Bishop's Weed

Generic name: Trachyspermum Ammi L. Sprague.
Brand names: Ajava Seeds, Ajowan Caraway, Ajowan Seed, Ajowanj, Ajwain, Bishop's Weed, Carum, Omum., Yavani

Usage of Bishop's Weed

Clinical studies are limited. However, the medical literature documents numerous pharmacological activities for bishop's weed including antifungal,17 antimicrobial,18 hypolipidemic,2 antihypertensive,19, 20 antilithiasis,21 abortifacient,2 antitussive,22 nematicidal,23, 24 anthelmintic,2 and antifilarial.2

Analgesia

In a double-blind, randomized, placebo-controlled trial (n=92), the effect of topical T. ammi 10% cream on neuropathic pain was investigated in adults with moderate to severe neuropathic pain. Burning feet was the main complaint and diagnoses included diabetic neuropathy, postsurgical or posttraumatic neuropathic pain, or neuropathic pain for at least 6 months. The essential oil of Ajwain seeds was extracted and compounded into a 10% cream that was applied twice daily for 28 days. The mean changes in absolute pain scores for feet burning (−3.55 vs −0.76), numbness (−0.58 vs −0.11), allodynia (−0.64 vs −0.06), and tingling (−1.69 vs −0.16) were all significantly greater in the Ajwain group versus placebo, respectively (P<0.001, P=0.011, P=0.023, P<0.001, respectively). No adverse effects were reported by patients in either group.48

Anticancer activity

Dietary administration of 2%, 4%, and 6% bishop's weed reduced skin tumor multiplicity, but not the incidence of skin tumors, in an induced skin papillomagenesis model.34 However, dietary administration of 2%, 4%, and 6% bishop's weed inhibited both tumor multiplicity and incidence in an induced forestomach papillomagenesis model. The difference in the anticancer activity may be related to bioavailability and the actual dose.

Antidiarrheal activity

A combination preparation (Arque-Ajeeb) containing bishop's weed was evaluated for its antidiarrheal activity. The preparation was less effective than diphenoxylate in serotonin- and prostaglandin E2–induced diarrhea. It reduced propulsive activity in the gut in a dose-dependent manner, and reduced the number and amount of stools.7

Antifilarial activity

Bishop's weed fruit methanolic extracts exhibited significant in vitro activity against worm motility in adult bovine Setaria digitata worms. The active chemical component is believed to be thymol. The extracts exhibited significant in vivo activity for adult worm mortality and female worm sterility for the human filarial worm Brugia malayi.35 The antiparasitic activity of bishop's weed fruit essential oils at a concentration of 5 mg/mL (60 min) or 10 mg/mL (10 min) was comparable with 20% hypertonic saline (15 min), 20% silver nitrate (20 min), 0.5% to 1% cetrimide (10 min), and 95% ethyl alcohol (15 min).36

Anthelmintic activity

One review article documents activity against Ascaris lumbricoides in humans and Haemonchus contortus in sheep.2

Antihypertensive activity

Animal studies have shown thymol (the active principle of bishop's weed) exerting a blood pressure–lowering action, suggesting a channel-blocking mechanism and possibly explaining the hypotensive and bradycardic effects observed in in vivo studies.19 The mechanism of action may be associated with a calcium channel blockade.20

Anti-inflammatory activity

Alcohol and aqueous extracts of bishop's weed demonstrated anti-inflammatory effects in rats comparable with aspirin and phenylbutazone.6 Competitive antagonism of histamine H1 receptors has been demonstrated in guinea pig tracheal chains.37 The mechanism of action is associated with carvacrol and not due to anticholinergic or beta-adrenergic stimulatory effects.38

Antimicrobial activity

In vitro data

Antimicrobial properties of the essential oil demonstrated in vitro activity against gram-positive and gram-negative bacteria as well as against yeast,25 while in another study an in vitro activity greater than 7 antibacterial drugs against clinically relevant pathogens (including Pseudomonas aeruginosa, EscheriChia coli, Corynebacterium diphtheriae, and Staphylococcus aureus).18 Another study documents antibacterial activity for hot water and acetone bishop's seed extracts against several gram-positive and -negative bacteria, except for Klebsiella pneumonia and 1 strain of P. aeruginosa.26, 27 The seeds inhibited dental caries by reducing the biofilm properties of S. mutans.9 The anticariogenic activity may be associated with the sterols, terpenes, fatty acids, and their derivatives in the petroleum ether fraction.

Another investigation revealed antifungal properties.28 The antifungal activity for bishop's seed on 10 fungi (Acrophialophora fusispora, Curvularia lunata, Fusarium chlamydosporum, Fusarium poae, Myrothecium roridum, Papulaspora sp., Alternaria grisea, Alternatia tenuissima, Drechslera tetramera, and Rhizoctonia solani) was tested and resulted in 72% to 90% growth inhibition of all test fungi.2 The essential oil exhibited a broad spectrum of antifungal activity against all tested fungi including Aspergillus niger, Aspergillus flavus, Aspergillus oryzae, Aspergillus ochraceus, Fusarium monoliforme, Fusarium graminearum, Pencillium citrium, Penicillium viridicatum, Pencillium madriti, and Curvularia lunata.17 Bishop's weed essential oil exhibited no inhibition or antifungal activity against Trichosporon ovoides, which may cause a fungal infection of the hair shaft.29

