Quantification of bioactive marker β-amyrin by validated high-performance thin-layer chromatographic- densitometric method in different species ofMaytenusgrown in Saudi Arabia

Quantitative analysis of rutin, quercetin, naringenin, and gallic acid by validated RP- and NP-HPTLC methods for quality control of anti-HBV active extract of Guiera senegalensis

CONTEXT

Guiera senegalensis J.F. Gmel (Combretaceae) is a folk medicinal plant used in various metabolic and infectious diseases. In addition to its antiviral activities against herpes and fowlpox, the anti-HBV efficacy is very recently reported.

OBJECTIVE

To develop and validate simple, sensitive RP-/NP-HPTLC methods for quantitative determination of biomarkers rutin, quercetin, naringenin, and gallic acid in the anti-HBV active G. senegalensis leaves ethanol-extract.

MATERIALS AND METHODS

RP-HPTLC (rutin & quercetin; phase- acetonitrile:water, 4:6) and NP-HPTLC (naringenin & gallic acid; phase- toluene:ethyl acetate:formic acid, 6:4:0.8) were performed on glass-backed silica gel plates 60F254-RP18 and 60F254, respectively. The methods were validated according to the ICH guidelines.

RESULTS

Well-separated and compact spots (Rf) of rutin (0.52 ± 0.006), quercetin (0.23 ± 0.005), naringenin (0.56 ± 0.009) and gallic acid (0.28 ± 0.006) were detected. The regression equations (Y) were 12.434x + 443.49, 10.08x + 216.85, 11.253x + 973.52 and 11.082x + 446.41 whereas the coefficient correlations (r2) were 0.997 ± 0.0004, 0.9982 ± 0.0001, 0.9974 ± 0.0004 and 0.9981 ± 0.0001, respectively. The linearity ranges (ng/spot) were 200-1400 (RP-HPTLC) and 100-1200 (NP-HPTLC). The LOD/LOQ (ng/band) were 33.03/100.1 (rutin), 9.67/29.31 (quercetin), 35.574/107.8 (naringenin), and 12.32/37.35 (gallic acid). Gallic acid (7.01 μg/mg) was the most abundant biomarker compared to rutin (2.42 μg/mg), quercetin (1.53 μg/mg) and naringenin (0.14 μg/mg) in the extract.

CONCLUSION

The validated NP-/RP-HPTLC methods were simple, accurate, and sensitive for separating and quantifying antiviral biomarkers in G. senegalensis, and endorsed its anti-HBV activity. The developed methods could be further employed in the standardization and quality-control of herbal formulations.

X-ray crystallographic and validated HPTLC analysis of the biomarker chromone glucoside (schumanniofioside A) isolated from Acalypha fruticosa growing in Saudi Arabia

A chromone glucoside 2-methyl-5,7-dihydroxychromone 5-O-β-D-glucopyranoside (schumanniofioside A, compound 1) was isolated from the methanol extract of Acalypha fruticosa. The structure of compound 1 was fully assigned based on nuclear magnetic resonance (NMR) (¹H, ¹³C and 2D) spectra and electrospray ionization mass spectrum (ESI-MS) in addition to X-ray Crystallography. The molecules were packed in the crystal structure by eight intermolecular O—H⋯O and C—H⋯O interactions. The structure of compound 1 belongs to monoclinic, P2₁, a = 9.1989 (4) Å, b = 4.6651 (2) Å, c = 20.4042 (7) Å, β = 97.862 (3)°, V = 867.31 (6) ų, Z = 2, wR_ref(F²) = 0.101, T = 100 K. Thus, the bond angles, bond lengths and absolute structure of compound 1 were confirmed by its X-ray structure. A validated HPTLC method was developed for the quantitative analysis of compound 1 in chloroform and methanol extracts of A. fruticosa. It was found to furnish a compact and sharp band of compound 1 at R_f = 0.13 ± 0.005 using chloroform, methanol and glacial acetic acid [17:3:0.5 (v/v/v)] as mobile phase. The LOD and LOQ for compound 1 were found to be 17.86 and 54.13 ng/band, respectively. Compound 1 was found in both chloroform and methanol extracts of the plant (0.03% w/w and 0.31% w/w, respectively). The proposed HPTLC method can be used for the further analysis of schumanniofioside A in different plant extracts, herbal formulations and biological samples as well as in process quality control.

