Investigation of mitigating effect of colon-specific prodrugs of boswellic acid on 2,4,6-trinitrobenzene sulfonic acid-induced colitis in Wistar rats: Design, kinetics and biological evaluation

Table 1 Doses of test and standard drugs

Compound	Dose1 in mg/kg	Compound	Dose1 in mg/kg
HC	0.9 % saline (1 mL)	P	759
BBA	2159	T	938
SLZ	300	TY	832
BH	2795	BBA + H	2871
BP	2841	BBA + P	2918
BT	3020	BBA + T	3097
BTY	2914	BBA + TY	2991
H	712

¹All doses are calculated on an equimolar basis to the dose of BBA. HC: Healthy control; BBA: β-boswellic acid; SLZ: Sulfasalazine; BH: Prodrug of BBA with L-histidine; BP: Prodrug of BBA with D-phenylalanine; BT: Prodrug of BBA with L-tryptophan; BTY: Prodrug of BBA with L-tyrosine; H: L-histidine; P: D-phenylalanine; T: L-tryptophan; TY: L-tyrosine; BBA + H: Physical mixture of BBA + L-histidine; BBA + P: Physical mixture of BBA + D-phenylalanine; BBA + T: Physical mixture of BBA + L-tryptophan; BBA + TY: Physical mixture of BBA + L-tyrosine.

Table 2 Scoring rate of clinical activity

Sr. No.	Weight loss, %	Stool consistency	Rectal bleeding	Score rate
1	No loss	Well-formed pellets	No blood	0
2	1-5	-	-	1
3	5-10	Pasty and semi-formed stools, not sticking to anus	Positive finding	2
4	10-20	-	-	3
5	> 20	Liquid stools, sticking to anus	Gross bleeding	4

Adapted from Hartmann et al[55].

Table 3 In vitro kinetics of prodrugs in aqueous buffers, gastrointestinal tract homogenates and fecal matter

Prodrug	Incubation medium
	HCl buffer (pH 1.2) and stomach homogenates	Phosphate buffer (pH 7.4) and intestinal homogenates	Colon homogenate				Fecal matter
			K ± SD (min-1)1	t1/2 (min)	Prodrug hydrolyzed	BBA released	K ± SD (min-1)1	t1/2 (min)	Prodrug hydrolyzed	BBA released
BH	Stable	Negligible	0.0013	514.1	78.10%	73.60%	0.0009	723.1	62.29%	57.37%
		hydrolysis
BP	Stable	Negligible	0.0014	488.3	75.08%	71.79%	0.0010	636.7	57.38%	56.67%
		hydrolysis
BT	Stable	Negligible	0.0018	379.4	86.67%	86.39%	0.0010	662.5	69.75%	72.52%
		hydrolysis
BTY	Stable	Negligible	0.0014	484.4	70.33%	68.57%	0.0010	677.6	55.95%	55.13%
		hydrolysis

¹Average of three readings; follows first-order kinetics.

