13C-NMR data of three important diterpenes isolated from Euphorbia species.

Euphorbia species are widely distributed plants, many of which are used in folk medicine. Over the past twenty years, they have received considerable phytochemical and biological attention. Their diterpenoid constituents, especially those with abietane, tigliane, ingenane skeletons, are thought to be the main toxicant and bioactive factors. In this work, the utility of (13)C-NMR spectroscopy for the structural elucidation of these compounds is briefly discussed.

1. Introduction

The Euphorbia is the largest genus in the plant family Euphorbiaceae, comprising about 2,000 known species [1]. Euphorbia are widely distributed throughout both hemispheres and range in morphology from large desert succulents to trees and even some small herbaceous plant types. Researched parts in various Euphorbia species include the roots, seeds, latex, lactiferous tubes, stem wood, stem barks, leaves, and whole plants.

Many studies have suggested that these plants have not only therapeutic relevance but that they also display toxicity [2]. Some constituents of Euphorbia species may be promising lead compounds for drug development. Certain Euphorbia species have been reported to possess antitumor activity and have been recommended for use as anticancer remedies [3,4]. Their antitumor activity was mainly attributed to the presence of abietane diterpene derivatives, most of which contain lactone structures reported to possess potent antineoplastic activity toards various cancer cell lines [5,6,7,8,9]. Moreover, some Euphorbia species have been also used as medicinal plants for the treatment of skin diseases, gonorrhea, migraines, intestinal parasites, warts and for mediating pain perception [10,11,12]. Many researchers have shown that Euphorbia species also possess antiproliferative activity [13], cytotoxicity [14], antimicrobial activity [15], antipyretic-analgesic activity [16], inhibition of HIV-1 viral infection [17], inhibitory activity on the mammalian mitochondrial respiratory chain [18], etc.

As mentioned, there are also some reports of toxicity in Euphorbia species. Their toxic substances originate from the milky sap, which is a deterrent to insects and herbivores [19]. Besides, they may possess extreme proinflammatory and tumor promoting toxicities [20,21]. Severe pain and inflammation can result from contact with the eyes, nose, mouth and even skin, which may be due to the activation of protein kinase C enzyme [22]. The toxic constituents of Euphorbia species were considered to be a kind of specific diterpenes, globally called phorboids, which comprise tigliane, ingenane and daphnane diterpene derivatives [23,24].

Terpenes, including diterpenes and triterpenes, have been frequently found in Euphorbia species. Steroids, cerebrosides, glycerols, phenolics and flavonoids were also isolated from plants of the genus [10], but the compounds most relevant to the toxicity and considerable biological activities in Euphorbia are diterpenes, especially those with abietane, tigliane, and ingenane skeletons [10].

Many researchers have suggested that there was a close relationship between the structures and the biological activity, so the structure elucidation is very important for these diterpenes. In this review article, we summarize the 13C-NMR data of these three important diterpene skeleton types of Euphorbia species, covering 42 abietanes, 51 ingenanes and 30 tiglianes. The structure-activity relationship and the features on the chemical shifts were also briefly discussed.

2. Abietane Derivates Isolated from Euphorbia Species (Table 1)

Most plants of the genus Euphorbia contain abietane diterpenoids, which usually have an extra α,β-unsaturated γ-lactone ring located between C-12 and C-13, and some of which have an epoxy ring at C-8 and C-14, or C-11 and C-12, as is the case of 7–14. Some carbons of these diterpenes, especially C-8, C-14, C-11 and C-12 are frequently substituted by hydroxyl groups or form double bonds. Compounds 32–36 indicate that the 18-Me and C-3 could form a three-membered ring. In addition, some abietanes (39–42) without lactone rings were also isolated from the genus Euphorbia. Many abietane diterpenoids exhibit inhibitive activity on various types of tumor cells, such as ANA-1, B16, Jurkat cells [25], K562 cells [7] and LNCaP cells [6]. By comparing the active compound 8 with the inactive one 12, it could be concluded that the C-11/C-12 epoxy ring system was necessary in mediating cytotoxicity. Compounds 2 and 3 are diastereomers, differing only in the stereochemistry at the chiral centers C-8 and C-14, but only compound 2 showed activity, which suggested that the ring C configuration is also crucial for the activity [25]. The α,β-unsaturated lactone is not the only necessary group for the cytotoxic effects, since compounds 3 and 12 do not show cytotoxicity [25]. In addition, the similar compounds 18, 19, 26 and 28 were tested in the inhibition of P-glycoprotein transport activity. The higher inhibitory effect of 26 might be derived from the carbonyl position at C-2, most probably due to the conformational and functional changes in the P-gp induced by the particular structures of helioscopinolides [26].

