162 Handbook of herbs and spices
native to southern Africa with anti-inflammatory properties while tormentil (Potentilla
tormentilla) is a member of the rose family and is said to be effective in the treatment
of diarrhoea and bowel inflammation. Wei tong ning is a Chinese herb used for
treatment of patients with peptic ulceration and other intestinal inflammatory disorders
(Langmead et al., 2002). Gingo biloba extract has a remarkable anti-inflammatory
effect in rats (Abdel-Salam et al., 2004). Commercial preparations also containing
bitter candytuft, chamomile flower, peppermint leaves, caraway fruit, licorice root,
lemon balm leaves, celandine herbs, angelica root and milk thistle fruit are effective
in alleviating irritable bowel syndrome symptoms (Madisch et al., 2004).
The anti-inflammatory activity of herbs and spices in most cases is attributed to
the antioxidant properties of their components. Measuring the lipid peroxidation,
curcumin, capsaicin and eugenol were found to be more effective antioxidants, while
piperine (black pepper), zingerone (ginger), linalool (coriander) and cuminaldehyde
(cumin) were only marginally inhibitory to lipid peroxidation (Reddy and Lokesh,
1992). Indeed curcumin, the polyphenol of dietary spice turmeric, posseses diverse
anti-inflammatory properties due to its antioxidant capacity at neutral and acidic pH
(Sharma et al., 2005).
Other herbal treatments investigated for efficacy in peptic ulcer disease are capsaicin/
chilli and mastic. The pungent ingredient of chilli, capsaicin is thought to have
effects on substance P release and has been tested for its efficacy in peptic ulcer
patients. Another ingredient of curry, Curcuma domestica val, was tested for its
efficacy in dyspepsia while mastic, the resin of the mastic or lentisc tree, was effective
for ulcer healing. The most researched herbal treatment for liver diseases is milk
thistle. Its active constituents are collectively known as silymarin (Langmead and
Rampton, 2001).
10.5.1 Experimental assays
The experimental assay for assessing anti-oxidant activity is conducted in vitro in
two cell-free, radical-generating systems and by the chemiluminescence of incubated
colorectal mucosal biopsies (or mucosal biopsy assay systems). Eicosanoid production
by biopsies and interleukin-8 release by CaCo2 epithelial cells in the presence of the
extract is measured by enzyme-linked immunosorbent assay (Langmead et al., 2004).
Studies include also in vivo clinical trials (Madisch et al., 2004) in irritable bowel
syndrome patients. The antioxidant properties of several spice principles were
investigated in rats by measuring the lipid peroxidation induced both in vivo and in
vitro (Joe and Lokesh, 1994; Reddy and Lokesh, 1992, 1994a,b,c,d).
10.5.2 Mechanisms of action – active compounds
Although the pathogenesis of inflammatory bowel disease has not been clearly
elucidated, the over-production by the involved colorectal mucosa of reactive oxygen
metabolites (Grisham, 1994; Simmonds and Rampton, 1993), eicosanoids (Rampton
and Hawkey, 1984) and the chemo-attractant chemokine, interleukin-8 (Gibson and
Rosella, 1995; Daig et al., 1996; Keshavarzian et al., 1999), is likely to play a
contributory role. The anti-inflammatory activity of herbs and spices in most cases is
attributed to the antioxidant properties of their phenolic constituents. Prevention of
the activity of radicals after their generation and release can occur as a result of
scavenging by antioxidants. In vitro studies (Langmead et al., 2004) have attributed