Table 4 Clinical activity score rate¹

Intervention	1 d	2 d	3 d	4 d	5 d	6 d	7 d	8 d	9 d	10 d	11 d
HC	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0
DC	0 ± 0	0.77 ± 1.34	1.00 ± 1.73	1.66 ± 1.52	1.66 ± 1.52	1.88 ± 1.71	3.11 ± 1.01	3.22 ± 1.07	3.33 ± 1.15	3.33 ± 1.15	3.33 ± 1.15
BBA	0 ± 0	0.66 ± 1.15	1.00 ± 1.73	1.66 ± 1.52	2.00 ± 1.73	2.77 ± 1.34	3.00 ± 1.00	2.33 ± 0.57	1.99 ± 0.66	1.33 ± 1.15	0.99 ± 1.10e
SLZ	0 ± 0	0.38 ± 0.67	0.83 ± 0.92	1.88 ± 0.83	2.72 ± 0.63	2.88 ± 0.83	2.44 ± 0.50	1.61 ± 1.13	1.11 ± 1.01	0.72 ± 0.75	0.38 ± 0.60e
BH	0 ± 0	0.66 ± 1.15	1.55 ± 1.50	2.11 ± 0.83	2.77 ± 1.01	3.00 ± 1.00	2.66 ± 0.57	2.11 ± 0.50	1.55 ± 1.07	1.31 ± 0.83	0.70 ± 1.10e
BP	0 ± 0	0.77 ± 1.34	1.00 ± 1.73	1.50 ± 1.58	2.16 ± 1.09	2.66 ± 0.88	2.55 ± 0.76	1.88 ± 1.01	1.22 ± 1.17	0.97 ± 1.07	0.61 ± 0.70e
BT	0 ± 0	0.72 ± 1.25	1.05 ± 1.82	2.16 ± 0.86	2.38 ± 0.67	2.38 ± 0.67	2.16 ± 0.92	1.44 ± 1.17	0.94 ± 1.10	0.50 ± 0.86	0.33 ± 0.50e
BTY	0 ± 0	0.66 ± 1.15	1.44 ± 1.50	2.00 ± 0.88	2.77 ± 0.69	3.05 ± 1.00	2.88 ± 1.07	2.00 ± 1.20	1.61 ± 1.25	1.22 ± 1.17	0.83 ± 0.90e
H	0 ± 0	0.66 ± 1.15	1.11 ± 1.16	1.33 ± 1.52	1.88 ± 1.01	2.33 ± 0.67	2.55 ± 0.50	2.88 ± 0.83	2.77 ± 0.69	2.60 ± 0.82	2.00 ± 1.00NS
P	0 ± 0	0.50 ± 0.86	0.88 ± 1.53	1.22 ± 1.57	1.99 ± 0.88	2.22 ± 0.83	2.55 ± 0.50	3.16 ± 1.04	3.33 ± 1.15	2.66 ± 1.44	2.27 ± 1.13NS
T	0 ± 0	0.61 ± 1.05	1.00 ± 1.73	1.66 ± 1.52	2.11 ± 0.83	2.44 ± 0.69	2.60 ± 0.58	2.94 ± 0.82	2.66 ± 0.66	2.16 ± 1.08	1.88 ± 1.17a
TY	0 ± 0	0.55 ± 0.95	1.00 ± 1.73	1.00 ± 1.73	1.99 ± 0.88	2.11 ± 0.84	2.55 ± 0.50	3.22 ± 1.07	3.33 ± 1.15	2.72 ± 1.49	2.33 ± 1.45NS
BBA + H	0 ± 0	0.44 ± 0.76	1.00 ± 1.73	1.88 ± 0.96	1.99 ± 0.88	2.33 ± 0.67	3.22 ± 1.07	3.33 ± 1.15	2.88 ± 1.92	2.72 ± 1.80	1.77 ± 1.34a
BBA + P	0 ± 0	0.66 ± 1.15	1.00 ± 1.73	1.44 ± 1.50	1.99 ± 0.88	2.33 ± 0.88	3.11 ± 1.01	3.22 ± 1.07	3.22 ± 1.07	2.55 ± 1.64	1.88 ± 1.17a
BBA + T	0 ± 0	0.38 ± 0.66	0.88 ± 1.53	1.66 ± 1.20	2.10 ± 0.77	2.44 ± 1.07	2.99 ± 0.87	3.33 ± 1.15	2.99 ± 1.45	2.55 ± 1.71	1.77 ± 1.34b
BBA + TY	0 ± 0	0.55 ± 0.95	0.88 ± 1.53	1.33 ± 1.52	1.88 ± 1.01	2.55 ± 0.50	2.99 ± 0.87	3.22 ± 1.07	3.27 ± 1.10	2.44 ± 1.26	1.88 ± 1.17a

¹Average of six readings; Two-way ANOVA followed by Bonferroni’s test, statistical significance considered at

^aP < 0.05,

^bP < 0.01,

^eP < 0.001 vs disease control. HC: Healthy control; DC: Disease control; BBA: β-boswellic acid; SLZ: Sulfasalazine; BH: Prodrug of BBA with L-histidine; BP: Prodrug of BBA with D-phenylalanine; BT: Prodrug of BBA with L-tryptophan; BTY: Prodrug of BBA with L-tyrosine; H: L-histidine; P: D-phenylalanine; T: L-tryptophan; TY: L-tyrosine; BBA + H: Physical mixture of BBA + L-histidine; BBA + P: Physical mixture of BBA + D-phenylalanine; BBA + T: Physical mixture of BBA + L-tryptophan; BBA + TY: Physical mixture of BBA + L-tyrosine; NS: Non-significant.

Table 5 Ulcerogenic activity

Code	Ulcer index ± SD1
HC	1.16 ± 0.40
BBA	3.66 ± 0.51e
SLZ	7.66 ± 1.21e
BH	3.16 ± 0.40e
BP	2.83 ± 0.40e
BT	3.06 ± 0.89e
BTY	3.33 ± 0.51e

¹Average of six readings; One-way ANOVA followed by Dunnett’s multiple comparison test, statistical significance was considered at

^eP < 0.001 vs healthy control. HC: Healthy control; DC: Disease control; BBA: β-boswellic acid; SLZ: Sulfasalazine; BH: Prodrug of BBA with L-histidine; BP: Prodrug of BBA with D-phenylalanine; BT: Prodrug of BBA with L-tryptophan; BTY: Prodrug of BBA with L-tyrosine.