Antitumor agents 50. 1 Morindaparvin-A, a new antileukemic anthraquinone, and alizarin-1-methyl ether from Morinda parvifolia, and the antileukemic activity of the related derivatives

Phytochemical Characterization, Antioxidant and Anti-Proliferative Properties of Rubia cordifolia L. Extracts Prepared with Improved Extraction Conditions

Rubia cordifolia L. (Rubiaceae) is an important plant in Indian and Chinese medical systems. Extracts prepared from the root, stem and leaf have been used traditionally for the management of various diseases. Some of the known effects are anti-inflammation, neuroprotection, anti-proliferation, immunomodulation and anti-tumor. A comparative account of the extracts derived from different organs that lead to the identification of the most suitable solvent is lacking. We explored the presence of phytochemicals, antioxidant activity and anti-proliferative properties of a variety of solvent-based extracts of root, and methanol extracts of stem and leaf of R. cordifolia L. The antioxidant potential was determined by DPPH, hydrogen peroxide, nitric oxide and total antioxidant assays. The anti-proliferative nature was evaluated by MTT assay on HeLa, ME-180 and HepG2 cells. The composition of the extracts was determined by UPLC-UV-MS. We found that the root extracts had the presence of higher amounts of antioxidants over the stem and leaf extracts. The root extracts prepared in methanol exhibited the highest cytotoxicity in HepG2 cells. The main compounds identified through UPLC-UV-MS of the methanol extract give credibility to the previous results. Our comprehensive study corroborates the preference given to the root over the stem and leaf for extract preparation. In conclusion, we identified the methanol extract of the root to be the most suited to have bioactivity with anti-cancer potential.

Regio-specific biotransformation of alizarin to alizarin methoxide with enhanced cytotoxicity against proliferative cells

Alizarin has been reported to have an antigenotoxic activity along with an inhibitory effect on the tumor cell growth of human colon carcinoma cells. Alizarin was biotransformed into an O-methoxide derivative using O-methyltransferase from Streptomyces avermitilis MA4680 (SaOMT2) to enhance its bioefficacy. The biotransformed product was extracted, purified, and characterized using various chromatographic and spectroscopic analyses, and confirmed to be an alizarin 2-O-methoxide. The antiproliferative activity of the compound against gastric cancer cells (AGS), uterine cervical cancer (Hela), liver cancer (HepG2), and normal cell lines was investigated. Alizarin 2-O-methoxide showed an inhibitory effect on all three cancer-cell lines at very low concentrations, from 0.078 µM, with no cytotoxicity against 267B1 (human prostate epithelial) and MRC-5 (normal human fetal lung fibroblast).

Indian Morinda species: A review

Morinda is a largest genus of Rubiaceae family, and its 11 species are found in India. In India, plant species are known by several common names as great morinda, Indian mulberry, noni, beach mulberry and cheese fruit. Various Morinda products (capsules, tablets, skin products and fruit juices) are available in the market, used by people for treatment of several health complaints. A diversity of phytochemicals including iridoids, flavonoids, flavonoid glycosides, anthraquinones, coumarins, lignanas, noniosides, phenolics and triterpenoids have been reported from Morinda species. Morinda species are used in the treatment of inflammation, cancer, diabetes, psyquiatric disorders, and bacterial and viral infections. The noni fruit juice (Morinda citrifolia) and its products are used clinically in the treatment of cancer, hypertension and cervical spondylosis affecting patients. M. citrifolia fuit juice, with different doses, is used in the maintaining blood pressure and reducing of superoxides, HDL and LDL levels. Similarly, oligosaccharide capsules and tablets of root extract of M. officinalis are recommended as medicine for the treatment of kidney problems and sexual dysfunctions of patients. The toxicological studies revealed that higher doses of fruit juice (4,000 or 5,000 mg/kg) of M. citrifolia for 2 or more months cause toxic effects on liver and kidneys. M. officinalis root extracts (ethanolic and aqueous) are found fully safe during treatment of diseases. A large number of reviews are available on M. citrifolia but very few studies are conducted on other Indian Morinda species. This review reports the comprehensive knowledge on state-wise distribution, botany, ethnomedicinal uses, phytochemistry, pharmacological activities, clinical applications and toxicological evaluations of 11 species of Morinda found in India.

Cytotoxic quinones from the aerial parts of Morinda umbellata L

Although Morinda umbellata L. has been used in numerous folk medicines, there is a lack of phytochemical studies on this plant. Sixteen undescribed quinones, namely, ten anthraquinones (umbellatas A-J), one naphthohydroquinone (umbellata K), one naphthohydroquinone dimer (umbellata L), and four dinaphthofuran quinones (umbellatas M-P), were isolated from the aerial parts of Morinda umbellata L. (Rubiaceae). The structures of all the isolated quinones were elucidated based on spectroscopic methods. Four of the unknown quinones (umbellatas A, H, K and M) showed potent cytotoxic effects against A431, A2780, NCI-H460, HCT116, HepG2, and MCF-7 human cancer cell lines with IC₅₀ values of 1.3-7.1 μM. These results reveal potential lead compounds for the development of new anticancer agents.

