**1. Introduction**

Plants conduct primary metabolism to support the growth and development. In addition to primary metabolism, plant also produce and collect secondary metabolites. Compared to primary metabolites that are found in every organism, secondary metabolite has limited distribution, has been produced and collected in specific organ, and has no physiological role in the producing plants. Secondary metabolites may function in protecting the producing plant from pests and facilitate plant breeding by spreading seeds through organisms consuming

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fruits produced by the plant. The mankind, however, has used secondary metabolite produced by plants since the ancient time. People use plant secondary metabolites as medicine, spices, perfumery, poison, pest control, etc.

extract of *Ageratum* leaf contains antifungal compound that is active toward *Aspergillus niger*, *Pestalotiopsis theae*, *Rhizoctonia solani*, and *Candida albicans* [5, 6]. The responsible compounds for the antifungal activity are volatile oil components and chromene compound that was further identified as coumarin [6, 7]. Garlic (*Allium sativum*) is commonly used as spices and herbal medicine and used as antibacteria, antifungi, antivirus, antihyperlipidemia, antiplatelet aggregation, and blood fibrinolytic agent [8]. The extract of garlic is active toward *Fusarium oxysporum*, *Phytophthora capsici*, *Aspergillus niger*, *Aspergillus flavus*, *Trichophyton rubrum*, and *Trichoderma harzianum* [9–12]. The compound that is responsible for the antifungal activity is

Plant Secondary Metabolites for Antifusarium and Antiphytophthora

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*Alpinia galanga* is one of the medicinal plants that belongs to family Zingiberaceae and also used as seasoning. Zingiberaceae is a plant family by which the member of the family is widely used as spices and herbal medicines. The organ used is mostly the subterranean part of the plant known as rhizome. When the rhizome of *A. galanga* is sliced transversally, it produces a rough surface and traditionally used by rubbing on the skin infected by fungi, such as ringworm. The extract of the rhizome is active against *Fusarium oxysporum*, and one of the active compounds is acetoxychavicol [13]. *Curcuma domestica* known as turmeric is popular as the main spice in making curry, a popular cuisine in India and South East Asia. Turmeric extract is active toward *Phytophthora infestans*, *Exserohilum turicicum*, *Fusarium oxysporum*, and *Colletotrichum cassiicola* [14–16]. The active compounds are the component of volatile oil, i.e., eucalyptol, β-pinene, and camphor. Differed from *Curcuma domestica*, *Curcuma xanthorrhiza*, known as Java turmeric due to its bitter taste is mainly for herbal medicine. Java turmeric extract is active against *Candida albicans*, *Candida glabrata*, *Candida guilliermondii*, *Candida krusei*, *Candida parapsilosisi*, and *Candida tropicalis*, and the active compound is xan-

*Curcuma zedoaria* is also widely used as herbal medicine and even claimed as anticancer. The extract obtained from the rhizome of *C. zedoaria* has antifungal activity toward *Trichophyton rubrum*, *Aspergillus niger*, *Saccharomyces cerevisiae*, *Epidermophyton floccosum*, *Aspergillus fumigates*, *Penicillium purpurogenum*, *Trigonopsis variabilis*, *Microsporum gypseum*, *Sclerotium rolfsii*, *Geotricullar candiade*, *Fusarium oxysporum*, *Helminthosporium oryzae*, *Candida krusei*, and *Trichophyton mentagrophytes*, and the active compound is ethyl-p-hydroxycinnamate [18]. Ginger (*Zingiber officinale*) is mainly used as spices and also as herbal medicine. The rhizome contains volatile oil and pungent compounds gingerol and shogaol that are well recognized as antiemetic agent. Ginger extract is active toward *Aspergillus flavus*, *Aspergillus niger*, *Penicillium griseofulvum*, *Fusarium oxysporum*, and *Pyricularia oryzae* [5, 19] with zingerone as the active compound. Zingerone is one of the ginger oil components that belongs to the group

*Cassia alata* is a shrub that belongs to the Caesalpiniaceae family. Traditionally, *C. alata* leaves are boiled and used by bathing to treat fungal infection causing skin diseases. The extract of the leaves is active toward *Trichophyton rubrum*, *Microsporum gypseum*, *Trichophyton mentagrophytes*, *Epidermophyton floccosum*, *Aspergillus niger*, *Phytophthora notatum*, and *Fusarium solani* [3, 20–22], and the active compound was identified to be anthraquinones. Cinnamomum leaves contain volatile oil that contains cinnamaldehyde and eugenol and are reported to

allicin and ajoene.

thorrhizol [17].

of phenylpropanoid compounds.

Plants have been traditionally used as fungicide for various purposes such as food preservatives and treatment of skin diseases. Tofu that is made from soya curd is rinsed with yellow pigment of turmeric to make the color of tofu into yellow and to extend the shelf life of tofu. Garlic is traditionally used together with cassava starch to catch spore of yeast needed for fermentation of soya bean to make *tempeh* (fermented soya bean) and *tape* (fermented cassava). The addition of garlic is intended to inhibit the growth of microorganism, but the spore can still survive and can grow under suitable environment, when it is mixed with the appropriate substrates such as cassava, rice, soya bean, and other carbohydrate-containing materials to produce fermented products. *Alpinia galanga* rhizome is sliced, and the rough surface is rubbed on the skin infected by *Trichophyton*. *Cassia alata* leaves are boiled and used for bathing to treat itchy and ringworm caused by fungal infection. *Piper betel* leaves are boiled and used for washing vaginal area to treat and to prevent candidiasis. *Ageratum conyzoides* leaves is rolled up and patched on a new cut to protect the tissue from infection by microorganisms and accelerate wound healing.

Many secondary metabolites from plants have been extracted, fractionated, isolated, and studied for the antifungal activity. Volatile oil is the secondary metabolites that play many important roles in human daily life, such as perfumery, spices, essence, medicine, aromatherapy, insect repellent, and also as fungicide [1]. Many medicinal plants contain volatile oil; many of them have been traditionally used in cut healing or as natural preservatives due to their capacity to control the growth of bacteria and or fungi [2]. Coumarin is reported to be one of the antifungal compounds present in the leaves of *Ageratum conyzoides* in addition to the volatile oil components. So far not much information on the traditional use of plants as antifungi for plants infected by fungi including soil-borne pathogenic fungi such as *Fusarium* and *Phytophthora*. Plants infected by soil-borne fungi are extremely hard to eradicate. In some cases, burning of the remaining plant is the only way to eradicate the pest accompanied by replacement with different crops. The possibility of plant secondary metabolites to be developed as source for natural fungicide especially for antifusarium and antiphytophthora is explored and discussed and supported with published reports and experimental data.
