A Comparative Study on Phenolic Content, Antioxidant Activity and Anti-Inflammatory Capacity of Aqueous and Ethanolic Extracts of Sorghum in Lipopolysaccharide-Induced RAW 264.7 Macrophages.

Shan Hong,Sarah Cox,Leela E Noronha,Dmitriy Smolensky,Vermont P Dia,Ramasamy Perumal,Philipus Pangloli

doi:10.3390/antiox9121297

Abstract

Sorghum is an important cereal with diverse phenolic compounds that have potential health promoting benefits. The current study comparatively characterized the phenolic contents of two novel black-seeded sorghum lines (SC84 and PI570481) using different extraction systems (water, ethanol and their acidified counterparts) and evaluated their antioxidant and anti-inflammatory activities. Phenolic compositions were determined by spectrophotometric assays and HPLC analysis. Antioxidant activities were assessed by radical scavenging effects on nitric oxide (NO) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals, and the oxygen radical absorbance capacity (ORAC). Anti-inflammatory capacity was estimated by measuring levels of pro-inflammatory markers produced by lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Results showed that effects of solvent types and HCl on extraction efficiency differed among phenolic compounds and sorghum samples. Tannins were the most dominant polyphenols in the studied extracts (11.11–136.11 mg epicatechin equivalent/g sorghum). Sorghum extracts exerted more potent scavenging activity on DPPH than NO radicals. In LPS-activated RAW 264.7 cells, sorghum extracts dose-dependently inhibited the production of NO, interleukin-6 (IL-6), and intracellular reactive oxygen species (ROS), with ethanolic extracts showing greater anti-inflammatory activity. Positive correlations were noted between tannin content and DPPH radical scavenging activity, and anti-inflammatory capacity. These results suggest the potential role of tannin-rich sorghum extracts against inflammation and associated diseases.

Highlights

Sorghum, a member of the Poaceae grass family, is one of the leading dryland crops in the world, appearing to be the fifth most produced cereal next to rice, wheat, barley, and corn [1,2]
The current study comparatively investigated the phenolic contents of three novel sorghum extracts, SC84MX, SC84KS and PI570481, that were obtained by aqueous and ethanolic extraction systems in the absence or presence of 0.1% v/v HCl, and tested their downstream antioxidant and anti-inflammatory activities
The results suggest that no single extraction system could effectively extract all phenolic compounds

Summary

Introduction

A member of the Poaceae grass family, is one of the leading dryland crops in the world, appearing to be the fifth most produced cereal next to rice, wheat, barley, and corn [1,2]. It has been widely cultivated worldwide, serving as food, feed, and fuel [3]. Sorghum tannins, composed of oligomers or polymers of mainly catechins (flavan-3-ol or flavan-3,4-diol) with high molecular weight and a high degree of polymerization (DP), are rarely found among other major cereals [7]

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