Process Balance of Natural Indigo Production based on Traditional Niram Method

Discovery and properties of a new indigoid structure type based on dimeric cis-indigos

“…The ratio between one-electron oxidized substrate to the initial substrate ([A + ]/[A]) after stoichiometric equivalent treatment of oxidant can be calculated by using the difference in the formal potentials of the oxidant and the substrate at 298 K. Although an irreversible redox process may change the equilibrium distribution, this calculation can still provide an insight to estimate the reaction progress. In the equimolar reaction with bromanil, the ratio between the indigo monoanion radical (A + ) and the starting dianion The 1 H and 13 C NMR spectra are fully consistent with the molecular structures. For 3.4, carbon chemical shifts were estimated through HSQC and HMBC experiments instead of 1D 13 C NMR due to a low quantity.…”

“…In the equimolar reaction with bromanil, the ratio between the indigo monoanion radical (A + ) and the starting dianion The 1 H and 13 C NMR spectra are fully consistent with the molecular structures. For 3.4, carbon chemical shifts were estimated through HSQC and HMBC experiments instead of 1D 13 C NMR due to a low quantity.…”

“…. 4 Assignments of C=O 13 C chemical shifts in dimeric cis-indigos. .................... properties upon boron coordination.…”

“…99 Recrystallization from hot nitrobenzene yielded the clean product in 78 % yield. 2.7 exhibits poor solubility in all organic solvents including DMSO; its 13 C NMR spectrum was collected over 3 days. Two C=O signals are observed at significantly different chemical shifts at 178.44 ppm (indigoid ketone) and 152.17 ppm (oxalyl bridge).…”

Effect of different physico-chemical parameters for natural indigo production during fermentation of Indigofera plant biomass

“…Teanglum et al (2012) found that indigo yield from Marsdenia tinctoria plant was 0.25 mg g -1 after 24 h fermentation at 40°C. A Korean research team worked on P. tinctorium suggested that without pretreatment (washing), the leaf biomass yield 0.03 mg pure indigo g -1 biomass during scale-up production (Shin et al 2014). Among the four specified temperatures, the setup under 40°C temperature produced best response for crude and pure indigo yield.…”