No abstract

Boswellic acids (BAs), a group of pentacyclic triterpenoids, have demonstrated very interesting biological properties that resulted in a number of protocols being developed for their synthesis. During the last twenty-five years (1990-2015), numerous BAs have been prepared. Both natural BAs and their synthetic derivatives can be used to treat various cancers as well as inflammatory diseases. Areas covered: This review covers patents on therapeutic activities of natural BAs and their synthetic derivatives published in last twenty-five years (1990-2015). Only BA patents to treat cancer and inflammation are available. A discussion about structure-activity relationships (SAR) of these analogs is also included. Expert opinion: BAs possess excellent anticancer and anti-inflammatory properties. A large number of BAs and their analogues have been prepared through modification at the C-OH and C-COH functional groups. Most importantly, the C-24 amide and amino derivatives demonstrated increased anticancer and anti-inflammatory activity compared with other BA derivatives. Furthermore, BAs have the potential to form conjugates with other anticancer drugs that will synergistically enhance their anticancer effects; and we believe that in order to get lead compounds, there needs to be a greater focus on the synthesis of halo derivatives of BAs.

Glycyrrhetinic acids (GAs) viz., 18β-glycyrrhetinic acid and 18α-glycyrrhetinic acid, are oleanane-type triterpenes having a carboxylic acid group at C-30, and are extracted from the Chines herbal medicine licorice (Glycyrrhiza uralensis). Although the pharmacological properties of GAs have long been known, attention to them has greatly increased in recent times due to their cytotoxic activity. Areas covered: This review represents the patents granted about natural and synthetic glycyrrhetinic acid analogs from January 2010 to December 2017, the advances made by research groups in conjunction with pharmaceutical companies in the discovery of new natural or synthetic glycyrrhetinic acid analogs. Expert opinion: GAs demonstrate excellent cytotoxic, antimicrobial, enzyme inhibitory, antiinflammatory, antioxidant, analgesic, and antiviral effects. It is interesting to note that the C-(OH) and CCOH functional groups make GAs very attractive lead structures for medicinal scientists since these functionalities allow the generation of further chemical diversity for improved pharmacological effects. Moreover, various GA analogues have been prepared via modification of the CCOH. It is noteworthy that the C-30 amide of GA demonstrated better cytotoxic effects compared to the parent compounds. In addition, GAs have the capability to conjugate with other anticancer drugs or be converted into their halo or amino analogs which is expected to stimulate medicinal chemist to synthesize new lead compounds in cancer drug discovery.

Two-dimensional oxyhydroxide materials are proved to be a potential candidate for oxygen evolution reaction (OER). Robust, efficient, and cost-effective electrocatalysts are critical to overcome the sluggish kinetics and high overpotential of OERs. Herein, a simple co-precipitation method followed by solvothermal treatment is used to synthesize Fe-doped α-CoOOH at higher pH under optimum conditions for OER. The α-Fe 0.24 Co 0.76 OOH/NF illustrates superior OER electrocatalytic performance and requires an overpotential of only 280 mV to produce a current density of 50 mA cm −2 with excellent stability. The detailed analysis reveals that the exceptional OER performance originates from thin nanorods and partially due to the replacement of Fe in α-CoOOH. This work illustrates the presence of interlayer chloride ions through energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.

Here, we present the fabrication of a reduced graphene oxide-supported PdCa (PdCa/rGO) alloyed catalyst via a NaBH 4 reduction method for direct alcohol fuel cells in basic medium and direct formic acid fuel cells in acidic medium. Powder X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer−Emmett− Teller, inductively coupled plasma mass spectrometry, and Raman spectroscopy are used to characterize the PdCa/rGO catalyst. We proved that the calcium oxide significantly enhances the electrocatalytic methanol, ethanol, and formic acid oxidation over the Pd/rGO surface. The obtained mass activities for PdCa/rGO are 4838.06, 4674.70, and 3906.49 mA mg −1 for formic acid, methanol, and ethanol, respectively. Long-term stability, high activity, and high level of tolerance to CO poisoning of the PdCa/rGO electrocatalyst are attributed to the presence of calcium oxide. These results prove that the PdCa/rGO catalyst has improved electrocatalytic performance for the oxidation of formic acid, methanol, and ethanol with reference to the Pd/rGO.