**3.1 Conventional products**

Worldwide, among the most used and studied spices and condiments known for the proven or supposed antibacterial activity we find aniseed (*Pimpinella anisum*), bay leaf (*Laurus nobilis*), black pepper (*Piper nigrum*), cinnamon (*Cinnamonum verum*), clove (*Syzygium aromaticum*), coriander (*Coriandrum sativum*), garlic (*Allium sativum*), ginger (*Zingiber officinale*), lime (*Citrus aurantifolia*), onion (*Allium cepa*), oregano (*Origanum vulgare*) and thyme (*Thymus vulgaris*). All of these are, generally, widely available in nearly every corner of the world.

Apart from the world areas associated with great vegetable diversity, like tropical regions, densely forested areas of South America, sub-Saharian Africa or Southeast Asia, we also can find a great number of plants/herbs with medicinal use. In an academic study made in 2002, in a Portuguese National Park, with a relatively small area, 346 hectare, 140 different plants were found, with 124 different medicinal uses, 15 aromatic, 16 categorized also as condiments and 20 others, including 2 specimens classified as toxic/poisonous (Rodrigues, 2002).

Table 1 lists a number of well-known plants and herbs, many used daily worldwide, and their most important antimicrobial component.


Table 1. Plants and herbs and their main antimicrobial components (adapted from Cowan, 1999).

Antimicrobial Activity of Condiments 115

turmeric were tested. The microorganisms used in the experiment were *Salmonella typhi*, *Salmonella typhimurium*, *Shigella flexneri*, *Shigella dysenteriae*, *Escherichia coli* O102 and *Escherichia coli* O157, *Yersinia enterocolitica* and *Campylobacter jejuni*. The most efficient plant was clove, with maximum inhibition diameters for all bacteria, followed by black pepper that showed a high inhibition of *Shigella dysenteriae*, *Campylobacter jejuni* and both strains of

Beyond the more conventional vegetable products known worldwide, there is a great number of plants and herbs that have a great importance in cooking and medicinal practices, especially in Eastern Asian countries. For some plants, the biological properties described include not only antimicrobial activity but also the ability to influence the

Among these properties, there is the ability to stimulate the production of cytokines, increase the activation of macrophages, lymphocytes and NK cells (Natural killer cells). Chinese traditional medicine often uses plants like *Aloe vera*, *Angelica* spp., *Astragalus membranaceus*, *Ganoderma lucidum*, *Panax ginseng*, *Scutellari*a spp. and *Zingiber officinale*, some of which, beyond the immunomodulatory activity refered, also show some antimicrobial activity, like toxicity to *Aspergillus candidus* (*Angelica* spp.) and toxicity to MRSA (methicillin-

The purpose of using plants and herbs may not be only a medicinal or therapeutic purpose. The presence of some herbs with antimicrobial activity in some dishes may act as food preservatives. Curry leaf (*Murraya koenigii*) and Vietnamese coriander (*Persicaria odorata*) have shown to be effective against some bacteria isolated from fish. Methanolic extracts of curry leaf and Vietnamese coriander were effective against *Streptococcus agalactiae* (MIC= 0.39 mg/mL)

Asafoetida (*Ferula assafoetida*), a spice used in Indian cuisine, was tested against endemic pathogens in India and shown antibacterial activity against *Salmonella typhi* and *Escherichia coli* O157, leading the authors of the study to conclude that the presence of some spices and condiments acts not only as flavouring agents but also as some sort of protection against

In Thai cuisine and traditional medicine, galangal (genus *Alpinia*) has a special relevance. Studies have shown that the ryzome of this plant has antimicrobial properties, in particular against *Vibrio paraheamolyticus*. Bacterial inhibition was performed using disks with 10 μL freshly squeezed galangal, although the chloroform extract also shown activity. One of the molecules envolved in the inhibition mechanism was identified as being 1'-acetoxychavicol

Ayurvedic medicinal tradition uses many plants and herbs to treat several diseases, including those of infectious nature. *Ocimum sanctum*, *Eugenia caryophillata*, *Achyranthes bidentata* and *Azadirachta indica* are plants used in Nepal and India and were tested for their antibacterial properties against *Escherichia coli*, *Salmonella typhi*, *Salmonella paratyphi*, *Staphylococcus aureus*, *Klebsiella pneumoniae* and *Pseudomonas aeruginosa* through cup diffusion method. The experimental results have shown that both *Klebsiella pneumoniae* and *Pseudomonas aeruginosa* were resistant to any of the four plant extracts, and *Achyranthes* 

resistant *Staphylococcus aureus*), shown by *Scutellaria* spp. (Tan & Vanitha, 2004).

and *Staphylococcus aureus*, respectively (MIC= 3.13 mg/mL) (Najiah et al., 2011).

gastroentestinal diseases (Vaishnavi *et al*., 2007).

acetate (Vuddhakul *et al*., 2006).

