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. 2022 Dec 16;27(24):8989.
doi: 10.3390/molecules27248989.

Comparative Investigation of Chemical Constituents of Kernels, Leaves, Husk, and Bark of Juglans regia L., Using HPLC-DAD-ESI-MS/MS Analysis and Evaluation of Their Antioxidant, Antidiabetic, and Anti-Inflammatory Activities

Ilhame Bourais  1 , Salma Elmarrkechy  1 , Douae Taha  1   2 , Bouabid Badaoui  3 , Yassine Mourabit  2 , Najoua Salhi  4 , Mohammed Merae Alshahrani  5 , Ahmed Abdullah Al Awadh  5 , Abdelhakim Bouyahya  1 , Khang Wen Goh  6 , Ching Siang Tan  7 , Souad El Hajjaji  2 , Nadia Dakka  1 , Naima Iba  1
Affiliations

Comparative Investigation of Chemical Constituents of Kernels, Leaves, Husk, and Bark of Juglans regia L., Using HPLC-DAD-ESI-MS/MS Analysis and Evaluation of Their Antioxidant, Antidiabetic, and Anti-Inflammatory Activities

Ilhame Bourais et al. Molecules. .

Abstract

Leaves, husk, kernels, and bark methanolic extracts of Juglans regia L. were tested for their in vitro antidiabetic, anti-inflammatory, and antioxidant activities. For these purposes, α-amylase and α-glucosidase were used as the main enzymes to evaluate antidiabetic activities. Moreover, lipoxidase and tyrosinase activities were tested to estimate anti-inflammatory properties. Antioxidant properties of Juglans regia L., extracts were determined using three different assays. Leaves extract has an important radical scavenging activity and a-amylase inhibition. Similarly, husk extracts showed high total phenolic content (306.36 ± 4.74 mg gallic acid equivalent/g dry extract) with an important α-amylase inhibition (IC50 = 75.42 ± 0.99 µg/mL). Kernels exhibit significant tyrosinase (IC50 = 51.38 ± 0.81 µg/mL) correlated with antioxidant activities (p < 0.05). Husk and bark extracts also showed strong anti-lipoxidase activities with IC50 equal to 29.48 ± 0.28 and 28.58 ± 0.35 µg/mL, respectively. HPLC-DAD-ESI-MS/MS analysis highlights the phenolic profile of methanolic extracts of Juglans regia L. plant parts. The identified polyphenols were known for their antioxidant, antidiabetic (dicaffeoyl-quinic acid glycoside in kernels), and anti-inflammatory (3,4-dihydroxybenzoic acid in leaves) activities. Further investigations are needed to determine molecular mechanisms involved in these effects as well as to study the properties of the main identified compounds.

Keywords: HPLC-DAD-ESI-MS/MS; Juglans regia L.; anti-inflammatory; antidiabetic activity; antioxidant; phenolic profile; plant parts.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Boxplots showing FRAP (A), ABTS (B), and DPPH (C) radicals scavenging activities of J. regia methanolic extracts. a p < 0.05, Data expressed as mean ± SD. Abbreviations. MWB: Methanolic Extract of bark, MWH: Methanolic extract of Husk, MWK: Methanolic Extract of Kernels, MWL Methanolic Extract of Leaves.
Figure 2
Figure 2
Effect of J. regia methanolic extracts on Lipoxygenase activity. a p < 0.05, Data expressed as mean ± SD. Abbreviations—MWB: Methanolic Extract of bark, MWH: Methanolic extract of Husk, MWK: Methanolic Extract of Kernels, MWL: Methanolic Extract of Leaves.
Figure 3
Figure 3
Effect of J. regia methanolic extracts on tyrosinase activity. a p < 0.05, Data expressed as mean ± SD. Abbreviations—MWB: Methanolic Extract of bark, MWH: Methanolic extract of Husk, MWK: Methanolic Extract of Kernels, MWL: Methanolic Extract of Leaves.
Figure 4
Figure 4
Effect of J. regia methanolic extracts on (A) α-amylase and on (B) α-glucosidase enzymatic activities. a p < 0.05, Data expressed as mean ± SD. Abbreviations—MWB: Methanolic Extract of bark, MWH: Methanolic extract of Husk, MWK: Methanolic Extract of Kernels, MWL: Methanolic Extract of Leaves.
Figure 5
Figure 5
Correlations among chemical activities (antioxidative, anti-inflammatory, antidiabetic, and anti-tyrosinase) within each J. regia extract (A) Methanolic Extract of bark, (B) Methanolic extract of Husk, (C) Methanolic Extract of Kernels, and (D) Methanolic Extract of Leaves.
Figure 6
Figure 6
Heatmap highlighting the relationships among the chemical screenings within the methanolic extract of bark.
Figure 7
Figure 7
Heatmap highlighting the relationships among the chemical screenings within the methanolic extract of kernels.
Figure 8
Figure 8
Heatmap highlighting the relationships among the chemical screenings within the methanolic extract of husk.
Figure 9
Figure 9
Heatmap highlighting the relationships among the chemical screenings within the methanolic extract of leaves.
See this image and copyright information in PMC

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