Standardizing Imperata cylindrica--source material for quality allergen preparations

Evaluation of The Safety and Efficacy of Newly Developed Domestic Allergenic Extracts for Skin Prick Testing

Background

Allergic disorders are common health problems worldwide with significant socio-economic impacts. The best diagnostic method using allergenic extract is the skin prick test. Regarding the effects of geo-climatic factors and allergenic extract source material quality, the aim of study was to determine the safety and efficacy of some in-house-developed allergenic extracts.

Methods

Forty-five different allergenic extracts, including common regional pollen, foods, and dog and cat hair, as well as positive and negative extracts, were prepared from domestic sources using optimum extraction methods. All extracts passed stability and sterility testing, and sterile final products containing 50% glycerin in 10 and 20 w/v concentrations were used. Skin prick testing was performed on volunteers and immediate or late side effects were recorded.

Results

In total, 56 students (mean age: 21.2±2.3y, M/F ratio: 1.07) participated in this study. For inhalant allergens, all extracts except dog hair extract caused positive responses. Salsola kali (Russian thistle) and Fraxinus velutina (ash tree) were the most common grass and tree pollen extracts, respectively. Of 18 different food extracts, five, including egg white, tomato, fig, melon, and green pepper caused skin reactivity in only one person. No participant reported any immediate or late side effects, including large local reaction or systemic response.

Conclusion

The result of the current study confirmed the safety of all our in-house-developed allergenic extracts. Regarding efficacy, almost all inhalant and five food allergens caused positive skin responses.

A study of extraction process and in vitro antioxidant activity of total phenols from Rhizoma Imperatae

The study investigated the extraction method of Rhizoma Imperatae and its antioxidant activity, and provided a basis for its rational development. The extraction method of Rhizoma Imperatae was determined using orthogonal design test and by total phenol content, its hydroxyl radical scavenging ability was measured by Fenton reaction, and potassium ferricyanide reduction method was used to determine its reducing power. The results showed that the optimum extraction process of Rhizoma Imperatae was a 50-fold volume of water, 30 °C, three times of extraction with 2 h each. Its IC50 for scavenging of hydroxyl radicals was 0.0948 mg/mL, while IC50 of ascorbic acid was 0.1096 mg/mL; in the ferricyanide considerable reduction method, the extract exhibited reducing power comparable to that of the ascorbic acid. The study concluded that Rhizoma Imperatae extract contains relatively large amount of polyphenols, and has a good anti-oxidation ability.

Current immunological approaches for management of allergic rhinitis and bronchial asthma

A large population world over is affected with allergic diseases and asthma. Pharmacotherapy for allergic diseases and asthma is effective in controlling symptoms but on discontinuation of medication, symptoms reoccur. In contrast, immunotherapy modifies and corrects the underlying pathological immune responses in an antigen-specific manner. Immunotherapy shows an increase in IgG (blocking antibody) that competes with IgE for allergen, inhibiting the release of inflammatory mediators. Recent studies suggest that immunotherapy acts by modifying CD4+ T-cell responses either by immune deviation, T-cell anergy and/or both. Current immunological approaches for management of allergies and asthma involve immunization with native allergen, modified allergen, peptides/cDNA of allergen, anti-IgE, adjuvants coupled allergen, including immunostimulatory DNA sequences, cytokines, and bacterial products. These approaches modulate the immune response and are intended to give long-term benefit.

Effect of various stabilizing agents on Imperata cylindrica grass pollen allergen extract

BACKGROUND

Allergen extracts are unstable, heat labile or susceptible to proteases. Stability of allergen extracts is important for proper diagnosis and therapy of allergic disorders.

OBJECTIVE

The present study was undertaken to determine the preservation and stabilization conditions of Imperata cylindrica (Ic) grass pollen extract.

METHODS

The Ic extract was kept with 0.1 mepsilon-aminocaproic acid (EACA), 0.75 m sucrose, 5% glycerol, 0.03% human serum albumin (HSA) or 0.4% phenol for different time periods. The extracts were stored for 3, 6 and 12 months each at 4 degrees C, 4 degrees C with daily exposure to room temperature (RT) for 1 h, and RT. The quality of extracts was analysed by SDS-PAGE, Western blot, ELISA, ELISA inhibition and skin test.

RESULTS

Extracts kept with EACA and sucrose retained most of the protein bands followed by glycerol as determined by SDS-PAGE and Western blot during all storage periods and conditions in comparison with standard extracts. The extracts kept with HSA, phenol and without preservative (WP) showed protein degradation below 33 kDa after 3 months storage at all conditions. However, a 67-kDa allergen was stable in these extracts. EACA extract required 75 to 120 ng of protein for 50% inhibition in IgE binding under different conditions, whereas standard extract required 70 ng for the same. ELISA also demonstrated high allergenic reactivity of EACA extract. ID test on allergy patients with EACA extract demonstrated same allergenic potency as that of standard extract.

CONCLUSION

EACA is the best preservative/stabilizing agent of Ic pollen extract, followed by sucrose and glycerol. Ic extract kept with phenol, HSA and without preservative showed degradation within 3 months. EACA preserved extract is equally potent as that of standard extract up to 1 year's storage.