3. Ingenane Derivates Isolated from Euphorbia Species (Table 2)

Ingenane diterpenoids have a very unique structural feature: they all have a same 5/7/7/3-tetracyclic ring system and a ketone bridge between C-8 and C-10. There is a double bond between C-1 and C-2 in ring A, and another double bond between C-6 and C-7 in ring B. A β-hydroxyl group is linked to C-4, so ring A/B must be trans-joined. Besides, ring D is a cyclopropane ring. Some positions at C-3, C-5, C-13, C-17 and C-20 may be linked to oxygen-substituted residues, such as hydroxyl, acetyl ester, long-chain alkyl ester, benzoyl ester groups, and so forth. This type of diterpenoids have been widely reported in many Euphorbia species. Some researchers have shown that these diterpenoids have antinematodal and termiticidal activity [45,46]. There were also reports about toxicity such as tumor promoting and proinflammatory activity [20,47,48]. Studies on the relationships between structure and irritant activity indicate that presence of a hydroxyl on C-20 is crucial for stimulatory properties. Introduction of an acetyl group in the 20-position results in a lower irritancy [49]. Some 20-deoxyingenol diterpenes induced cell cleavage arrest, but this activity became weak when C-16 had an acyl residue [50]. Acetylation in the 5-position resulted into a considerable depression of irritancy [49]. The skin tumor promoting and irritant activities of the ingenol-3-esters depend on the length of the aliphatic chain in their ester moiety [51]. In addition, the presence of one free hydroxy group at C-3 or C-5 may play an important role in the antinematodal activity [45].

4. Tigliane Derivates Isolated from Euphorbia Species (Table 3)

The tigliane diterpenoids in Euphorbia have a 5/7/6/3-tetracyclic ring system. Rings A/B are usually in trans-integrated configuration, as in compounds 94–98 and 100–120. Only a few tigliane diterpenoids, such as 99 and 121, are in cis-configuration. Rings B/C are joined in trans-configuration and Rings B/C in cis-configuration. Most tigliane diterpenoids have polyhydroxy groups located on C-4, C-9, C-13 and C-20. C-3 forms a carbonyl group. C1,2 and C6,7 form double bonds, respectively. Like the abietane and the ingenane diterpenoids, the hydroxyl groups of tigliane diterpenoids are easily esterified, as in compounds 98–103. This type of macrocyclic deterpene, which is widespread in the seeds, roots, latex and stem of Euphorbia genus, is the main toxic constituent causing irritant, proinflammatory and tumor promoting activity [18,61,62]. When the C12-OH and C13-OH were esterified as a bis-ester, the tumor promoting activity was reinforced at the same time. For example, 12-O-tetradecanoylphorbol 12-acetate (TPA) is well-known as a tumor promotor. The diterpene ester with a saturated aliphatic long chain acyl group exhibited high irritant activity and high tumor promoting activity, and the highly unsaturated analogue exhibits high irritant activity, but very weak tumor promoting activity, suggesting that the irritant activity but not the tumour promoting activity of these diterpenoids is related to the degree of unsaturation of the aliphatic long chain [63]. The absence of a C20-OH is known to be important for the irritant and tumor promoting activities of phorbol esters [64]. Introduction of an acetyl group in the 20-position gives rise to a lower irritancy [65]. Compounds 122 and 123 belong to the daphnane diterpene group, which may be derived from the tigliane diterpenoids by cleavage of ring D and isopropenyl linked on C-13.

5. 13C-NMR Data of Diterpenes

Table 4 shows the 13C-NMR data of the diterpenoids 1–123. All the 13C-NMR data were recorded in CDCl3. The structures and the carbon chemical shifts of the abietane diterpenoids are quite different from each other. Here we only discuss the most frequent abietane lactones 1–35. Four carbons (C-12, C-13, C-15 and C-16) of the lactone ring are the main feature, and their chemical shifts are around δC 78.5–80.0, 148.4–165.0, 117.0–132.8 and 167.0–178.0, respectively.

Table 4

13C-NMR data (in CDCl3) of diterpenes from Euphorbia species.

