Polymorphic Nucleic Acid Binding of Bioactive Isoquinoline Alkaloids and Their Role in Cancer

Table 4

Spectroscopic and thermodynamic parameters for the interaction of various alkaloids with DNA triple helical structure with references^a.

Complexes	𝐾^a	𝑛	Δ𝑇𝑚^b	Δ𝐺^∘	Δ𝐻^∘	Δ𝑆^∘	References
	(×10^5 M^−1)		(°C) (3→2) at 𝑟max	kcal mol^−1	kcal mol^−1	cal⋅deg^−1 mol^−1
Poly(dT)⋅poly(dA)xpoly(dT)+ berberine	3.2	6.4	7.80	−7.35	−4.61	+9.52	[48]
Poly(dT)⋅poly(dA)xpoly(dT)+ coralyne	dna	dna	19.0	dna	dna	dna	[68]
Poly(dT)⋅poly(dA)xpoly(dT)+ sanguinarine	26.0	3.3	24.5	−8.56	−4.14	+15.11	[48]
Poly(dC)⋅poly(dG)xpoly(dC^+)+ sanguinarine	16.0	2.5	7.50	−8.28	−10.73	−8.36	[48]

^a𝐾 (the intrinsic binding constant) determined using equation 𝑟/𝐶_f=𝐾(1−𝑛𝑟)[(1−𝑛𝑟)/(1−(𝑛−1)𝑟)]^𝑛−1, where 𝑟 is the number of alkaloid molecules bound per mole of nucleotide and 𝐶_f is the molar concentration of free alkaloid.
^bΔ𝑇_𝑚 (3→2) is the 𝑇_𝑚 of the triplex DNA in the presence of alkaloid-𝑇_𝑚 of the free triplex DNA. (3→2) denotes the transition temperature from triplex complex to duplex complex formation.
* dna: data not available.