Iridoids belong to a family of monoterpenoids comprising the cyclopentan[c]-pyran system; this class of compounds offers a wide range of biological effects, namely antileishmanial, anticancer, antiplasmodial, and anti-inflammatory potency. To date, a large number of biologically active iridoid derivatives have been reported from various plant families, including Rubiaceae, Plantaginaceae, Scrophulariaceae, and Verbenaceae. Furthermore, iridoids have the potential to form conjugates with other anticancer, antidiabetic, antileishmanial, and antimalarial drugs which synergistically have the potential to increase their effects. Additionally, future research should focus on the synthesis of halo analogs as well as preparing homo dimers or heterodimers of iridoids, since these might quite conceivably possess an increased bioactivity.

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.

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.

Background: Cucurbitacins belong to a group of tetracyclic triterpenoids that display a wide range of biological effects. In the past, numerous cucurbitacins have been isolated from natural sources and many active compounds have been synthesized using the privileged scaffold in order to enhance its cytotoxic effects.Objective: This review covers patents on the therapeutic effects of natural cucurbitacins and their synthetic analogs published during the past decade. By far, the majority of patents published are related to cancer and Structure-Activity Relationships (SAR) of these compounds are included to lend gravitas to this important class of natural products.Methods: The date about the published patents was downloaded via online open access patent databases.Results: Cucurbitacins display significant cytotoxic properties, in particular cucurbitacins B and D which possess very potent effects towards a number of cancer cells. Numerous cucurbitacins isolated from natural sources have been derivatized through chemical modification at the C(2)-OH and C(25)OH groups. Most importantly, an acyl ester of the C(25)-OH and, iso-propyl, n-propyl and ethyl ether groups of the C(2)-OH demonstrated the most increased cytotoxic activity.Conclusion: The significant cytotoxic effects of natural and semi-synthetic cucurbitacins make them attractive as new drug candidates. Moreover, cucurbitacins have the capability to form conjugates with other anticancer drugs which will synergistically enhance their anticancer effects. The authors believe that in order to get lead compounds, there should be a greater focus on the synthesis of homodimers, heterodimers, and halo derivatives of cucurbitacins. In the opinion of the authors the analysis of the published patents on the cucurbitacins indicates that these compounds can be developed into a regimen to treat a wide spectrum of cancers.

Gold is considered as an inert metal and ranks as one of the noblest among all the metals. Progressive importance associated with nanotechnology offers potential development of new methods and controlled morphologies of the anisotropic gold nanostructures to develop its innovative properties and commensurate applications. The unique gold nanostructures are considered for their potential applications in various fields due to their large surface area, excellent adhesion properties and resistance to corrosion. In this review, we will present recent developments for gold nanorings and nanotubes, under the headings of synthesis, properties and potential applications in various fields.

Phenazines are nitrogen-containing heterocycles which possess a wide range of biological activities and in particular, cytotoxic effects. Moreover, various phenazines have been prepared having alkyl, amide, carboxylic acid, aldehyde, and pyrano groups. These synthetic phenazines possess significant anticancer effects towards various cancers. On the other hand, only a few natural phenazines have been reported with anticancer effects. This chapter presents a comprehensive overview of the most recent patents related to the phenazines as anticancer agents.

Compounds isolated from different natural sources have over the years played crucial roles in the treatment of a wide range of human diseases. Over the past six decades, microorganisms have provided valuable active compounds for the treatment of various diseases. Fungi, in general, produce diverse structural classes of natural products including polyketides, a major class of secondary metabolites obtained from various natural sources‚ which as a group have interesting chemical diversity. In addition, polyketides are known to possess a number of biological and pharmacological effects, viz. cytotoxic, antibacterial, antifungal, antiparasitic, and immunosuppressive effects. In this chapter the focus is on describing the cytotoxic effects of polyketides isolated from fungi and in particular their potential as cancerostatic pharmaceuticals.