Phenolic compounds as antioxidants and chemopreventive drugs from Streptomyces cellulosae strain TES17 isolated from rhizosphere of Camellia sinensis

Abstract

BackgroundOxidative stress in an intracellular environment created by the accumulation of reactive oxygen species results in oxidative damage to biomolecules which ultimately become a hallmark for severe diseases like cancer, aging, diabetes, and cardiovascular and neurodegenerative diseases.MethodsVarious in vitro assays were employed to assess the antioxidant potential of strain, DNA protective activity was demonstrated using DNA nicking assay and cytotoxicity of the extract was evaluated using MTT assay. Further identification of the compounds was done using UPLC analysis.ResultsThe extract of Streptomyces cellulosae strain TES17 demonstrated significant antioxidant activity with percentage inhibition of 78.47 ± 0.23, 91.08 ± 0.98 and 82.08 ± 0.93 for DPPH, ABTS and superoxide radical assays at 5 mg/mL, respectively. Total antioxidant and reducing power were found to be 76.93 ± 0.76 and 231.96 ± 0.51 mg AAE/100 mg of dry extract, respectively. Moreover, the extract was shown to inhibit lipid peroxidation upto 67.18 ± 1.9% at 5 mg/mL. TPC and TFC measured in the extract was 55 mg GAE/100 mg and 11.17 ± 4.05 mg rutin/100 mg, respectively. The protective nature of the TES17 extract to oxidative stress induced damaged DNA was shown by percentage of supercoiled DNA i.e. Form I was increased from 26.38 to 38.20% at concentrations ranging from 2 μg to 10 μg. TES17 extract also showed the cytotoxic activity against lung cancer cell line with 74.7 ± 1.33% inhibition whereas, limited toxicity was observed against normal cell line with percentage viability of 87.71 ± 6.66 at same concentration (30 μg/mL) tested. The antioxidant capacity of extract was well correlated with its TPC and TFC and this in turn was in keeping with the UPLC analysis which also revealed the presence of phenolic compounds that were responsible for the antioxidant and cytotoxic potential of S. cellulosae strain TES17.ConclusionsThe present study describes that S. cellulosae strain TES17 isolated from the rhizosphere of Camellia sinensis (tea) plant; produces potent compounds with antioxidant activity, further might be developed into therapeutic drugs to combat oxidative stress.Electronic supplementary materialThe online version of this article (10.1186/s12906-018-2154-4) contains supplementary material, which is available to authorized users.

Unique secondary metabolites of a Streptomyces strain isolated from extreme salty wetland show antioxidant and antibacterial activities

“…Not surprisingly, antioxidant activity, measured with the DPPH assay, was remarkable in AR2 strain (Table 1), as is the case of S. lavendulae strain SCA5 (Kumar et al 2014), although examples exist with lower (Streptomyces strain TES17; Rani et al 2018) and higher antioxidant activity (Streptomyces sp. VITMSS05; Revathy et al 2013). In addition to the scavenging activity of reactive oxygen species, assessed by the DPPH assay, iron chelation seems to be another antioxidant mechanism involved in the antioxidant activity of the AR2 extract as this extract has the ability to chelate iron (Table 1).…”

“…marine, halophilic, acidophilic), these studies have successfully isolated new species, and concomitantly new useful secondary metabolites (e.g. polyketides, pigments, flavonoids) have been characterized (Gomes et al ; Rani et al ). Among the secondary metabolites found in Streptomyces , polyketides are one of the most abundant classes of compounds with remarkable structural diversity and biological activities (reviewed by Risdian et al, ).…”

“…A general consensus emerged from these studies that extreme environments could represent an exceptional ecological niche for the discovery of novel Streptomyces species with an amazing assortment of useful compounds. The secondary metabolism of Streptomyces has been shown to be extremely rich in the production of many different chemicals, some of them common to phytochemicals (Álvarez‐Álvarez et al ), and also with a wide variety of bioactivities (Rani et al ). This threw light on our interest in these organisms and their secondary metabolites putting into consideration the number of emerging antibiotic‐resistant strains that is constantly increasing and the potential applications of secondary metabolites in medicine, food industry, cosmetics and environment (Zaidi et al ).…”

Drought stress response of Westerwolths ryegrass Lolium multiflorum ssp. multiflorum) cultivars differing in their ploidy level

“…The correlation analysis between the morphological and physiological parameters (reduction in leaf elongation, relative water content, chlorophyll fluorescence ratio, antiradical activity and phenolic content) at the end of mild drought simulation showed a medium positive correlation between the growth reduction and phenolic contents and strong positive correlation between the antiradical activity and phenolic content (r = 0.75, p ≤ 0.01). A large group of phenolic compounds have antioxidant properties (Rani et al, 2018), and this could explain why the phenolic content correlated positively with antiradical activity. The correlation between the antiradical activity and phenolic contents at the end of the mild drought with the morphological traits in 2018 field trials characterized by a lower amount of rainfall was estimated.…”

Peer Review #1 of "Antioxidant activity, α-glucosidase inhibition and phytochemical profiling of Hyophorbe lagenicaulis leaf extracts (v0.1)"

“…The extract yields, TPC and TFC with respect to solvent system used for extraction are given in (Prieto et al, 1999;Rani et al, 2018).…”