**3. Plant extract antifungal activity on** *Phytophthora palmivora* **and**  *Fusarium oxysporum*

Most plants reported or traditionally used as antifungi are indeed all active toward *Phytophthora palmivora*. **Table 1** shows the antiphytophthora activity of 11 Indonesian plants that are traditionally used or experimentally reported as antifungi [36]. The capacity to inhibit the growth of *P. palmivora* can be detected by testing methanol extract that was prepared by soaking dried powder plant material at concentration 0.5%. Their activity however is different to one another. The strongest capacity is demonstrated by extract obtained from clove bud followed by *C. xanthorrhiza*, *C. zedoaria*, and *C. domestica*. These differences may be due to the concentration and the capacity of the active substances present in the individual plant


Note: Extract was made by maceration in methanol: +: 1–25% inhibition; ++: 26–50% inhibition; +++: 51–75% inhibition; ++++: 76–100% inhibition.

**Table 1.** Activity of 11 antifungal plants on *Phytophthora palmivora*.

be active toward *Candida albicans* [23–25]. *Cymbopogon nardus* leaves contain high quantity of volatile oil that is frequently used as insect repellent. The oil is also active as antifungal agent toward *Erysiphe cichoracearum*, *Aspergillus, Penicillium*, and *Erollium*, and the active antifungal compounds are citronellal and linalool [26]. *Eclipta alba* is commonly used as an ingredient in making hair tonic. The extract was reported to be active toward *Candida tropicalis* and *Candida albicans* [27]. *Garcinia mangostana* fruit is one of the most delicious tropical fruit. Garcinia fruit cortex that is rich in tannin and mangosteen is now commercially used as raw material for herbal medicine. Garcinia extract is active as antifungi toward *Candida albicans*, *Epidermophyton floccosum*, *Alternaria solani*, *Mucor* sp., *Rhizopus* sp., and *Cunninghamella echi-*

68 Fusarium - Plant Diseases, Pathogen Diversity, Genetic Diversity, Resistance and Molecular Markers

*Piper betel* leaf is traditionally chewed together with limestone and gambier by Melanesian to stain teeth and protect from infection. The leaf is also used to treat and to prevent vagina and mouth cavity from candidiasis. Betel leaf extract is reported to be active as antifungal agent for *Colletotrichum gloeosporioides*, *Botryodiplodia theobromae*, *Rhizoctonia solani*, *Aspergillus* sp., *Penicillium* sp., and *Fusarium* sp. Hydroxychavicol and eugenol were reported to be the responsible antifungal compounds [29]. *Piper crocatum* is locally named as red betel; it has more bitter taste than the ordinary betel. It is considered to be more potent as herbal medicine compared to the ordinary betel; however, the volatile oil content and the antimicrobial activity were lower. The extract of red betel is active toward *Candida albicans*, *Colletotrichum gloeosporioides*, and *Botryodiplodia theobromae* [30, 31]. *Syzygium aromaticum* flower bud and leaves contain volatile oil with eugenol as the major component. The oil content of the flower bud is much higher compared to the leaves and so the eugenol content [32]. The flower bud is usually used as seasoning in cigarette-making. It is also used as local anesthesia for dental illness. The extract of clove is an active antifungi and is also active toward *Fusarium oxysporum* [4, 33, 34]. Eugenol is one of the clove oil components that

The antifungal plants described above were extracted using methanol, and the extract obtained were tested toward *Fusarium oxysporum* and/or *Phytophthora palmivora*. The relative

Most plants reported or traditionally used as antifungi are indeed all active toward *Phytophthora palmivora*. **Table 1** shows the antiphytophthora activity of 11 Indonesian plants that are traditionally used or experimentally reported as antifungi [36]. The capacity to inhibit the growth of *P. palmivora* can be detected by testing methanol extract that was prepared by soaking dried powder plant material at concentration 0.5%. Their activity however is different to one another. The strongest capacity is demonstrated by extract obtained from clove bud followed by *C. xanthorrhiza*, *C. zedoaria*, and *C. domestica*. These differences may be due to the concentration and the capacity of the active substances present in the individual plant

**3. Plant extract antifungal activity on** *Phytophthora palmivora* **and** 

activities were compared, and the results are described in Section 3.