Inter-species comparative antioxidant assay and HPTLC analysis of sakuranetin in the chloroform and ethanol extracts of aerial parts of Rhus retinorrhoea and Rhus tripartita

Context: Extensive research on Rhus (Anacardiaceae) shows their antioxidant potential, which warrants further evaluation of its other species.

Objective: To perform a comparative antioxidant assay on extracts of R. retinorrhoea and R. tripartita, including sakuranetin quantification by a validated HPTLC method.

Materials and methods:In vitro antioxidant assay was performed on chloroform and ethanol extracts of R. retinorrhoea Steud. ex Oliv. (RRCE and RREE) and R. tripartita (Ucria) Grande (RTCE and RTEE) by DPPH radical scavenging (at 31.25, 62.5, 125, 250 and 500 μg/mL concentrations) and β-carotene-linoleic acid bleaching methods at 500 μg/mL concentration. Densitometric HPTLC method was developed and validated using toluene: ethyl acetate: methanol (8:2:0.2; v/v/v) as mobile phase, executed on glass-backed silica gel F₂₅₄ plate and scanned at 292 nm.

Results: Antioxidant activity of Rhus extracts tested by the two methods (DPPH/BCB) was found in order of RTEE > RREE > RTCE > RRCE with IC₅₀ 118.67/256.26, 315.75/82.35, 827.92/380.0 and 443.69/292.75, respectively. Scanning of the HPTLC plate provided an intense peak of sakuranetin at R_f = 0.59. The estimated sakuranetin content in the dry weight of the extracts was highest in RREE (27.95 μg/mg) followed by RRCE (25.22 μg/mg), RTEE (0.487 μg/mg) and RTCE (0.0 μg/mg). Presence of sakuranetin in RREE, RRCE and RTEE supported the highest antioxidant property of the two Rhus species. Nonetheless, low sakuratenin in R. tripartita indicated the presence of other bioactive constituents responsible for synergistic antioxidant activity.

Conclusion: The developed HPTLC method therefore guarantees its application in quality control of commercialized herbal drugs and formulations containing sakuranetin.

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.

Simultaneous quantification of biomarkers bergenin and menisdaurin in the methanol extract of aerial parts of Flueggea virosa by validated HPTLC densitometric method

A simple, sensitive high-performance thin-layer chromatography (HPTLC) method was developed for the simultaneous quantification of biomarker bergenin and menisdaurin in the methanol extracts of aerial parts of Flueggea virosa (FVME). Chromatography was performed on glass-backed silica gel 60F254 HPTLC plates using dichloromethane: methanol as mobile phase. Scanning and quantification was done at UV absorption maxima of 260 nm. The system was found to give compact spot for bergenin and menisdaurin at Rf = 0.29 ± 0.01 and 0.16 ± 0.01, respectively. The linearity ranges for bergenin and menisdaurin were found to be the same (100-800 ng/spot) with correlation coefficients (R(2) values) of 0.997 and 0.999, respectively. The limit of detection for bergenin and menisdaurin was found to be 27 and 36.2 ng/band, respectively, while the limit of quantification was found to be 81 and 108 ng/band, respectively. Intra- and interday precisions (n = 6) for bergenin and menisdaurin were found to be 1.41-1.71 and 1.65-1.87%, and 1.68-1.89 and 1.75-1.93%, respectively. The percent recoveries were found to be 98.7-99.4 and 99.5-99.9%, respectively, for bergenin and menisdaurin. The percentage of bergenin and menisdaurin was found to be 15.25 and 4.22% (w/w), respectively, in FVME. The developed method permitted the simultaneous quantification of bergenin and menisdaurin and showed good resolution and separation from other constituents of extract; hence, the method can be used to standardize herbal formulations as well as bulk drugs for bergenin and menisdaurin.