Edible Medicinal and Non-Medicinal Plants T. K. Lim Volume 11, Modified Stems, Roots, Bulbs Lim, T. K. (2016). Kava. In Edible medicinal and non-medicinal plants: Volume 11, modified stems, roots, bulbs. Springer. https://doi.org/10.1007/978-90-481-8661-7 Edible Medicinal and Non-Medicinal Plants 147 ' Springer International Publishing Switzerland 2016 T.K. Lim, Edible Medicinal and Non-Medicinal Plants: Volume 11, Modified Stems, Roots, Bulbs, DOI 10.1007/978-3-319-26062-4_15 Piper methysticum Scientific Name Piper methysticum G. Forster Synonyms Methysticum methysticum (G.Forst.) A.Lyons Family Piperaceae Common/English Names Awa, Kava, Kava-Kava, Kava Pepper, Kava Shrub, Kawa, Yangona Pepper Vernacular Names Arabi c: Fulful Kâwah Brazil : Cava Cava Chinese : Ka Wa Hu Jiao Czech : Pep ř ovník Opojný Danish : Kava, Kava Kava, Kavarod Esperanto : Kavao Estonian : Kavapipar Fiji : Yangona, Yaqona Finnish : Kavakava French : Ava, Kava, Kava Kava, Kawa-Kawa German : Kava-Kava, Kavapfeffer, Kawa-Kawa, Kawa-Pfeffer, Kawapfeffer, Rauschpfeffer Hawaiian : ‘Awa Hungarian : Kava, KÆvacserje, MÆmorbors Irian Jaya : Bari, Dikoi, Ikawati, Tigwa, Waghi, Wati Italian : Pepe Kava Marquesan : Kava, Kav-Kava Niuean : Kavainu Papua New Guinea : Ayuw, Bari, Bikwe, Dikoi, Gamada, Gamoda, Gumada, Irka, Jeliki, Ka, Karangimi, Kau, Keu, Koi, Komata, Koniak, Koriar, Kurar, Oyo, Sagainya, Sika, Tigwa, Toa, Toe, Towe, Tue, Tui, Tokarabu, Uati, Waghi, Wariki, Wati Pohnpei : Sakau Polish : Pieprz Kawakawa; Pieprz Metystynowy Samoa : ‘Ava, Ava Ava, Kava Slovašcina : Kavakava Spanish : Kava, Kava Kava, Kavaka, Kawa Swedish : Kava Kava Tahiti : Ava, Ava-Ava, Evava Tongan : Kava, Kav-Kava Tubuai : Ava Turkish : Kava Biberi, Kawa Kawa 148 Vanuatu : M Nigui (Hiu), Maloku (Maewo), Namaloku (Nguna), Sini (Central Pentecost) Mele (south Pentecost), Maloku (North Pentecost), Nga (Ureparapara), Naga (Mota Lava), Gwie (Vanua Lava), Malop (Mere Lava), Amaloku (West Ambae), Maloku (East Ambae), Bir (Central Santo), Naxai (North Santo), Malou (Southwest Santo), Malohu (West Santo), Hae (Malo), Malox (North Malakula), Nem Leu, Melo, Melu, Malok (Northeast Malakula), Malk, Malox (Northwest Malakula), Nimvulm (Southwest Malakula), Maix, Namonggomongg, Monggmongg, Merox (Southeast Malakula), Meruh (East Malakula), Lewewe Ndrame (North Ambryn) Vatimeai (North Panama) Malou (South Panama), Malk, Miau, Mia, Mio, Mak (West Epi), Namaluk (Tongoa), Namaloku (Emae) Malok (Makira), Namloku (Nguna) Wallis and Futuna : Kava Origin/Distribution The species is indigenous to and cultivated in the islands of south Pacific, from Hawaii to Papua New Guinea, with the notable exception of New Caledonia, New Zealand and most of the Solomon Islands (Singh 1992). Phytochemical studies conducted by Lebot and LŁvesque (1989) to elucidate the origin of this Oceania plant found the lineage of chemical chemotypes suggested that Piper wichmanii was the wild species from which farmers domesti- cated cultivars of Piper methysticum. Based on morphological, chemical, cytological and genetic evidence demonstrating the absence of taxo- nomic distinction between Piper methysticum and Piper wichmannii , Lebot and Levesque (1996) concluded that Piper methysticum is not a separate species, but rather a group of sterile cul- tivars selected from somatic mutants of P. wich- mannii . As P. methysticum was described first (1786), it had priority making P. wichmannii (1910) superfluous. Agroecology Piper methysticum being a tropical species requires tropical conditions to flourish. It thrives best in loose, well-drained, moist, well- composted soils in a protected, partially shaded position, between 300 and 500 m above sea level in a tropical environment of 20–35 °C, 70–100 % relative humidity and rainfall above 2000 mm per annuum. Edible Plant Parts and Uses The root and rhizome (underground stem) of kava are used to prepare beverages, extracts, cap- sules, tablets, and topical solutions (NCAM 2006 ). Its thick roots and stumps (stem bases) are shaved, mashed or grounded into powder (Plates 2 and 3 ) and made into a cold beverage used similarly to alcohol and has a sedative effect. Kava is widely and commonly consumed as a social beverage to establish kinship in the Pacific island communities (McDonald and Jowitt 2000). The roots or shavings can also be chewed. Chewing produces the strongest effect because it produces the finest particles. Botany An evergreen, robust, dioecious, vine-like peren- nial shrub, 1–4 m high, with glabrous, woody, branching stems and massive base with lateral roots to 2 m long and 8 cm diameter. Leaves green, alternate, glabrous, cordate, 10–30 cm by 9–24 cm, entire, apex acute, palmately veined and borne on 2–7 cm long petioles (Plate 1 ). The flowers are small, unisexual, whitish, occurring in short, irregular, axillary spikes or opposite leaves. The floral bracts are rounded and peltate on pubescent pedicels. The male spikes with flowers bearing two short