Screening for Anti-allergic Activity of Natural Products

Increasing prevalence of allergic diseases with inadequate variety of treatment drives forward search for new alternative drugs. The untapped potential of natural products as an inexhaustible mine of biologically active compounds encouraged us to investigate the potential of separating natural products with promising anti-allergic activity. We utilized degranulation assay [1], which is based on β-hexosaminidase release from RBL-2H3 cells activated either by calcium ionophore A23187 or antigen (IgE plus DNP-BSA). Over 200 samples were screened for anti-allergic activity revealing a potential of several plants. For instance, ornamental plant Dietes bicolor, seeds of Aquilaria malaccensis, aerial parts of Pandanus amaryllifolius and Liriope platyphylla, leaves of Carica papaya, Artabotrys vinhensis, or nonpolar extracts of Typhonium blumei and T. roxburghii [2] exerted promising anti-allergic activity. The fractionation of these extracts, aiming to purify and identify the active compound, yielded various results, with each tested material developing its own unique story. For example, pursuing bioactivity-guided fractionation, anti-allergic phorbol ester was isolated from the seeds of Aquilaria malaccensis [3]. In contrast, the component of active fraction of Liriope platyphylla was never identified, while the ethanol layer of Carica papaya leaves was much more active than any of the isolated pure compounds. Interestingly, some of the chlorophyll-rich fractions showed potent activity, however, the toxicity of the samples raised upon light exposure, thus limiting their utilization. The active compound or mixture may serve as a new candidate for further anti-allergic evaluation and mechanism of action study.