Method development and validation for the quantitative determination of total flavonoids through the complexation of iron (III) and its application in real sample

BACKGROUND

The determination of flavonoids in real sample using UV-Vis spectrophotometer commonly uses quercetin and catechin with Al+3 complexing agent as reference materials for the calibration of the instrument. However, getting these standard materials is challenging due to its expense and unavailability in the chemical reserve of the country. Moreover, the Al+3 - quercetin complexation standard method demands high amount of quercetin in spite of its high cost. Hence, developing alternative method that can solve this problem is crucial for the determination of flavonoids in the real sample.

RESULTS

An iron-based complexation method for the determination of flavonoids in the real sample was developed that reduces the amount of quercetin by 200 times (1 mg/mL to 0.005 mg/mL) during the calibration of UV-Vis spectroscopy as an alternative method. The reaction parameters (incubation time, pH, and concentration of quercetin) were optimized using software Design Expert 11 and confirmed by the practical experiments. The kinetics of reaction between iron and quercetin was found to be pseudo first order with rate constant of kobs at 340 and 510 nm. The analysis window for the flavonoid complex was achieved with the kinetic discrimination of the interferences at its optimized time of complexation 20 min and absorbance maxima of 510 nm. The developed method was validated by evaluating its precision, accuracy, recovery test (84-117%), detection limit and quantification limit following the standard protocols. The calibration of the instrument has been developed for the new method and the linear regression coefficient (R2) of 0.998 was obtained.

SIGNIFICANCE

Applying the developed standard material (Fe3+ - quercetin complex) gives freedom for the analytical chemists to find the standard materials that is accessible and cheaper than the existing one (Al3+-quercetin complex). The developed method can also be easily applied for determination of flavonoid in the real samples without potential interferences coming from sample matrix.

Shelf-life improvement of raw milk using ethanolic extracts of selected medicinal plants (Moringa stenopetale, Artemesia anua and MenthaSpicata)

The current study was designed to examine the Shelf life extension ability and antioxidant activity of the ethanolic extracts processed from Moringa stenopetale, Artemesia anua and Mentha Spicata. The raw milk and preservative plants was collected from Chencha woreda, Arba Minch. Purposive sampling techniques were used for collection of milk and plant samples. The crude extracts were isolated from three plant species using Soxhlet extraction method and characterized for the presence of bio-active compounds qualitatively and quantitatively. He accelerated shelf-life testing method was used to estimate the shelf-life of milk samples. Deterioration was tracked using measurements of the peroxide values and sensory characteristics. The DPPH free radical scavenging assay was used to determine the antioxidant capacity of various extracts, and the absorbance was measured at 517 nm. Mentha Spicata had the highest TPC value of 2.842 ± 0.109 mg GAE/g, while Moringa stenopetale had the lowest at 0.285± 0.0098 mg GAE/g. Similarly, Moringa stenopetale had the greatest TTC value of 69.86 ± 1.25 mg QE/g, while Mentha Spicata had the lowest at 46.2 ± 0.7 mg QE/g. The extracts of Moringa stenopetale, Artemesia anua, and Mentha Spicata showed good antioxidant activities, with IC₅₀ values of 39.490 ± 0.029, 61.189± 0.058, and 68.062± 0.014 g/mL, respectively. The shelf-life of the milk sample improved with Moringa stenopetale was 6.99 days at 27 °C. Generally, Moringa stenopetale had the longest shelf life of all the plant extracts tested for milk samples.

Anchote (Coccinia abyssinica) starch extraction, characterization and bioethanol generation from its pulp/waste

A polysaccharide molecule called starch exists in nature and is cheap, renewable, biodegradable, and readily accessible. The main objective of this project is to extract and characterize anchote (Coccinia abyssinica) starch, as well as to generate bio-ethanol from its pulp/waste. The anchote sample used in this investigation came from Ethiopia's western Oromia region. Anchote (Coccinia abyssinica) starch was extracted, and the pulp from the tuber was peeled and the supernatant isolated for bio-ethanol production. The extracted starch from anchote and bio-ethanol from pulps were characterized by physicochemical, functional properties and FT-IR analysis. The result of physicochemical and functional properties of anchote starch was found to be pH (4.44), WHC (112%), Solubility (5.03%), swelling power (5.781%), Gelatinization temperature (53.33 °C), WAC (2 g/g), bulk density (0.605 g/cm³) and OAC (3 g/g). According to this FTIR research, anchote starch has a chemical structure that is similar to corn, cassava, and potato starch. As the results showing a promising alcoholic content (25% v/v) and the existence of bioethanol being validated by a combustion test, the pulps/wastes recovered from anchote are also good sources of bioethanol. Finally, the FTIR spectroscopic analysis revealed that ethyl alcohol was produced from anchote pulps/waste after acid hydrolysis, fermentation, and distillation.