Modulating Effects of Arabinogalactans from Plant Gum Exudates on Human Complement System.

Gum arabic and cashew nut tree gum exudate polysaccharide (CNTG) are plant polysaccharides composed of galactose and arabinose known as arabinogalactans (AGs). Although these fractions are used in food and pharmaceutical industry, cases of allergic reactions were described in clinical reports. As AGs were reported as modulators of the classical (CP) and alternative pathways (AP) of complement system (CS), in the present work, we investigate whether gum arabic and CNTG have an effect on both CS pathways. The complement fixation tests were performed with (CP-30 and AP-30) and without pre-incubation (CP-0 and AP-0). For CP-30, CNTG and gum arabic (833 µg/ml) showed a reduction of 28.0% (P = 0.000174) and 48.5% (P = 0.000143), respectively, on CP-induced haemolysis. However, no effect was observed for CP-0 in the CP-induced haemolysis. For AP-30, both CNTG and gum arabic (833 µg/ml) showed 87% reduction on the CP-induced haemolysis, with IC50 values of 100 and 7 µg/ml, respectively. For AP-0, a reduction of 11.3% for gum arabic and no effect for the CNTG on the CP-induced haemolysis were observed. These results suggested that gum arabic and CNTG could be acting as activators of the CS. Thus, this effect on the CS, especially on the AP, which accounts for up to 80-90% of total CS activation, indicates that both fractions may be harmful because of their potential pro-inflammatory action. Considering that CS activation induces inflammatory response, further studies confirming this immunomodulatory effect of these fractions are required to insure their safe use.

Acacia ferruginea inhibits inflammation by regulating inflammatory iNOS and COX-2.

Inflammation is a local defensive reaction of a host to cellular injury or infection. Prolonged inflammation can contribute to pathogenesis of many disorders. Identification of naturally occurring phytoconstituents that can suppress inflammatory mediators can lead to the discovery of anti-inflammatory therapeutics. Acacia ferruginea is used traditionally to treat numerous ailments including hemorrhage, irritable bowel syndrome and leprosy. The present study evaluated the anti-inflammatory activity of A. ferruginea extract against acute (carrageenan) and chronic (formaldehyde) inflammation in Balb/c mice. Pre-treatment with A. ferruginea extract (10 mg/kg BW) for 5 consecutive days via intraperitonial (IP) administration significantly inhibited subsequent induction of paw edema in both models; the effects were comparable to that of the standard drug indomethacin. The results also showed the A. ferruginea extract significantly inhibited nitric oxide (NO) synthesis and iNOS expression (as measured in serum), diminished inflammation in - and neutrophil infiltration to - the paw tissues and led to a reduction in the number of COX-2(+) immunoreative cells (as evidenced by histologic and immunohistochemical analyses) in the paws relative to those in paws of mice that received the irritants only. Further, in vitro studies showed the extract could significantly scavenge free radicals generated as in DPPH and NO radical generating assays. Taken together, the results showed that A. ferruginea extract imparted potent anti-oxidant and -inflammatory effects, in part by maintaining oxidative homeostasis, inhibiting NO synthesis and suppressing iNOS and COX-2 expression and so could potentially be exploited as a potential plant-based medication against inflammatory disorders.

Molecular Cloning and Expression of a New Allergen of Acacia farnesiana (Aca f 2).

Inhalation of pollens from different species of Acacia is a common cause of respiratory allergy in tropical areas of the world. Acacia farnesiana is commonly used as street trees in towns and ornamental shade trees in parks and gardens throughout arid and semi-arid regions of Asia. This study aimed to produce and purify the A. farnesiana pollen profilin (Aca f 2) and evaluate its nucleotide sequence homology with profilins of common allergenic plants to predict allergenic cross-reactivity. Thirty-nine patients who were allergic to Acacia pollens were included in the study. Cloning of Acacia profilin-coding sequence was performed by polymerase chain reaction using primers from Acacia pollen RNA. The cDNA of Acacia pollen profilin was then expressed in Escherichia coli using pET-21b(+) vector and purified by metal affinity chromatography. Immunoreactivity of the recombinant Acacia profilin (rAca f 2) was evaluated by specific ELISA, immunoblotting, and inhibition assays. The coding sequence of the Acacia profilin cDNA was recognized as a 399-bp open reading frame encoding 133 amino acid residues. Eighteen patients (18/39, 46.15%) had significant specific IgE levels against Aca f 2. Immunodetection and inhibition assays indicated that purified Aca f 2 might be the same as that in the crude extract. Aca f2, the first allergen from A. farnesiana pollen, was identified as belonging to the family of profilins. The amino acid sequence homology analysis showed high cross-reactivity between Aca f 2 and other profilins from botanically unrelated common allergenic plants.

