**2.3. Triterpenoids**

Some oleanane type triterpenoids with highly oxygenated were isolated form *Barringtonia racemosa* as shown in Fig 6. Six friedelane type triterpenoids were isolated from bark of *Hibiscus tiliaceus* collected from Hainan province as shown in Figure 7.

**Figure 7.** Structures of friedelane type triterpenoids from *Hibiscus tiliaceus*

13

### **2.4. Cardiac glycosides**

More than 30 cardiac glycosides were isolated from the seeds of *Cerbera manghas* and the skeleton of the obtained compounds were calssified into three classess including digitoxigenin (A), Oleandrin (B), and tanghinin (C) as shown in Fig 8.

13

O

RO

H

<sup>A</sup> <sup>B</sup> <sup>C</sup>

19

9 13 14

1

3 5

O

21 22

RO

H

19

9 13 14

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1

3 5

OH

18

O

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<sup>21</sup> <sup>22</sup>

O

<sup>21</sup> <sup>22</sup> <sup>O</sup>

O

18

O

OH

18

RO

H

19

9 13 14

1

**2.3. Triterpenoids**

198 Column Chromatography

Some oleanane type triterpenoids with highly oxygenated were isolated form *Barringtonia racemosa* as shown in Fig 6. Six friedelane type triterpenoids were isolated from bark of *Hibiscus*

More than 30 cardiac glycosides were isolated from the seeds of *Cerbera manghas* and the skeleton of the obtained compounds were calssified into three classess including digitoxigenin

R1=R2=O, R3=R5=H, R4=OH, R6=R7=CH3 (1) R1=R2=H, R3=R4=O, R5=OH, R6=R7=CH3 (2) R1=R2=R5=H, R3=R4=O, R6=R7=CH3 (3) R1=R2=R4=R5=H, R3=OH, R6=R7=CH3 (4) R1=R4=R5=H, R2=R3=OH, R6=R7=CH3 (5) R1=R2=R5=H, R3=R4=O, R6=R7=COOH (6)

R7

R6

**Figure 7.** Structures of friedelane type triterpenoids from *Hibiscus tiliaceus*

(A), Oleandrin (B), and tanghinin (C) as shown in Fig 8.

*tiliaceus* collected from Hainan province as shown in Figure 7.

R=E-coumaroyl

R=Z-coumaroyl

**Figure 6.** Triterpenoids from *Barringtonia racemosa*

R2

R3

R1

R4 R5

**2.4. Cardiac glycosides**

14

15

**Figure 8.** Cardenolides from *Cerbera manghas*

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**Figure 8.** Cardenolides from *Cerbera manghas*

14

200 Column Chromatography

### **2.5. Lignans**

Many lignans were isolated from the semi-mangroves, and lignans obtained from *Cerbera manghas* with unique structures have attracted more attention. These lignans were classified to be monomerlignans (1-4), sesquilignans (5-7), dilignans (8-16), sesterlignans (17) and trilignans (19). They are listed as belows.

18

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203

Natural Products from Semi–Mangrove Plants in China http://dx.doi.org/10.5772/55933 203

**2.5. Lignans**

202 Column Chromatography

trilignans (19). They are listed as belows.

17

Many lignans were isolated from the semi-mangroves, and lignans obtained from *Cerbera manghas* with unique structures have attracted more attention. These lignans were classified to be monomerlignans (1-4), sesquilignans (5-7), dilignans (8-16), sesterlignans (17) and

OMe

OH OH

OH

cycloolivil

OH MeO

HO

OH

**2.6. Others**

**3. Biological activities**

**3.1. Antitumor activities**

Apart from these above mentioned compounds, courmains, iridoids, and alkaloids have also been obtained from semi-mangroves distributed in China. For example, cerbinal, p-hydroxy‐ benzaldehyde, benzamide, n-hexadecane acid monoglyceride, loliolide, *β*-sitosterol, *et al*.

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205

The seeds extract of *Cerbera manghas* were found possessing obvious cytotoxic activity against some human cancer cell lines by MTT methods. Feng and coworkers obtained two cardiac glycosides named GHSC-73 and GHSC-74. Further study suggested GHSC-73 and GHSC-74 can significantly inhibited growth and proliferation of HepG2 cells in dose-dependent manner. GHSC-73 inhibited the growth and proliferation of HepG2 cells through blocking S phase and inducing apoptosis, while GHSC-74 through blocking S and G2 phases and inducing apopto‐ sis.Wang and coworkers tested 24 compounds isolated from *Pluchea indic* and found that valenc-l (10)-ene-8α, 13-diol showed inhibiting activity against Bel-7402 and A2780 cells. Lanceolatin B purified from *Pongamia pinnata* can prevent the development of cancer [20]. The cytotoxic activities of mansonone D, mansonone H, thespesone, and thespone were tested against MCF-7 cells by Johnson using the MTT methods. The results indicated that they all showed certain cytotoxic activities [21]. Ethnomedical survey has shown that the seeds of *Barringtonia racemosa* are traditionally used in certain remote villages of Kerala (India) to treat cancer like diseases. Thomas [22] tested the seed extracts for their anti-tumor activity and toxicity. Intraperitoneal (i.p.) daily administration of 50% methanol extract of this seed to mice challenged with 1 million Dalton's Lymphoma Ascitic (DLA) cells resulted in remarkable dose dependent anti-DLA activity in mice. The optimum dose was found to be 6 mg/kg. This dose protected all the animals challenged with the tumor cells. The efficacy of the drug was found to be better than that of a standard drug, vincristine in this tumor model. However, the oral administration showed only marginal activity compared to i.p. administration. The extract was found to be devoid of conspicuous acute and short-term toxicity to mice, when adminis‐ tered daily, (i.p.) for 14 days up to a dose of 12 mg/kg (which was double the concentration of optimum therapeutic dose). The treated mice showed conspicuous toxic symptoms only at 24 mg/kg. The LD (50) to male mice for a single i.p. dose was found to be 36 mg/kg. Consequently, they found that the seed extract is an attractive material for further studies leading to drug development. Anbu and coworkers [23] evaluated anti-tumor activity of the roots of *Hibiscus tiliaceus* against Dalton's Ascitic Lymphoma (DAL) in Swiss albino mice. A significant enhancement of mean survival time (MST) of *H. tiliaceus* treated tumor bearing mice was found with respect to control group. *H. tiliaceus* treatment was found to enhance peritoneal cell counts. When these *H. tiliaceus* treated animals under-went intraperitoneal (i.p.) inoculation with DAL cells, tumor cell growth was found to be inhibited. The results indicated that, *H. tiliaceus* treated group were able to reverse the haematological parameters, protein and Packed

**Figure 9.** Structures of lignans from *Cerbera manghas*
