Densitometric Validation and Optimisation of Polyphenols in Ocimum sanctum Linn by High Performance Thin-layer Chromatography

Recent advances in methods of extraction, pre-concentration, purification, identification, and quantification of kaempferol

As a naturally widely-occurring dietary, cosmetic, and therapeutic flavonoid, kaempferol has gained much consideration for its nutritional and pharmaceutical properties in recent years. Although there have been performed a high number of studies associated with different aspects of kaempferol's analytical investigations, the lack of a comprehensive summary of the various methods and other plant sources that have been reported for this compound is being felt, especially for many biological applications. This study, aimed to provide a detailed compilation consisting of sources (plant species) and analytical information that was precisely related to the natural flavonoid (kaempferol). There is a trend in analytical research that supports the application of modern eco-friendly instruments and methods. In conclusion, ultrasound-assisted extraction (UAE) is the most general advanced method used widely today for the extraction of kaempferol. During recent years, there is an increasing tendency towards the identification of kaempferol by different methods.

Densitometric Quantification and Optimization of Polyphenols in Phyllanthus maderaspatensis by HPTLC

Quantifying and optimizing the polyphenol content of Phyllanthus maderaspatensis was accomplished using a single-solvent HPTLC system. Analyzing hydroalcoholic extracts for kaempferol, rutin, ellagic acid, quercetin, catechin, and gallic acid, we simultaneously quantified and optimized their concentration. In the experiment, the methanol to water ratio (%), temperature (°C), and time of extraction (min) were all optimized using a Box-Behnken statistical design. Kaempferol, rutin, ellagic acid, quercetin, catechin, and gallic acid were among the dependent variables analyzed. In the HPTLC separation, silica gel 60F254 plates were used, and toluene, ethyl acetate, and formic acid (5:4:1) made up the mobile phase. For kaempferol, rutin, ellagic acid, quercetin, catechin, and gallic acid, densitometric measurements were carried out using the absorbance mode at 254 nm. Hydroalcoholic extract of P. maderaspatensis contains rutin (0.344), catechin (2.62), gallic acid (0.93), ellagic acid (0.172), quercetin (0.0108) and kaempferol (0.06). Further, it may be affected by more than one factor at a time, resulting in a varying degree of reaction. A negative correlation was found between X1 (extraction time (min)) and X2 (temperature), as well as X1 and X3 (solvent ratios). Taking these characteristics into consideration, the method outlined here is a validated HPTLC method for measuring kaempferol, rutin, ellagic acid, quercetin, catechin, and gallic acid.

Optimization of Ultrasonicated Kaempferol Extraction from Ocimum basilicum Using a Box-Behnken Design and Its Densitometric Validation

Kaempferol (KA) is a natural flavonol that can be found in plants and plant-derived foods with a plethora of different pharmacological properties. In the current study, we developed an efficient extraction method for the isolation of KA from ultrasonicated basil leaves (Ocimum basilicum). We successfully employed a Box-Behnken design (BBD) in order to investigate the effect of different extraction variables including methanol concentration (40-80%), extraction temperature (40-60 °C), and extraction time (5-15 min). The quantification of KA yield was carried out by employing a validated densitometric high performance thin layer chromatography in connection with ultraviolet detection (HPTLC-VIS). The obtained data showed that the quadratic polynomial model (R² = 0.98) was the most appropriate. The optimized ultrasonic extraction yielded 94.7 ng/spot of KA when using methanol (79.99%) at 60 °C for 5 min. When using toluene-ethyl acetate-formic acid (70:30:1 v/v/v) as a solvent, KA was detected in basil leaves at an Retention factor (Rf) value of 0.26 at 330 nm. Notably, the analytical method was successfully validated with a linear regression of R² = 0.99, which reflected a good linear relationship. The developed HPTLC-VIS method in this study was precise, accurate, and robust due to the lower obtained results from both the percent relative standard deviation (%RSD) and SEM of the O. basilicum. The antioxidant activity of KA (half maximal inhibitory concentration (IC₅₀) = 0.68 μg/mL) was higher than that of the reference ascorbic acid (IC₅₀ = 0.79 μg/mL) and butylated hydroxytoluene (BHT) (IC₅₀ = 0.88 μg/mL). The development of economical and efficient techniques is very important for the extraction and quantification of important pharmaceutical compounds such as KA.

Comparative study of antioxidant activity and validated RP-HPTLC analysis of rutin in the leaves of different Acacia species grown in Saudi Arabia

The present study assessed the comparative antioxidant potential of the ethanol extract (EE) of leaves of four Acacia species (Acacia salicina, AS; Acacia laeta, AL; Acacia hamulosa AH; and Acacia tortilis, AT) grown in Saudi Arabia, including RP-HPTLC quantification of antioxidant biomarker rutin. In vitro DPPH radical scavenging and β-carotene-linoleic acid bleaching assays showed the promising antioxidant activities of Acacia extracts: ASEE (IC₅₀: 60.39 and 324.65 μg/ml) >ALEE (IC₅₀: 217.06 and 423.36 μg/ml) >ATEE (IC₅₀: 250.13 and 747.50 μg/ml) >AHEE (IC₅₀: 255.83 and 417.28 μg/ml). This was comparable to rutin tested at 500 μg/ml. Further, a RP- HPTLC densitometric method was developed (acetonitrile:water; 6:4; v/v) using glass-backed RP-18 silica gel F₂₅₄ plate, and scanned at UV max 254 nm. The method was validated as per the ICH guidelines. Analysis of the validated RP-HPTLC displayed an intense peak (R_f = 0.65 ± 0.004) of rutin that was estimated (μg/mg dry weight) to be highest in ASEE (10.42), followed by ALEE (2.67), AHEE (1.36) and ATEE (0.31). Taken together, presence of rutin strongly supported the high antioxidant property of the tested Acacia species, especially Acacia salicina. The developed RP-HPTLC method therefore, affirms its application in the quality control of commercialized herbal drugs or formulation containing rutin.