stamens, female spikes (rare) female flower with a unilocular ovary and stigma. The fruit, a berry is seldom produced and the plant must be propagated by dividing the roots or through stem cuttings. Piperaceae 149 Nutritive/Medicinal Properties Phytonutrients Fresh kava root was reported to contain 43 % starch, 20 % fiber, 12 % water, 3.2 % sugars, 3.6 % proteins, 3.2 % minerals and up to 20 % kava lactones (Leung and Foster 1996). The com- position of kava drug from kava basal stem and roots in Fiji was determined to have respectively: moisture 14.60, 13.66%; carbohydrates 74.11, 64.22 %; fibre 10.66, 13.09 %; ash 2.33, 3.57 %; K 2.161, 2.00 %; Ca 0.455, 0.201 %; mg 0.105, 0.179 %; Na 0.0362, 0.060 %; Al 0.0202, 0.15 %; Fe 0.017, 0.106 %; Zn 60.66, 55.35 ppm; Mn 12.04, 51.77 ppm; Cu 13,08, 16.95 ppm (Duve and Prasad 1983). Dry commercial kava powder was analysed by IRCC (Institut de Rechrches sur le CafØ et le Cacao) laboratory in Vanuatu to have sugars 0.50 % sucrose, 0.10 % maltose, 1.75 % fructose and 0.85 % glucose; amino acids – aspartic acid 0.28 %, threonin 0.08 %, serine 0.11 %, glutamic acid 0.26 %, glycine 0.11 %, phenylalanine 0.07 %, histidine 0.05 %, lysine 0.10 %, arginine 0.08 %, alanine 0.16 %, valine 0.11 %, methionine 0.02 %, isoleucine 0.07 %, leucine 0.14 % and tyrosine 0.06 %; kavalactones 5.23 %; dihydro-5,6 kavalactones plus dehydro- 5,6-kavalctones; minerals K 2.37 %, Ca 0.372 %, Mg 0.099 %, Na 0.111 %, Fe 0.017 %, Zn 22.07 ppm, Mn 7.30 ppm, Cu 15 ppm, cl 0.012 ppm, S 0.018 ppm, B 11.6 ppm (Lebot and Cabalion 1988 ). Phytochemicals – Kavalactones/ Chalcones More than 40 compounds belonging to the classes of kavapyrones, alkaloids, steroids, chalcones, long-chained fatty acids and alcohols have been isolated and identified from Piper methysticum (Parmar et al. 1997). Van Veen (1939) isolated a Plate 2 Dried kava roots ( right ) and shavings ( left ) Plate 1 Cordate leaves of young kava seedling Piper methysticum 150 narcotic substance from dried kava stems and roots, and called it marindinin which later was found to be identical with dihydrokawain of Borsche. The concentrations of desmethoxyyan- gonin, yangonin, dihydromethysticin, methysticin, dihydrokawain and kawain in kava ether extract were determined (Young et al. 1966). Dutta et al. (1972) isolated yangonin and methysticin from kava roots. Recoveries of known compounds were 80–85 % for yangonin and 90–95 % for all others. Fresh kava root stock contained 80 % water, while dried rootstock consists of approximately 43 % starch, 20 % fibre, 12 % water, 3.2 % sugars, 3.6 % proteins, 3.2 % minerals and 15 % (3–20 %) kava- lactones (Lebot et al. 1992). Kavalactone content was reported to be greatest in the roots and to decrease higher up the plant. Relative concentra- tions of 15 %, 10 % and 5 % have been observed in the root, stumpand basal stems, respectively. Kavalactones (amounting to %) had been reported in all parts of the kava plant comprising the major ones: kavain (1.8 %), methysticin (= kavahine, kavakin, kavatin, kanakin) (1.2 %), demethoxy- yangonin (1 %), yangonin (1 %), dihydrokavain (0.6 %), dihydromethysticin (0.5 %) and traces of 11,12-dimethoxyhydrokavain, 11-hydroxy12- methoxykavain, 11-methoxy-nor-yangonin, 11-methoxy-yangonin and the two ethylketones cinnamoylacetone and methylendioxy-3,4- cinnamoylidenacetone (Shulgin 1973; Young et al. 1966). The content (weight %) of six major kavalac- tones in the dried kava roots was reported as: kavain 2.58 %, dihydrokavain 1.37 %, methysti- cin 1.82 %, dihydromethysticin 1.89 %, yangonin 1.73 %, desmethoxyyangonin 0.81 % analysed in Hawaii (Young et al. 1966); kavain 1.90 %, dihydrokavain 2.37 %, methysticin 2.12 %, dihy- dromethysticin 1.12 %, yangonin 1.21 %, desme- thoxyyangonin 0.59 % analysed in Fiji (Duve 1981); kavain 2.30 %, dihydrokavain 3.28 %, methysticin 2.06 %, dihydromethysticin 1.60 %, yangonin 1.16 %, desmethoxyyangonin 0.91 % analysed in Vanuatu (Lebot and LØvesque 1996). The composition of the major kavalatones in kava root, stem and leaf were reported respectively by Smith (1983) askavain (34.5, 0.6, 2.5 %); dihy- drokavain (17.1,23.2,69.8 %); methysticin (20.8, 13.9, 0.8 %); dihydromethysticin (5.3, 59.6, 22.5 %); yangonin (0.8,0.8, 1.2 %) and desme- thoxyyangonin (21.6, 1.8, 3.0 %). The first compound isolated from Piper methysticum was methysticin (Cuzent 1981 ) also known as kavatin, kavahin and kanakin. The IUPAC has recommended the name 5,6-dihydro- 4-methoxy-6-[3 ′ ,4 ′ -(methylenedioxy)styryl]-2H- pyran-2-one but chemical abstracts indexing has adopted the latter path, using 5-hydroxy-3- methoxy-7-[3,4-methylenedioxyphenyl]-2,6- hepta-dienoic acid- lactone. The ethylenic dihydroanalog dihydromethysticin was isolated almost 50 years later by Winzheimer (1908 ). Plate 3 Pure pounded kava powder Piperaceae 151 Nolting and Kopp (1874) isolated yangonin. The most extensive studies on the constituents of kava plant were conducted by Borsche and