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Hydroxybenzoic Acids Are Significant Contributors to the Antioxidant Effect of Borututu Bark, Cochlospermum angolensis Welw. ex Oliv.

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ABSTRACT

1234514: Borututu (Cochlospermum angolensis) is an African tree whose bark has recently emerged as a herbal dietary supplement with claims for antioxidant activity. In order to substantiate the claimed activity of borututu supplements, we performed an activity-guided fractionation of the total extract utilizing a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Subsequent flash and centrifugal chromatography resulted in the isolation of gallic acid () and protocatechuic acid () as the main antioxidant constituents. Two apocarotenoids and one flavonoid were also isolated from the chloroform fraction and were identified as cochloxanthin (), dihydrocochloxanthin (), and 7,4′-dimethyltaxifolin (), respectively. A High-performance liquid chromatography (HPLC) method was also developed for fingerprinting borututu samples, with Compounds – suggested as chemical markers for quality control purposes.

No MeSH data available.


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TLC analysis and visualization of active borututu fractions by DPPH dipping. (A) Solvent fractions HF, CHCl3 fraction (CF), ethyl acetate fraction (EF), and methanol fraction (MF) in comparison to total methanolic extract (TME). (B) Flash fractions SF1–5 in comparison to EF.
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antioxidants-06-00009-f002: TLC analysis and visualization of active borututu fractions by DPPH dipping. (A) Solvent fractions HF, CHCl3 fraction (CF), ethyl acetate fraction (EF), and methanol fraction (MF) in comparison to total methanolic extract (TME). (B) Flash fractions SF1–5 in comparison to EF.

Mentions: Extraction of borututu bark powder (500 g) yielded 102.7 g of total methanolic extract (TME), of which 57.2 g were used for subsequent fractionation. The utilized weight (57.2 g) subsequently yielded four fractions obtained by successive solvent extraction of TME-coated silica (HF, 0.64 g; CF, 5.63 g; EF 6.58 g; MF, 29.45 g). The ethyl acetate fraction (EF) showed the highest DPPH scavenging activity followed by the methanol fraction (MF). This was qualitatively verified by a visible inspection of DPPH-dipped TLC plates and quantitatively determined by 96-well plate DPPH-scavenging assays as shown in Figure 2A and Figure 3, respectively. Thus, EF was further investigated to identify active compounds. Flash chromatography of an aliquot of EF (1.40 g) resulted in five subfractions (SF1–5) with SF4 (0.17 g) and SF5 (0.14 g) showing the highest activity (Figure 3). TLC analysis of SF4 and SF5 showed two major compounds that bleached the purple background after dipping in DPPH solution (Figure 2B). Each subfraction was subjected to centrifugal preparative TLC (Chromatotron), resulting in one major compound per subfraction (SF4: Compound 2, 0.07 g; SF5: Compound 1, 0.03 g). Although the CHCl3 fraction (CF) exhibited lower DPPH scavenging activity, its TLC profile showed two orange spots and one faint yellow spot that were isolated by preparative flash chromatography (Isolera One®) of an aliquot (0.48 g) to yield Compounds 3 (0.03 g), 4 (0.03 g), and 5 (0.005 g).


Hydroxybenzoic Acids Are Significant Contributors to the Antioxidant Effect of Borututu Bark, Cochlospermum angolensis Welw. ex Oliv.
TLC analysis and visualization of active borututu fractions by DPPH dipping. (A) Solvent fractions HF, CHCl3 fraction (CF), ethyl acetate fraction (EF), and methanol fraction (MF) in comparison to total methanolic extract (TME). (B) Flash fractions SF1–5 in comparison to EF.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384172&req=5

antioxidants-06-00009-f002: TLC analysis and visualization of active borututu fractions by DPPH dipping. (A) Solvent fractions HF, CHCl3 fraction (CF), ethyl acetate fraction (EF), and methanol fraction (MF) in comparison to total methanolic extract (TME). (B) Flash fractions SF1–5 in comparison to EF.
Mentions: Extraction of borututu bark powder (500 g) yielded 102.7 g of total methanolic extract (TME), of which 57.2 g were used for subsequent fractionation. The utilized weight (57.2 g) subsequently yielded four fractions obtained by successive solvent extraction of TME-coated silica (HF, 0.64 g; CF, 5.63 g; EF 6.58 g; MF, 29.45 g). The ethyl acetate fraction (EF) showed the highest DPPH scavenging activity followed by the methanol fraction (MF). This was qualitatively verified by a visible inspection of DPPH-dipped TLC plates and quantitatively determined by 96-well plate DPPH-scavenging assays as shown in Figure 2A and Figure 3, respectively. Thus, EF was further investigated to identify active compounds. Flash chromatography of an aliquot of EF (1.40 g) resulted in five subfractions (SF1–5) with SF4 (0.17 g) and SF5 (0.14 g) showing the highest activity (Figure 3). TLC analysis of SF4 and SF5 showed two major compounds that bleached the purple background after dipping in DPPH solution (Figure 2B). Each subfraction was subjected to centrifugal preparative TLC (Chromatotron), resulting in one major compound per subfraction (SF4: Compound 2, 0.07 g; SF5: Compound 1, 0.03 g). Although the CHCl3 fraction (CF) exhibited lower DPPH scavenging activity, its TLC profile showed two orange spots and one faint yellow spot that were isolated by preparative flash chromatography (Isolera One®) of an aliquot (0.48 g) to yield Compounds 3 (0.03 g), 4 (0.03 g), and 5 (0.005 g).

View Article: PubMed Central - PubMed

ABSTRACT

1234514: Borututu (Cochlospermum angolensis) is an African tree whose bark has recently emerged as a herbal dietary supplement with claims for antioxidant activity. In order to substantiate the claimed activity of borututu supplements, we performed an activity-guided fractionation of the total extract utilizing a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Subsequent flash and centrifugal chromatography resulted in the isolation of gallic acid () and protocatechuic acid () as the main antioxidant constituents. Two apocarotenoids and one flavonoid were also isolated from the chloroform fraction and were identified as cochloxanthin (), dihydrocochloxanthin (), and 7,4′-dimethyltaxifolin (), respectively. A High-performance liquid chromatography (HPLC) method was also developed for fingerprinting borututu samples, with Compounds – suggested as chemical markers for quality control purposes.

No MeSH data available.


Related in: MedlinePlus