruits. Total phenolic content was determined using the Folin-Ciocalteu reagent assay, and the identification and quantification of anthocyanins were done via HPLC-MS and HPLC-UV, respectively. Proximate and physicochemical analyses were also carried out. The findings of the analyses were associated with those of a consumer sensory analysis. The WR fruits had a greater quantity of the deep red anthocyanin, cyanidin-3-glucoside (66.2 mg/100 g FW), and a significantly lower lightness value. They also received a significantly higher sweetness score, which is associated with their higher total sugar content (4.8 g/100 g) and maturity index (6.7). The R fruits had a higher quantity of the orange-coloured pelargonidin-3-rutinoside (17.2 mg/100 g FW) and significantly higher titratable acidity (1.3 g citric acid/100 mL), the latter being associated with its significantly more sour taste. The high total phenolic contents suggest a health-functional value of these R. rosifolius berry fruits. Our findings, which revealed that the WR variety was the preferred choice among consumers, may be used to guide future product-development endeavours of these commercially valuable fruits

Effect of Berry Polyphenols on Glucose Metabolism : A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The effect of berry polyphenols on glucose metabolism has been evaluated in several studies; however, the results are conflicting. A systematic review and meta-analysis was therefore conducted to evaluate the effect of berry polyphenol consumption on glucose metabolism in adults with impaired glucose tolerance or insulin resistance. PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, CINAHL (EBSCO), and Scopus were searched for randomized controlled trials published by June 2019. Of the 3240 articles found, 21 met inclusion criteria. Study-specific effects were calculated as mean differences, which were pooled using fixed-effect, inverse-variance weighting. Overall, berry polyphenol consumption did not have a clear effect on biomarkers of glucose metabolism compared with placebo or no treatment. Although some analyses showed statistically significant effects, these effects were too small to be of clinical relevance. The review protocol was registered in the PROSPERO International Prospective Register of Systematic Reviews as CRD42019130811

Hypoglycemic effect of the fruit extracts of two varieties of Rubus rosifolius

Oral glucose tolerance test on male Sprague–Dawley rats was done to determine the hypoglycemic effect of the n-hexane, ethyl acetate and methanol fruit extracts (50 mg/kg BW; oral administration) of two varieties of Rubus rosifolius. Metformin was used as a positive control (15 mg/kg BW; intravenous administration). The n-hexane extract was most potent and was investigated phytochemically to yield compound 1, a mixture of triacylglycerols. In its oxidized state compound 1 produced a significant hypoglycemic effect which was more effective than metformin for the first 30 min of the assay (p = .03) and not significantly different for up to 120 min. Mechanisms through which the oxidized triacylglycerol species could form were explored and presented. This is the first account of the hypoglycemic activity of R. rosifolius and it is also the first account of this activity being credited to compounds other than polyphenols and terpenes in Rubus plants

Morphological Characterisation of Wild Rubus rosifolius (Rosaceae) Plants Growing in Jamaica Prior to Agricultural Pursuits

Precise identification of plants is critical for informed agriculture where nutraceutical properties and productivity are simultaneously important. The Jamaican-grown West Indian raspberry (Rubus rosifolius) falls into this category. The first step to taking this wild-growing plant into agricultural production is morphological identification. Although there are no botanical reports of multiple varieties of this species in Jamaica, two morphotypes were found, which were named ‘Red' and ‘Wine Red’ based on fruit colour. Morphological methods were used to characterise these plants growing at Holywell (located over 900 m above sea level), in the Blue Mountain region of Jamaica. Morphological analyses revealed that growth form, leaf, flower, and fruit characteristics of the morphotypes were statistically distinctive between the two morphotypes for 48 of the 59 measured parameters. Several descriptors allowed the morphotypes to be distinguished before their fruits became visible. These findings support the hypothesis that there is a standard morphotype having a scrambling morphology, smaller leaves, and darker red, oblong, solitary fruits (Wine Red, WR), and a distinct morphotype with more upright stems, larger leaves, and lighter red, spherical, bunched fruits (Red, R). This information can now be used to facilitate molecular analyses and ramp-up clonal production of these morphotypes to determine the agricultural factors that are linked to yield and nutritionally relevant traits