coworkers in 13 papers wherein they reported the isolation and structure of two compounds kawain (also known as kavain and gonosan) and dihydro- kawain and the structural elucidation of the crys- talline components methysticin, dihydromethysticin and yangonin (Borsche 1927; Borsche and Bodenstein 1929 ; Borsch and Blount 1930 , 1932 , 1933; Borsche and Gerhard 1914; Borsch and Lewinsohn 1933 ; Borsche et al. 1927a, b , 1929a, b; Borsche and Peitzsch 1929a, b , 1930 ; Borsche and Roth 1921; Borsche and Walter 1927 ). Yangonin (= 4-methoxy-6-(p-methoxy- β -styryl)- α -pyrone) was not so recognised by Borsche and co-workers (Borsche and Gerhard 1914 ; Borsche and Bodenstein 1929). They had postulated it as a γ -pyrone, although they had correctly inter- preted the structures of all other substances iso- lated from kava (Borsche et al. 1927a, b ; Borsche and Peitzsch 1929a, 1930). Yangonin served as the basis for two additional substances the meta- methoxy analogue 11-methoxyyangonin (Hänsel and Klaproth 1966 ) and the phenolic counterpart 11-methoxy-nor-yangonin (Hänsel et al. 1966c) isolated from Kava-kava, both of which had been established synthetically as possessing the α -pyrone ring. The completely conjugated ana- logue, 5,6-dehydromethysticin, was identifed as a component of kava-kava by Hänsel (1968 ). The following kavalactones were isolated from kava roots: 5,6,7,8-tetrahydro-yangonin (Achenbach et al. 1971 ); 11-hydroxy-12-methoxy-dihydro- kawain and 11,12-dimethoxy-dihydrokawain (Achenbach et al. 1972 ). Two yellow pigment materials, flavokawin A and B, were isolated from kava rhizomes (Hänsel et al. 1961 ). The structures of these were established by synthesis to be substituted chalcones bearing an obvious biogenetic relationship to the styrylpyrones (Hänsel et al. 1963). Hänsel and Schulz (1973) synthesized 5,6,- cis -kavain 5-ol and 5,6- trans - kavain-5-ol. Flavokawin A was elucidated as 2 ′ -hydroxy-4-4 ′ -6 ′ -trimethoxychalcone and fla- vokawin B as 2 ′ -hydroxy-4 ′ -6 ′ dimethoxychal- cone. The flavokavins A, B and C were reported to have a different skeleton (Duve 1976 ; Hänsel et al. 1963 ; Dutta et al. 1973 , 1976 ). A total of 19 kavalactones namely 10- methoxyyangonin; hydroxykavain; dihydro- 5,6-dehydrokavain; 7,8-dihydrokavain; 7,8- dihydroyangonin; kavain; 7,8-dihydro-5- hydroxykavain; 5,6-dihydroyangonin; 11- h y d r o x y - 1 2 - m e t h o x y d i h y d r o k a v a i n ; 11-methoxyyangonin; 5,6-dehydrokavain (des- methoxyyangonin); 5,6,7,8-tetrahydroyango- nin; methysticin; dihydromethysticin; 11,12 dimethoxydihydrokavain; yangonin; 11-methoxy- 12-hydroxydehydrokavain; 11-hydroxyyango- nin; 5,6-dehydromethysticin were identified in kava roots (Hänsel 1968 ; Lebot and Cabalion 1988 ; He et al. 1997; Whittaker et al. 2008; Dharmaratne et al. 2002; Xuan et al. 2008; Teschke 2011; WHO 2007), with flavokavains A, B and C (He et al. 1997); kava lactones (Hänsel et al. 1968) identified in kava roots included: kavain; 7,8-dihydrokavain; 5,6-dehydrokavain; yangonin; 5,6,7,8-tetrahydroyangonin; methysti- cin; dihydromethysticin; 5,6-dehydromethysticin; 5,6-dihydroyangonin; 7,8-dihydroyangonin; 10- methoxy-yangonin; 11-methoxy-yangonin; 11- hydroxy-yangonin; hydroxykavain; 11-methoxy- 12-hydroxy-dehydrokavain (Lebot and Cabalion 1988). Major compounds identified in Kava extracts by low-resolution GC/MS included kava lactones like kavain, dihydro-and dehydro- kavains, yangonin and tetrahydroyangonin, methysticin and dihydromethysticin (Nerurkar et al. 2004 ; Lopez-Avila and Benedicto 1997 ). Other kavalactones were identified as minor components including 1-methoxyyangonin (Hänsel and Klaproth 1966), 11- metho xynoryangonin and 5,6-dehydromethysticin (Hänsel et al. 1966b ); 1-methoxyyangonin (Hänsel and Klaproth 1966 ), 11-methoxynoryan- gonin and 5,6-dehydromethysticin (Hänsel et al. 1966b); 10-methoxyyangonin, 11-hydroxyyan- gonin and 11-methoxy-12-hydroxydehydroka- vain (Duve 1981; He et al. 1997 ). Additionally, three hydro-derivatives of yangonin were identi- fied from kava plant. These include 5,6-dihydroy- angonin (Hänsel 1968; Duve 1981), 7,8-dihydroyangonin (Duve 1981) and 5,6,7,8-tet- rahydroyangonin (Achenbach et al. 1971; Hänsel 1968). Hydroxylated α -pyrone derivatives, includ- ing cis -5-hydroxykavain (Duve 1981) and 5-hydroxydihydrokavain (Achenbach and Piper methysticum 152 Wittman 1970), had also been isolated from P. methysticum as minor components. The kavalactone, 11-methoxy-5,6-dihydro- yangoninand eight previously reported analogs along with four other aromatic compounds were isolated from kava root extracts (Ranjith et al. 2002). Nine kava lactones were detected from kava roots using GC-MS including desmethoxyy- agonin, kavain, 7,8-dihydrokavain, hydroxyka- vain, yagonin, 5,6,7,8-tetrahydroxyyagonin, methysticin, dihydromethysticin and 11-hydroxy- 12-methoxydihydrokavain (Xuan et al. 2006 ). Quantities of desmethoxyyagonin, kavain, 7,8-dihydrokavain, yagonin, methysticin