A compound represented by the formula (I) [R1 to R3 represent an alkyl group, an alkenyl group, and the like; n represents 0 or 1; R4 represents an amino group or —(CX2)m—COOH (m represents 0 to 3, and X represents hydrogen atom); R5 represents —(CY2)p—COOR6 (p represents an 0 to 3, Y represents hydrogen atom, and R6 represents hydrogen atom or an alkyl group)], or a salt thereof.
A compound represented by the formula (I) [R
1
to R
8
represent an alkyl group, an alkenyl group, and the like; n represents 0 or 1; R
4
represents an amino group or —(CX
2
)
m
—COOH (m represents 0 to 3, and X represents hydrogen atom); R
5
represents —(CY
2
)
p
—COOR
6
(p represents an 0 to 3, Y represents hydrogen atom, and R
6
represents hydrogen atom or an alkyl group)], or a salt thereof.