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The tropone sesquiterpene phaeocaulisin D, isolated from the rhizomes of Curcuma phaeocaulis, has previously been shown to inhibit nitric oxide production in macrophages. A total synthesis of phaeocaulisin D was accomplished by using an intramolecular cyclization–dearomatization as a key step. The highlights of the synthesis are effective formation of the 5–7 fused tropone system, and selective methylation of a late-stage intermediate.

Chemical composition, antioxidant and antibacterial activities of the essential oil of Curcuma phaeocaulis were analysed. In the aerial part, 22 compounds account for 69.23% of the total essential oil and authenticated, while in the underground part, 32 compounds account for 84.28% of the total essential oil and authenticated. Among the compounds detected, α-pinene, camphene, eucalyptol, camphor, borneol, β- tumerone, epi-curzerenone were the main compounds of volatile oil in both parts of Curcuma phaeocaulis. In addition, various lipid antioxidant properties by peroxidation assays, inoxidizability and antibacterial action were assessed. The result may be considered as a baseline study for the further development and application of Curcuma phaeocaulis.

Curcuma zedoaria (dry stenophora of Curcuma phaeocaulis Val., Curcuma kwangsiensis S. G. Lee et C. F. Liang, or Curcuma wenyujin Y. H. Chen et C.Ling) is a representative herb with clinical effects on liver diseases after being vinegar-processed. The crude Curcuma zedoaria and the processed Curcuma zedoaria (vinegar-boil) have been widely used as mixtures, but their equivalence has not been fully investigated. In this manuscript, quality markers of processed (vinegar-boil) Curcuma zedoaria were investigated by comparison of the compounds and hepatoprotective activities with the crude (three spices) ones. First, GC-MS-based untargeted metabolomics were applied to reveal the discriminatory components and discover potential markers. As a result, a total of six components were identified as potential markers. Then, the hepatoprotective activities were evaluated by dual cell damage models induced by a certain concentration of H2O2 or tertbutyl hydfroperoxide (t-BHP) (55 &mu, M H2O2 or 40 &mu, M t-BHP), which highlighted the potential of the processed Curcuma zedoaria on oxidative stress. Finally, epicurzerenone was identified as its quality marker on oxidative liver injury based on the above results and the cell-based biological assay. Overall, vinegar-processed Curcuma zedoaria was more suitable for the treatment of oxidative liver diseases, and epicurzerenone could be considered as its quality marker.

A new norsesquiterpene named phaeocaulisin N (1), and three new guaiane-type sesquiterpenes named phaeocaulisins O–Q (2–4), together with a known norsesquiterpene (5) were isolated from the rhizomes of Curcuma phaeocaulis. Their structures were established based on extensive spectroscopic analysis. Compounds 1 and 5, as far as we know, are the first example of 13-norguaiane-type sesquiterpenes isolated from the genus Curcuma. All of the isolated compounds were tested for inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages. Compound 1 showed strong inhibitory activity on nitric oxide production with IC50 value of 3.58 ± 0.17 μM.

Seven pairs of new enantiomeric sesquiterpenoids, (+)/(−)-phaeocauline A − G [(+)/(−)-1–7], were isolated from the rhizomes of Curcuma phaeocaulis by chiral HPLC separation. Their structures, including absolute configurations, were determined by spectroscopic analyses and ECD data. The isolates were assessed for vasorelaxant, anti-platelet aggregative, and neuroprotective activities. Enantiomers (+)-1 and (−)-1 showed similar activity against abnormal platelet aggregation induced by arachidonic acid, while their C-4 epimers (+)-2 and (−)-2 were inactive, which indicated that those effects were stereoselective, but not enantioselective. Compounds (+)/(−)-3–5 exhibited vasorelaxant effects against KCl-induced contraction of rat aortic rings.

Three new guaiane-type sesquiterpenes named phaeocaulisins K-M (1-3), and one germacrane-type sesquiterpenoid with new ring system of 1,5- and 1,8-ether groups named phagermadiol (4), were isolated from rhizomes of Curcuma phaeocaulis. Their structures were established based on extensive spectroscopic analysis. Compound 1, the first example of norsesquiterpene with tropone backbone, and compound 3 with a novel 1,2-dioxolane sesquiterpene alcohol were isolated from the genus Curcuma. All of the isolated compounds were tested for inhibitory activity against lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 macrophages. Compound 3 inhibited NO production with IC50 value of 6.05 ± 0.43 μM. The plausible biosynthetic pathway for compounds 3 and 4 in C. phaeocaulis was also discussed.