and dihydromethysticin detected were 4.3, 6.9, 18.6, 5.7, 1.4 and 5.4 mg/g of dry weight, respec- tively. Eighteen kava lactones, cinnamic acid bor- nyl ester and 5,7-dimethoxy-flavanone, and seven compounds, including 2,5,8-trimethyl-1-naphthol; 5-methyl-1-phenylhexen-3-yn-5-ol; 8,11-octa- decadienoic acid-methyl ester; 5,7-(OH)(2)-4 ′ - one-6,8-dimethylflavanone; pinostrobin chalcone; and 7-dimethoxyflavanone-5-hydroxy-4 ′ , were identified from kava roots (Xuan et al. 2008). Glutathione (26.3 mg/g) was found in the water extract. Dihydro-5,6-dehydrokavain (DDK) was present at a higher level than methysticin and des- methoxyyagonin, indicating that DDK to be a major constituent of kava roots. Of 18 kavalactones or kava pyrones found in kava, kawain, dihydrokawain, methysticin, dihydromethysticin, yangonin and desmethoxyy- angonin were the six major kavalactones (Whittaker et al. 2008). The following kavalactone compounds were isolated from kava roots: kavalactones:10-methoxyyagonin; hydroxykavain; dihydro-5,6-dehydrokavain; 7,8-dihydrokavain; 7,8-dihydroyagonin; kavain; 7,8-dihydro-5- hydroxykavain; 5,6-dihydroyagonin; 11-hydroxy- 12-methoxydihydrokavain; 11-methoxyyagonin; desmethoxyyagonin, 5,6,7,8-tetrahydroyagonin; methysticin; dihydromethysticin; 11,12-dimethy- oxydihydrokavain; yagonin; 11-methoxy-12-hy- droxydehydrokavain; 11-hydroxyyagonin; and 5,6-dehydromethysticin (Xuan et al. 2008). Duve and Prasad (1983) investigated the stability of kav- alactones in powdered kava root stored in screw- capped glass bottles at room temperature for 22, 36 and 39 months. After 39 months of storage 93.9 % of dihydrokavain, 81.6 % of kavain, 72.4 % of dehydrokavain, 54.9 % of tetrahydroyangonin, 25.8 % of dihydromethysticin, 32.1 % of yangonin and 29.5 % of methysticin had deteriorated in the powdered root samples. Concentrations of total kava lactones (methysticin, dihydromethysticin, kawain, dihy- drokawain, yangonin and desmethoxyyango- nin), ranged between 135 and 0.035 mg per serving in 10 beverage products, two chocolate products, three unbrewed tea products, a drink mix product tested and between 40 and 61 mg per serving for the three dietary supplement products tested using LC-UV and LC-MS anal- yses (de Jager et al. 2004). One percent of kava extract could be detected in food supplements using liquid chromatography-atmospheric pres- sure chemical ionisation tandem mass spec- trometry, corresponding to approximately 0.05–0.2 mg/g of the individual kava lactones kavain, dihydrokavain, yangonin, desmethoxyy- angonin, methysticin and dihydromethysticin (Bobeldijk et al. 2005). Reliable quantification was obtained from concentrations of 0.25–1 mg/g, depending on the compound. Reliable quantification was obtained from con- centrations of 0.25–1 mg/g, depending on the compound. Gautz et al. (2006) found the combi- nation of near-infrared reflectance spectroscopy and partial least-squares methods to be a conve- nient, versatile and rapid analytical tool for determination of kavalactones in dried kava powder. Major and trace constituents of kava resin were identified using methane negative ion chemical ionization (NICI) mass spectrometry (Duffield and Lidgard 1986 ; Duffield et al. 1986 ). Several of the kava lactones (kawain, methysti- cin, desmethoxyyangonin and yangonin) pro- duced abundant molecular anions when analysed by methane NICI mass spectrometry, in contrast to their 7,8-dihydro analogues which ionized with poor efficiency to yield weak [M − H] − anions. Several new trace compounds formally resulting from decarboxylation of the 4-methoxy- 2-pyrone ring system in the known compounds were also found. A simultaneous HPLC separa- Piperaceae 153 tion of the enantiomers of kavain, dihydrokavain, methysticin and dihydromethysticin as well as the achiral dienolides yangonin and desme- thoxyyangonin was carried out on a ChiraSpher NT column (Boonen et al. 1997; Häberlein et al. 1997). Using reverse-phase high-performance liquid chromatographic method, six major kava- lactones [methysticin, dihydromethysticin (DHM), kavain, dihydrokavain (DHK), deme- thoxyyangonin (DMY) and yangonin] in Piper methysticum (kava) were simultaneously deter- mined (Shao et al. 1998). The detection limits ( S / N = 3) for methysticin, DHM, kavain, DHK, DMY and yangonin are approximately 0.5, 1.1, 0.7, 1.1, 0.6 and 0.6 μ g/ml, respectively. The average recoveries are 100.2 % for methysticin, 100.6 % for DHM, 100.0 % for kavain, 100.3 % for DHK, 98.9 for DMY and 98.2 % for yango- nin. A rapid micellar electrokinetic chromatogra- phy method with diode-array detection was used to separate kavalactones kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin and demethoxyyangonin from dry kava extracts (Lechtenberg Lechtenberg et al. 1999 ). Three kava lactone constituents of Piper methysticum , namely, kawain, methysticin and desmethoxyyangonin, were separated and identi- fied by reverse-phase HPLC using superheated deuterium