International Journal of Biology Research

Authors
Al Mamun, Nazmul Hasan, Hazrat Belal, Rokon Ul Karim, Dobirul Islam, Sayela Afroz, Ariful Islam, Tabassum Ara, Sirajam Munira, Masudul Hasan Khan, Amirul Islam

Abstract
Background: Garlic (Allium sativum L.) belonging to the Alliaceae family has played important dietary and medicinal roles throughout the history. Objectives: The present study was undertaken to investigate the phytochemical content as well as antioxidant activity of local variety garlic extract using different solvent systems in Bangladesh. Methods: Five different types of extract were prepared using methanol, ethanol, acetone, chloroform and petroleum ether as solvent. We performed the phytochemical screening and determined the total phenolic, flavonoid, flavonol and proanthocyanidin content of the extracts using standard procedures. Several in vitro assay models were employed to investigate the antioxidant activity. Results: Out of the five extracts, the acetone extract of local variety possessed the highest content of phenolics (110.76±1.9mg of gallic acid equivalent/gm of dry extract)), flavonoids (43.32±2.7mg of catechin equivalent/gm of dry extract), flavonols (15.31±2.3mg of quercetin equivalent/gm of dry extract)) and proanthocyanidins (8.54±0.5 mg of catechin equivalent/gm of dry extract). The radical scavenging activity, the total antioxidant capacity as well as the reducing power of the extracts increased with the increase of concentration. In total antioxidant capacity test and ferric reducing antioxidant power assay acetone extract of local variety showed the highest activity. In DPPH, ABTS, hydroxyl radical scavenging assay and lipid peroxidation inhibition assay strong antioxidant activities were observed by each extract in which acetone extract of local variety was found to be the best one with the IC₅₀ values (in µg/ml) of 5.1±0.9 (DPPH assay), 11.3±0.2 (ABTS assay), 15.7±0.6 (Hydroxyl radical assay) and 19.5±0.3 (Lipid peroxidation assay). Conclusion: Findings of the present study suggested that local variety garlic of Bangladesh is a promising source of natural antioxidant and could have great importance as therapeutic agent in various diseased conditions. The study also recommended that acetone would be the preferable solvent for extracting polyphenols from garlic.