*nulata* [28].

has antifungal activity [35, 36].

*Fusarium oxysporum*

material. The individual active compound may be very active but present only at low concentration; consequently, the activity becomes low when the sample concentration is calculated based on the plant material. The flower bud of *Syzygium polyanthum* contains approximately 15% with eugenol content that can reach 80%. Coumarin in *Ageratum conyzoides* on the other hand only presents at very low concentration. However, for the application purpose, clove is considered potential to be used as source of antiphytophthora from plants. The rhizome of *C. xanthorrhiza*, *C. zedoaria*, *C. domestica*, and *Cassia alata* leaves can be used as alternatives. The price of the plant materials are much cheaper compared to clove bud.

Compared to *P. palmivora*, *F. oxysporum* is less susceptible toward the extract of antifungal plant. Higher concentration of plant extract is needed to observe the growth inhibition of the *F. oxysporum* culture by the extract. On *P. palmivora*, culture growth inhibition can be observed at extract concentration lower than 0.5%, whereas on culture of *F. oxysporum*, the inhibition can be observed at higher than 1%. Seven of 17 plants reported or traditionally used as antifungal agents inhibit the growth of *F. oxysporum* (**Table 2**). High inhibition activity is demonstrated by clove bud extract, and relatively high activity is shown by clove leaf extract. Inhibition by the extract of *Piper betel*, *Curcuma domestica*, *Curcuma xanthorrhiza*, *Zingiber officinale*, and *Acorus calamus* can be considered to be low [31].

**Tables 1** and **2** show that clove bud and clove leaves are potential source of secondary metabolite for antifusarium and antiphytophthora. Clove bud contains 15–20% volatile oil with major components consisting eugenol (80–90%), eugenol acetate (10–15%), and caryophyllene (3%). Clove leaves also contain volatile oil, but the composition is different, and the content is much lower


suggesting that the active compound is nonpolar compound. Upon extraction of plant material with hexane, most volatile oil components will also present in the extract. Clove oil also demonstrates strong antifungal activity. These findings lead to the hypothesis that the antifungal compound of clove is also the component of clove oil. The major component of clove oil is eugenol. At least two compounds from the extract and the volatile oil of clove are responsible for the antiphytophthora and antifusarium activity. The two compounds were identified as eugenol and eugenol acetate. The activity of eugenol is higher than euge-

Plant Secondary Metabolites for Antifusarium and Antiphytophthora

http://dx.doi.org/10.5772/intechopen.71552

71

Observation under scanning electron microscope showed that the hypha of *F. oxysporum* shrank after treated with eugenol (**Figure 1**). Higher magnification showed that the surface of hypha is no longer smooth and the cells may be leaking [38]. A number of mechanisms have been proposed to explain how eugenol acts as antifungal agent. Eugenol alters the membrane and cell wall [39] and induces leakage of protein and lipid from the cells due to the leakage of cell walls [40]. Extensive lesion of the cell membrane reduces quantity of ergosterol [41].

**Figure 1.** Scanning electron microscopy of normal *Fusarium oxysporum* (a) treated with eugenol (b) at 350× magnification

(above) and at 2000× magnification (below).

nol acetate.

Note: Extract was made by maceration in methanol: +: 1–25% inhibition; ++: 26–50% inhibition; +++: 51–75% inhibition; ++++: 76–100% inhibition.

**Table 2.** Activity of antifungal plant on *Fusarium oxysporum*.

compared to the clove bud. However, the oil content of clove leaf is relatively high compared to the other leaves. The oil content of clove leaves is approximately 2% with the major components which are eugenol 60% and caryophyllene 21**%** [37]. Clove leaves are considered to be a potential source of secondary metabolite for antifusarium and antiphytophthora. Volatile oil from clove leaves can be obtained from leaves that have already fallen on the ground; therefore, it can be collected throughout the year without disturbing the growth of the tree. In addition, the availability of clove leaves does not depend on the season and can be collected at any time.
