Nitric-Oxide-Mediated Vasodilation of Bioactive Compounds Isolated from Hypericum revolutum in Rat Aorta.

Vasodilators are an important class in the management of hypertension and related cardiovascular disorders. In this regard, the chloroform fraction of Hypericum revolutum (HR) has been reported to produce vasodilating activity in phenylephrine-precontracted aortae. The current work aims to identify the active metabolites in the chloroform fraction of HR and illustrate the possible mechanism of action. The vasodilation activities were investigated using the isolated artery technique. NO vascular release was assessed by utilizing the NO-sensitive fluorescent probe DAF-FM. Free radical scavenging capacity was assessed utilizing DPPH. Chemical investigation of this fraction yielded two new compounds, revolutin (1) and hyperevolutin C (2), along with three known metabolites, ß-sitosterol (3), euxanthone (4), and 2,3,4-tirmethoxy xanthone (5). Compounds 1, 2, 3, and 5 showed significant vasodilation activities that were blocked by either endothelial denudation or L-NAME (nitric oxide synthase inhibitor), pointing towards a role of endothelial nitric oxide in their activities. In confirmation of this role, compounds 1-3 showed a significant release of NO from isolated vessels, as indicated by DAF-FM. On the other hand, only compound 5 showed free radical scavenging activities, as indicated by DPPH. In conclusion, isolated compounds 1, 2, 3, and 5 produce vasodilation activities that are dependent on endothelial nitric oxide release.

Natural Peroxisome Proliferator-Activated Receptor γ (PPARγ) Activators for Diabetes.

CONTEXT: Metabolic syndrome (MetS) represents a worldwide problem. Drugs used in MetS target different symptoms, like excessive body weight, insulin resistance, hyperglycemia, dyslipidemia, or hypertension. Peroxisome proliferator-activated receptors (PPAR) regulate the gene expression involved in lipid metabolism, inflammation, and adipogenesis. Activation of PPARγ has become a target of interest to counter hyperglycemia linked with MetS and type 2 diabetes (T2DM). OBJECTIVE: The current review intended to summarize reported research on medicinal plants, or their bioactive constituents, with PPARγ-activating potential. DESIGN: The research team searched the literature up to 2016 using electronic databases- ScienceDirect, PubMed, Google-Scholar, SpringerLink, Scopus, and Wiley-for publications on medicinal plants with promising PPARγ modulators using keywords diabetes mellitus, natural products, peroxisome proliferator-activated receptors, metabolic syndrome, adipogenesis. SETTING: This study was conducted in the Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia, Department of Pharmacognosy, Faculty of Pharmacy, Cairo University, Cairo, Egypt, and Department of Pharmacognosy and Pharmaceutical Chemistry, College of Pharmacy, Taibah University, Al Madinah, Al Munawwarah, Saudi Arabia. RESULTS: Several natural products were considered to be good ligands for PPARγ. The PPARγ agonistic activity of over 100 plants covered in this review was supported by experimental evidence. Some of the plants and their constituents had been studied for their possible mechanisms of action. CONCLUSIONS: Findings discussed in this review highlighted PPARγ's role as an organizer of lipid metabolism and glucose homeostasis, thus supporting its function as a target for antidiabetic agents. The discovery that some natural compounds and plants could activate PPARγ opens up the prospect for future development of strategies to take advantage of its therapeutic potential in diabetes. Therefore, the current review could provide significant information for biotechnological or pharmaceutical applications in targeted drug delivery and design.

Perisomalien A, a new cytotoxic scalarane sesterterpene from the fruits of Periploca somaliensis.

The CHCl3 fraction of MeOH extract of Periploca somaliensis (family Asclepiadaceae) fruits afforded a new scalarane sesterterpene, namely perisomalien A (1), along with lupeol acetate (2), ß-amyrin (3), cycloart-23Z-ene-3ß,25-diol (4), and ß-sitosterol-3-O-ß-D-glucopyranoside (5). Their chemical structures were established by various spectroscopic analyses, in addition to comparison with the formerly reported data. Moreover, the cytotoxic activity of these metabolites was assessed towards MCF-7, HepG2, and HCT-116 tumour cell lines using sulforhodamine B (SRB) assay. Compound 4 showed the most potent cytotoxic profile with IC50 9.0 µM towards MCF-7, compared to doxorubicin (IC50 0.18 µM). Also, 1 and 4 possessed the most potent effect towards HepG2 with IC50s 26.7 and 25.9 µM, respectively. In addition, all tested compounds showed cytotoxic effects with IC50 values ranging from 19.9 to 39.3 µM against HCT-116.

Anti-inflammatory activity of selected plants from Saudi Arabia.

Thirteen selected Saudi Arabian plants, belonging to seven different families, were tested for possible anti-inflammatory activity using the carrageenin-induced paw edema model in rats. The methanolic extracts of Vernonia schimperi, Trichodesma trichodesmoides var. tomentosum, and Anabasis articulata exhibited the highest anti-inflammatory activity. The active extracts were further subjected to fractionation with chloroform, ethyl acetate, and n-butanol and tested together with their mother liquor for their anti-inflammatory activity in the same rat model. The most potent fractions were the n-butanol fractions of Anabasis articulata and Vernonia shimperi and the aqueous mother liquor of Trichodesma trichodesmoides. Nevertheless, the three potent methanolic extracts showed higher anti-inflammatory activities than their individual fractions. The antioxidant properties were assessed by their in vitro 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activities. It was concluded that the anti-inflammatory activity is dependent, at least in part, on the reduction of prostaglandin (PGE2) and tumour necrosis factor-alpha (TNF-alpha) levels and cyclooxygenase-2 (COX-2) activity.

Antihyperglycemic activity of Caralluma tuberculata in streptozotocin-induced diabetic rats.

The current study aimed at evaluating the potential and mechanisms of the antidiabetic activity of the methanolic extract (ME) of Caralluma tuberculata as well as its chloroform (CF), n-butanol (BF) and the remaining water fractions (RFs) in streptozotocin-induced diabetic rats. The antidiabetic activity was evaluated through assessing fasting blood glucose (FBG), insulin levels, oral glucose tolerance test (OGTT), glucose utilization by isolated rat psoas muscle, gut glucose absorption and G-6-Pase activity in isolated rat liver microsomes. Both ME and RF showed the highest potency, where ME had superior activity. The mechanism underlying the observed antihyperglycemic activity of ME could be attributed, at least in part, to enhanced skeletal muscle utilization of glucose, inhibition of hepatic gluconeogenesis and stimulation of insulin secretion. ME was standardized through LC-MS analysis for its major pregnanes.