Carbon	Compound / δC (in ppm)
	1	2	3	4	5	6	7	8	9	10	11	12	13	14
1	38.0	40.9	38.3	43.2	40.5	41.9	41.6	41.4	41.4	41.3	40.0	41.4	39.3	37.6
2	18.4	18.0	17.3	20.1	18.7	17.4	17.1	18.5	18.5	18.5	18.4	18.4	18.4	27.0
3	42.0	40.9	41.3	43.2	43.1	39.9	38.6	40.0	39.2	39.0	41.5	39.8	41.5	78.2
4	32.7	32.3	32.4	34.2	34.1	37.8	37.6	33.3	33.5	33.5	33.5	33.4	33.5	39.2
5	46.8	54.7	55.3	56.6	57.0	55.6	55.4	53.2	53.6	53.5	53.5	53.4	53.5	52.9
6	30.2	19.8	16.7	22.0	19.2	18.0	17.7	21.2	21.0	20.9	20.8	20.8	20.9	20.5
7	68.9	39.9	34.9	43.1	36.3	35.5	35.4	36.5	36.6	35.7	33.8	34.0	34.0	33.9
8	35.1	75	74.4	75.7	77.6	75.0	74.8	60.8	66.9	67.4	61.3	61.1	61.3	61.0
9	42.5	62.6	56.3	58.0	47.4	72.0	72.1	66.6	47.0	47.8	51.9	51.7	51.8	51.6
10	38.0	36.9	37.2	40.3	39.0	40.5	40.5	48.2	39.1	39.3	41.6	41.3	41.4	41.1
11	27.5	67.3	65.0	29.9	29.0	57.2	65.4	61.3	61.6	61.9	107.6	104.1	106.4	103.4
12	78.5	79.0	79.7	79.0	79.9	79.7	79.8	85.4	85.5	85.3	149.5	147.4	147.3	147.6
13	163.4	157.5	160.3	165.3	166.5	161.2	160.3	148.4	150.8	154.5	147.2	144.9	146.5	144.8
14	26.7	71.9	71.8	73.5	74.3	65.2	57.4	55.6	53.6	55.3	54.3	54.4	54.4	54.3
15	120.5	124.2	125.9	123.2	125.5	125.0	126.0	130.1	150.8	128.3	122.3	125.1	127.4	125.4
16	175.4	175.4	176.2	178.0	177.8	175.4	175.3	169.8	168.2	167.4	170.5	170.6	169.2	170.4
17	8.4	6.7	7.9	8.2	9.4	9.2	9.0	8.6	56.5	54.9	55.4	8.6	56.3	8.6
18	33.1	33.0	32.4	34.6	34.1	16.7	16.4	33.2	33.5	33.5	33.4	33.4	33.5	28.3
19	21.6	20.8	20.6	22.4	22.4	21.8	21.3	22.1	21.9	21.9	21.9	21.9	21.9	15.5
20	12.6	16.8	15.7	18.1	15.4	33.6	33.7	15.4	15.6	15.1	15.0	14.9	15.1	15.0
Carbon	Compound / δC (in ppm)
	15	16	17	18	19	20	21	22	23	24	25	26	27	28
1	41.9	31.7	39.7	37.4	32.1	29.9	39.4	39.0	39.6	40.2	51.2	55.9*	30.5	37.4
2	19.0	18.7	19.1	27.5	25.7	27.3	19.0	18.6	18.8	18.9	209.4	209.4	34.2	34.4
3	39.5	41.6	41.9	78.5	75.6	78.3	41.7	41.7	41.7	41.8	82.4	54.0*	216.4	215.6
4	33.1	33.2	33.6	39.0	37.8	39.0	33.6	33.4	32.9	41.0	45.0	38.7	47.1	47.5
5	47.1	39.9	55.3	54.3	48.4	45.4	55.4	54.0	46.8	46.7	53.4	54.5	46.0	54.8
6	31.0	31.0	23.9	23.4	23.4	23.0	23.8	22.3	29.9	30.7	23.0	23.6	24.1	24.6
7	72.4	74.4	37.2	36.8	37.1	32.7	37.1	36.0	71.5	71.1	36.3	36.4	32.2	36.6
8	151.2	148.4	156.3	151.4	152.0	152.6	152.6	154.4	153.4	155.2	149.4	149.5	152.2	150.2
9	46.7	79.1	51.9	51.5	51.6	77.2	60.8	51.4	54.8	55.3	51.3	51.3	76.9	50.7
10	41.9	44.7	41.6	41.2	41.3	44.2	40.3	38.9	40.9	32.7	46.9	46.2	43.8	40.9
11	27.2	38.4	27.5	27.5	27.5	39.7	64.6	31.2	69.6	70.2	27.6	27.6	40.0	27.8
12	76.1	77.2	76.1	75.9	76.0	77.1	79.4	102.4	102.7	104.3	75.3	75.3	76.9	75.6
13	155.1	153.9	152.3	156.0	156.0	154.7	150.1	154.2	152.8	156.0	155.0	155.0	154.6	155.5
14	115.9	118.8	113.9	114.2	114.1	115.7	113.5	113.4	114.7	115.4	115.2	114.9	115.9	114.8
15	118.9	130.0	116.2	116.4	116.4	117.9	118.2	116.3	121.0	124.0	117.5	117.3	118.1	117.1
16	174.9	174.3	175.4	175.3	175.2	174.7	175.4	173.1	173.6	172.1	174.9	174.7	174.6	175.1
17	8.5	8.6	8.3	8.2	28.7	28.9	8.5	8.1	8.4	55.5	8.3	33.5	27.1	26.5
18	33.6	33.8	33.9	28.6	22.2	16.0	33.9	33.5	32.9	32.9	29.5	23.0	21.7	21.8
19	21.7	22.0	21.8	15.6	16.7	17.5	21.8	22.0	21.6	21.4	16.4	17.3	17.8	16.2
20	16.1	17.4	16.8	16.7	8.2	8.4	17.3	14.6	14.3	14.4	17.3	8.2	8.3	8.3
Carbon	Compound / δC (in ppm)
	29	30	31	32	33	34	35	36	37	38	39	40	41	42
1	23.4*	37.9	28.2	33.6	30.4	31.0	29.8	31.4	37.5	37.4	38.9	39.3	36.6	36.1
2	145.2	18.2	26.8	18.8	19.3	19.1	19.2	19.2	34.7	34.6	18.4	18.31	19.0	19.2
3	200.2	41.4	78.1	19.1	18.5	19.9	18.4	19.9	216.5	216	41.8	41.5	41.3	41.3