Glycosides of naphthohydroquinones and anthraquinones isolated from the aerial parts of Morinda parvifolia Bartl. ex DC (Rubiaceae) increase p53 mRNA expression in A2780 cells

Eight previously undescribed naphthohydroquinone glycosides, namely morindaparvins H-O, together with four known anthraquinone glycosides were isolated from the n-BuOH extract of the aerial parts of Morinda parvifolia Bartl. ex DC (Rubiaceae). The structures of morindaparvins H-O were elucidated on the basis of spectroscopic analysis. To our knowledge, this is the first isolation of quinone glycosides from the plant M. parvifolia. The results showed that all 12 compounds at the concentration of 50 μM significantly increased p53 mRNA expression in A2780 cells compared with the blank control group.

Naphthohydroquinones, naphthoquinones, anthraquinones, and a naphthohydroquinone dimer isolated from the aerial parts of Morinda parvifolia and their cytotoxic effects through up-regulation of p53

Five unknown compounds, morindaparvins C-G, consisting of naphthohydroquinones, a naphthoquinone, an anthraquinone, and a naphthohydroquinone dimer, together with three known quinones and seven other known compounds, were isolated from the aerial parts of Morinda parvifolia. The structures of morindaparvins C, D, E, F, and G were elucidated on the basis of spectroscopic or X-ray diffraction analysis as methyl 4-hydroxy-1,6-dimethoxy-naphthalene-2-carboxylate, methyl 4,8-dihydroxy-1-methoxy-naphthalene-2-carboxylate, 3-amino-6-methoxy-2-methoxycarbonyl-1,4-naphthoquinone, 1,4-dihydroxy-7-hydroxymethyl-anthraquinone, and dimethyl 1,1'-dihydroxy-4,4',7,7'-tetramethoxy-2,2'-binaphthalene-3,3'-dicarboxylate, respectively. Naphthoquinones and naphthohydroquinone dimers were previously unknown in the genus Morinda. In addition, the compounds were tested for cytotoxicity against four human cancer cell lines HeLa, A2780, Ketr3 and MCF-7 and their effects on p53-activated transcription. Three naphthoquinones had moderate cytotoxic effects with IC50 values ranging from 1.51 to 9.56 μM, through up-regulation of p53 transcriptional activity.

Further constituents of Galianthe thalictroides (Rubiaceae) and inhibition of DNA topoisomerases I and IIα by its cytotoxic β-carboline alkaloids

A new cytotoxic β-carboline alkaloid, 1-methyl-3-(2-hydroxypropan-2-yl)-2-(5-methoxy-9H-β-carbolin-1-yl)-cyclopentanol (1), was isolated from roots of Galianthe thalictroides, together with the alkaloid 1-(hydroxymethyl)-3-(2-hydroxypropan-2-yl)-2-(5-methoxy-9H-β-carbolin-1-yl)-cyclopentanol (2), the anthraquinones 1-methyl-alizarin and morindaparvin-A, the coumarin scopoletin, homovanillic alcohol, (-)-epicatechin, and the steroids stigmast-4-en-3-one, 4,22-stigmastadien-3-one, campest-4-en-3-one, stigmast-4-en-3,6-dione, 6-β-hydroxy-stigmast-4-en-3-one, stigmasterol, campesterol, β-sitosterol, and β-sitosterol-3-O-β-D-glucopyranoside. Among the previously known compounds, homovanillic alcohol is a novel finding in Rubiaceae, while 1-methyl-alizarin, morindaparvin-A, scopoletin, stigmast-4-en-3-one, 4,22-stigmastadien-3-one, campest-4-en-3-one, stigmast-4-en-3,6-dione, and 6-β-hydroxy-stigmast-4-en-3-one is reported for the first time in the genus Galianthe. The cytotoxic β-carboline alkaloids 1 and 2 exhibited potent antitopoisomerase I and IIα activities and strong evidence is provided for their action as topoisomerase IIα poisons and redox-independent inhibitors.

