Table 1 Plant extracts used in this study and some of their common chemical constituents

Alfalfa

Medicago sativa L.

Fabaceae

Leaf and stem

Organic acids, non-protein amino acids (canavanine), stachydrine, coumarins (medicagol), isoflavonoids (coumestrol), saponins (hederagenin) and steroids (B-sitosterol) [19].

Angelica

Angelica archangelica L.

Apiaceae

Root

Furanocoumarins (including xanthotoxin, angelicin, archangelin and osthol in roots) [19, 20].

Anise

Illicium verum Hook. F.

Illiaceae

Fruit

Essential oil (up to 8% dry weight) consisting of trans-anethole, anisaldehyde, methylchavicol and other monoterpenoids [19].

Bladderwrack

Fucus vesiculosus L.

Fucaceae

Thallus

Alginic acid, alginates, polysaccharides and iodine [20].

Borage

Borago officinalis L.

Boraginaceae

Leaf, flowers and stem

Mucilages, trace amounts of pyrrolizidine alkaloids including amabiline and supinidine [19, 20].

Buchu

Agathosma betulina (Berg) Pill.

Rutaceae

Leaf

Essential oils, mucilages, resins and flavonoids (mainly diosmin) [19].

Burdock

Arctium lappa L.

Asteraceae

Root

Sulfur containing Polyacetylenes in roots (including artinal and lappaphens) [19, 20].

Celery

Apium graveolens L.

Apiaceae

Fruit

Essential oils, flavonoids, phenolic acids, coumarins and furanocoumarins [20].

Chamomile

Matricaria recutita L.

Asteraceae

Leaf, flowers and stem

Flavonoids (Apigenin, luteolin, patuletin-7-glycosides), coumarins (umbelliferone and herniarin) [19].

Chickweed

Stellaria media (L.) Vill.

Caryophyllaceae

Leaf and stem

Triterpene saponins, coumarins, phytosterols, flavonoids (apigenin, rutin), organic acids and vitamin C [19].

Cleavers

Galium aparine L.

Rubiaceae

Leaf and stem

Tannins, phenolic acids, flavonoids and iridoid glycosides [19].

Comfrey

Symphytum spp

Boraginaceae

Leaves and stem

Allantoin, mucilage, and rosmarinic acid [19].

Gotu kola

Centella asiatica (L.) Urb.

Apiaceae

Leaf and stem

Triterpenes (Asiatic acid and madecassic acid) and triterpenoid ester glycosides (asiaticoside and brahminoside). Also contains volatile oil [19, 20].

Lavender

Lavandula angustifolia L.

Lamiaceae

Leaves and flowers

Essential oil monoterpenoids (including linaloyl-acetate, linalool, 1-terpinen-4-ol), leaves contain rosmarinic acid, tannins, coumarins, triterpenes and phenolic acids [19].

Mahonia

Mahonia aquifolium Nutt.

Berberidaceae

Fruit tincture

Roots and unripe berries contain the alkaloid berberine [19].

Milk thistle

Silybum marianum (L.) Gaertn.

Asteraceae

Fruit

Lipids, flavolignans (silymarin), benzodioxane (silybinin), isosilybinin, silychristin and silydianin [19].

Orange

Citrus aurantium subsp. amara

Rutaceae

Flowers

Peel contains essential oils, bitter flavonone glycosides and bitter triterpenes. Neroli oil is distilled from petals [19]. Flowers contain flavonoids (naringen and neoeriocitrin) [20].

Pomegranate

Punica granatum L.

Lythraceae

Glycerin fruit preparation

Fruit rind has gallotannins and ellagitannins (punicalin and punicalagen). Alkaloids present in roots, leaves, bark and young fruit but not rind [19].

Rose

Rosa centifolia L.

Rosaceae

Flowers (both aqueous and tincture)

Petals contain tannins, rosehips contain ascorbic acid, carotenoids, pectins, flavonoids, tannins, organic acids and sugars [19].

Tea

Camellia sinensis Kuntze

Theaceae

Leaf extracts of green tea (in glycerine) and white tea (lyophilized powder)

Flavan-3-ols (catechins) up to 30% dry weight, quercetin, kaempferol, other acids: gallic acid, caffeic acid, coumaric acids [22].

Witch hazel

Hamamelis virginiana L.

Hamamelida-ceae

Leaf

Leaves and bark both contain tannins (bark has catechols and hamamelitannins while leaves contain proanthocyanidins, ellagitannins and essential oils) [19].