oxide as the mobile phase and on-line 1H-NMR detection (Chienthavorn et al. 2005 ). Meissner and Häberlein (2005) used simultane- ous HPLC for the separation of six major kavapy- rones and the flavokavins A–C in an ethanolic extract of Piper methysticum . Flavokavins A–C contents of 0.62 mg/100 mg, 0.34 mg/100 mg and 0.14 mg/100 mg ethanolic kava extract was determined respectively. Compounds identified in commercial kava extracts by gas chromatogra- phy (GC) and quadrupole time-of-flight mass spectrometry (QTOFMS) with an electron ionization source: 7,8 dihyrokavain; kavain; 5,6-dehydrokavain; 5,67,8-tetrahydroyangonin; 7,8-dihydromethysticin; yangonin; methysti- cin; bornyl cinnamate; dihydroxy- methoxyphenyl-phenyl-propen-one; hydroxyl- dimethoxy phenyl- 3-phenyl-2-propen-1-one; and hydroxyl-dimethoxyphenyl-3-methoxyphenyl-2- propen-1-one (Lopez-Avila and Yefchak 2009 ). For ground kava (250–500 μ m), 2 h of sub- critical water extraction was required for a com- plete extraction of kava lactones at 100 °C, while at 175 °C, 20 min were sufficient (KubÆtovÆ et al. 2001 ). For a complete extraction of the unground (shredded) kava, the time of extraction was extended to 40 min at 175 °C. Boiling for 2 h and extraction with Soxhlet apparatus for 6 h, both of which employed water at atmospheric pressure, produced yields 40–60 % lower than those obtained with subcritical water. With unground kava, 40 min of subcritical water extraction yielded essentially the same recoveries of lac- tones as 18 h of sonication with acetone, methy- lene chloride or methanol. Kava root extracted in acetone yielded 100 % kavalactones, 96 % etha- nol yielded 100 % kavalactones, 25 % ethanol yielded 15 % kavalactones and water yielded 2.97 % kavalactones (Denham et al. 2002 ). Extraction rates also varied depending on the temperature at which the products were prepared. Analysis of flavokavins in extracts of 172 sam- ples originating from four cultivars groups (noble, medicinal, 2-days and wichmannii) indi- cated that the ratio flavokavin B /kavalactones was much higher in 2 days (0.39) and wichman- nii (0.32) compared to nobles (0.09) and medici- nal cultivars (0.10) (Lebot et al. 2014). For each group, the ratios of flavokavins/kavalactones did not change significantly between roots, stumps or basal stems and among clones, indicating that they were genetically controlled. Phytochemicals – Alkaloids/ Flavonoids/Miscellaneous Compounds There had been reports of isolation of alkaloids, flavonoids – flavokavins, sterols, organic acids, aliphatic alcohols and other compounds from kava plant. Three flavokavins (also known as fla- vokawins or flavokavains), designated A, B and C, had been identified from kava root (Dutta and Ray 1973; Dutta et al. 1973 , 1976; Hänsel et al. 1961 , 1963 ). Structures of these compounds had been confirmed by synthesis (Hänsel et al. 1963 ; Dutta et al. 1976; Dutta and Som 1978). Two Piper methysticum 154 alkaloids were isolated from a methanolic extract of kava root and were identified as 1-cinnamoylpyrrolidine and 1-(methoxycinnam- oyl)pyrrolidine (Achenbach and Karl 1970) and an alcohol dihydrokawain-5-ol (Achenbach and Wittman 1970). A third alkaloid, pipermethys- tine, was isolated from leaves by Smith (1979; 1983) and was found in small amounts in the stems and roots (Singh 1992). A few piperidine alkaloids (i.e., pipermethystine, 3,4-epoxy-5- pipermethystine, and awaine) were identified in the aerial parts of kava plant (stem peelings and leaves) (Dragull et al. 2003). Pipermethystine was concentrated in the stem peelings and leaves. 3,4-epoxy-5-pipermethystine and awaine were new alkaloids with 3,4-epoxy-5-pipermethys- tine found only in cv. Isa among the 11 cultivars examined, and awaine occurred primarily in young leaves of all cultivars. None of the three piperidine alkaloids were detected in the com- mercial root powders from Fiji, Tonga or Hawaii. Two conjugated diene ketones, cin- namylidineacetone and 3,4-methylenedioxy- cinnamylidineacetone (Jössang and Holho 1967 ), and organic acids (Achenbach and Karl 1971) were isolated from kava roots. Kava plant had been found to contain amides (2-methoxy cin- namic pyrrolide, cinnamic acid pyrollide), chal- cones (flavokavin A and B) and free and aromatic acids, anisic acid, benzoic acid, capri- onic acid, hydroxyl cinnamic acid and deriva- tives (Klohs 1967; Halzl et al. 1993). The kava methanol root extract yielded bornyl esters of 3,4-methylenedioxy cinnamic acid and cin- namic acid, pinostrobin, flavokawain B and 5,7-dimethoxyflavanone (Wu et al. 2002a). Two C-glycoside flavonoid compounds identified as 2 ′′ - O -rhamnosylvitexin and schaftoside were iso- lated from kava leaves (Jhoo et al. 2007) and phy- tosterols such as stigmasterol, stigmastanol, β -sitoserol and campesterol (Jössang and Molho 1970; Gracza and Ruff 1986). Trace amount of a nitrogen-containing compound (cepharadione) had also been isolated from the kava rootstock (Jaggy