Extraction and Isolation from Specific Plants

Conventional productions involve various mostly physical but sometimes chemical methods to isolate and enrich phytochemicals from selected wild or pur­posely farmed plants. Representative methods consist of solid-liquor extraction (including steam distillation), liquid—liquid extraction, or membrane separation, whose choices are based on effectiveness (low cost) and effi­ciency (recovery, especially for labile or low-abundance phytochemicals). In principle, phytochemical produc­tions may involve mechanical grinding of feedstocks, sin­gle or multiple steps of extraction, and enrichment or purification of final products. The extraction (leaching) parts may be simple binary systems or assisted by enhanced energy inputs (ultrasound, microwave, high pressure, sub — or supercritical condition) (Huang and Ramaswamy, 2012). Proper selection of solvent, adsor­bent, and other conditions is critical. Chemical transfor­mation is also applied to convert phytochemical precursors to final products, as exemplified by sulfuric acid treatment of madder to yield alizarin or purpurin.

Plant-derived colorants are mostly produced by the methods listed above: betalains (including betanin) extracted from red beet (Beta vulgaris); bixin/norbixin (annatto) from the tree Bixa orellana (Chattopadhyay et al., 2008); gossypol from cotton seed; lutein from mari­gold (Tagetes erecta); capsanthin/capsorubin from paprika; capsorubin from Capsicum annuum; crocin from saffron (Crocus sativus) flower; anthocyanins from grape skin, apple or cranberry; acylated anthocyanins from black carrot; curcumin (turmeric) from Curcuma longa; carminic acid from Dactylopius coccus; alizarin or purpurin from madder (Rubia) plants; chlorophyll from spinach; and indigo from Indigofera or Isatistinctoria (woad) plants.

For plant-derived S-compounds, glutamylcysteine or (allyl)cysteine sulfoxide are prepared from Allium spe­cies (including garlic); betaine from sugar beet (Kripp,

2006) ; tannin from tea, quebracho, chestnut or barks; caffeine from coffee and tea plant; nicotine from tobacco; camphor from camphor laurel; bromelain from pine­apple; papain from papaya; essential oils from a variety of fruits, seeds, leaves, woods, barks and roots; and menthol from mint.

Plant-derived drugs or precursors have been prepared by combinations of the methods listed above: quinine from cinchona tree, artemisinin from sweet wormwood (Artemisia annua), paclitaxel from Pacific yew (Taxus brevi — folia)’s endophytic fungi, 10-deacetylbaccatin from a few yews, (—)-shikimic acid from shikimi tree, diosgenin from Dioscorea plants, cytisine from Cytisus laburnum, vinblastine from Madagascar periwinkle (Catharanthus roseus), salicylic acid from willow bark, salicin from meadow sweet (Filipendula ulmaria), galanthamine from Caucasian snowdrop (Galanthus caucasicus), digoxin from foxglove (Digitalis lanata), and ephedrine from Ephedra sinica (Simard et al., 2012; Braz-Filho, 1999).

Plant-derived phytochemicals active as plant protec­tion and other bioactive agents are also produced from specific plants. For instance, pyrethrum is prepared from Chrysanthemum cinerariifolium and Chrysanthemum coccineum, rotenone from jicama vine, thymol from thyme (O’Brien et al., 2009; Dayan et al., 2009), and flavo — noid glycosides or polymethoxylated flavones from citrus peels (juice-extracted residues) (Manthey, 2012).