Antimicrobial Bioactive Phytocompounds

Different approaches to drug discovery using higher plants can be distinguished random selection followed by chemical screening; random selection followed by one or more biological assays; biological activity reports and ethnomedical use of plants . The latter approach includes plants used in traditional medical systems; herbalism, folklore, and shamanism; and the use of databases. The objective is the targeted isolation of new bioactive phytocompounds. When an active extract has been identified, the first task to be taken is the identification of the bioactive phytocompounds, and this can mean either a full identification of a bioactive phytocompound after purification or partial identification to the level of a family of known compounds


For screening selection, plants are collected either randomly or by following leads supplied by local healers in geographical areas where the plants are found. Initial screening of plants for possible antimicrobial activities typically begins by using crude aqueous or alcohol extractions followed by various organic extraction methods. Plant material can be used fresh or dried. The aspects of plant collection and identification will be discussed further in this chapter. Other relevant plant materials related to antimicrobial activity are the essential oils. Essential oils are complex natural mixtures of volatile secondary metabolites, isolated from plants by hydro or steam distillation and by expression (citrus peel oils). The main constituents of essential oils , along with carbohydrates, alcohols, ethers, aldehydes, and ke-tones, are responsible for the fragrant and biological properties of aromatic and medicinal plants. Due to these properties, since ancient times spices and herbs
have been added to food, not only as flavoring agents but also as preservatives. For centuries essential oils have been isolated from different parts of plants and are also used for similar purposes.

Drying medicinal plant material directly on bare ground should be avoided. If a concrete or cement surface is used, the plant materials should be laid on a tarpaulin or other appropriate cloth or sheeting. Insects, rodents, birds and other pests,and livestock and domestic animals should be kept away from drying sites. For indoor drying, the duration of drying, drying temperature, humidity and other conditions should be determined on the basis of the plant part concerned and any volatile natural constituents, such as essential oils. If possible, the source of heat for directs drying (fire) should be limited to butane, propane or natural gas, and temperatures should be kept below 60 °C . If other sources of fire are used, contact between those materials, smoke, and the medicinal plant material should be avoided.