Antidiabetic and wound healing effects of smeathxanthone A

Wound healing is a natural and spontaneous phenomenon that takes place in three orderly and timely interactive phases: inflammation, proliferation, and remodelling. Normal wound healing cascade begins immediately following injury. Tissue damage and the activation of clotting factors during the vascular phase stimulate the release of inflammatory mediators, such as prostaglandins and histamine, from cells such as mast cells. The transition from the inflammatory to the proliferative phase, the stage characterized by the filling of the wound with new connective tissues, is orchestrated by macrophages. A decrease in wound size is achieved by a combination of the physiological processes of granulation, contraction, and epithelialization. Reepithelialization phase rebuilds the structure while the remodeling phase involves the final form. Surgery in diabetic patients is associated with slow wound healing process and hence requiring longer hospital stay, higher health care resource utilization, and greater perioperative mortality than nondiabetic subjects. The exact pathogenesis of the poor wound healing process in diabetic patients is not clearly understood, but evidence from studies involving both human and animal models reveal increased rate of infections and several abnormalities in the various phases of wound healing process. With the worldwide diabetes incidence now considered to be increasing in an epidemic proportion, there is a growing need to search for novel drugs to combat diabetes and the associated disorders, such as wound complications. Over 278 natural xanthones belonging to the plant families of Gentianaceae, Guttiferae, Moraceae, Clusiaceae, and Polygalaceae are known to occur. Most xanthones are polyphenols and hence regarded as powerful antioxidants that can offer beneficial health effect either by direct scavenging of reactive oxygen species or by acting as chain-breaking peroxyl radical scavengers. In addition to possessing antioxidant effects, xanthones have also been reported to be hepatoprotective, mutagenic, immunomodulatory, anticomplement, cardioprotective, antitumoral, antidiabetic, anti-inflammatory, antiulcer, and analgesic agents. Smeathxanthone A is a unique xanthone that combines a polyphenolic skeleton with four free hydroxyl groups and a terpenoid geranyl structural moiety. Although the compound has previously been isolated in our laboratories from Garcinia smeathmanii, it has never been investigated for its potential antidiabetic properties. In the present communication, the blood glucose lowering and wound healing effects of smeathxanthone A in diabetic mice are reported

SIGMOISIDE E: A NEW ANTIBACTERIAL TRITERPENOID SAPONIN FROM ERYTHRINA SIGMOIDEA (HUA)

Chemical analysis of the stem bark of Erythrina sigmoidea (Leguminoseae) yielded two known isoflavones, 6,8-diprenylgenisteine (3) and warangalone (4) as well as a new triterpenoid saponin designated sigmoiside E (1). Its structure was established by chemical and spectroscopic means as 16-O-β-D-galactopyranosyl maniladiol (1). Sigmoiside E exhibited antibacterial activity against gram-negative bacteria. KEY WORDS: Erythrina sigmoidea, Stem bark, Triterpenoid, Saponin, Isoflavone, Leguminoseae Bull. Chem. Soc. Ethiop. 2007, 21(3), 373-378

Antioxidant benzophenones and xanthones from the root bark of Garcinia smeathmannii

A new geranylated xanthone (1) was isolated from the root bark extract of Garcinia smeathmannii Oliver along with known guttiferone I, isoxanthochymol, smeathxanthones A and B, and triacontanyl caffeate. The structures of these compounds were elucidated by spectral analysis and by comparison with the reported data. These compounds showed significant antioxidant DPPH radical scavenging activities.   KEY WORDS: Garcinia smeathmanii, Xanthone, Antioxidant  Bull. Chem. Soc. Ethiop. 2006, 20(2), 247-252

Polyanxanthone A, B and C, three xanthones from the wood trunk of Garcinia polyantha Oliv.

Three xanthones, polyanxanthone A (1), B (2) and C (3) have been isolated from the methanol extract of the wood trunk of Garcinia polyantha, along with five known xanthones: 1,3,5-trihydroxyxanthone (4); 1,5-dihydroxyxanthone (5); 1,3,6,7-tetrahydroxyxanthone (6); 1,6-dihydroxy-5-methoxyxanthone (7) and 1,3,5,6-tetrahydroxyxanthone (8). Their structures were determined by means of 1D- and 2D-NMR techniques. Some of the above compounds were screened for their anticholinesterase activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes.info:eu-repo/semantics/publishedVersio

The use of plants in the traditional management of diabetes in Nigeria: Pharmacological and toxicological considerations

Ethnopharmacological relevance: The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system. Materials and methods: Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. ‘Diabetes’ and ‘Nigeria’ were used as keywords for the primary searches; and then ‘Plant name – accepted or synonyms’, ‘Constituents’, ‘Drug interaction’ and/or ‘Toxicity’ for the secondary searches. Results: The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs. Conclusion: This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb–drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided

Ovalifolone A and B: New friedelane derivatives from Garcinia ovalifolia

Lannang AM, Noudou BS, Sewald N. Ovalifolone A and B: New friedelane derivatives from Garcinia ovalifolia. Phytochemistry Letters. 2013;6(2):157-161.Two new friedelane type triterpenoids, ovalifolone A (1) and ovalifolone B (2), together with eight known compounds were isolated from the stem bark of Garcinia ovalifolia. Their structures were established on the basis of mass spectrometric, NMR data and by the comparison with literature data. Some of the isolated compounds were evaluated for their cytotoxicity and antibacterial activities and garcinane showed interesting activity against Artemia salina with LD50 value of 2.69 mu g/mL. (C) 2013 Phytochemical Society of Europe. Published by Elsevier B. V. All rights reserved

Cytotoxic Compounds from the Leaves of Garcinia polyantha

Lannang AM, Tatsimo SJN, Fouotsa H, Dzoyem JP, Saxena AK, Sewald N. Cytotoxic Compounds from the Leaves of Garcinia polyantha. Chemistry & Biodiversity. 2014;11(6):975-981.A new compound, named banganxanthone C (=12-(1,1-dimethylprop-2-en-1-yl)-5,10-dihydroxy-9-methoxy-2-methyl-2-(4-methylpent-3-en-1-yl)-2H, 6H-pyrano[3,2-b]xanthen-6-one; 4), together with five known compounds, were isolated from the leaves of Garcinia polyantha. The structures of the compounds were elucidated on the basis of 1D- and 2D-NMR spectroscopy. Among the known compounds, two were xanthones, one was a pentacyclic triterpene, one sterol, and one benzophenone derivative. Isoxanthochymol (2) and 4-[(2E)-3,7-dimethylocta-2,6-dien-1-yl]-1,5,8-trihydroxy-3-methoxy-9H-xanthen-9-one (3) exhibited significant antiproliferative activity against the leukemia cell line TPH-1 with IC50 inhibition values of 1.5 and 2.8 mu g/ml, respectively. The cytotoxic activity was found to be related to apoptosis induction

<b>Sigmoiside E: A new antibacterial triterpenoid saponin from <i>Erythrina sigmoidea</i> (Hua)</b>

Chemical analysis of the stem bark of <i>Erythrina sigmoidea</i> (Leguminoseae) yielded two known isoflavones, 6,8-diprenylgenisteine (<b>3</b>) and warangalone (<b>4</b>) as well as a new triterpenoid saponin designated sigmoiside E (<b>1</b>). Its structure was established by chemical and spectroscopic means as 16-O-β-D-galactopyranosyl maniladiol (<b>1</b>). Sigmoiside E exhibited antibacterial activity against gram-negative bacteria