Total phenolics, capsaicinoids, antioxidant activity, and α-glucosidase inhibitory activity of three varieties of pepper seeds

Figures & data

Figure 1. Generation of pepper seeds during the processing of pepper products.

Table 1. Total phenolics content (TPC) of WPS, LPS, and BRPS extracted with various solvents.

Extraction solvent	TPC (μg GAE/g dw)
	WPS	LPS	BRPS
80% Methanol	4210 ± 143^Bb	4136 ± 98^Bc	6208 ± 32^Aa
80% Ethanol	3934 ± 77^Cc	4661 ± 36^Bb	6087 ± 89^Aa
80% Acetone	4467 ± 145^Ca	4861 ± 93 ^Ba	6071 ± 108^Aa

Values were expressed means ± standard deviation of three determinations. Values within each row marked with different superscript upper case letters (A-C) indicate significant differences (p< 0.05) among WPS, LPS, and BRPS from the same extracted solvent. Values within each column marked with different superscript lowercase letters (a-c) demonstrate significantly different (p< 0.05) among different extraction solvent extracts from the same CPS.

Table 2. Capsaicin, dihydrocapsaicin, and nordihydrocapsaicin in terms of total capsaicinoids contents of WPS, LPS, and BRPS extracted with various solvents.

	Capsaicinoids contents (μg/g dw)
	80% Methanol			80% Ethanol			80% Acetone
Compounds	WPS	LPS	BRPS	WPS	LPS	BRPS	WPS	LPS	BRPS
Capsaicin	723 ± 34^Cb	968 ± 12 ^Ba	1950 ± 60^Ab	683 ± 7^Cb	968 ± 37 ^Ba	2067 ± 88^Aab	775 ± 26^Ca	988 ± 44 ^Ba	2151 ± 56^Aa
Dihydrocapsaicin	341 ± 16^Cb	391 ± 5^Ba	1108 ± 39^Ab	326 ± 4^Cb	405 ± 27 ^Ba	1209 ± 14^Aa	368 ± 10^Ca	405 ± 11 ^Ba	1246 ± 37^Aa
Nordihydrocapsaicin	44 ± 1^Cb	69 ± 2 ^Ba	271 ± 7^Ab	43 ± 1^Cb	70 ± 2 ^Ba	297 ± 4^Aa	48 ± 2 ^Ca	69 ± 4 ^Ba	294 ± 8^Aa
Total capsaicinoids	1109 ± 51^Cb	1428 ± 15 ^Ba	3329 ± 106^Ab	1052 ± 11^Cb	1443 ± 55 ^Ba	3573 ± 77^Aa	1191 ± 37^Ca	1461 ± 59 ^Ba	3692 ± 101^Aa

The result data were expressed means ± standard deviation of three determinations. Data in the same row marked with different superscript capital letters (A-C) at the same solvent extraction are statistically different (p< 0.05) among WPS, LPS, and BRPS. Data in the same row marked with different superscript lowercase letters (a-c) are remarkably different (p< 0.05) among different extraction solvent extracts from the same CPS (WPS, LPS or BRPS).

Figure 2. Ferric reducing antioxidant power (FRAP) (a), scavenging effect of DPPH radical (b), ABTS·⁺ scavenging ability (c) and reducing power (RP) (d) of the various extracts from WPS, LPS, and BRPS. Values were represented as mean ± standard deviation of triplicate assay. Values followed by different superscript capital letters (a–c) are remarkably different (p< .05) among WPS, LPS and BRPS from the same extracted solvent. Values followed by variant superscript small letters (a-c) suggest considerably different (p< .05) among 80% methanol, 80% ethanol, and 80% acetone extracts from the same CPS samples (WPS, LPS, or BRPS).

Figure 3. Inhibitory activity against α-glucosidase of the various extracts from WPS, LPS, and BRPS. Values are means ± standard deviation of triplicate assay. Values with different superscript uppercase letters (a–c) indicated significantly different (p< .05) among WPS, LPS, and BRPS from the same extracted solvent. Values with different superscript lowercase letters (a-c) demonstrated remarkably different (p< .05) among 80% methanol, 80% ethanol, and 80% acetone extracts from the same CPS samples (WPS, LPS, or BRPS).

Figure 4. (a) Loading plot of principal component analysis (PCA) of total phenolic content (TPC), capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin, total capsaicinoids), antioxidant activities, and α-glucosidase inhibitory activity. (b) Score plot of principal component analysis (PCA) of discrepant solvent extracts of WPS, LPS, and BRPS. M-, E- and A- indicate CPS (i.e., WPS, LPS, and BRPS) were extracted with 80% methanol, 80% ethanol, and 80% acetone, respectively.