A. J. J. van den Berg

Curcacycline A — a novel cyclic octapeptide isolated from the latex of Jatropha curcas L.

From the latex of Jatropha curcas L. (Euphorbiaceae) a novel cyclic octapeptide was isolated, which we named curcacycline A. The compound was found to contain one threonine, one valine, two glycine, and four leucine residues. By two‐dimensional 1H‐NMR spectroscopy (HOHAHA and ROESY), its sequence was determined to be Gly1‐Leu2‐Leu3‐Gly4‐Thr5‐Val6‐Leu7Leu8‐Gly1. Curcacycline A displays a moderate inhibition of (i) classical pathway activity of human complement and (ii) proliferation of human T‐cells.

Inhibition of human complement by beta-glycyrrhetinic acid.

Licorice, the root extract of Glycyrrhiza glabra L., is used as a medicine for various diseases. Anti‐inflammatory as well as anti‐allergic activities have been attributed to one of its main constituents, glycyrrhizin. These activities are mainly ascribed to the action of the aglycone, β‐glycyrrhetinic acid. β‐Glycyrrhetinic acid has a steroid‐like structure and is believed to have immunomodulatory properties. To determine whether interference with complement functions may contribute to the immunomodulatory activity of β‐glycyrrhetinic acid, its effects on the classical and alternative activation pathways of human complement were investigated. We found that β‐glycyrrhetinic acid is a potent inhibitor of the classical complement pathway (IC50=35 μm), whereas no inhibitory activity was observed towards the alternative pathway (IC50>2500 μm). The anticomplementary activity of β‐glycyrrhetinic acid was dependent on its conformation, since the α‐form was not active. It was also established that naturally occurring steroids, e.g. hydrocortisone and cortisone, did not inhibit human complement activity under similar conditions. Detailed mechanistic studies revealed that β‐glycyrrhetinic acid acts at the level of complement component C2.

Effects of low molecular constituents from Aloe vera gel on oxidative metabolism and cytotoxic and bactericidal activities of human neutrophils

In traditional South-East Asian medicine the therapeutic value of the parenchymous leaf-gel of Aloe vera for inflammatory-based diseases is well-reputed. The aim of this study is to investigate at which level gel-constituents exert their activity. We show here that low -Mr constituents of an aqueous gel-extract inhibit the release of reactive oxygen species (ROS) by PMA-stimulated human PMN. The compounds inhibit the ROS-dependent extracellular effects of PMN such as lysis of red blood cells. The capacity of the PMN to phagocytose and kill micro-organisms at the intracellular level is not affected. The inhibitory activity of the low-Mr compounds is most pronounced in the PMA-induced ROS production, but is significantly antagonized by the Ca-ionophore A23187. It is shown that the inhibitory effect of the low-Mr compounds is the indirect result of the diminished availability of intracellular free Ca-ions.

Immunomodulatory and anti-inflammatory activity of Picrorhiza scrophulariiflora.

Extracts of the rhizomes of Picrorhiza scrophulariiflora Pennell (Scrophulariaceae) were investigated for their in vitro and in vivo immunomodulatory properties. Diethyl ether extracts showed potent inhibitory activity towards the classical pathway of the complement system, the respiratory burst of activated polymorphonuclear leukocytes, and mitogen-induced proliferation of T-lymphocytes. Furthermore, such extracts showed anti-inflammatory activity towards carrageenan-induced paw edema. No effects were observed in experimentally induced arthritis in mice.

Anti-inflammatory properties of a liposomal hydrogel with povidone-iodine (Repithel®) for wound healing in vitro

A liposomal hydrogel with 3% povidone-iodine (PVP-ILH, Repithel) has shown clinical benefit in settings where inflammation and/or reactive oxygen species are thought to impede wound healing (e.g., burns, chronic wounds and in smokers). This in vitro study investigated whether PVP-ILH is able to reduce inflammatory events responsible for the impairment of the wound healing process in such patients. Therefore, the following assays were conducted with PVP-ILH (and derived control hydrogels to identify the component responsible for the effect): inhibition of reactive oxygen species production by human polymorphonuclear neutrophils (PMNs) and in a cell-free system, oxygen consumption assay of PMNs (prior to oxidative burst), inhibition of human complement (limiting the generation of complement factors), mast cell degranulation, nitric oxide production by murine macrophages and TNF-alpha production by human monocytes/macrophages. Where toxicity could cause cell inhibition, cell viability was assessed. PVP-ILH and its components interacted in our series of bioassays at various stages in the inflammation cascade. Scavenging of superoxide anions was the most pronounced effect. Furthermore, povidone-iodine inhibited PMN production of reactive oxygen species (inhibition of oxygen consumption) and a mast cell inhibitory (stabilising) activity was observed. Based on these results, the clinically observed, beneficial wound healing effects of PVP-ILH may also be attributed to an impediment of inflammatory activity, mainly by iodines free radical scavenging. Controlling oxidative stress in the wound may be of great importance, especially since further reactions as, e.g., the formation of peroxynitrite from NO and ROS are prevented.