and Achenbach 1992). Alipahtic and alicyclic alcohols had been isolated from the rhizome: docosan-1-ol, docecanol-1-ol, eicosanol- 1-ol, hexacosan-1-ol, hexadecane-1-ol, octadeca- nol-1ol and n-triacontane (Gracza and Ruff 1986 ). The root was also known to contain flavoka- vins A and B, pipermethystine, cepharadione A, cinnamalketone, and methylene dioxy-3, 4-cinnamalketone (Lebot et al. 1992 ). Bornyl cinnamate and a series of hydroxylated com- pounds resulting from the decarbonylation of the lactones had also been identified in kava resin by methane chemical ionization GC/MS and two previously described N -cinnamoyl pyrrolidine alkaloids along with stigmasterol (Cheng et al. 1988 ). Three dihydrochalcones: flavokavain A, flavokavain B, flavokavain C; cinnamic acid bor- nyl ester and 5,7-dimethoxy-flavanone; and compounds detected for the first time in kava roots: 2,5,8-trimethyl-1-naphthol; 5-methyl-1- phenylhexen-3-yn-5-ol; 8,11-octadecadienoic acid-methyl ester; 5,7-(OH)(2)-4 ′ -one-6,8- dimethylflavanone; pinostrobin chalcone; and 7-dimethoxyflavanone-5-hydroxy-4 ′ Glutathione (26.3 mg/g) was found in the water extract (Xuan et al. 2008). Acetone was the most effective sol- vent in terms of maximum yield and types of kava lactones isolated, followed by water and chloroform, whereas hexane, methanol and etha- nol were less effective as solvents. Total phenolic and antioxidant activity varied among the extract- ing solvents, with acetone and chloroform pro- ducing the highest effects, followed by water, while methanol, ethanol and hexane were less effective. Two alkaloids, (−)-pipermethystine and (−)-epoxypipermethystine, and two lactones, (+)-dihydromethysticin and yangonin, were iso- lated from the kava plant (Naumov et al. 2008 ). Pharmacological Activities Kava kavalactones were reported to possess phar- macological effects which include sedative, anx- iolytic, anti-stress, analgesic, local anaesthetic, anticonvulsant and neuroprotective properties (Gounder 2006). Kava’s biological effects, due to a mixture of compounds called kavalactones, had been reported to include sedative, anxiolytic, Piperaceae 155 antistress, analgesic, local anaesthetic, anticon- vulsant and neuroprotective properties (Singh and Singh 2002 ). The pharmacological proper- ties of kava were postulated to include blockade of voltage-gated sodium ion channels, enhanced ligand binding to gamma-aminobutyric acid (GABA) type A receptors, diminished excitatory neurotransmitter release due to calcium ion chan- nel blockade, reduced neuronal reuptake of nor- adrenaline (norepinephrine), reversible inhibition of monoamine oxidase B and suppression of the synthesis of the eicosanoid thromboxane A(2), that was antagonistic to GABA(A) receptor function. Antioxidant Activity The lipid oxidation assay did not reveal antioxidant activities for kava root compounds demethoxyangonin, dihydrokawain, kawain, dihydromethysticin or methysticin at 50 μ g/ml (Wu et al. 2002b). The antioxidant activities of flavokawain A and yangonin could not be tested in the lipid oxidation assay due to solubility prob- lems. However, yangonin and methysticin showed moderate antioxidant activities in the free radical scavenging assay at 2.5 mg/ml. Cyclooxygenase Enzyme Inhibitory Activity Six compounds isolated from the ethyl acetate kava root extract were found to possess cyclo- oxygenase inhibitory activity (Wu et al. 2002b). Dihydrokawain and yangonin showed the high- est COX-I and COX-II inhibitory activities at 100 μ g/ml, respectively. All kava compounds bornyl esters of 3,4-methylenedioxy cinnamic acid and cinnamic acid, pinostrobin, flavoka- wain B and 5,7-dimethoxyflavanone tested gave good COX-I and moderate COX-II enzyme inhibitory activities at 100 μ g/mL (Wu et al. 2002a). Flavokawain B showed the highest COX-I inhibitory activity at 100 μ g/mL. Anticancer Activity Findings of a cancer incidence survey for the Pacific Islands completed in the 1980s indicated that the more kava consumed by a population the lower the cancer incidence for that population (Steiner 2000). Crude kava extracts (dichloro- methane and hexane fractions) showed good activity against A2780 ovarian tumour and K562 human leukaemia cancer cell lines in-vitro (Tabudravu and Jaspars 2005 ). Bioassay-guided isolation afforded six known kava lactones dihy- dromethysticin; 7,8 dihydrokavain; kavain; demethoxyyangonin; cis -yangonin and trans- yangonin and two flavokavains A and B. The anticancer of the fractions and eight compounds gave IC 50 values ranging from 0.42 to 9.15 μ g/ml against K562 and 0.43–5.15 μ g/ml against A2780. Flavokawain A, B and C naturally occurring chalcones isolated from kava may hold promis- ing anti-cancer effects as numerous studies revealed that both flavokawain A and B were involved in the induction of cell cycle arrest in several cancer cell lines (Abu et al. 2013 ). Flavokawain B was shown to be more effective in treating in-vitro cancer cell lines as