4	44.0*	32.7	37.2	15.7	16.4	14.7	16.6	14.8	47.8	47.8	33.2	33.1	33.6	33.7
5	52.6	53.9	43.8	51.1	47.6	44.8	41.6	44.1	55.0	54.7	49.8	54.2	52.0	52.8
6	23.2	38.9	35.7	22.7	20.6	27.5	28.9	27.6	23.1	22.7	37.5	19.21	17.3	18.9
7	36.7	209.8	209.4	33.5	24.4	140.4	62.5	139.9	35.5	34.6	200.7	41.01	26.2	33.0
8	148.9	44.2	49.4	76.1	134.6	136.8	135.7	134.8	139.9	139.9	138.9	69.5	143.4	139.1
9	48.3	50.1	53.0	52.6	160.5	41.6	164.9	40.6	49.0	50.0	51.8	61.3	150.3	141.5
10	41.7*	37.4	39.1	36.6	38.9	34.3	39.8	35.2	38.1	37.7	35.9	37.8	39.3	39.8
11	27.6	28.1	23.8	27	34.2	27.2	33.9	27.7	18.6	26.3	18.6	71.7	152.0	154.6
12	75.4	77.5	77.0	79.5	78.8	77.9	78.4	76.7	31.0	69.8	29.7	197.5	125.4	112.8
13	154.9	160.7	160.4	153.3	150.6	151.1	149.9	52.9	46.7	52.1	71.8	136.9	176.4	135.0
14	116.0	24.0	38.5	196	185.7	187.5	187.0	196.2	123.7	121.9	139.5	151.4	184.8	123.0
15	117.7	121.9	122.0	131.8	131.1	132.5	132.8	40.0	214.1	215.1	37.8	137.3	120.2	198.0
16	174.9	174.8	174.8	172.9	172.8	173.5	173.3	178.2	64.8	65.2	17.6	–	144.2	26.4
17	27.0	8.4	8.4	9.4	9.8	10.0	9.9	16.2	23.8	17.5	16.2	128.8	8.5	33.7
18	2.0	13.1	27.6	21.5	22.3	20.5	22.2	20.4	25.8	25.6	32.6	33.8	33.5	22.2
19	19.4	33.5	14.9	23.9	23.2	24.5	23.2	24.7	22.3	22.3	21.2	21.9	21.9	19.6
20	8.3	21.0	13.1	16.9	16.8	11.5	15.7	12.4	14.7	14.3	14.1	17.8	20.4	–
Carbon	Compound / δC (in ppm)
	43	44	45	46	47	48	49	50	51	52	53	54	55	56
1	130.0	129.0	131.7	130.0	132.2	131.8	130.5	132.2	132.1	132.2	131.6	131.4	131.4	132.1
2	138.8	139.3	136.3	138.8	133.2	133.6	136.0	133.4	135.8	135.8	136.0	136.2	136.2	133.3
3	80.5	80.3	80.2	80.6	82.2	82.0	81.7	82.1	82.9	82.7	81.6	82.5	82.5	82.1
4	84.3	84.0	74.7	84.4	85.8	85.7	85.7	86.0	85.0	84.9	85.8	84.5	84.4	86.0
5	75.3	75.2	75.0	73.8	74.8	74.6	74.8	75.0	77.3	74.8	74.8	76.7	76.7	75.0
7	127.4	126.2	128.4	128.3	131.9	131.0	129.7	131.8	123.1	129.5	130.9	127.2	127.3	128.2
8	44.0	43.2	42.9	44.1	43.6	43.1	42.9	43.7	43.0	43.6	43.2	42.6	42.6	43.7
9	207.8	206.5	205.2	208.0	205.4	204.6	204.7	205.4	206.0	206.2	204.7	205.9	205.9	205.6
10	72.4	72.6	72.0	72.6	71.9	71.8	71.8	72.1	72.0	72.1	72.0	71.8	71.8	72.1
11	39.8	38.6	37.7	39.6	38.6	38.6	37.9	38.7	38.7	38.5	38.6	37.4	37.4	38.6
12	30.8	35.0	35.2	31.0	31.1	30.8	35.0	31.1	30.8	31.2	30.7	35.0	35.0	31.2
13	23.1	68.8	29.1	23.9	23.1	23.2	69.1	23.1	24.0	24.0	24.1	69.0	69.0	23.2
14	22.9	28.2	29.4	23.2	22.9	24.0	28.0	23.3	23.7	23.3	23.2	28.2	28.2	23.0
15	24.0	30.2	30.1	22.7	24.4	27.7	30.7	24.4	27.4	28.5	27.6	30.3	30.3	24.3
16	28.5	22.5	24.7	28.5	28.4	24.2	22.2	28.5	24.3	23.1	24.2	22.4	22.5	28.4
17	15.4	16.7	66.8	15.5	15.5	65.7	16.8	15.4	65.6	15.5	65.7	16.7	16.7	15.5
18	17.3	18.4	18.2	17.4	17.0	16.6	18.0	17.1	16.7	17.3	16.6	18.2	18.2	17.1
19	15.5	15.4	15.5	15.4	15.4	15.4	15.3	15.6	15.6	15.6	15.4	15.4	15.5	15.4
20	67.2	66.8	62.3	66.4	65.8	65.7	65.7	65.9	21.9	66.8	65.7	67.1	67.2	65.9
Carbon	Compound / δC (in ppm)
	57	58	59	60	61	62	63	64	65	66	67	68	69	70
1	132.2	132.0	132.2	132.2	132.2	132.0	132.3	132.1	131.5	131.0	131.2	131.8	131.5	131.1
2	133.4	135.9	135.9	136.1	136.1	–	133.5	136.2	136.3	136.8	136.8	136.4	136.2	136.7
3	82.5	82.7	81.8	82.8	82.5	82.4	82.4	82.0	82.7	82.1	82.2	82.9	82.6	82.0
4	86.0	84.8	84.1	85.0	85.1	–	85.9	85.2	84.9	84.8	84.9	85.0	84.5	84.8
5	78.5	76.7	74.0	74.9	75.0	75.0	75.1	76.7	77.0	76.0	76.5	77.4	76.9	76.0
6	135.8	139.4	136.6	136.1	136.2	–	135.5	138.4	138.2	140.2	140.1	138.3	139.6	140.1
7	128.4	128.2	128.3	129.3	129.4	132.0	131.7	122.8	122.0	125.6	126.1	122.2	127.3	125.7
8	43.7	43.5	43.6	43.9	43.8	43.7	43.7	42.8	42.6	42.7	43.0	42.9	42.7	42.6