Fermentation in traditional medicine: the impact of Woodfordia fruticosa flowers on the immunomodulatory activity, and the alcohol and sugar contents of Nimba arishta

Abstract The impact of Woodfordia fruticosa flowers on the immunomodulatory activity, and alcohol and sugar contents of the ayurvedic drug ‘Nimba arishta’ was investigated by means of model preparations. The use of Woodfordia flowers in model preparations resulted in a substantial increase of the inhibition of both human complement activity and chemiluminescence generated by zymosan-stimulated human polymorphonuclear leukocytes. It was established that the increased biological activity was not due to microbial interference, but to immuno-active constituents released from the Woodfordia flowers. It was also found that the flowers themselves are not the source of alcohol-producing microorganisms. Experiments performed with yeasts isolated from commercial Nimba arishtas showed, in agreement with empirical findings, significantly raised alcohol content upon addition of Woodfordia. An invertase activity exhibited by Woodfordia flowers may be causative of this effect.

Characterization of anti-complement compounds from azadirachta indica

The crude aqueous extract of Azadirachta indica bark possesses an inhibitory activity on both classical (CP) and alternative pathway (AP) activation of human complement. Purification of the compounds with the guidance of the AP-inhibitory activity involved extraction with methanol, dialysis, ion-exchange procedures and gel-permeation chromatography. This sequence yielded two polymers, NB-I and NB-II, one a highly active compound with a relatively low molecular weight (NB-II) and the other a less active compound with a high molecular weight (NB-I). The polymers were characterized by using colour reactions, TLC, GLC and HPLC after hydrolysis and gel-permeation chromatography as peptidoglycans. The carbohydrate part consisted predominantly of glucose. Arabinose, galactose and mannose were present in minor amounts (NB-II) or only as traces (NB-I). Protein was present for 5.5% in NB-I and for 9.8% in NB-II.

In vitro immunomodulatory activity of Filipendula ulmaria

Extracts of the roots, herb and flowers of Filipendula ulmaria (L.) Maxim. were investigated for in vitro immunomodulatory properties. Strong inhibitory activity was found towards the classical pathway of complement in the ethyl acetate extracts of roots and flowers, in all methanol extracts and in the aqueous root extract. Except for the light‐petroleum extracts, all fractions tested inhibited the production of reactive oxygen species by human polymorphonuclear leukocytes. The diethyl ether root extract was found to be most potent in inhibiting lymphocyte proliferation. The role of tannins and other constituents in these processes are discussed.

Anthra-derivatives in suspension cell cultures of rhamnus frangula

Abstract Suspension cultures of Rhamnus frangula accumulated, predominantly, glycosides of physcion (and its reduced forms). The total content of anthra-aglycones was determined to be 0.28% (w/w, dry wt.) by an HPLC procedure based on gradient elution.

Rhamnus spp.: In Vitro Production of Anthraquinones, Anthrones, and Dianthrones

Dried bark of Rhamnus purshiana and Rhamnus frangula (family Rhamnaceae), stored for at least 1 year before use, is used medicinally as a purgative. Rhamnus purshiana DC (cascara buckthorn, chittem bark, sacred bark, bitter bark, bearwood) is a small tree (1.5 to 12 m) or large shrub indigenous to the Pacific Coast of North America. The bark of R. purshiana is light- to dark brown, marked with lenticels and yellow on the inside. The transversely cut surface of the bark shows a yellowish-grey cortex in which darker translucent points (groups of sclereids) are present. Most of the present-day market supply comes from wild trees in Oregon, Washington and British Columbia (Tyler et al. 1981). Efforts to cultivate the tree commercially in Canada, Kenya, and the western United States have been largely unsuccessful (Morton 1977). Rhamnus frangula L. (Frangula alnus Mill., buckthorn, alder buckthorn) is a shrub (1 to 3 m) growing in Europe and Western Asia. The bark of R. frangula is grey-brown and bears many transversely elongated whitish lenticels (Fig. 1). The structure of the bark is very similar to that of R. purshiana, from which it is distinguished, however, by the absence of groups of sclereids. The commercial supply is obtained from Russia and the southern Balkan countries. The main cathartic principles of both barks are known to be 1,8-dihydroxyanthraquinone glycosides (Fairbairn and Moss 1970). For medical application usually aqueous or dry extracts are used. However, not only anthraquinones but also other 1,8-dihydroxyanthracene derivatives, i.e., anthrones and dianthrones, are found in these barks. The structural relationships between 1,8-dihydroxyanthraquinones and their corresponding anthrones and dianthrones are given in Fig. 2. 1,8-Dihydroxyanthracene derivatives accumulating in Rhamnus species are biosynthesized by the acetate-malonate pathway (poly-ketides) (Leistner and Zenk 1969).