compared to flavokawain A and C. Flavokawain B also exerted antinociceptive effects as well as anti- inflammation properties. Flavokawain A, a chal- cone from kava extract, induced apoptosis in bladder cancer cells by involvement of Bax protein-dependent and mitochondria-dependent apoptotic pathway and suppresses bladder tumor growth in mice (Zi and Simoneau 2005 ). Studies by Tang et al. (2008) found that kava flavokawain A exerted different effects in bladder cancer cells with wild-type versus mutant p53. In a p53 wild- type, low-grade, and papillary bladder cancer cell line (RT4), flavokawain A increased p21/WAF1 and p27/KIP1, which resulted in a decrease in cyclin-dependent kinase-2 (CDK2) kinase activ- ity and subsequent G(1) arrest. In contrast, flavo- kawain A induced a G(2)-M arrest in six p53 mutant-type, high-grade bladder cancer cell lines (T24, UMUC3, TCCSUP, 5637, HT1376 and HT1197). Flavokawain A significantly reduced the expression of CDK1-inhibitory kinases, Myt1 Piper methysticum 156 and Wee1, and caused cyclin B1 protein accumu- lation leading to CDK1 activation in T24 cells. Suppression of p53 expression by small interfer- ing RNA in RT4 cells restored Cdc25C expres- sion and down-regulated p21/WAF1 expression, which allowed Cdc25C and CDK1 activation, which then led to a G(2)-M arrest and an enhanced growth-inhibitory effect by flavokawain A. Consistently, flavokawain A also caused a pro- nounced CDK1 activation and G(2)-M arrest in p53 knockout but not in p53 wild-type HCT116 cells. Studies showed that a 30-week kava treatment inhibited 4-(methylnitrosamino)-1-(3-pyridyl)- 1-butanone plus benzo[a]pyrene-induced lung tumorigenesis in A/J mice (Johnson et al. 2008 ). Kava treatment inhibited proliferation and enhanced apoptosis in lung tumors, as shown by a reduction in proliferating cell nuclear antigen (PCNA), an increase in caspase-3, and cleavage of poly(ADP-ribose) polymerase (PARP). Kava treatment also inhibited the activation of nuclear factor kappaBNF-kappaB, a potential upstream mechanism of kava chemoprevention. In subse- quent studies, Johnson et al. (2011) reported that mice-fed diets containing kava at dosages of 1.25, 2.5, 5 and 10 mg/g of diet had 8.4, 6.6, 4.3 – 2.4 and 3.8 lung adenomas per mouse, respectively corresponding to a reduction of 31 %, 46 %, 65 % and 69 % in tumor multiplicity. They found that flavokawains A, B and C, from kava, demonstrated greatly reduced chemopre- ventive efficacies even at concentrations much higher than their natural abundance, suggesting that they alone were unlikely to be responsible for kava’s chemopreventive activity. Kava at all dosages and treatment regimens did not induce detectable adverse effects, particularly with respect to liver. Specifically, kava treatment showed no effect on liver integrity indicator enzymes or liver weight, indicating that kava may be potentially safe for long-term chemopre- ventive application. Shaik et al. (2009 ) demon- strated that kava suppressed nuclear factor-kappaB (NF-kappaB) activation in lung adenoma tissues, potentially a mechanism responsible for kava’s chemopreventive activity. Methysticin was iden- tified as a potent NF-kappaB inhibitor in kava with minimum toxicity. Other kava constituents, including four kavalactones of similar structures to methysticin, demonstrated minimum activities in inhibiting NF-kappaB. A potent chalcone ana- log, (E)-3-(3-hydroxy-4-methoxyphenyl)-1- (3,4,5-trimethoxyphenyl)prop-2-en-1-one derived from flavokawain compounds found in kava, dose-dependently inhibited A549 lung can- cer cell viability, NF- κ B, activation of caspases and activation of mitogen-activated protein kinases such as extracellular signal regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) (Warmka et al. 2012) Studies by Tang et al. (2010 ) demonstrated that flavokawain B (FKB), a kava chalcone, was about 4- to 12-fold more effective in reducing the cell viabilities of androgen receptor (AR)- negative, HRPC cell lines DU145 and PC-3 than AR-positive, hormone-sensitive prostate cancer cell lines LAPC4 and LNCaP, with minimal effect on normal prostatic epithelial and stromal cells. FKB induced apoptosis with an associated increased expression of proapoptotic proteins: death receptor-5, Bim and Puma and a decreased expression of inhibitors of apoptosis protein: XIAP and survivin. Additionally, FKB syner- gized with TNF-related apoptosis-inducing ligand (TRAIL) for markedly enhanced induc- tion of apoptosis. Furthermore, FKB treatment of mice bearing DU145 xenograft tumors resulted in tumor growth inhibition and increased Bim expression in tumor tissues. Flavokawain B sig- nificantly inhibited the cell proliferation of human adenoid cystic carcinoma in-vitro in a dose-dependent manner that was associated with induced apoptosis and cell cycle G2-M arrest, and the half maximal inhibitory concentration (IC 5 0) of flavokawain-B treatment for 48 oursh was estimated to be 4.69 μ mol/L (Zhao