Chemical composition, antioxidative and antimicrobial activities of turmeric spent oleoresin

Abstract

Disposal of the turmeric waste commonly known as turmeric spent oleoresin (TSO) left after separation of curcuminoids has been considered as serious concern and has attracted scientific community at large for its sustainable utilization.In order to establish the utility of TSO, present study has been aimed to chemically characterize the TSO and evaluate its antioxidative and antimicrobial potential employing robust in vitro models. The fractionation of TSO was achieved using column chromatography and the fractions thus obtained were characterized using high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry-quadruple time of light (LCMS-qToF) techniques. The isolated fractions and turmeric were examined for their antioxidant activity employing standard procedures such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging assay, Ferric reducing antioxidant power (FRAP) assay and Phosphomolybdate assays. Antimicrobial potential of TSO and isolates was performed against different microbial strains using the broth dilution method. Chemical characterization of TSO revealed the presence of ferulic acid, myristicin, furanodience, cyclocurcumin, 6-methoxy-2-[2-(3′methoxyphenyl) ethyl] chromone, dihydrocurcumin, bisabolocurcumin ether, terpecurcumin Q, curcumin, cyclobisdesmethoxycurcumin, and bisdemethoxycurcumin. Among different fractions isolated, Fraction 9 (F9) exhibited the strongest antioxidative activity (Inhibitory concentration 50 (IC50) values 16.14 ± 0.12 for DPPH and 23.98 ± 0.16 μg/mL for ABTS scavenging activity). The highest antimicrobial activity was recorded for Fraction 1 (F1) (Inhibitory zone diameter (IZD) = 25.33 ± 0.33 mm), Fraction 6 (F6) (IZD = 23.67 ± 0.33 mm), Fraction 7 (F7) (IZD = 22.67 ± 0.33 mm), Fraction 9 (F9) (IZD = 24.00 ± 00 mm) and Fraction 11 (F11) (IZD = 22.33 ± 0.67 mm) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), Candida albicans (C. albicans), and Salmonella abony (S. abony) respectively. Present study indicates that the major industrial waste, TSO is a rich source of phytochemicals and can be utilized as antioxidant, antimicrobial agent and as preservative in food products. Further studies are required to establish TSO as therapeutic candidate against microbial diseases and related issues.