3. Phytochemical ContentsOf all par

3. Phytochemical Contents
Of all parts of the plant, the RZZ has been the subject of extensive chemical investigations because of its high medicinal values. Various reports have been published regarding the phytochemical content of RZZ. Attempts to isolate and identify bioactive compounds from the RZZ had started since 1944 with the identification of humulene [22], monoterpenes [23, 24], and zerumbone (2,6,10-cycloundecatrien-1-one, 2,6,9,9-tetramethyl-,(E,E,E)-) [24] from the essential oil of RZZ (EOZZ). This is followed by the success of Ramaswami and Bhattacharyya [25] in identifying two new oxygenated derivatives of humulene (humulene monoxide and humulene dioxide) and Nigam and Levi [26] in reporting the presence of 8 fractions when the EOZZ was subjected to the column chromatography with petroleum ether, benzene, ether, and methanol used as eluants. Those fractions were reported to contain α-pinene, β-pinene, Δ3-carene, camphor, β-caryophyllene, ar-curcumene, zerumbone, humulene oxide, humulene dioxide, linalool, borneol, α-terpineol, unidentified sesquiterpene ketones and sesquiterpene alcohol. Meanwhile Damodaran and Dev [27, 28] reported the isolation of new sesquiterpenoids (e.g., humulene epoxide-I, humulene epoxide-II, humulenol-II, dihydro-ψ-photo-zerumbone and ψ-photozerumbone) and sesquiterpene alcohols (humulenol-I and humulenol-III) from the sesquiterpene fractions and EOZZ, respectively. Chhabra et al. [29] have successfully isolated zerumbone oxide from RZZ while Matthes et al. [30] managed to isolate one new (3 ″ , 4 ″-0-diacetylafielin) and five known compounds (zerumbone, zerumbone epoxide, diferuloylmethane, feruloyl-p-coumaroyl-methane and di-p-coumaroyl-methane) from pentane and ether extracts of RZZ, respectively. Masuda et al. [31] have successfully isolated three new acetylated (3-O-(2-O-acetyl-α-L-rhamnopyranoside), 3-O-(3-O-acetyl-α-L-rhamnopyranoside),  3-O-(4-O-acetyl-α-L-rham-nopyrano-side)) and one known (3-O-α-L-rhamnopyranoside) kaempferol glycosides from the acetone extract of the fresh RZZ. Dung et al. [32, 33] reported high proportions of (Z)-nerolidol (22–36%) in extracts of stems, leaves, and flowers, but not rhizomes, and found zerumbone to predominate in leaves. Further phytochemical investigations demonstrated the presence of sesquiterpenoids, flavonoids, aromatic compounds (e.g., hydroxybenzaldehyde), vanillin and kaempferol derivatives in the RZZ [34–36]. The ethyl acetate fractions of the RZZ (EAZZ) have been reported to contain kaempferol-3-O-rhamnoside, kaempferol-3-O-(2 ″- or 3 ″-acetyl) rhamnoside, kaempferol-3-O-(4 ″-acetyl) rhamnoside, kaempferol-3-O-(3 ″ , 4 ″-diacetyl) rhamnoside and kaempferol-3-O-(2 ″ , 4 ″-diacetyl) rhamnoside [18], which concur with report by Lako et al. [37] on the presence of high content of kaempferol in the RZZ. All reports mentioned above were further confirmed by findings of Srivastava et al. [38] and Yu et al. [39] who reported the presence of approximately 86% sesquiterpenoids with zerumbone being the major component in the EOZZ. Yu et al. [39] also reported the presence of β-caryophyllene, caryophyllene oxide andβ-eudesmol in the EOZZ. Besides having zerumbone as its main constituent, earlier study also reported that the EOZZ has characteristics of being dextrorotatory and congeals at 3°C [40]. In contrast to these findings, the EOZZ of another proposed variety of Z. zerumbet was characterized as being levorotatory, congeals at −27°C and contains 4-terpinenol as its main constituent. In a latest study, attempt to identify anti-inflammatory compounds from the rhizome of Z. zerumbet led to isolation of one sesquiterpene (zerumbone), one flavone (3-O-methyl kaempferol), and two flavonoid glycosides (kaempferol-3-O-(2,4-di-O-acetyl-α-L-rhamnopyranoside) and kaempferol-3-O-(3,4-di-O-acetyl-α-L-rhamnopyranoside)) from the methanol extract of Z. zerumbet (MEZZ) [36]. According to Dae et al. [34] study on the chloroform soluble fraction of Z. zerumbet led to the isolation and identification of two aromatic compounds, p-hydroxybenzaldehyde and vanillin, and six kaempferol derivatives. Chane-Ming et al. [41] reported the EOZZ was rich in zerumbone, α-pinene, and camphene. In contrast, the oils from leaves and flowers contained high amount of (E)-nerolidol, β-caryophyllene, and linalool, respectively, with the former differed from the others by their high levels of α- andβ-pinene. In addition to these, leaves and flowers also contain zingiberene [5]. Interestingly, in most of the studies that described the presence of zerumbone, the compound has been reported as the predominant compound in RZZ. Recent study revealed the presence of a sesquiterpene, zederone, in ethanol extract of RZZ (EEZZ) [42]. Phytochemical screening to the aqueous extract of RZZ (AEZZ) was reported to contain phenolic, saponins, and terpenoids [43].