et al. 2011). Induction of apoptosis was by up- regulation of Bim and down-regulation of Bcl-2 expression. Li et al. (2012) treated prostate can- cer (LNCaP, LAPC-4, 22Rv1, C4-2B, DU145 and PC-3) cell lines having different androgen receptor (AR) expression and a transformed prostate myofibroblast cell line (WPMY-1), with a commercial kava extract, kavalactones (kawain, 5 ′ 6 ′ -dehydrokawain, yangonin, methysticin) and Piperaceae 157 flavokawain B. The kava extract and flavokawain B effectively down-regulated the expression of both the full-length AR and AR splice variants. The kava extract and kavalactones accelerated AR protein degradation, while flavokawain B inhibited AR mRNA transcription via decreasing Sp1 expression and the binding of Sp1 to the AR promoter. The kava root extract and flavokawain B reduced tumor growth, AR expression in tumor tissues and levels of serum PSA in the patient- derived prostate cancer xenograft in mice. The results suggested a potential usefulness of a safe kava product or its active components for preven- tion and treatment of advanced prostate cancer by targeting AR. Flavokawain B (FKB) potently inhibited the growth of synovial sarcoma cell lines SYO-I and HS-SY-II through induction of apoptosis (Sakai et al. 2012). Treatment with FKB increased cas- pase 8, 9 and 3/7 activity compared to vehicle- treated controls, indicating that both extrinsic and intrinsic apoptotic pathways were activated. In addition, FKB treatment of both cell lines resulted in increased mRNA and protein expression of death receptor-5 and the mitochondrial pro- apoptotic proteins Bim and Puma, while down- regulating the expression of an inhibitor of apoptosis, survivin in a dose-dependent manner. Treatment with flavokawain B (FKB), a novel kava chalcone, preferentially inhibited the growth of uterine leiomyosarcoma (SK-LMS-1), endo- metrial adenocarcinoma (ECC-1) cells compared to the non-malignant, human endometrium fibroblast-like (T-HESC) cell lines (Eskander et al. 2012). FKB treatment resulted in cell cycle arrest and a robust induction of apoptosis in SK-LMS-1 and ECC-1 cell lines. In a recent study, flavokawain B, a kava chal- cone, inhibited the growth of human osteosar- coma cell lines 143B and Saos-2 through G2/M cell cycle arrest and induction of apoptosis involving both extrinsic and intrinsic pathways (Ji et al. 2013). Furthermore, migration and inva- sion ability was decreased by FKB in a dose- dependent manner. The cytotoxicity profile showed FKB had significant lower side effects on bone marrow cells and small intestinal epithelial cells compared with adriamycin. Oral adminis- tration of flavokawain A (FKA), the predominant chalcone from kava, to UPII-SV40T transgenic mouse for 318 days inhibited the occurrence of high-grade papillary urothelial cell carcinoma, a precursor to invasive urothelial cancer, by 42.1 % (Liu et al. 2013). A decreased expression of Ki67, survivin and X-linked inhibitor of apoptotic pro- teins (XIAP) and increased expression of p27 and DR5, and the number of terminal deoxynucleoti- dyl transferase-mediated dUTP nick end labeling (TUNEL)-positive apoptotic cells were observed in the urothelial tissue of FKA-fed mice. The results suggested a potential of FKA in prevent- ing the recurrence and progression of non- muscle- invasive urothelial cell carcinoma. The results of animal studies by Triolet et al. (2012 ) suggested that kava may reduce colon cancer risk. After 14 weeks, rats fed the nonpolar fraction of kava extract 12 days prior to, during and after the administration of dimethylhydra- zine, a colon-specific carcinogen, had a signifi- cant reduction in precancerous lesions [aberrant crypt (AC) foci (ACF)] as well as large ( ≥ 4 AC/ ACF) sialomucin-only expressing foci, an indica- tor of greater tumorigenic potential, compared to the control group (Triolet et al. 2012). Groups fed the ethanolic kava extract and polar kava fraction trended toward reductions in ACF and large sialomucin-only expressing foci. The combined kava groups had significantly fewer total AC, ACF, large ACF and large sialomucin-only expressing foci compared to the control group. Histological examination found no hepatic lesions in animals consuming the kava diets. Studies by Leitzman et al. (2014) demonstrated the outstanding efficacy of kava in preventing 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice with high selectivity for the initiation stage in association with the reduction of O 6 -methylguanine adduct in DNA. Kava treatments covering the ini- tiation stage reduced the multiplicity of lung adenomas by approximately 99 %. A minimum effective dose was not defined because kava at two lower dosages (2.5 and 1.25 mg/g of diet) were equally effective as 5 mg/g of diet in completely inhibiting lung adenoma formation. Dihydromethysticin from kava completely Piper methysticum 158 suppressed tobacco carcinogen 4-(methyl- nitrosamino)-1-(3-pyridyl)-1-butanone-induced lun