Anti-allergic and anti-inflammatory properties of Zizyphus mauritiana root bark

Abstract

An allergy may sometimes be very dangerous and one of the main factors responsible for allergy is the complement system which can lead to a life-threatening reaction called anaphylaxis. Cycloxygenase-1 (COX-1), Cycloxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) trigger allergic and inflammatory reactions. A number of anti-allergic synthetic drugs are available but are costly and show many side effects. Hence, the ancient traditional system of medication mentioned in Ayurveda finds an edge over various synthetic drugs. Zizyphus mauritiana is referred to as the store house of phytochemicals in Ayurveda. The stem and root barks of Zizyphus mauritiana were dried and powdered under controlled conditions. Extractions of the dried powders were performed separately in different solvents in increasing order of their polarity and were tested for their ability to inhibit the complement system. The aqueous extract of the root bark was found to be more effective in inhibiting the complement system. Fractionation of the aqueous extract resulted in the isolation of the Most Active Fraction (MAF) which inhibited the complement system, COX-1, COX-2, and 5-LOX with IC₅₀ values of 0.006 μg ml⁻¹, 0.065 μg ml⁻¹, 0.008 μg ml⁻¹, and 0.083 μg ml⁻¹, respectively. The MAF was proven to be successful in down-regulating pro-inflammatory mediators like TNF-α, COX-2, and iNOS when tested on a RAW 264.7 cell line. In vivo, the MAF was found to be preventive against anaphylactic shock and the Arthus reaction, when orally administered daily to Wistar rats. Phytochemical analysis of the MAF has indicated that it is rich in tannins. Results indicate that the MAF, a fraction isolated from the aqueous extract of the root bark of Zizyphus mauritiana, has potent anti-allergic and anti-inflammatory properties.