Total synthesis, cytotoxic effects of damnacanthal, nordamnacanthal and related anthraquinone analogues

Naturally occurring anthraquinones, damnacanthal (1) and nordamnacanthal (2) were synthesized with modified reaction steps and investigated for their cytotoxicity against the MCF-7 and K-562 cancer cell lines, respectively. Intermediate analogues 2-bromomethyl-1,3-dimethoxyanthraquinone (5, IC50 = 5.70 ± 0.21 and 8.50 ± 1.18 mg/mL), 2-hydroxymethyl-1,3-dimethoxyanthraquinone (6, IC50 = 12.10 ± 0.14 and 14.00 ± 2.13), 2-formyl-1,3-dimethoxyantharquinone (7, IC50 = 13.10 ± 1.02 and 14.80 ± 0.74), 1,3-dimethoxy-2-methylanthraquinone (4, IC50 = 9.40 ± 3.51 and 28.40 ± 2.33), and 1,3-dihydroxy-2-methylanthraquinone (3, IC50 = 25.60 ± 0.42 and 28.40 ± 0.79) also exhibited moderate cytotoxicity against MCF-7 and K-562 cancer cell lines, respectively. Other structurally related compounds like 1,3-dihydroxyanthraquinone (13a, IC50 = 19.70 ± 0.35 and 14.50 ± 1.28), 1,3-dimethoxyanthraquinone (13b, IC50 = 6.50 ± 0.66 and 5.90 ± 0.95) were also showed good cytotoxicity. The target compound damnacanthal (1) was found to be the most cytotoxic against the MCF-7 and K-562 cancer cell lines, with IC50 values of 3.80 ± 0.57 and 5.50 ± 1.26, respectively. The structures of all compounds were elucidated with the help of detailed spectroscopic techniques.

Antitumor activities of an anthraquinone fraction isolated from in vitro cultures of Ophiorrhiza rugosa var decumbens

The biological effects of the anthraquinone fraction (AQf) isolated from in vitro cultures of Ophiorrhiza rugosa Wall. var decumbens (Rubiaceae) were evaluated. AQf showed differential activity on reactive oxygen species; it mediated the generation of superoxide radical and inhibited hydroxyl radical and lipid peroxidation. No considerable nitric oxide scavenging activity was observed for AQf. The AQf induced 50% cytotoxicity in Ehrlich ascites carcinoma and Dalton's lymphoma ascites at concentrations of 130 and 60 µg/mL, respectively. It effectively reduced the inflammation induced by carrageenan in mice. An AQf concentration of 200 mg/kg body weight reduced solid tumor progression in mice. It also prolonged the life span of ascites tumor-bearing mice compared with control mice.

A review on plant-derived natural products and their analogs with anti-tumor activity

Traditional medicines, including Chinese herbal formulations, can serve as the source of potential new drugs, and initial research focuses on the isolation of bioactive lead compound(s). The development of novel plant-derived natural products and their analogs for anticancer activity details efforts to synthesize new derivatives based on bioactivity- and mechanism of action-directed isolation and characterization coupled with rational drug design - based modification. Also, the anticancer activity of certain natural products and their analogs can be enhanced by synthesizing new derivatives based on active pharmacophore models; drug resistance and solubility and metabolic limitations can be overcome by appropriate molecular modifications; and new biological properties or mechanisms of action can be added by combining other functional groups or molecules. Preclinical screening for in vitro human cell line panels and selected in vivo xenograft testing then identifies the most promising drug development targets.

Anthraquinones with quinone reductase-inducing activity and benzophenones from Morinda citrifolia (noni) roots

Two new benzophenones, morintrifolins A ( 1) and B ( 2), together with 14 known anthraquinones and four other known compounds, were isolated from a chloroform-soluble extract of Morinda citrifolia roots. Of the isolated compounds, four known anthraquinones, namely, 1,2-dihydroxyanthraquinone ( 3), 1,3-dihydroxy-2-methylanthraquinone ( 4), 2-hydroxy-3-(hydroxymethyl)anthraquinone ( 5), and 1,3,6-trihydroxy-2-methylanthraquinone ( 6), exhibited quinone reductase (QR)- inducing activity in Hepa lclc7 cells, with concentrations required to double QR activity of 12.0, 8.1, 0.94, and 0.56 microM, respectively.

Novel antitumor agents from higher plants

This review article describes research on cytotoxic natural products isolated from plant sources, primarily preclinical lead identification and structural modification studies performed in the Natural Products Laboratory of Dr. K. H. Lee. As a result of this work, more than 100 new cytotoxic antitumor compounds and their synthetic analogs have shown confirmed activity in NCI's in vitro human tumor cell lines bioassay and are of current interest to NCI for further in vivo evaluation. A significant and ongoing project involves novel antitumor analogs related to podophyllotoxin and etoposide, and has led to a potent derivative designated GL331 (17). This compound is currently in Phase IIa clinical trials and shows promise as an anticancer drug, especially for drug-resistant cancers. Bioactivity-directed fractionation and isolation of medicinal herbs (primarily herbs of Chinese origin) have also led to many classes of cytotoxic compounds including polyphenolic compounds, sesquiterpene lactones, lignans, quassinoids, triterpene glucosides, flavonoids, colchicine derivatives, and quinone derivatives.