**2.2. Antimicrobial activity**

menthone, diosphenol and one of its isomers (ψ)-diosphenol, and *l*-pulegone [7]. Aganthosma crenulata contains the same main constistuents, but has trace amounts of diosphenol and larger amounts of *l*-pulegone [7]. These are responsible for the odour, flavour and medicinal properties of Buchu oil [8]. Two monoterpene thiols are accountable for the distinguishing odour of Buchu oil, one being 9-mercapto-*p*-menthan-3-one [6]. This sulphur-containing

True to its description of being a multi-purpose specie, Buchu has long been used as an antiseptic, an anti-inflammatory agent, for urinary problems including maladies such as haematuria, calculi, kidney disease and infections of the bladder, prostate and urethra [9]. Today it is also used to stimulate perspiration in rheumatic disease and gout, as a digestive tonic [9] which treats cholera and stomach complaints, an antispasmodic, an antipyretic, as a treatment for colds and flu, and most importantly, as a diuretic. In current Pharmacopoeias, it is listed as a diuretic and a urinary tract antiseptic [2]. It is also listed as a treatment for

A number of Buchu preparations are used to deliver it to the body. It may be prepared as a brandy, a tincture (an alcohol or aqueous solution), a tea, or soaked in vinegar [9]. The vinegar can be used for external applications to treat bruises, contusions, sprains and fractures, to clean wounds and to treat rheumatism [10]. The Khoi-San used the plant as an 'antibiotic repellent' to repel insects and mixed it with oil to use as a moisturiser, which was essential in their natural environment and desert climate surroundings [9]. Topical application allowed entry of the active ingredients of Buchu oil through the skin and provided antibacterial and antifungal

Buchu has a long-standing traditional use, but it has made its way into the fragrance and flavour industries due to its sulphur-containing compounds and sensory properties [2]. It is used to enhance fruit flavours and fragrances, and boost blackcurrant-like flavours. It has a naturally minty, sweet berry, apricot, peach and green herbal taste, and its oils are used in

The list of ailments Buchu is capable of counteracting and the multitude of its historical and current uses are what help to define it as an ethnomedicinally important product, making it an outstanding phytomedicine and natural product to stave off illnesses (see Table 1).

Diospenol is responsible for the diuretic action of Buchu [3]. There is no explanation of the mechanism of action, but the available literature states that diosphenol acts by irritating the gallbladder, causing the production of urine [18]. Buchu also contains flavonoids that induce

arthritis, cellulite, nausea and diarrhoea, flatulence, prostatitis and UTI's [1, 2, 9].

properties, and also acted as an insect repellent and deodarant [9].

perfumes and colognes [2].

**2. Pharmacological activity**

**2.1. Diuretic activity**

urine production [11].

terpene is essential to the aroma and flavour of the plant [6].

298 Antioxidant-Antidiabetic Agents and Human Health

Buchu essential oils and extracts were analysed to assess the antimicrobial activity of the plant. The essential oils and extracts were found to be active against the selected pathogens, namely Staphylococcus aureus, Bacillus cereus, Klebsiella pneumonia and Candida albicans [12, 13]. Buchu extracts have a good antibacterial activity, and has been found to be more active against gram positive than gram negative bacteria [12, 13]. Buchu was found to affect the development of biofilms by preventing attachment of bacteria to the polyvinyl chloride surface2 . This was, however, not the case with the fungus (*C. albicans*), as exposure to the extracts improved the attachment to the surface, allowing the formation of a biofilm [2]. The more well known Buchu species are thus effective against bacteria, but not against fungi. There is, however, a less extensively researched member of the Agathosma family called A. arida that is effective against Candida albicans [1]. Agathosma species have been found to contain coumarins, phenolic substances with benzene and α-pyrone rings [14]. A number of these compounds have been found to be active against microbials by stimulating macrophages, allowing the plant to have an indirect ability to eliminate infection [14].

### **2.3. Anti-oxidant activity**

Free radicals are molecules with one or more unpaired electron(s) [15] that are highly reactive, attacking nearby stable molecules to gain an electron. The two forms of free radicals are reactive oxygen species (ROS) and reactive nitrogen species (RNS) [15]. Free radical scavengers are known as antioxidants, and these assist in keeping free radicals at physiologically homeostatic levels [15]. Polyphenolics in plants are scavengers of free radicals, allowing them to act as antioxidants [16]. These compounds act via several mechanisms to reduce free radicals, and make wonderful antioxidants due to the hydrogen donating ability of the phenolic groups [16]. Members of the Agathosma specie have been found to contain flavonoids such as diosmin, hesperidin,rutin, quercitin, mucilage and resins which have extensive anti-oxidant proper‐ ties1 . These are some of the compounds that give the Buchu plant its anti-oxidant ability, allowing it to be effective against many ailments that result from an increase in oxidative stress.

