Three new flavonoids, proanthocyanidin, and accompanying phenolic constituents from Feijoa sellowiana

Figures & data

Table 1. ¹H-NMR assignment of compound 1–3 and correspond known compounds 7, 9, and 10 [¹H-NMR 600 MHz, Acetone-d₆–D₂O (13:2), 27 °C] (J in Hz).

Position	1	9	2	10	3	7
2′	7.70 (d 2.4)	7.62 (d 1.8)	7.49 (d 1.8)	7.42 (d 2.4)	7.79 (d 2.4)	7.70 (d 2.4)
5′	6.95 (d 8.4)	6.95 (d 8.4)	6.97 (d 8.4)	6.96 (d 8.4)	6.92 (d 8.4)	6.91 (d 8.4)
6′	7.59 (dd 8.4, 2.4)	7.50 (dd 8.4, 1.8)	7.40 (dd 8.4, 1.8)	7.32 (dd 8.4, 2.4)	7.68 (dd 8.4, 2.4)	7.58 (dd 8.4, 2.4)
6	6.33 (s)	6.23 (d 1.8)	6.32 (s)	6.22 (d 1.8)	6.31 (s)	6.22 (d 1.8)
8		6.47 (d 1.8)		6.43 (d 1.8)		6.47 (d 1.8)
1″	5.43 (br s)	5.49 (br s)	5.37 (d 1.8)	5.37 (d 1.8)	5.22 (d 7.2)	5.24 (d 7.2)
2″	^a	4.33 (d 1.8)	4.22 (dd 3.6, 1.8)	4.21 (dd 3.6, 1.8)	3.47 (d 7.2)	3.46 (d 7.2)
3″	3.97 (dd 4.8, 2.4)	^a	3.74 (dd 6.0, 3.6),	3.74 (dd 6.0, 3.6)	3.54 (dd 9.0, 7.2)	3.52 (dd 9.0, 7.2)
4″	3.90 (dd 8.4, 4.8)	3.88 (dd 9.0, 4.2)	3.34–3.36 (m)	3.34–3.35 (m)	3.50 (dd 9.0, 5.4)	3.51 (dd 9.0, 5.4)
5″	3.48 (dd 12.0, 4.8)	3.48 (dd 12.0, 4.2)			3.10 (dd 12.0, 9.0)	3.09 (dd 12.0, 9.0)
	3.45 (dd 12.0, 8.4)	3.45 (dd 12.0, 9.0)			3.72 (dd 12.0, 5.4)	3.71 (dd 12.0, 5.4)
6″			0.85 (d 6.0)	0.84 (d 5.4)

^a Overlapped with the HDO signals.

Figure 1. Phenolic constituents of Feijoa sellowiana. Arrows in structure 1 indicate key HMBC correlations.

Figure 2. RP-HPLC profiles of the crude methanol extracts from (a) fruits, (b) buds, (c) leaves, and (d) branches of Feijoa sellowiana. Red and blue lines indicate profiles monitored at 280 and 320 nm, respectively.

Table 2. Contents of flavonoids and ellagic acids in the leaves, flower buds, branches, and fruits of Feijoa sellowiana^a.

	Leaves	Flower buds	Branches	Fruits
Hyperoside (5)	94.7 ± 5.1	30.2 ± 0.2	28.6 ± 0.3	Tr ^b
Isoquercitrin (6)	9.5 ± 0.5	Tr	Tr	57.2 ± 4.2
Reynoutrin (7)	57.8 ± 1.8	Tr	Tr	Tr
Guaijaverin (8)	90.9 ± 5.4	Tr	Tr	Tr
Avicularin (9)	88.0 ± 5.3	Tr	Tr	Tr
Quercitrin (10)	46.2 ± 1.0	Tr	Tr	Tr
Flavone (11)	85.2 ± 5.3	56.3 ± 2.8	26.0 ± 0.1	57.2 ± 4.2
Arabinofuranosylellagic acid (13)	Tr	Tr	Tr	8.3 ± 0.5
Ellagic acid (16)	120.4 ± 7.7	76.4 ± 1.7	44.7 ± 1.6	45.3 ± 3.0

^a Data are expressed as the mean μg ± SD/10 mg of the extract based on the triplicate experiments.

^b Tr, trace. It means lower than the LOQ of each of the flavonoids (ca. 5 μg/10 mg of the extracts), and 13, 16 (ca. 5 μg/10 mg of the extracts).

Table 3. Tyrosinase inhibitory activity of flavonoids.

Compound type	Compound	% Inhibition of tyrosinase ^a
Glycosides	Hyperoside (5)	29.4 ± 3.8
	Isoquercitrin (6)	1.1 ± 4.4
	Reynoutrin (7)	16.2 ± 6.8
	Guaijaverin (8)	5.4 ± 2.0
	Avicularin (9)	18.7 ± 8.8
	Quercitrin (10)	4.8 ± 6.4
Unglycosylated compounds	Flavone (11)	15.4 ± 5.6
	Kaempferol (24)	97.6 ± 8.1
	Quercetagetin (25)	91.6 ± 1.7
	Gossypetin (15)	68.2 ± 3.0
	Myricetin (26)	139.8 ± 6.9
	Morin (27)	81.5 ± 10.2
	Luteolin (28)	65.4 ± 5.4
	Apigenin (29)	32.7 ± 4.6
	Naringenin (30)	30.3 ± 5.0
	Ellagic acid (16)	−47.0 ± 7.5
Tannins	Pedunculagin (21)	−1.4 ± 10.4
	PAOF-1 (22)	7.2 ± 6.5
Positive controls	Quercetin (14)	90.8 ± 0.7
	Kojic acid	73.1 ± 0.8

^a Data are expressed as the mean % inhibition ± SD for 0.1 mM of the sample based on triplicate experiments.

Table 4. Antitumor activity of PAOF-1 and antitumor agents.

	CC50 (μM)
	Human oral squamous cell carcinoma cell lines					Human normal oral cells				TS
	Ca9-22	HSC-2	HSC-3	HSC-4	Mean	HGF	HPLF	HPC	Mean
	(A)				(B)	(C)			(D)	(D)/(B)	(C)/(A)
PAOF-1	109 ± 3.5	83 ± 4.5	323 ± 6.7	88 ± 3.0	151	>500	430 ± 61	>500	>477	>3.2	>4.6
Positive controls
5-FU	389 ± 206	34 ± 10	256 ± 133	54 ± 20	183	>2000	>2000	>2000	>2000	>10.9	>5.1
Doxorubicin	1.00 ± 0.45	0.22 ± 0.06	0.45 ± 0.06	0.29 ± 0.01	0.49	>5	>5	3.7 ± 0.47	>4.6	>9.4	>5
Docetaxel	<0.0078	<0.0078	0.18 ± 0.17	0.29 ± 0.09	<0.12	>1	>1	>1	>1	>8.3	>128