Fijian medicinal plants and their role in the prevention of Type 2 diabetes mellitus.

Medicinal plants (MPs) are natural sources of active compounds with potential therapeutic benefits in alleviating various illnesses for decades. Fijian people also are using these MPs for the management/prevention of Type 2 diabetes mellitus (T2DM) and associated complications. However, till date, none of these Fijian MP's antidiabetic potential have been explored or evaluated. Here, we investigated the antidiabetic potential of Fijian MPs scientifically. Phytochemicals such as polyphenols were detected to inhibit the activity of α-amylase and α-glucosidase, the two key carbohydrate enzymes linked to T2DM. Therefore, in the present study, the total phenolic content (TPC), α-amylase and α-glucosidase inhibitory activity of five Fijian MPs: Vobo (Mussaenda raiateensis, MR), Vula walu (Blechnum orientale, BO), Gasau (Miscanthus floridulus, MF), Molikaro (Citrus limon, CL) and Beki ni sina (Dicranopteris caudate, DC) collected from mainland region of Vitilevu, Fiji Islands, were evaluated in vitro. The hydromethanolic (ME) and dichloromethane (DM) extracts of these selected MPs were investigated. The ME extracts of BO (0.102 ± 0.009 mM CE) and DC (0.098 ± 0.09 mM Catechin Equivalence [CE]) showed a higher TPC compared with the control [vanillic acid (0.052 ± 0.003 mM CE, *P value < 0.05)]. However, the TPC of MF, MR and CL were found in the range of 0.020 ± 0.009 to 0.009 ± 0.01 mM CE. The ME extracts of MF and MR inhibited α-glucosidase significantly in comparison with acarbose as evidenced from the IC50 values (IC50 of MF = 1.58 ± 0.03 ng/µl; IC50 of MR = 1.87 ± 0.43 ng/µl and IC50 of acarbose = 3.34 ± 0.15 ng/µl). Moreover, DM extracts of MR (IC50 = 1.31 ± 0.29 ng/µl) also showed significantly higher α-glucosidase inhibitory activity. In contrary, MR (IC50 = 16.18 ± 0.16 ng/µl) and CL (IC50 = 9.21 ± 0.51 ng/µl) also showed significant α-amylase inhibitory activity in ME and DM extracts, respectively. These, results suggest that Fijian MPs could be a potential source of natural inhibitors of enzymes involved in carbohydrate digestion and thus may possibly be used in managing T2DM.

Geometrically Precise Building Blocks: the Self-Assembly of ß-Peptides.

Peptides comprised entirely of ß-amino acids, or ß-peptides, have attracted substantial interest over the past 25 years due to their unique structural and chemical characteristics. ß-Peptides form well-defined secondary structures that exhibit different geometries compared with their α-peptide counterparts, giving rise to their foldamer classification. ß-Peptide foldamers can be functionalized easily and are metabolically stable and, together with the predictable side-chain topography, have led to the design of a growing number of bioactive ß-peptides with a range of biological targets. The strategic engineering of chemical and topographic properties has also led to the design of ß-peptide mimics of higher-order oligomers. More recently, the ability of these peptides to self-assemble into complex structures of controlled geometries has been exploited in materials applications. The focus of this mini-review is on how the unique structural features of ß-peptide assemblies have been exploited in the design of self-assembled proteomimetic bundles and nanomaterials.

Folate content and retention in commonly consumed vegetables in the South Pacific.

This paper reports the effect of boiling and frying on the retention of folate in commonly consumed Fijian vegetables (drumstick leaves, taro leaves, bele leaves, amaranth leaves, fern/ota, okra and French bean). The folate content was determined by microbiological assay (Lactobacillus casei rhamnosus) and tri-enzyme (protease, α-amylase and chicken pancreas conjugase) extraction treatment. The folate loss varied among the vegetables from 10-64% on boiling while 1-36% on frying. The higher folate loss was observed during boiling. The folate content in the water derived after boiling different vegetables ranged from 11.9 ± 0.5 to 61.6 ± 2.5 µg/100mL. The folate loss on boiling was accounted for in the cooking water. The predominant way of folate loss on boiling was leaching rather than thermal degradation which makes boiling the better choice of cooking the studied vegetables for folate intake, provided the cooking water is consumed together with the vegetables.

Conformational stability studies of a stapled hexa-ß3-peptide library.

A library of 14-helical hexa ß(3)-peptides was synthesized in order to determine the influence of sequence variation as well as staple size and location on conformational stability. From this study we show that appropriately stapled hexa-ß(3)-peptides can allow for a number of variations without significant perturbation of the 14-helix.

Synthesis of stapled beta3-peptides through ring-closing metathesis.

The first synthesis of carbon-stapled beta(3)-peptides is reported. The precursor beta(3)-peptides, with O-allyl beta-serines located in an i/i+3 relationship, were prepared on solid phase. We show that efficient ring-closing metathesis (RCM) of these new beta(3)-peptides proceeds smoothly either in solution or on an appropriate solid support. All products were generated with high selectivity for the E-isomer.