9	205.7	207.0	207.6	206.2	206.1	–	205.3	206.7	205.1	205.2	204.9	205	205.8	205.1
10	72.2	72.0	72.3	72.1	72.3	–	72.1	71.5	71.9	71.9	71.9	72.0	71.9	71.7
11	38.5	38.4	37.6	38.8	38.6	38.6	38.7	38.5	38.1	37.8	38.0	38.4	37.5	37.8
12	31.1	31.2	31.2	31.2	31.3	31.2	31.2	30.5	35.6	35.6	35.3	35.3	34.4	35.0
13	23.2	23.3	23.5	23.3	23.4	23.1	23.1	23.8	68.3	68.3	69.3	69.3	69.0	68.5
14	23.0	23.0	23.0	23.1	23.3	23.3	23.3	23.4	28.7	28.5	28.6	29.0	28.3	28.4
15	24.3	24.0	24.0	24.0	24.0	–	24.4	27.5	33.9	34.0	34.5	34.4	30.3	34.0
16	28.4	28.5	28.5	28.5	28.5	28.5	28.5	24.2	18.7	18.5	18.7	18.7	22.5	18.5
17	15.6	15.5	15.6	15.5	15.5	15.4	15.4	66.2	65.5	65.5	65.6	65.7	16.7	65.5
18	17.1	17.3	17.5	17.3	17.3	17.1	17.1	16.4	18.0	18.1	18.0	17.9	18.2	17.9
19	15.4	15.5	15.5	15.6	15.5	15.6	15.6	15.3	15.5	15.4	15.6	15.6	15.4	15.5
20	66.1	67.1	64.3	66.8	66.7	65.9	65.6	21.6	21.7	66.6	67.0	21.8	67.2	66.7
Carbon	Compound / δC (in ppm)
	71	72	73	74	75	76	77	78	79	80	81	82	83	84
1	128.6	128.6	128.4	128.8	131.4	131.5	132.0	131.5	132.0	132.0	132.0	131.5	132.1	131.6
2	139.7	139.8	139.7	139.6	136.8	136.8	136.0	136.8	136.0	136.0	136.0	133.7	135.7	136.2
3	80.4	80.2	80.1	80.4	83.0	83.0	83.3	83.0	83.6	81.8	85.7	81.5	82.5	82.2
4	84.3	84.3	84.3	84.3	84.9	85.1	84.6	84.9	85.1	85.8	80.5	85.7	84.7	84.9
5	73.8	75.2	74.0	73.8	77.3	76.3	76.9	77.2	77.2	74.9	43.7	74.6	77.1	76.6
6	137.7	141.2	137.5	137.8	139.8	140.2	139.0	139.8	138.0	133.0	132.0	135.9	139.0	139.7
7	126.8	125.2	125.5	126.7	126.4	126.0	128.0	126.4	122.0	132.0	129.0	130.8	128.6	127.2
8	43.2	43.3	43.3	43.3	42.9	43.0	42.7	42.9	42.8	43.6	44.2	43.1	43.5	43.2
9	204.9	205.4	205.3	204.8	205.0	205.1	206.0	204.9	205.0	206.0	208.0	204.6	206.6	205.9
10	72.9	72.7	72.8	72.7	72.2	72.0	72.0	72.0	72.1	72.0	75.0	71.9	72.0	72.0
11	38.8	38.8	38.8	38.9	38.0	38.2	37.6	38.1	38.5	38.6	37.0	38.5	38.3	38.4
12	35.9	35.4	35.6	35.4	35.9	35.3	35.2	35.4	35.4	31.1	31.5	30.6	31.1	30.9
13	68.1	68.4	68.3	68.3	69.4	69.3	69.0	68.6	68.6	23.1	23.7	23.1	23.3	24.3
14	28.7	28.7	28.6	28.7	28.6	28.6	28.3	28.6	28.8	22.9	23.2	23.9	23.0	23.5
15	33.8	33.9	33.9	33.9	34.0	34.4	30.3	34.1	34.1	24.3	23.6	27.5	24.0	27.7
16	18.8	18.7	18.6	18.7	18.9	18.6	22.5	18.7	18.7	28.4	28.6	24.1	28.5	24.6
17	65.4	65.7	65.5	65.5	65.5	65.6	16.7	65.5	65.6	15.4	15.5	65.6	15.5	66.2
18	18.5	18.2	18.2	18.2	18.4	18.1	18.4	18.1	18.1	17.0	18.2	16.5	17.3	16.9
19	15.2	15.4	15.3	15.3	15.6	15.6	15.6	15.6	15.6	15.5	15.6	15.3	15.5	15.6
20	65.7	66.6	66.4	65.7	67.1	66.9	67.4	67.1	21.8	65.9	68.5	65.6	67.5	67.2
Carbon	Compound / δC (in ppm)
	85	86	87	88	89	90	91	92	93	94	95	96	97	98
1	131.6	131.7	131.3	131.3	131.7	131.7	131.7	131.7	131.7	160.6	161.4	161.3	160.4	160.5
2	136.2	136.4	136.8	136.8	136.3	136.3	136.7	136.3	136.3	132.9	132.7	132.7	133.5	133.5
3	82.3	82.5	84.7	84.7	84.2	84.4	83.6	83.9	84.1	209.2	209.3	209.4	208.3	208.4
4	84.9	84.9	74.2	74.2	74.2	74.5	74.3	74.4	74.1	73.8	73.8	73.8	72.8	72.8
5	74.7	74.9	74.0	74.0	74.5	74.2	74.3	74.3	75.0	38.7	38.6	38.5	34.4	34.6
6	136.4	136.3	136.8	136.8	136.7	136.5	136.7	136.3	136.6	140.4	139.8	140.0	142.9	142.9
7	128.2	128.7	128.5	128.5	128.3	128.4	128.0	128.1	128.4	130.4	130.6	130.4	158.1	158.2
8	43.2	43.3	42.1	42.1	42.9	42.9	42.4	42.8	42.9	39.1	39.2	39.1	41.4	41.5
9	205.5	205.5	207.2	207.2	206.0	205.7	205.0	205.4	205.2	76.0	76.0	76.2	77.1	77.1
10	72.0	72.1	71.7	71.7	71.9	71.9	71.7	71.8	71.9	56.2	55.8	55.7	55.8	55.8
11	38.5	38.5	37.2	37.2	37.7	37.6	37.6	37.6	37.7	36.6	36.3	36.3	36.5	36.5
12	30.9	30.9	34.9	34.9	35.1	35.1	35.2	35.3	35.2	32.3	32.0	31.9	31.7	31.8
