Phenolic and Terpenoid Constituents from the Sri Lankan Medicinal Plant Osbeckia aspera.

Figures & data

Table 1 HPLC retention times, UV spectral data, and APCI-MS fragment ions of identified constituents from O. aspera., their relative concentrations in the crude extracts, and the fractions in which they were present.

Comp. no.	tR (min)^a.	Identification^b.	Fractions of the acetone/water extract in which the compound was present^c.	UV λmax (nm)	APCI-MS [A+H]^+ [M+H]^+	Rel. conc.^d.
1	2.9	Gallic acid	C40, C77	273	—	+
2	4.9	Protocatechuic acid	C77, E75	260, 295	—	±
3	13.1	Ellagic acid	B13, C13, D12, E15	253, 367	—	±
4	12.5	Quercetin 3-O.-β-galactopyranoside	D37, D62, E40	256, 355	303 465	++
5	12.7	Quercetin 3-O.-β-glucopyranoside	D37, D62, E40	256, 355	303 465	++
6	14.4	Quercetin 3-O.-(3″-O.-acetyl-β-galactopyranoside)	D62, E40	256, 355	303 507	++
7	13.9	Kaempferol 3-O.-β-glucopyranoside	D37, D62, E40	264, 349	287 449	+
8	17.2	Kaempferol 3-O.-[6″-O.-(E.)-p.-coumaroyl-β-glucopyranoside] (tiliroside)	E40	265, 314	287 595	++
9	19.5–20.2	Kaempferol 3-O.-[2″, 6″-di-O.-(E.,E.)-p.-coumaroyl-β-glucopyranoside]^e.	E40, F28	267, 313	287 741	++
10	16.6	Quercetin	F07	255, 372	303 303	+
11	18.6	Kaempferol	F07	265, 366	287 287	±
12	10.3	6,9-Dihydroxy-4,7-megastigmadien-3-one (vomifoliol)	Present in 100% MeOH	241	225	++
13	17.0	9-Hydroxy-4,7-megastigmadien-3-one	Present in 100% MeOH extract only	242	209	+
14	16.9	9-Hydroxy-4-megastigmen-3-one	Present in 100% MeOH extract only	—	211	+

^a.HPLC retention times. For composition of the solvents and other details, see “Materials and Methods” section.

^b.Compounds 1–3 were detected in the water and acetone/water extracts, compounds 4, 5, 7 and 10 in all three extracts, compounds 6, 8, 9, and 11 in the acetone/water and MeOH extracts, and compounds 12–14 in the MeOH extract.

^c.Fractions with liver protective activity in the BB test are printed in bold face, see “Materials and Methods” section for details about the fractions.

^d.Relative concentrations of the compounds in the crude extracts. ++means a relatively high concentration in the extracts; +medium concentration; ± low concentration.

^e.The corresponding (E.,Z.), (Z.,E.), and (Z.,Z.) isomers of this compound were detected as minor components of the sample by NMR.

Table 2 Percentage of liver cell protection against bromobenzene (BB) and 2,6-dimethyl-N.-acetyl p.-quinoneimine (2,6-diMe-NAPQI) toxicity of phenolic acid and flavonol standards.

	% Protection against BB toxicity^a.		% Protection against 2,6-diMeNAPQI toxicity^a.
Pure compound concentration (μg/mL)	125	250	125	250
Gallic acid (1)	26	41	48	56
Protocatechuic acid (2)	19	24	40	48
Ellagic acid (3)	3	6	−13	−10
Quercetin 3-O.-rutinoside (rutin)	7	15	8	N/D

N/D, not determined.

^a.Mean of two determinations against either BB or 2,6-diMeNAPQI.

Table 3 Percentage of protection against bromobenzene (BB) and 2,6-dimethyl-N.-acetyl p.-quinoneimine (2,6-diMeNAPQI) toxicity of crude extracts of Osbeckia aspera. and active fractions.

Extract or active fraction	Cone. (μg/mL)	% Protection against BB toxicity^a.	% Protection against 2,6-diMeNAPQI toxicity^a.	Main compounds present^b. (major constituents in each fraction are underlined)
Osbeckia. crude water extract	1000	38	37	1–5, 7, 10
Osbeckia. crude aq. 50% acetone extract	1000	12	N/D	1–11
Fraction C13 (C: Sephadex; 40% MeOH)	250	9	8	3 Unidentified compounds
Fraction D62 (D: Sephadex; 60% MeOH)	250	7	32	4, 5, 7, Unidentified compounds
Fraction E40 (E: Sephadex; 80% MeOH)	250	7	10	4–6, 7–9
Fraction F28 (F: Sephadex; 100% MeOH)	250	13	22	8, 9, Unidentified compounds
Osbeckia. crude 100% MeOH extract	1000	12	N/D	4–14
(+)-Catechin^c.	1000	69	64
Silymarin^c.	1000	25	25

N/D, not determined.

^a.Mean of two determinations.

^b.For the identification of the compounds, see Table 1. The unidentified compounds in fractions C13 were an inseparable mixture of polar compounds with very short retention times (2.2 min).

^c.Positive controls.