RESUMO

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.

RESUMO

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. PRACTICAL APPLICATIONS: A significant percentage of the world's population is affected by diabetes and diabetes-related illnesses. One of the most popular antidiabetic drug on the market is metformin which is used to lower blood glucose concentrations. The findings of this study indicate that an oxidized mixture of triacylglycerols is more fast-acting than metformin for the first 30 min of an oral glucose tolerance test. This effect was also not significantly different from that of the popular drug up to 120 min. These results demonstrate the hypoglycemic activity of an oxidized R. rosifolius fruit extract and indicate its potential use in applications such as functional food product development and drug discovery. Therapeutic applications can also include the plant extract as a potential primary treatment or as adjunct therapy to conventional medications.

Assuntos

RESUMO

Psidium cattleianum (strawberry guava) is one of many underutilised edible fruits that grow wild in Jamaica, and could potentially be commercially exploited to yield health and economic benefits. In this study, the total phenolics, proximate contents, and antioxidant, anti-inflammatory, and antimicrobial activities of P. cattleianum and P. guajava (common guava), a well-known species, were compared. Strawberry guavas were found to be superior to common guavas in antioxidant and antimicrobial activities, total phenolics and vitamin C content. They also possessed relatively high fibre content (24.9%). The hexane and ethyl acetate extracts of strawberry guavas showed cyclooxygenase-2 enzyme inhibitory activities of 18.3% and 26.5%, respectively (250 µg/mL), indicating anti-inflammatory activity. The EtOAc and MeOH extracts of P. guajava showed 56.4% (COX-2) and 44.1% (COX-1) inhibitory activity, respectively. Additionally, nine compounds were isolated from strawberry guava fruits, some of which demonstrated anti-inflammatory activity. These results indicate that strawberry guavas are beneficial for health.

Assuntos

RESUMO

Consumption of improperly ripened ackee ( Blighia sapida K.D. Koenig) often results in fatalities. The causal toxin, hypoglycin A, decreases in the edible arilli upon maturity; regulation of hypoglycin A in the arilli is thus critical. Hypoglycin B, also toxic, is confined to the seeds. Hypoglycins A and B were tracked in ackees grown in Jamaica over different maturity stages using RP-HPLC. Studies on the 'Butter' and 'Cheese' ackee varieties and across two different harvest seasons were conducted. In 'Cheese' ackees, hypoglycin A decreased from about 8000 mg/kg in the green arilli and seeds to 271 and 1451 mg/kg, respectively, in the ripe fruit whereas hypoglycin B levels in the seeds increased from 1629 to 11774 mg/kg. The strong inverse relationship demonstrated that hypoglycin B in the seeds serves as a sink for hypoglycin A from the ripening arilli and is thereby involved in the detoxification mechanism of the fruit.

Assuntos

RESUMO

The dipeptide hypoglycin B, one of two toxins of the ackee fruit (Blighia sapida Koenig), was characterized for the first time by NMR spectral data, which led to the discovery that it exists naturally as a pair of diastereomers. No distinction was observed in the (1)H NMR signals of the diastereomers; however, complete and distinct (13)C NMR assignments for the individual diastereomers were made. The (13)C NMR spectrum of hypoglycin B compared very well with that of the corresponding signals in the spectrum for hypoglycin A, which is one of its constituent amino acids. The (1)H and (13)C NMR assignments were further supported by DEPT, gCOSY, gHSQC and gHMBC experiments.

Assuntos