Germacrane-type sesquiterpenes, with a flexible 10-membered ring unit as the structural and conformational features, play a central role in the biosynthesis and synthesis of other sesquiterpenes. In this report, two pairs of new sesquiterpene alkaloids, (+)/(−)-phaeocaulin A [(+)-1/(−)-1] and B [(+)-2/(−)-2], and two pairs of new sesquiterpenes, (+)/(−)-phaeocaulin C [(+)-3/(−)-3] and D [(+)-4/(−)-4], along with one related known analog (5), were isolated from the rhizomes of Curcuma phaeocaulis. The absolute configurations of (+)-1/(−)-1, (+)-2/(−)-2, (+)-3/(−)-3 and (+)-4/(−)-4 were unambiguously determined by analysis of single-crystal X-ray diffractions and quantum chemical electronic circular dichroism (ECD) method. It is noteworthy that (+)/(−)-phaeocaulin A [(+)-1/(−)-1] and B [(+)-2/(−)-2] are two pairs of rare N-containing germacrane-type sesquiterpenes. A possible biogenetic pathway for 1–5 was postulated. All of the isolated compounds were tested for their inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages.

A comparison of trace elements contained in Rhizoma Curcumae and their corresponding vinegar products, derived from three different origins, namely Curcuma phaeocaulis Val., Curcuma kwangsiensis S. G. Lee et C. F. Liang and Curcuma wenyujin Y. H. Chen et C. Ling, was undertaken using inductively coupled plasma mass spectrometry (ICP-MS). SPSS 19 was adopted for cluster and discriminant analyses. Rhizoma Curcumae is rich in Cu, Zn, Se, Cr, Co, V, Ni and other essential trace elements, and among them, Zn is present the most, followed by Ti, Cu, etc. After processing with vinegar, the contents of some essential trace elements may more likely increase, while the contents of some heavy metal elements tend to decrease. Rhizoma Curcumae from the same species and origin can be well clustered into one group. The results of the cluster analysis confirm the correlation between genuineness and the material base of Rhizoma Curcumae. In addition, the discriminant function of Rhizoma Curcumae was obtained, with an accuracy of 90.5%. Thus, a new concept was provided that Rhizoma Curcumae, even the other TCMs, from different sources may be identified by the discriminant function. One of the basic mechanisms of the processing technique of TCMs, “effect-enhancing and toxicity-reducing,” may be associated with the increase or decrease of some trace elements, which provides a new conception for the quality control of TCMs and the processed products.

Ten new guaiane-type sesquiterpenes (1-10), phaeocaulisins A-J, and 18 known guaiane derivatives were isolated from rhizomes of Curcuma phaeocaulis. Their structures were established on the basis of extensive spectroscopic analyses, X-ray crystallographic analysis, and comparison with literature data. Compound 10 is the first example of a norsesquiterpene with this unusual skeleton isolated from the genus Curcuma. All of the isolated compounds were tested for inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages. Compounds 1, 2, 20, and 22-24 inhibited nitric oxide production with IC50 values less than 2 μM. Preliminary structure-activity relationships for these compounds are discussed.

Traditional Chinese medicines (TCMs), Paeonia suffruticosa Andr. (PSA), Paeonia lactiflora Pall. (PLP), and Curcuma phaeocaulis Val. (CPV) all contained abundant starch in tubers, which have usually been discard as waste in the pharmaceutical industry. In this paper, the intrinsic properties of three TCM starches were studied and the structure–property relationships were analyzed, on the purpose of exploring new starch resource for food and non-food industries. PSA starch with the highest amylose (AM) content showed the lowest water binding capacity (WBC), while the CPV starch showed the contrary. Moreover, the starches differed in granule shape and size. The PSA and PLP starches had larger spherical or elliptic granules, whereas CPV starch possessed the smallest granules in large number among the three starches. PSA starch displayed the typical C-type diffraction pattern, while the PLP and CPV starches were classified as A-type pattern. The degrees of crystallinity of the three TCM starches were about 22.8, 16.6, and 24.2%, respectively. The starch separated from CPV indicated the highest transition temperatures (To, Tp, and Tc) and gelatinization temperature range (R) value with lowest peak height indices (PHI), whereas PLP starch showed the lowest transition temperatures and enthalpy of gelatinization (ΔHgel).

