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Analyses of essential oils obtained from fresh and dried leaves and inflorescences of Piper clausenianum were performed using GC-FID, GC-MS and NMR techniques. Forty compounds were detected for these four oils with the total of identified constituents ranging from 88.7% for the dried inflorescences to 97.7% for the dried leaves. Sesquiterpenes were the main constituents in the volatile fraction from leaves with a high percentage of (E)-nerolidol (up to 83%). However, monoterpenes were identified in greater amount in the inflorescences, with linalool percentages from 50% up. The essential oils from fresh leaves and inflorescences were submitted to anti-parasitic activity against a strain of Leishmania amazonensis. Both samples showed biological activity, but the essential oil from P. claussenianum fresh leaves, which was rich in (E)-nerolidol, showed effective growth inhibition of L. amazonensis due to the high percentage of this metabolite in the mixture.

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Abstract:The essential oil of Pectis brevipedunculata (EOPB), a Brazilian ornamental aromatic grass, is characterized by its high content of citral (81.9%: neral 32.7% and geranial 49.2%), limonene (4.7%) and α-pinene (3.4%). Vasodilation induced by EOPB and isolated citral was investigated in pre-contracted vascular smooth muscle, using thoracic aorta from Wistar Kyoto (WKY) rats which was prepared for isometric tension recording. EOPB promoted intense relaxation of endothelium-intact and denuded aortic rings with the concentration to induce 50% of the maximal relaxation (IC 50 ) of 0.044% ± 0.006% and 0.093% ± 0.015% (p < 0.05), respectively. The IC 50 values for citral in endothelium-intact and denuded rings were 0.024% ± 0.004% and 0.021% ± 0.004%, respectively (p > 0.05). In endothelium-intact aorta, EOPB-induced vasorelaxation was significantly reduced by L-NAME, a nitric oxide synthase inhibitor. The vasodilator activity of citral was increased in the KCl-contracted aorta and citral attenuated the contracture elicited by Ca 2+ in depolarized aorta. EOPB and citral elicited vasorelaxation on thoracic aorta by affecting the NO/cyclic GMP pathway and the calcium influx through voltage-dependent L-type Ca 2+ channels, respectively.

Candidiasis is a major opportunistic fungal infection in humans, and its incidence has increased steadily over the last two decades. Candida albicans, the main species of the genus, has a large arsenal of virulence attributes that contribute to successful infections, such as dimorphism and biofilm formation. The adverse effects of eukaryotic antimicrobial therapies associated with an increase in resistance to the compounds presently available have boosted efforts to improve the therapeutic arsenal against candidiasis with a newer and cheaper range of drugs. In this study, a novel nerolidol-rich essential oil (EO) derived from Piper claussenianum (Miq.) C. DC., Piperaceae, was tested on the growth, transition (yeast to hyphae), formation and stability of biofilms produced by C. albicans. Both inflorescence and leaf EOs were evaluated and revealed MIC values ranging from 0.04 to 0.1 % and 0.2 to 1.26 %, respectively. Furthermore, leaf EO managed to downregulate the yeast-to-hyphae transition by 81 %, as well as reducing biofilm formation by about 30 and 50 % after incubation for 24 and 48 h, respectively. The EO was also able to reduce the viability of pre-formed biofilm by 63.9 %. Finally, the association between the leaf EO and fluconazole was evaluated and revealed an interesting synergistic effect. Taken together, these results demonstrate that this novel compound could be a promising agent and could reinforce the arsenal of therapeutic alternatives for the treatment of candidiasis. Furthermore, it may represent a novel and natural source of nerolidol, which could be of interest pharmaceutically.

The mosquito, Aedes aegypti, is the principal vector of the viruses responsible for dengue and dengue hemorrhagic fevers. The mosquito is widespread throughout tropical and sub-tropical regions; its prevalence makes dengue one of the most important mosquito-borne viral diseases in the world occurring annually in more than 100 endemic countries. Because blood is essential to their development cycle, the Aedes species maintains a close association with humans and their dwellings. Fittingly, the most widely adopted strategy to decrease the incidence of these diseases is the control of the mosquito larvae population. The emergence of insecticide-resistant mosquitoes has amplified the interest in finding natural products effective against Aedes aegypti adults, as well as larvae. Plantderived compounds have played an important role in the discovery of new active entities for vector management as they are safer and have lower toxicity to humans in comparison to conventional insecticides. This review assesses a naturally occurring plant matrix and pure compounds of the Piper species, which have been shown to be active against Aedes aegypti.

Inflammatory bowel diseases (IBD), which is classified into Crohn’s disease and ulcerative colitis, are among chronic gastrointestinal diseases with unknown pathogenesis. Diverse strategies have been applied for the treatment of this chronic disease. However, selective and site-specific routes of drug delivery to the inflamed location of the colon remain of high importance. Consequently, the application and effects of natural products in the form of nanoformulation and stimuli responsive nanoparticles as a novel strategy for the treatment of IBD are discussed in this review article. This approach may potentially overcome some complications that are associated with conventional means of colon drug delivery. Meanwhile, in vitro and in vivo studies pave the way for understanding of the mechanism that lies behind this chronic relapsing disease and potentially more effective treatment. Graphical abstractᅟ

Irritable bowel syndrome (IBS) is a well diagnosed disease, thoroughly attributed to series of symptoms criteria that embrace a broad range of abdominal complainers. Such criteria help to diagnosis the disease and can guide controlled clinical trials to seek new therapeutic agents. Accordingly, a verity of mechanisms and pathophysiological conditions including inflammation, oxidative stress, lipid peroxidation and different life styles are involved in IBS. Predictably, diverse therapeutic approaches are available and prescribed by clinicians due to major manifestations (i.e., diarrhea-predominance, constipation-predominance, abdominal pain and visceral hypersensitivity), psychological disturbances, and patient preferences between herbal treatments versus pharmacological therapies, dietary or microbiological approaches. Herein, we gathered the latest scientific data between 1973 and 2019 from databases such as PubMed, Google Scholar, Scopus and Cochrane library on relevant studies concerning beneficial effects of herbal treatments for IBS, in particular polyphenols. This is concluded that polyphenols might be applicable for preventing IBS and improving the IBS symptoms, mainly through suppressing the inflammatory signaling pathways, which nowadays are known as novel platform for the IBS management.