GC-MS Analysis and Inhibitory Evaluation of Terminalia catappa Leaf Extracts on Major Enzymes Linked to Diabetes

Table 7

Molecular docking analysis showing binding affinity, inhibition constant, and interacting residues in the binding site of α-amylase and α-glucosidase.

Protein	Compound	BE (kcal/mol)	Ki (μM)	Hb-IR	VdWb-IR	πb-IR
α-Amylase	Ethyl-α-D-glucopyranoside	−6.0	40.51	Arg 361, Arg 282, Asp 332, Ile 327, Gln 317, Gly 319	Leu 328, Trp 331, Thr 329, Asn 316, Arg 318, Phe 363, Ala 325	—
	Vitamin E	−8.0	1.39	—	Gln 78, Trp 74, Asp 315, Val 249, Glu 248, His 320	Val 178, Leu 180, Leu 177, His 314, Trp 73, Tyr 77, Tyr 166, Ile 250, Ala 213
	Acarbose	−8.3	0.84	Gly 321, His 320, Asp 212, Arg 210, Glu 248, Lys 215	His 216, Asp 315, Asp 251, His 314, Gln 78, Trp 73, Trp 74, Tyr 77, Leu 180, His 116, Ala 213, Ala 322, Ile 250, Tyr 166, Glu 255	Leu 177, Val 178
Glucosidase	Ethyl-α-D-glucopyranoside	−5.1	184.70	Gln 743, His 742	Val 740, Val 763, Val 755, Thr 768, Thr 753, Gly 765, Pro 754, Leu 756, Gln 757	Trp 804
	n-Hexadecanoic acid	−5.2	156.05	Val 358	Leu 195, Leu 577, Leu 574, Leu 565, Gly 605, Ala 604, Ala 582, Tyr 609, Pro 194, Thr 578, Thr 491, Phe 490, Arg 585	Leu 496, Ile 581
	Phytol	−5.5	94.11	—	Asp 282, Asp 616, Asp 404, Asp 443, Arg 600, Ile 441, Leu 405, Leu 650, Ser 676	Phe 525, Phe 649, Trp 481, Trp 376, His 674, Ala 284, Met 519,
	Vitamin E	−5.9	47.95	—	Arg 281, Arg 500, Ala 284, Ser 523, Met 519, Phe 649, Asp 616	Trp 376, Trp 481, Leu 283, Phe 525, Asp 262
	Acarbose	−7.4	3.83	Asn 524, Asp 282, Asp 404, Asp 616, Asp 518, Arg 600, Ser 676, Trp 481	—	Ala 284

BE: binding energy; K_i: inhibition constant; Hb-IR: hydrogen bond interacting residues; VdWb-IR: van der Waals bond interacting residues; πb-IR: pi bond interacting residues.