Antioxidant activity and hepatoprotective effect of 10 medicinal herbs on CCl4-induced liver injury in mice

BACKGROUND Many natural products confer health benefits against diverse diseases through their antioxidant activities.Carbon tetrachloride(CCl4)is often used in animal experiments to study the effects of substances on liver injury and the related mechanisms of action,among which oxidative stress is a major pathogenic factor.AIM To compare antioxidant and hepatoprotective activities of ten herbs and identify and quantify phytochemicals for the one with strongest hepatoprotection.METHODS The antioxidant activity of ten medicinal herbs was determined by both ferricreducing antioxidant power and Trolox equivalent antioxidant capacity assays.The total phenolic and flavonoid contents were determined by Folin–Ciocalteu method and aluminum chloride colorimetry,respectively.Their effects on CCl4-induced oxidative liver injury were evaluated and compared in a mouse model by administrating each water extract(0.15 g/mL,10 mL/kg)once per day for seven consecutive days and a dose of CCl4 solution in olive oil(8%,v/v,10 mL/kg).The herb with the strongest hepatoprotective performance was analyzed for the detailed bioactive components by using high-performance liquid chromatography-electrospray ionization source-ion trap tandem mass spectrometry.RESULTS The results revealed that all tested herbs attenuated CCl4-induced oxidative liver injury;each resulted in significant decreases in levels of serum alanine transaminase,aspartate transaminase,alkaline phosphatase,and triacylglycerols.In addition,most herbs restored hepatic superoxide dismutase and catalase activities,glutathione levels,and reduced malondialdehyde levels.Sanguisorba officinalis(S.officinalis)L.,Coptis chinensis Franch.,and Pueraria lobata(Willd.)Ohwi root were the three most effective herbs,and S.officinalis L.exhibited the strongest hepatoprotective effect.Nine active components were identified in S.officinalis L.Gallic acid and(+)-catechin were quantified(7.86±0.45 mg/g and 8.19±0.57 mg/g dried weight,respectively).Furthermore,the tested herbs displayed a range of in vitro antioxidant activities proportional to their phenolic content;the strongest activities were also found for S.officinalis L.CONCLUSION This study is of value to assist the selection of more effective natural products for direct consumption and the development of nutraceuticals or therapeutics to manage oxidative stress-related diseases.

Biotechnological Strategies of Riboflavin Biosynthesis in Microbes

Riboflavin is an essential micronutrient for humans and must be obtained exogenously from foods or sup-plements.Numerous studies have suggested a major role of riboflavin in the prevention and treatment of various diseases.There are mainly three strategies for riboflavin synthesis,including total chemical syn-thesis,chemical semi-synthesis,and microbial fermentation,the latter being currently the most promis-ing strategy.In recent years,flavinogenic microbes have attracted increasing attention.Fungi,including Eremothecium ashbyii and Ashbya gossypii,and bacteria,including Bacillus subtilis,Escherichia coli,and lac-tic acid bacteria,are ideal cell factories for riboflavin overproduction.Thus they are good candidates for enhancing the level of riboflavin in fermented foods or designing novel riboflavin bio-enriched foods with improved nutritional value and/or beneficial properties for human health.This review briefly describes the role of riboflavin in human health and the historical process of its industrial production,and then highlights riboflavin biosynthesis in bacteria and fungi,and finally summarizes the strategies for ribofla-vin overproduction based on both the optimization of fermentation conditions and the development of riboflavin-overproducing strains via chemical mutagenesis and metabolic engineering.Overall,this review provides an updated understanding of riboflavin biosynthesis and can promote the research and development of fermented food products rich in riboflavin.