α-spinasterol isolated from Achyranthes aspera L. ameliorates inflammation via NF-κB and Nrf2/HO-1 pathways

Abstract

On the basis of previous studies, the low-polar part of Achyranthes aspera L. (A. aspera) had strong anti-inflammatory activity. Three compounds were isolated from the low polarity fraction of A. aspera, and their structures were identified as α-spinasterol (1), 7,8-dihydrospinasterol (2), 22,23-dihydrospinasterol (3). Among them, the content of α-spinasterol (1) in A. aspera was higher in the spring and winter seasons through HPLC methods, ranging from 0.0085 to 0.0157%. Futhermore, in the LPS-induced RAW264.7 cells inflammation model, α-spinasterol significantly reduced the levels of cytokines such as IL-6, PGE2 and TNF-α, inhibited the expression of COX-2, 5-LOX, p-IKKβ, p-NFκB and p-IkBα proteins, and promoted the expression of Nrf2, HO-1 and NQO1 proteins. Therefore, this study showed that α-spinasterol can inhibit LPS-induced RAW264.7 cells inflammation, and its mechanism may be related to the inhibition of NF-κB pathway, activation of Nrf2 pathway, and reduction of excessive release of inflammatory factors.

Keywords: Anti-inflammatory; Content determination; NF-κB; Nrf2; α-Spinasterol.

Fig. 1

The chemical structures of three compounds (1: α-spinasterol, 2: 7,8-dihydrospinasterol, 3: 22,23-dihydrospinasterol).

Fig. 2

The content change of α-spinasterol in A. aspera with seasonal harvest.

Fig. 3

The effects of α-spinasterol on cell viability in RAW264.7 cells.

Fig. 4

(a) Morphological observation of RAW264.7 cells treated with α-spinasterol; (b) The effects of α-spinasterol on NO production in LPS-Induced RAW264.7 cells (^####p < 0.0001 vs. Control group; ****p < 0.0001 vs. Model group).

Fig. 5

The effects of α-spinasterol on TNF-α, IL-6 and PGE2 levels in LPS-Induced RAW264.7 cells ((a) TNF-α, (b) IL-6, (c) PGE2). Results are shown as the mean ± SD (n = 3). ^####p < 0.0001 vs. Control group; ***p < 0.001, ****p < 0.0001 versus Model group.

Fig. 6

(a) Quantification and expression of COX-2. (b) Quantification and expression of 5-LOX. Results are shown as the mean ± SD (n = 3). ^####p < 0.0001 versus Control group; ***p < 0.001, ****p < 0.0001 versus Model group.

Fig. 7

(a) Quantification and expression of p-IKKβ. (b) Quantification and expression of p-NF-κB. (c) Quantification and expression of p-IkBα. Results are shown as the mean ± SD (n = 3). ^##p < 0.01, ^####p < 0.0001 versus Control group; **p < 0.01, ***p < 0.001, ****p < 0.0001 versus Model group.

Fig. 8

(a) Quantification and expression of Nrf2. (b) Quantification and expression of HO-1. (c) Quantification and expression of NQO1. Results are shown as the mean ± SD (n = 3). ^##p < 0.01, ^###p < 0.001 versus Control group; **p < 0.01, ****p < 0.0001 versus Model group.