Acacia ferruginea inhibits cyclophosphamide-induced immunosuppression and urotoxicity by modulating cytokines in mice.

Cyclophosphamide (CTX), commonly used as an anti-neoplastic drug, can cause adverse side-effects including immunotoxicity and urotoxicity. Increasingly, plants have become sources of therapeutics that can help to restore host immunity to normal. In this study, Acacia ferruginea was assessed for an ability to protect mice against/mitigate CTX-induced toxicity. Co-administration of an extract of A. ferruginea (10 mg/kg BW, IP daily) for 10 consecutive days reduced CTX (25 mg/kg BW, IP daily)-induced toxicity. Apart from improvements in bladder and small intestine morphology, there was marked improvement in anti-oxidant (glutathione) levels in the bladder, suggesting a role for the anti-oxidant in reducing CTX-induced urotoxicity. Moreover, use of the extract significantly increased total leukocyte counts and bone marrow cellularity/α-esterase activity in CTX-treated mice which suggested a protective effect on the hematopoietic system. Co-treatment with the extract also prevented decreases in organ (liver, kidney, spleen, thymus) weight as well as body weight, thereby seemingly lessening the potential impact of CTX on the host immune system. Further, CTX-induced increases in serum aspartate transanimase, alanine transaminase, and alkaline phosphatase were reversed by extract co-treatment, as were alterations in in situ formation/release of interferon (IFN)-γ, interleukin (IL)-2, granulocyte-macrophage colony stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-α. Overall, this study indicated there were some protective effects from use of an extract of A. ferruginea against CTX-induced toxicities, in part through modulation of levels of anti-oxidants and pro-inflammatory cytokines.

A study of pollen prevalence in relation to pollen allergy in Malaysian asthmatics.

In this paper we report results of skin prick tests (SPT) using pollen extracts on 200 patients with clinical symptoms of asthma, and results of a parallel study in which pollen was collected and classified over a period of 18 months. The patients were outpatients from the University Hospital in Kuala Lumpur, Malaysia, while the pollen grains were collected with a spore trap placed in the campus of the University of Malaya, approximately one kilometer from the University Hospital. Pollen extracts of 3 grasses (Bahia, Bermuda, rough pigweed) and 2 flowering trees, Acacia and Melaleuca, were used in the SPT. Of the 29.5% asthmatics with positive SPT reactions, 21.5% were to one or more of the grass pollens, 21.5% to Acacia and 7.5% to Melaleuca pollen. Acacia and Bermuda grass extracts were the most allergenic, which agreed with results of the pollen collection which showed grass and Acacia pollen grains to be the two most commonly found pollens.

Cross-reactivity between Acacia (wattle) and rye grass pollen allergens. Detection of allergens in Acacia (wattle) pollen.

Immunoglobulin E (IgE), directed against components of Acacia (wattle) pollen, has been detected by radioallergosorbent tests (RAST) in the sera of some children and adults who develop allergic symptoms in the presence of flowering Acacia trees in Australia. All these subjects also had high levels of IgE directed against Lolium perenne (rye grass) pollen. Inhibition by RAST showed that most of the IgE molecules which bound to Acacia pollen components also bound to L. perenne pollen extracts, and to Glycoprotein 1, the major allergen of L. perenne pollen. In these assays, the allergens have been immobilized on polyvinyl chloride microtitre trays: the sensitivity of this approach is compared to that of commercial RAST kits.