Tulbaghia violacea

1.1. Source and History

Tulbaghia violacea is an African herb used historically to treat some infectious diseases, which is due to an anti-microbial potential of the herb.^[1] The herb appears to be synergistic with itself in this regard, suggesting that multiple components within the herb itself work together.^[1]

It belongs to the Alliaceae family of herbs, similar to Garlic. It is sometimes referred to as Sweet Garlic (as its consumption is not associated with bad breath), Wild Garlic, or Society Garlic and possesses a strong garlic odour, although the roots are sometimes referred to as skunky.^[2][3][4] It is also referred to as 'Isihaqa' by the Zulus, who use this plant as an aphrodisiac, and as 'Wildeknoffel' by the Afrikaans.^[5] It may share nutrient motifs with the garlic family.^[2] It is referred to as a modest, unassuming plant with small flowers and grassy foliage.^[2] 

1.2. Composition

As a herbal supplement, Tulbaghia violacea may contain a wide variety of compounds. Some of these compounds include:

• 3 Cysteine derivates known as Marasmin, Ethiin and Methiin^[6][3][7]

• Kaempferol

• From the leaves, 2,4,5,7-tetrathiaoctane-2,2-dioxide, 2,4,5,7-tetrathiaoctane, and 2,4,5,7-tetrathiaoctane-4-oxide^[2][8]

• Steroidal saponins

• Methyl-alpha-D-glucopyranoside^[2] 

Compounds that are inherent to the Allium (Garlic) family, and show motifs with Tulbaghia (in regards to traditional usages and preparation) include (note, it is plausible but not assured Tulbaghia contains these molecules):

• Cysteine Sulfoxide derivatives (Alliin, Isoalliin, and Methiin) found in both onions and garlic^[2] These compounds have been reported in T.Acutiloba.^[9]

Of the Tulbaghia family of herbs, violacea appears to have the highest known concentration of sulfur-containing compounds (although not all species have been analyzed).^[2]

2.1. Blood Pressure

Tulbaghia Violacea appears to have ACE inhibiting properties, reaching 68% ACE inhibition with the water extract and 71% with the ethanolic extract in vitro.^[10][11] When rats were subject to 0.1mg/kg Angiotensin I injections (increasing the control groups blood pressure by 14.5%) co-injection of 50mg/kg bodyweight Tulbaghia Violacea was able to attenuate the increase to 2.2%, showing bioactivity.^[10]

Tulbaghia Violacea has been shown in a model of spontaneously hypertensive rats to reduce both systolic and diastolic blood pressure, as well as heart rate, by acting as a ACE inhibitor.^[4] It may also have interactions with B(1)adrenoreceptors.^[4]

Tulbaghia Violacea has been implicated in exerting anti-diabetic effects in vitro, by increasing glucose uptake by 140.5% in muscle cells at a concentration of 0.5ug/mL with the ethanolic extract.^[12] The water extract increased glucose uptake by 119% at this concentration, and uptake was increased by approximately 117% by both extracts at a concentration of 50ug/mL, although insulin incubation at 0.5ug/ml seemed to reduce glucose uptake induced by T.Violacea.^[12]

One in vitro study conducted on testicular cells noted that the extract of Tulbaghia violacea was able to increase testosterone release from testicles in response to stimulation from Luteinizing Hormone.^[5] The cells were incubated at varying concentrations ranging from 156.25-5000ug/ml at doubling intervals and, although only showing statistical significant at a concentration of 312.5ug/ml and above, did not show any dose-dependent effects but rather constant elevation of testosterone secretion.^[5] The increases in testosterone were quantified to be 30-72% greater than control cells, and was dependent on the presence of lutenizing hormone. No direct testicular increases in estradiol were noted.^[5]

Historically, it has been noted that prolonged and excessive use of Tulbaghia Violacea bulbs causes gastrointestinal distress and may be associated with acute inflammation and sloughing of intestinal tissue as well as cessation of peristalsis.^[2] Contraction of the pupils and delayed response to stimuli have been mentioned additionally.^[2]