Evaluation of Chemical Constituents and Important Mechanism of Pharmacological Biology in Dendrobium Plants

Table 5

Inhibition of compounds from D.  loddigesii and D.  nobile species on NO and DPPH formation.

Species	Chemical constituent	NO	DPPH
D.  loddigesii	Phenanthrenes (1a)	2.6	26.1
	Phenanthrenes (2a)	6.4	59.8
	Phenanthrenes (3a)	5.3	12
	Phenanthrenes (4a)	10.9	—
	Dihydrophenanthrenes (5a)	4.6	62.2
	Dihydrophenanthrenes (6a)	29.1	—
	Dihydrophenanthrenes (7a)	29.2	—
	Loddigesiinols A	2.6	—
	Loddigesiinols B	10.9	—
	Loddigesiinols C	—	23.7
	Loddigesiinols D	69.7	—
D.  nobile	Nobilin D (1)	15.3	—
	Nobilin E (2)	19.2	—
	Nobilone F (3)	38.1	—
	Phenanthrenes and bibenzyls related-composition  (4–10)
	RO R1 = R2 = OCH3 R3 = OH R4 = H (4)	—	—
	RO R1 = R2 = R3 = OCH3 R4 = H (5)	48.2	—
	RO R1 = R2 = OH R3 = R4 = H (6)	—	—
	RO R1 = R3 = OCH3 R2 = OH R4 = H (7)	—	—
	RO R1 = OCH3 R2 = R3 = OH R4 = H (8)	36.8	—
	RO R1 = R3 = OH R2 = R4 = H (9)	32.9	—
	RO R1 = R3 = OH R2 = H R4 = OCH3 (10)	13.4	—

Notes: —: no tests; RO: relation composition.
Inhibitory effects of different compounds from D.  loddigesii and D.  nobile species on NO production. Result shown in Table 5, ranked from high to low as follows: loddigesiinol D > R₁ = R₂ = R₃ = OCH₃ R₄ = H (5) > nobilone F (3) > R₁ = OCH₃ R₂ = R₃ = OH R₄ = H (8) > R₁ = R₃ = OH R₂ = R₄ = H (9) > dihydrophenanthrenes (7a) > dihydrophenanthrenes (6a) > nobilin E (2) > nobilin D (1) > R₁ = R₃ = OH R₂ = H R₄ = OCH₃ (10) > phenanthrenes (4a) = loddigesiinols B > phenanthrenes (2a) > phenanthrenes (3a) > dihydrophenanthrenes (5a) > phenanthrenes (1a) > loddigesiinols A, and all of the compounds inhibit DPPH prodruction (from high to low): dihydrophenanthrenes (5a) > phenanthrenes (2a) > phenanthrenes (1a) > loddigesiinol C > phenanthrenes (3a).