Introduction: Dipeptidyl peptidase 4 (DPP-4) belongs to the family of serine proteases and is involved in the degradation of GLP-1 and GIP hormones, which enhance the production and release of insulin. Targeting DPP-4 inhibitors is increasingly being considered as promising paradigms to treat type 2 diabetes mellitus and therefore DPP-4 inhibitors are being considered as promising antidiabetic drugs.Areas covered: This review provides an overview of published patents describing natural and synthetic DPP-4 inhibitors from January 2015 to December 2018.Expert opinion: A fair number of new synthetic and natural DPP-4 inhibitors have been reported in last four years which describe the progress in the development of various heterocyclic scaffolds or heterocyclic hybrid compounds. As a result of this, many marketed DPP-4 inhibitors that have been approved by the appropriate governing bodies during the past decade, have been introduced as inhibitors. Molecular hybridization is an emerging idea in medicinal chemistry and therefore hybrid compounds of DPP-4 inhibitors with other DPP-4 inhibitors or with antidiabetic drugs should be formulated for a comprehensive evaluation. More detailed pharmacovigilance of DPP-4 inhibitors is required because this will address the pancreas-related adverse events as well as their impact on cardiovascular outcomes via long-term studies.

The whole plant material of Corydalis adiantifolia Hook.f. & Thomson was investigated for biological activities e.g. antifungal, antibacterial, insecticidal, cytotoxic, anticancer and phytotoxic activities and preliminary phytochemical screening. The methanol extract and dichloromethane fraction of the plant species exhibited 5% inhibition each against the fungus Aspergillus flavus. The methanol extract and water and dichloromethane fractions exhibited non-significant antibacterial activity and they showed inhibition against Hela cell lines and insignificant insecticidal activity. To understand the bioactive profile of C. adiantifolia, phytochemical screening approach is considered effective. The samples including methanol extract and n-hexane, dichloromethane, ethyl acetate and water fractions were subjected to qualitative phytochemical screening for the presence of various phytochemicals i.e. alkaloids, flavonoids, saponins, diterprenes, triterpenoids, anthraquinones, anthranol glycosides, reducing sugars and phenols. The results exhibited the efficacy of methanol extract showing the presence of more phytochemicals in comparison to the fractions of C. adiantifolia. Moreover, as a result of phytochemical isolation, 8-acetonyldihydrosanguinarine (1), β-sitosterol (2) and β-sitosterol-β-D-glucoside (3) were isolated, purified, and characterized by spectroscopic methods. To the best of our knowledge, all this study was carried out for the first time on C. adiantifolia.

Hunteria umbellata K. Schum has been reported for the treatment of diabetes in Nigeria. In the present study, the ethanolic extract of dried leaves of Hunteria umbellata K. Schum was investigated for the chemical principles. The isolated pure compounds were characterized by NMR, IR and Mass spectral studies. Ursolic acid (1), oleanolic acid (2) and squalene (3) were the main constituents isolated from the extract.

Introduction: Protein tyrosine phosphatase 1B (PTP1B) inhibition has been recommended as a crucial strategy to enhance insulin sensitivity in various cells and this fact is supported by human genetic data. PTP1B inhibitors improve the sensitivity of the insulin receptor and have the ability to cure insulin resistance-related diseases. In the latter years, targeting PTP1B inhibitors is being considered an attractive target to treat T2DM and therefore libraries of PTP1B inhibitors are being suggested as potent antidiabetic drugs.Areas covered: This review provides an overview of published patents from January 2015 to December 2018. The review describes the effectiveness of potent PTP1B inhibitors as pharmaceutical agents to treat type 2 diabetes.Expert opinion: Enormous developments have been made in PTP1B drug discovery which describes progress in natural products, synthetic heterocyclic scaffolds or heterocyclic hybrid compounds. Various protocols are being followed to boost the pharmacological effects of PTP1B inhibitors. Moreover these new advancements suggest that it is possible to get small-molecule PTP1B inhibitors with the required potency and selectivity. Furthermore, future endevours via an integrated strategy of using medicinal chemistry and structural biology will hopefully result in potent and selective PTP1B inhibitors as well as safer and more effective orally available drugs.