13	24.3	24.3	29.4	29.4	29.4	29.3	29.5	29.8	29.2	63.8	63.2	63.2	63.0	63.0
14	23.5	23.5	29.1	29.1	29.6	29.4	29.8	29.6	29.7	32.8	32.6	32.8	32.0	32.1
15	27.7	27.5	29.7	29.7	30.2	29.8	30.0	30.0	30.0	22.5	26.6	22.9	22.9	22.7
16	24.5	24.4	24.8	24.8	24.8	24.9	24.7	24.9	24.7	23.2	23.1	23.6	23.1	23.2
17	66.1	65.6	66.2	66.2	66.3	66.3	62.5	66.3	62.2	15.3	15.4	15.4	15.3	15.3
18	16.9	17.0	18.5	18.5	18.6	18.7	18.8	18.2	18.4	18.8	18.6	18.6	18.5	18.6
19	15.6	15.6	16.1	16.1	15.3	16.0	16.0	15.9	15.5	9.9	10.1	10.1	10.1	10.1
20	66.5	66.7	62.2	62.2	62.4	62.3	65.5	66.3	66.4	67.9	68.3	68.2	193.8	193.8
Carbon	Compound / δC (in ppm)
	99	100	101	102	103	104	105	106	107	108	109	110	111
1	156.9	159.7	161.0	160.8	161.3	160.3	160.3	160.3	160.3	160.3	160.3	160.3	160.3
2	143.0	137.3	138.3	135.7	132.9	136.3	136.3	136.2	136.2	136.3	136.3	136.2	136.3
3	213.8	208.9	203.0	208.6	208.9	210.2	210.3	210.3	210.3	210.3	210.3	210.3	210.3
4	50.1	42.6	44.4	73.6	73.7	44.5	44.5	44.5	44.5	44.6	44.5	44.6	44.6
5	25.1	35.1	34.0	38.8	38.9	34.0	34.0	34.1	34.0	34.0	34.0	34.1	34.1
6	136.3	136.5	136.2	132.9	135.2	139.6	139.6	139.7	139.7	139.6	139.6	139.6	139.7
7	127.7	130.2	126.8	132.7	133.7	125.0	125.7	125.7	125.7	125.7	125.6	125.6	125.6
8	41.0	42.3	41.9	39.4	39.5	42.2	42.2	42.2	42.2	42.2	42.2	42.2	42.2
9	75.5	77.8	75.2	78.2	75.9	77.9	77.9	77.9	77.9	77.9	77.9	77.9	77.9
10	47.1	54.1	53.9	56.2	55.8	54.3	54.3	54.3	54.4	54.3	54.3	54.3	54.3
11	37.1	44.1	46.2	43.2	36.3	42.3	42.3	42.3	42.3	42.3	42.3	42.4	42.4
12	30.5	76.1	31.8	76.1	31.9	56.7	56.7	54.8	56.8	56.7	56.7	56.7	52.7
13	62.7	65.4	62.8	65.7	63.6	65.0	65.0	65.0	65.1	65.0	65.0	65.0	65.0
14	33.1	35.4	32.0	36.1	32.4	35.9	35.8	35.9	36.0	35.9	35.9	36.0	36.0
15	22.5	25.7	22.5	25.7	22.6	25.8	25.8	25.8	25.8	25.8	25.8	25.8	25.8
16	23.7	23.8	15.2	23.8	23.2	23.9	23.9	23.9	24.0	23.9	24.0	23.9	23.9
17	15.2	16.7	22.9	16.7	15.3	17.0	17.0	16.9	16.9	17.0	16.9	16.9	16.8
18	15.9	15.1	19.0	14.4	18.6	15.1	15.1	15.1	15.2	15.1	15.2	15.2	15.0
19	10.4	10.2	10.0	10.1	10.1	10.2	10.2	10.3	10.3	10.2	10.3	10.3	10.3
20	69.5	68.9	25.2	69.4	69.4	62.2	66.4	67.4	68.2	66.9	66.7	66.5	65.9
Carbon	Compound / δC (in ppm)
	112	113	114	115	116	117	118	119	120	121	122	123
1	160.3	160.2	161.5	161.4	160.2	159.8	160.0	159.4	159.8	156.2	158.2	158.3
2	136.2	136.2	132.8	132.8	136.3	136.4	136.6	136.5	136.5	143.3	136.6	136.5
3	210.3	210.3	209.1	209.0	210.2	209.7	209.7	210.1	209.6	213.3	208.4	209.0
4	44.5	44.5	73.6	73.6	44.5	44.2	44.0	44.3	44.1	49.6	73.3	73.5
5	34.1	34.1	39.0	39.0	34.0	29.6	29.0	33.6	30.0	25.1	40.0	39.8
6	139.6	139.7	134.8	134.8	139.0	142.0	142.4	139.3	137.2	137.0	135.0	138.9
7	125.7	125.6	134.1	133.2	125.8	126.5	125.3	125.0	130.3	126.5	130.8	130.8
8	42.2	42.2	39.5	39.4	42.2	42.1	42.4	42.6	42.2	40.7	39.1	38.9
9	77.9	77.9	76.0	75.9	77.9	77.8	–	77.5	77.8	78.1	81.1	81.2
10	54.3	54.3	55.7	56.7	54.3	54.2	53.8	53.9	54.0	47.4	55.4	55.5
11	42.4	42.4	36.4	36.3	42.3	42.4	42.4	42.5	42.3	43.2	33.0	33.1
12	53.8	56.8	31.9	31.7	76.7	76.7	76.1	76.2	76.4	75.3	35.7	35.7
13	65.0	65.1	63.1	63.9	65.0	65.0	65.2	65.3	64.8	64.8	84.4	84.5
14	36.0	35.9	32.7	32.3	35.9	35.8	36.4	36.5	35.5	37.1	80.6	80.8
15	25.8	25.8	22.9	23.0	25.8	25.9	30.0	29.8	25.8	25.3	146.5	146.4
16	23.9	24.0	23.6	23.0	23.9	23.8	–	19.5	23.8	24.2	110.7	110.7
17	17.0	16.9	15.4	15.3	16.9	16.9	63.3	63.5	16.8	16.5	18.8	18.8
18	15.2	15.2	18.6	18.5	15.1	15.1	15.2	15.2	15.0	11.9	19.8	19.9
19	10.3	10.3	10.1	10.1	10.2	10.2	10.3	10.3	10.3	10.5	10.2	10.2
20	67.2	65.9	69.8	69.7	25.4	67.5	67.1	25.4	68.9	69.3	70.4	69.3