The sesquiterpenoid curdione is one of the main bioactive components in the essential oil of Rhizoma Curcumae (Curcuma wenyujin, Curcuma phaeocaulis, and Curcuma kwangsiensis), which has been clinically used for the treatment of cancer in mainland China. Recently it was reported that natural curdione could be hydroxylated by Aspergillus niger and transferred to its corresponding curcumalactones under acidic conditions. Based on this study, the development of a sesquiterpenoid library through the "mirror-image" manipulation of bioactive (non)natural curdione scaffolds by chemical and biological approaches is presented herein. A. niger induced the hydroxylation of two pairs of curdione enantiomers, yielding the corresponding mirror-image hydroxylated curdiones. Simultaneously, the acid-mediated intramolecular "ene" rearrangements of these curdiones and hydroxylated curdione enantiomers yielded the corresponding mirror-image curcumalactones and hydroxylated curcumalactones. Among the 16 pairs of enantiomers obtained in this study, 23 compounds are new sesquiterpenoids. These curdione and curcumalactone derivatives are of particular interest, as they have the potential to be used as lead compounds and scaffolds in drug discovery.

Four new cadinane-type sesquiterpenes named phacadinanes A–D (1–4) were isolated from the rhizomes of Curcuma phaeocaulis. Their structures were elucidated by 1D and 2D NMR, as well as accurate mass measurements. Compound 4 was the first example of a rare 4,5-seco-cadinane sesquiterpene isolated from the Zingiberaceae family. Furthermore, inhibitory effects of the isolated compounds on nitric oxide production in LPS-activated macrophages were evaluated. Compounds 1 and 2 showed strong inhibitory activities on NO production with IC50 values of 3.88 ± 0.58 and 2.25 ± 0.71 μM, respectively. A possible biogenetic pathway for 4,5-seco-cadinane sesquiterpene (4) was postulated.

Curcuma phaeocaulis Val. has been used as a health food in China for a long time. This research aimed to isolate and identify its active compounds with protective effects against hydrogen peroxide-induced PC12 cell death. 70% ethanol extracts of C. phaeocaulis were re-extracted and three fractions of water, petroleum ether and ethyl acetate were obtained. Three diphenylheptane compounds from the ethyl acetate fraction were identified for the first time from C. phaeocaulis, and compound III was considered to be a new structure. All of the three compounds displayed certain protective effects against toxicity in PC12 cells. For all concentrations, compound III displayed a more significant protective effect than ethanol extracts, the ethyl acetate fraction, and the other two compounds. At a concentration of 50 μg mL(-1), the survival rate of damaged PC-12 cells treated with compound III reached 84.7%. Diphenylheptanes were concluded to be the main compounds responsible for the health effects of C. phaeocaulis.

To quantitatively analyze volatile oil in curcuma kzoangsiensis S. G. Lee C. F. Liang. produced in different places and seasons, and to quantitatively analyze crucumol by gas chromatographic (GC). The volatile oil was distilled by the steam distillation(XD) and the crucumol was determined by GC on a HP-5 column (0.32 mm!`30m, 0.2|m), Inlet -1 temperature 200!aC, FID 250!aC, flow 1.0 ml!/ , splitless. Temperature programming started at 60!aC holding for 4 -1 min, then increased to 210!aC at a rate of 3!aC!/ . The quantity of volatile oil in Curcuma kzoangsiensis S. G. Lee C. F. Liang. in different places and collecting time were detected. The contents of volatile oil and crucumol was the hightest in Bingyang place. The quantity of volatile oil was the richtest in January and February, and the same result was obtained for crucumol. As a result, January and February was the best time for the collection of Curcuma kzoangsiensisS. G. Lee C. F. Liang.. The contents of volatile oil and crucumol should be taken as a standard for the evaluation of the quantity 0f curcuma phaeocaulis val.. and the determination of its collecting time.

Rhizoma Curcumae (Ezhu) is a traditional Chinese medicine that has been used in removing blood stasis and alleviating pain for over a thousand years. Three species of Curcuma rhizomes are being used, which include Curcuma wenyujin, Curcuma phaeocaulis, and Curcuma kwangsiensis. In China, the production of Rhizoma Curcumae largely depends on agricultural farming. The essential oils are considered as active constituents in Rhizoma Curcumae, which include curdione, curcumol, and germacrone. On the basis of the yield of curdione, curcumol, and germacrone in an orthogonal array design, the optimized extraction condition was developed. The amounts of these compounds within essential oils in Rhizoma Curcumae varied according to different species and their regions of cultivation. Chemical fingerprints were generated from different species of Curcuma, which therefore could serve as identification markers. In molecular genetic identification of Rhizoma Curcumae, the 5S-rRNA spacer domains of 5 Curcuma species, including the common adulterants of this herb, were amplified, and their nucleotide sequences were determined. Diversity in DNA sequences among various species was found in their 5S-rRNA spacer domains. Thus, the chemical fingerprint together with the genetic distinction could serve as markers for quality control of Curcuma species.