Phenolic profile and Enzyme Inhibitory activities of Almond (Terminalia catappa) leaf and Stem bark

Figures & data

Figure 1. A. angiotensin-1-converting enzyme (ACE), B. phosphodiesterase-5 (PDE-5), C. acetylcholinesterase (AChE) and D. arginase inhibitory activities of almond leaf and stem bark extracts.

Table 1. Total Phenolic content, flavonoid content and ABTS radical scavenging ability of almond leaf and bark.

Parameter	Leaf	Stem bark
Total phenol (mgGAE/g)	62.50 ± 1.84^b	37.30 ± 1.05^a
Total flavonoid (mgQUE/g)	7.80 ± 1.32^b	3.44 ± 0.51^a
ABTS radical scavenging ability (mmolTEAC/g)	0.17 ± 0.002^b	0.09 ± 0.001^a

Values represent mean±standard deviation of replicate readings.

Values with the same superscript along the same row are not statistically different at p < 0.05.

Table 2. IC₅₀ values for DPPH radical scavenging ability and arginase, phosphodiesterase-5 (PDE-5), acetylcholinesterase (AChE) and angiotensin-1-converting enzyme (ACE) inhibitory activities of almond leaf and stem bark.

Parameter	Leaf	Stem bark	Positive Control
DPPH* scavenging ability (mg/ml)	0.49 ± 0.05^a	0.57 ± 0.09^b
Arginase inhibition (µg/ml)	51.65 ± 2.57^b	53.91 ± 4.03^b	0.78 ± 0.21^a
AChE inhibition (µg/ml)	265.39 ± 5.79^b	303.53 ± 4.99^c	2.35 ± 0.22^a
PDE-5 inhibition (µg/ml)	238.44 ± 3.57^b	273.43 ± 4.03^c	2.68 ± 0.10^a
ACE inhibition (µg/ml)	64.74 ± 1.57^c	57.29 ± 2.03^b	0.20 ± 0.05^a

Results are expressed as mean ± standard deviations (SD) of three determinations. Values with the same alphabet along the same row are not significantly different (p < 0.05). N^ѡ-hydroxy-L-arginine (NOHA) was used as positive control for arginase, Prostigmine for acetylcholiesterase, Sildenafil citrate for phosphodiesterase-5 and Lisinopril for angiotensin-1-converting enzyme.

Figure 2. A. DPPH radical scavenging ability B. ferric reducing antioxidant power of almond leaf and stem bark extracts.

Figure 3. Representative of high performance liquid chromatography profile A. almond leaf; Gallic acid (peak 1), catechin (peak 2), chlorogenic acid (peak 3), caffeic acid (peak 4), ellagic acid (peak 5), epicatechin (peak 6), rutin (peak 7), quercitrin (peak 8), isoquercitrin (peak 9), quercetin (peak 10) and kaempferol (peak 11) B. almond stem bark; Gallic acid (peak 1), catechin (peak 2), caffeic acid (peak 3), ellagic acid (peak 4), resveratrol (peak 5), rutin (peak 6), quercetin (peak 7) and kaempferol (peak 8).

Table 3. Phenolics composition of Almond leaf and stem bark extracts.

	Leaf	Stem bark
Compounds	mg/g	mg/g
Gallic acid	64.23 ± 0.01^b	1.05 ± 0.02^a
Catechin	25.18 ± 0.01^b	1.78 ± 0.03^a
Chlorogenic acid	53.47 ± 0.03
Caffeic acid	46.15 ± 0.02^b	6.93 ± 0.01^a
Ellagic acid	98.82 ± 0.03^b	5.87 ± 0.01^a
Epicatechin	21.83 ± 0.01
Rutin	45.06 ± 0.02^b	1.06 ± 0.01^a
Quercitrin	79.65 ± 0.01
Isoquercitrin	52.03 ± 0.02
Quercetin	26.71 ± 0.01^b	3.45 ± 0.02^a
Kaempferol	65.13 ± 0.01^b	1.76 ± 0.01^a
Resveratrol		5.91 ± 0.03

Results are expressed as mean ± standard deviations (SD) of three determinations. Averages followed by different letters differ by Tukey test at p < 0.05.