(–) Data not observed; *interchangeable.

Affected by the α,β-unsaturated γ-lactone, the carbon chemical shifts of Me-17 is very low at δC 6.7–10.0, as shown in 1–7, 12, 14–18, 21–23, 25 and 30–34. Thus, the assignment of the four methyl groups (C-17, C-18, C-19 and C-20) in compounds 19–20 and 26–29 [40,42] were doubtful. In their 13C-NMR spectra, chemical shifts around δC 8.0 should be assigned to C-17 instead of C-20, δC 27.0-34.0 should be assigned to C-18 instead of C-17, and δC 16.0–23.0 should be assigned to C-19 instead of C-18. Other positions, such as C-2, C-3, C-7, C-8, C-11 and C-14 are usually substituted by oxygen groups, whose carbon chemical shifts are around δC 65.0–78.0. Values close to δC115.0 can be assigned to tertiary carbon (C-14) on double bond in 15–29. Some carbons of the abietane diterpenoids (27, 28 and 30–36) may be carbonylated when their chemical shifts are above δC 185.0.

The carbon chemical shifts do not show very characteristic features for ingenane skeleton type. Their characteristic carbon chemical shifts are observed around δC 127.0–140.0 and 204.0–208.0, which are assigned to four carbons (C-1, C-2, C-6 and C-7) on two double bonds and the bridged carbonyl (C-9). The carbon chemical shift around δC 71.8–72.8 is assigned to the quaternary carbon (C-10) near the bridged carbonyl. The carbon chemical shifts around δC 74.0–86.0 (assigned to C-3, C-4 and C-5 with oxygen substituted) are registered in the 13C-NMR spectra of these compounds. Besides, there is another carbon (C-20) usually oxygen substituted, but it show little lower values (δC 62.3–67.2), while its value is around δC 21.6–21.8 without oxygen substitution, as the compounds 64, 65 and 68. The carbon chemical shifts of 65–79 show C-13 and C-17 are registered δC 65.5–69.1 after acylation.