#### **2.4. Anti-inflammatory activity**

Buchu oil contains limonene, a monoterpene hydrocarbon with anti-inflammatory properties [12, 13]. Essential oils found in Agathosma have been found to inhibit the synthesis of leukotrienes by blocking synthesis of the key enzyme 5-lypoxygenase. By doing so, it reduces inflammation by preventing the initiation and maintenance of the inflammatory process, thereby limiting an infection and preventing its progression [2]. Limonene has also shown to be effective in reducing cyclooxygenase 1 and 2 biosynthesis [2], reducing the proinflammatory agents prostaglandins and leukotrienes from being synthesised, reducing inflammation.

#### **2.5. Toxicity**

The Buchu plant should be used at low dosages for most purposes as it contains diosphenol, a compound known to be toxic at higher doses [1]. Pulegone, another compound found in Buchu, is hepatotoxic [2]. It has been found to reduce the levels of glutathione, a substance used by the liver in several detoxification steps [2], which would allow the accumulation of toxins within the liver. The depletion of glutathione and the excess amounts of pulegone found at high dosages lead to hepatocellular necrosis. Care should thus be taken when Buchu is consumed to ensure that the maximal therapeutic benefits are acquired, without any of the unwanted toxic effects.

muscular cells comes an increased demand of nutrition and oxygen to be delivered to the prostate [17]. This leads to local tissue hypoxia, promoting neovascularisation to cope with the increased demand for blood flow, and the production of ROS [17]. The increase in ROS leads to further fibroblast to myofibroblast differentiation, perpetuating the cell proliferation cycle

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The roles of other steroidal hormones [20] have been proposed in the pathophysiology of BPH. The reason for this stemmed from the finding that prostatic cells continue to grow, even in the face of declining androgen levels [23]. This led to the rationale that other factors being secreted by the testes may stimulate growth or even sensitize cells of the prostate to the actions of androgens [23]. As men age, the increase in their body weight increases the amount of adipose tissue within the body, leading to an increase in circulating oestrogen levels [24]. This is evident in the levels of free estradiol found circulating in the bloodstream, which remains constant due to the age-related increases in body weight [25, 26]. Adipose tissue causes increased secretion of the enzyme aromatase, which stimulates the conversion of androgen to oestrogen. Increased circulating oestrogen levels stimulate the increased proliferation of cells seen in BPH as oestrogens have been found to increase the number of prostatic epithelial and stromal cells [27, 29]. Oestrogen also has an indirect effect on the increase in prostate volume through its role in

The changes seen in androgen levels with age disrupt the interaction of growth factors with prostate cells [22]. The growth of prostate cells is enhanced by the production of growth factors, which are supplied to the prostate via circulation [17] or locally through autocrine production by stromal cells [18]. The locally produced growth factors control cell differentiation and proliferation, and matrix protein production through a network that is interactive, providing for a negative feedback control mechanism that controls normal cell growth [18]. Any disrup‐ tion in this network leads to abnormal proliferation and stromal hyperplasia [18], which manifects as BPH. Stromal cell proliferation is enhanced by fibroblast growth factors (FGF 1 and 9), insulin-like growth factors (IGF I and II) and transforming growth factor β (TGFβ1) [18]. Expression of these growth factors is upregulated in BPH and are a mechanism which

The prostate is located at the neck of the bladder, enveloping the urethra [17]. This location plays a role in the obstructive symptoms seen in patients with BPH, which also correlate with the size of the prostate [17]. There are two components of prostatic enlargement that play a role in obstruction of the bladder outlet which lead to lower urinary tract symptoms, namely

The static component is related to enlargement of the prostate which is attributed to the nodular proliferation classically seen in benign prostatic hypertrophy and hyperplasia [17]. This component accounts for the symptoms related to obstruction of the lower urinary tract seen in cases of BPH. The dynamic component related to the tone of prostatic smooth muscle [17]. Smooth muscle accounts for a rather large percentage of prostatic volume in BPH [17]. These provide binding sites for α1-adrenoreceptors, making the prostate susceptible to changes in adrenoreceptor signalling. α-adrenergic signalling has a significant influence on survival of stromal cells of the prostate and on the activity of smooth muscle cells in the prostate and the

and resulting in a further increase in prostate volume.

mediating the alterations in other circulating serum hormones [20].

may be altered to reduce accumulation of prostatic cells.

static and dynamic [17].