*Escherichia coli*. The less efficient plants were ginger and mint (Vaishnavi *et al*., 2007).

**3.2 Ethnic products** 

immune system.

There are some generally accepted conclusions about the antimicrobial abilities of these natural products: spices are less effective in foods than in culture media, probably because of the higher concentration *in vitro* and non-existing co-factors, and Gram-positive bacteria are more sensible than Gram negatives, although some Gram negative strains may be extremely affected as well (Jay, 1982; Zaika *et al*., 1983), as *Escherichia coli* to varying concentrations of cumin, for example (Allahghadri *et al*., 2010). Within the Gram positive group, lactic bacteria are considered the less sensitive (Zaika *et al*., 1983).

Confirming the greater susceptibility to herbs and condiments of Gram positive bacteria when compared with Gram negative, an experiment using forty-six methanolic extracts of dietary spices and medicinal herbs reached results in which *Staphylococcus aureus* was the most sensitive bacteria and *Escherichia coli* the less sensitive bacteria to the extracts tested. The other test species included *Bacillus cereus*, *Listeria monocytogenes* and *Salmonella anatum*. The experiment also has shown a strong positive correlation between antibacterial activity and the total phenolic content of the herbs (Shan *et al*., 2007).

Garlic and clove are widely used for culinary purposes due to their strong flavour and aroma. They are also some of the most widely refered condiments in scientific literature when comes to antibacterial activity. Some bacteria that show resistance to conventional antibiotics are susceptible to decoctions or extracts of garlic and clove. Garlic, in particular, was able to inhibit *Staphylococcus epidermidis* and *Salmonella typhi* after one and three hours, respectively. In terms of yeast inhibition, it took one hour to achieve it, and in terms of inhibition diameter, reached larger areas of inhibition for *Candida* than those produced by nystatin. Clove took five hours to completely inhibit yeasts, including *Candida* species (Arora & Kaur, 1999).

There are indications that some spices, or their components may be active not only against resistant strains, but also against clinical isolates (usually studies are carried on academic collection strains). Rahman *et al*., proved the effectiveness of spice extracts on multi-resistant *Escherichia coli*. In spite the fact each extract, alone, caused no inhibition, the combination of three different aqueous extracts (1:1:1) of ginger, lime and garlic had a synergistic effect, inhibiting the bacteria. The incorporation of 0.3% in culture media was sufficient to inhibit 21 of the 24 Gram positive bacteria tested (Shelef *et al*., 1980). In a study conducted by Masood et al*.,* using oral isolates as test targets, black pepper decoction shown bacterial toxicity against 75% of the samples, bay leaf was effective against 53% and aniseed against 18%. Coriander did not show any inhibiting activity.

Many herbs and spices also have antifungal activity, which is important to relate, as fungi and its toxins also have a role as origin of food spoilage and food contaminants. Out of 29 spices and herbs studied, clove (genus *Caryophyllus*), star anise (*Illicium anisatum*) and allspice (genus *Pimenta*) completely inhibited the growth of 3 different *Aspergillus* species (*Aspergillus ochraceus*, *Aspergillus versicolor* and *Aspergillus flavus*) and also inhibited the toxin production. Eugenol extracted from clove and anethol extracted from star anise were incorporated in PDA (Potato Dextrose Agar) medium to test its growth inhibition ability. The concentrations required for total inhibition were 0.4 and 2.0 mg/mL, respectively (Hitokoto *et al*., 1980).

Dietary and medicinal plants and spices have been constantly studied for their antimicrobial properties, in particular for their antibacterial activity. In a study aimed at finding solutions against diarrhoegenic bacteria, onion, garlic, ginger, black pepper, clove, mint, cumin and turmeric were tested. The microorganisms used in the experiment were *Salmonella typhi*, *Salmonella typhimurium*, *Shigella flexneri*, *Shigella dysenteriae*, *Escherichia coli* O102 and *Escherichia coli* O157, *Yersinia enterocolitica* and *Campylobacter jejuni*. The most efficient plant was clove, with maximum inhibition diameters for all bacteria, followed by black pepper that showed a high inhibition of *Shigella dysenteriae*, *Campylobacter jejuni* and both strains of *Escherichia coli*. The less efficient plants were ginger and mint (Vaishnavi *et al*., 2007).
