Effects of frankincense on experimentally induced renal stones in rats

Abstract

Objectives: Frankincense (Luban) is a resin obtained from trees of genus Boswellia. The south of Oman hosts Boswellia sacra trees known to have many social, religious and medicinal uses. The anti-inflammatory and therapeutic potential of Luban has recently attracted the interest of the scientific community. The aim is to study the efficacy of Luban water extract and its essential oils on experimentally induced renal stones in rats.

Materials and methods: A rat model of urolithiasis induced by trans-4-hydroxy-L-proline (HLP) was used. Wistar Kyoto rats (27 males, 27 females) were randomly distributed into nine equal groups. Treatment groups were given Uralyt-U (standard) or Luban (50, 100 and 150 mg/kg/day), starting Day 15 from HLP induction for a duration of 14 days. The prevention groups were given Luban in similar doses, starting Day 1 of HLP induction for 28 days. Several plasma biochemical and histological parameters were recorded. Data were analysed with GraphPad Software. Comparisons were performed by one-way analysis of variance (ANOVA) and the Bonferroni test.

Results: The lithogenic effects of HLP, such as an increase in urine oxalate and cystine, an increase in plasma uric acid and an increase in kidney levels of calcium and oxalate, have all been best significantly reversed by the Luban dose of 150 mg/kg/day. The histological changes of HLP on the kidney tissue including calcium oxalate crystal formation, cystic dilatation, high degree of tubular necrosis, inflammatory changes, atrophy and fibrosis have also been ameliorated by Luban dose of 150 mg/kg/day.

Conclusion: Luban has shown a significant improvement in the treatment and prevention of experimentally induced renal stones, particularly at a dose of 150 mg/kg/day. Further studies on the effect of Luban in other animal models and humans with urolithiasis are warranted.

Keywords: Boswellia; Luban; frankincense; kidney; rats; renal; stones.

FIGURE 1

Biochemical and physical changes. (A) oxalate in urine, (B) cysteine in urine, (C) osmolality in urine, (D) uric acid in plasma, (E) calcium in kidney, (F) oxalate in kidney. Group 1: control (Con); group 2: lithogenic (H); group 3: Uralyt‐U (H + U); group 4: (H + B‐50); group 5: (H + B‐100); group 6: (H + B‐150); group 7: p (H + B‐50); group 8: p (H + B‐100); group 9: p (H + B‐150).

FIGURE 2

Representative photomicrographs of renal tissues from male rats stained with haematoxylin and eosin where (A) represents control group; (B) group given trans‐4‐hydroxy‐L‐proline (HLP) alone; (C) group given HLP and treated with Uralyt‐U (from Day 15 onward); while (D), (E) and (F) represent groups given HLP and then Boswellia sacra (from Day 15 onward as treatment) at the doses 50, 100 and 150 mg/kg, respectively; and (G), (H) and (I) represent: groups given HLP and B. sacra concomitantly (on all 28 days as a preventive regimen) at the doses 50, 100 and 150 mg/kg, respectively. The asterisks indicate cystic dilatation of renal tubules, and the arrowhead indicates mononuclear cell infiltrations. Inset: intratubular calcium oxalate crystals showing birefringence under polarized light. (Bar = 100 μm).

FIGURE 3

Representative photomicrographs of renal tissues from male rats stained with picro–Sirius red where (A) represents control group; (B) group given trans‐4‐hydroxy‐L‐proline (HLP) alone; (C) group given HLP and treated with Uralyt‐U (from Day 15 onward); while (D), (E) and (F) represent groups given HLP and then Boswellia sacra (from day 15 onward as treatment) at the doses 50, 100 and 150 mg/kg, respectively; and G, H and I represent: groups given HLP and B. sacra concomitantly (on all 28 days as a preventive regimen) at the doses 50, 100 and 150 mg/kg, respectively. The photomicrographs show the distribution of Sirius red‐stained fibrotic areas (arrowhead) and the non‐collagen structures (stained in yellow). Inset: birefringence of the stained collagen fibres using polarized light. (Bar = 100 μm).