Table 2.

Regression coefficients estimated for TPC and DPPH values of Argel (Solenostemma argel) leaf extracts

Factor	TPC				DPPH
	Coefficient estimate	Standard error	95% CI low	95% CI high	Coefficient estimate	Standard error	95% CI low	95% CI high
Intercept
β0 Linear	68.62a	0.3847	67.71	69.53	85.69a	1.30	82.62	88.77
β1	1.95a	0.3041	1.24	2.67	−1.65	1.03	−4.08	0.7839
β2	0.7078	0.3041	−0.011	1.43	2.00	1.03	−0.4366	4.43
β3	2.66a	0.3041	1.94	3.38	−3.30a	1.03	−5.73	−0.8655
Interaction
β12	0.7883	0.4301	−0.228	1.81	0.5208	1.46	−2.92	3.96
β13	−1.13a	0.4301	−2.14	−0.1090	1.39	1.46	−2.05	4.83
β23	−0.3700	0.4301	−1.39	0.6470	3.82a	1.46	0.3784	7.26
Quadratic
β11	0.7850	0.4192	−0.206	1.78	1.34	1.42	−2.02	4.69
β22	−0.6145	0.4192	−1.61	0.3768	−2.14	1.42	−5.49	1.22
β33	−0.6306	0.4192	−1.62	0.3607	−3.00	1.42	−6.36	0.3504
R2	0.9530				0.8214
Adjusted R2	0.8925				0.5918
F probability value	0.001				0.053
Lack of fit probability	0.087				0.073

TPC total phenolic content, DPPH 1,1-diphenyl-1-2-picrylhydrazyl scavenging activity, CI confidence interval

^ap < 0.05