Inhibition of angiotensin I converting enzyme by anacardic acids isolated from Cashew nut (Anacardium occidentale Linn.) shell liquid

Figures & data

Figure 1. Structures of the alkyl phenols detected in Cashew nut shell liquid. I = anacardic acid-1, II = anacardic acid-2, III = anacardic acid-3, IV = anacardic acid-4, V = cardonol-1, VI = cardonol-2, VII = cardonol-3, VIII = cardol-1, IX = cardol-2.

Table 1. Inhibition of Angiotensin I converting enzyme (ACE) by alkyl phenols, and anacardic acids purified to homogeneity by semi-preparative HPLC compared to selected reference and published data

Alkyl phenols	IC50 (µM)
CNSL	50
Anacardic acids	18
Cardanols	> 500
Cardols	> 500
Anacardic acid-1	39
Anacardic acid-2	33
Anacardic acid-3	12
Anacardic acid-4	20
Captopril (postive control)	6.85 nM (=0.0069 µM)
Other phenolic compounds
Pentagallate	> 500
Ellagic acid	> 500
Mangiferin	> 500
Maclurin	> 500
Luteolin	> 500
Taxifolin	negative
Salicylic acid	negative
Published values
(-)-Epicatechin	1783 ^(Actis-Goretta ^et al., 2003)
(+)-Catechin	1593 ^(Actis-Goretta ^et al., 2003)
Procyanidin dimer	267 ^(Actis-Goretta ^et al., 2003)
Procyanidin trimer	126 ^(Actis-Goretta ^et al., 2003)
Procyanidin tetramer	12 ^(Actis-Goretta ^et al., 2003)
Procyanidin pentamer	25 ^(Actis-Goretta ^et al., 2003)
Procyanidin hexamer	10 ^(Actis-Goretta ^et al., 2003)
Cyanidin sambubioside	118 ^(Ojeda et al., 2010)
Delphinidin sambubioside Rutin	142 ^(Ojeda et al., 2010) 71 ^(Shaw et al., 2017)

Figure 2. Inhibition by different concentrations of anacardic acids of ACE activity as determined by analytical HPLC (a) and by anacardic acid-3 showing ± SEM (b).

Figure 3. (b) Lineweaver Burk plot demonstrating non-competitive ACE inhibition by anacardic acid-1. Blue circle, control; red circle, anacardic acid-1 (40 µM).

Figure 4. (a) Initial velocity of ACE inhibition by anacardic acid-1. Red circle, control; black square, anacardic acid-1 (40 µM).