Several studies examine the antimicrobial actions of the essential oils and extracts of bishop's weed against food-borne and spoilage bacteria.12, 30, 31 Bishop's weed fruit oil exhibited potential antimicrobial activity against S. aureus, Bacillus subtilis, P. aeruginosa, Salmonella typhimurium, E. coli, Enterobacter aerogenes, and Salmonella enteritidis.12 The thymol (49.64%), b-cymene (16.33%), eugenol (3.04%), and b-pinene (2.51%) content in the oil may contribute to the antimicrobial activity. A bishop's seed extract versus tea leaf extract showed greater antimicrobial activity against the growth of food-borne Salmonella isolates.30

The inhibitory effects of extracts32 on hepatitis C viral (HCV) protease have been reported and an aqueous extract of bishop's weed was demonstrated to have potent activity against Helicobacter pylori, even against metronidazole- and tinidazole-resistant isolates.33

Antiplatelet activity

An in vitro study with human platelets demonstrated inhibition of arachidonic acid–induced platelet aggregation by an extract of bishop's weed. The mechanism, in part, was postulated to be caused by redirection of arachidonic acid from the cyclooxygenase to the lipoxygenase pathway, reducing thromboxane B2 formation. The same study showed antiaggregatory effects and alteration of arachidonic acid metabolism by the extract.39

Antitussive activity

The antitussive effects of aerosols using 2 different concentrations of aqueous and macerated bishop's weed extracts and carvacrol, codeine, and saline were tested in guinea pigs. The results documented a reduction in the number of coughs obtained with both concentrations of aqueous and macerated bishop's weed extracts and codeine (P < 0.001 for extracts and P < 0.01 for codeine). The antitussive effect was not associated with the main constituent carvacrol.22

Detoxification of aflatoxins

The seed extract of bishop's weed degraded and detoxified aflatoxin G1 up to 65%.40 The dialyzed extract was more effective degrading more than 90% of the toxin. Aflatoxins are highly toxic and carcinogenic to several animal species.

Hepatoprotective activity

A C. copticum seed extract given at 500 mg/kg orally for 2 days at 12-hour intervals protected rats from paracetamol 640 mg/kg and carbon tetrachloride or CCl4 150 mL/kg–induced rise in serum alkaline phosphatase and aminotransferases. The hepatoprotective activity was confirmed in mice with the same dose of seed extract preventing CCl4–induced prolongation in pentobarbital-induced sleeping time.20 Antioxidant activity may be a mechanism of action as documented by the protective effects of bishop's weed extract on hexachlorocyclohexane-induced oxidative stress and toxicity in rats.41

Hypolipidemic activity

A review article documents how a dose of bishop's weed 2 g/kg powder and its equivalent methanol extract reduced total cholesterol, LDL-cholesterol, triglycerides, and total lipids in albino rabbits.2

Mosquitoes

Bishop's weed extracts have significant larvicidal potential against an Indian strain of dengue fever mosquito, Aedes aegypti L., with an LC50 value of 65.57 ppm.42, 43

Nematicidal activity

The pinewood nematode Bursaphelenchus xylophilus, which is responsible for pine wilt disease, causes substantial ecological and economical damage in Korean forests. Bishop's weed essential oils have nematicidal activities against the pinewood nematode. The exact mechanism of action is unclear.23, 24

Ophthalmic uses

A combination preparation containing bishop's weed was evaluated for efficacy and adverse reactions in ophthalmic conditions. The preparation was effective in acute conjunctivitis and dacrocystitis, as well as in postcataract surgery and conjunctival xerosis, with no adverse reactions reported.5

Spermicidal activity

In vitro studies document the spermicidal activity of bishop's weed essential oil by inhibiting sperm motility and damaging membrane integrity and DNA of human spermatozoa.3, 44

Termites

Bishop's weed essential oils have insecticidal activity against Japanese termites.45

Ticks

A combined herbal extract containing bishop's weed seeds inhibited the developmental stages of Rhipicephalus (Boophilus) microplus, the common cattle tick, which is capable of transmitting viral diseases and can cause anemia in cattle.46

Urolithiasis

Bishop's weed contains an anticalcifying protein that helped maintain renal function, reduced renal injury by inhibiting calcium oxalate monohydrate crystal size and adhesion, and decreased crystal excretion in urine in rats.21

Bishop's Weed side effects

Caution may be warranted in patients taking NSAIDS or antiplatelet medications due to platelet aggregation inhibition by bishop's weed.39

Before taking Bishop's Weed

Avoid use. Documented adverse effects. Avoid use. Bishop's weed was listed as 1 of 14 indigenous medicinal plants used for abortion in some districts of India in 1987 and it may also cause congenital defects. A risk of human fetotoxicity was documented as observed in rat teratogenicity studies.2

How to use Bishop's Weed

Bishop's weed is commercially available as a single entity or herbal blend in numerous dosage forms including capsules, liquids, and powders. Internet sources list the product primarily marketed as "ajwain" and as an overall panacea. One herbal blend prescribes 1 or 2 capsules (200 mg/capsule) with a full glass of water for GI discomfort. The prescription drug methoxsalen, as documented by various Internet resources, was developed from bishop's weed (Ammi majus Linn) and is used to treat several skin conditions. Use of a 10% topical cream twice daily has been supported by a clinical trial in adults with neuropathic pain.48

Warnings

Bishop's weed is toxic in high doses and can result in fatal poisoning.10 The essential oils isolated from bishop's weed seeds showed cytotoxic activity against P388 mouse leukemia cells.47 Avoid use during pregnancy due to documented adverse effects.2

What other drugs will affect Bishop's Weed

Data are lacking concerning specific drug interactions. Potentiation of the effects of antibiotics and antiplatelet medications39 could be theorized.

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