Table 4.

The content of TRP and its KP metabolites in honey and honeybee products. 3HKyn, 3HAA, AA, QA, PIC, and CA were not included in a target list of the analytical methods utilized for quantitative analysis.

Type of Honey Product	N	Concentration Range (mg/kg)				Ref.
		TRP	KYN	KYNA	XA
Acacia honey dew	5	0.69–0.78	0.30–0.36	0.11–0.15	0.05–0.28	[15]
Bee pollen	2	n.a	n.a.	0.65	n.a.	[38]
Blackberry	5	0.28–0.35	0.18–0.24	11.65–12.35	<LOD–0.02	[15]
Buckwheat	2	n.a.	n.a.	0.33	n.a.	[14]
	2	n.a.	n.a.	0.18	n.a.	[38]
Chestnut	5	0.07–0.12	0.10–0.15	103.50–141.15	0.23–0.34	[15]
	5	n.a.	n.a.	129–601	n.a.	[14]
Clover	1	n.a.	n.a.	0.34–0.75	n.a.
Eucalyptus	5	1.57–1.78	2.14–4.47	0.49–0.54	0.03–0.60	[15]
	1	n.a.	n.a.	11.30	n.a.	[14]
Fir	1	n.a.	n.a.	1.06	n.a.
Forest	5	9.56–9.94	0.14–0.18	1.15–1.18	<LOD–0.02	[15]
Heather	5	0.03–0.11	0.03–0.09	1.01–1.07	0.01–0.35
Holm oak	5	1.04–1.26	0.02–0.06	0.45–0.50	<LOD
Honey made from Pueblo plants	1	n.a.	n.a.	3.46	n.a.	[14]
Honey dew	1	n.a.	n.a.	0.12	n.a.
Lavandin	5	0.63–0.74	0.04–0.23	0.60–0.71	0.01–0.04	[15]
Lavender	2	n.a.	n.a.	0.15	n.a.	[14]
Lavender (French)	5	2.51–2.87	0.84–0.98	0.20–0.26	0.04–0.28	[15]
Lavender (spike)	5	2.73–6.68	3.50–5.37	0.29–0.37	<LOD–0.02
Linden	1	n.a.	n.a.	0.18–0.39	n.a.	[14]
	2	n.a.	n.a.	0.18	n.a.	[38]
Luceme	1	n.a.	n.a.	0.10	n.a.	[14]
Multifloral	5	1.86–2.16	4.68–5.47	3.01–3.24	0.02–0.03	[15]
	1	n.a.	n.a.	0.09–0.12	n.a.	[14]
	2	n.a.	n.a.	0.88	n.a.	[38]
Oak	5	1.10–1.35	0.13–0.31	1.01–1.05	0.01–0.03	[15]
Orange	5	0.95–1.10	1.07–1.32	0.02–0.08	0.01–0.10
	1	n.a.	n.a.	0.27–0.61	n.a.	[14]
Pine	1	n.a.	n.a.	14.20	n.a.
Propolis	2	n.a.	n.a.	1.62	n.a.	[38]
Rosemary	5	4.88–14.64	0.33–0.89	0.12–1.17	<LOD–0.02	[15]
Sunflower	5	0.45–0.53	3.13–3.77	0.31–0.37	0.05–0.10
	1	n.a.	n.a.	1.73	n.a.	[14]
Sulla	2	n.a.	n.a.	0.22	n.a.
Thyme	5	0.14–3.50	2.04–3.51	0.40–2.12	0.02–0.34	[15]
	1	n.a.	n.a.	0.14	n.a.	[14]
Winter savory	5	0.18–1.07	0.14–0.23	0.26–0.32	0.01–0.08	[15]

n.a.—data are not available, the analyte was not included in the target list of the applied analytical methods; <LOD—not detected; and N—number of analyzed samples. AA—anthranilic acid; CA—cinnabarinic acid; 3HAA—3-hydroxyanthranilic acid; 3HKyn—3-hydroxykynurenine; KYN—kynurenine; KYNA—kynurenic acid; PIC—picolinic acid; QA—quinolinic acid; TRP—tryptophan; and XA—xanthurenic acid.