The structures of tigliane diterpenes can be confirmed by carbon chemical shifts around δC 203.0–210.3, 156.2–160.6, 132.7–138.3, 132.9–142.9 and 125.0–158.2 assigned to C-3, C-1, C-2, C-6 and C-7, respectively (except 99 and 121). Values close to δC 73.0 and 77.0 are assigned to the carbons C-4 and C-9 substituted by hydroxyl groups. The carbon chemical shift of C-20 is at δC 193.8 when it is substituted by hydroxyl group (97 and 98), as well as the chemical shift of C-7 is obvious higher than other tigliane diterpenes because of conjugated effect. Compounds 99 and 121 are rare A/B cis-integrated compounds, and the structure of these isomers can be confirmed from the data of 13C-NMR, for the chemical shifts of C-2 and C-3 are 4–7 ppm higher than that of the A/B trans-integrated ones.

Table 1

Abietane diterpenoids isolated from Euphorbia species.

No	Name	Species	Ref
1	7β-Hydroxy-8α,14-dihydro jolkinolide E	E. terracina	[27]
2	Yuexiandajisu D	E. ebracteolata	[25]
3	Yuexiandajisu E	E. ebracteolata	[25]
4	ent-8β,14α-Dihydroxy-13(15)-ene-16(12β)-abietanolide	E. wallichii	[28]
5	ent-8β,14β-Dihydroxy-13(15)-ene-16(12β)-abietanolide	E. wallichii	[28]
6	Ebracteolatanolide B	E. ebracteolata	[25]
7	Ebracteolatanolide A	E. ebracteolata	[25]
8	Jolkinolide B	E. fischeriana,	[29]
		E. sessiliflora	[30]
9	17-Hydroxyjolkinolide B	E. fischeriana	[31]
10	17-Acetoxyjolkinolide B	E. fischeriana	[31]
11	17-Acetoxyjolkinolide A	E. fischeriana	[32]
12	Jolkinolide A	E. wallichii	[28]
		E. fischeriana	[29]
		E. fidjiana	[33]
		E. guyoniana	[34]
13	17-Hydroxyjolkinolide A	E. fischeriana	[32]
		E. fidjiana	[33]
14	3α-Hydroxyjolkinolide A	E. wallichii	[28]
15	7β-Hydroxy-ent-abieta-8(14),13(15)-dien-12α,16-olide	E. seguieriana	[35]
16	7β,9β-Dihydroxy-ent-abieta-8(14),13(15)-dien-12α,16-olide	E. seguieriana	[35]
17	ent-Abieta-8(14),13(15)-dien-16,12-olide [Jolkinolide E]	E. fidjiana	[33]
		E. characias	[34]
		E. guyoniana	[36]
18	Helioscopinolide A	E. pubescens	[37]
		E. semiperfoliata	[38]
		E. helioscopia	[39]
19	Helioscopinolide B	E. pubescens	[37]
		E. semiperfoliata	[38]
		E. helioscopia	[39]
		E. calyptrata	[40]
20	Helioscopinolides H	E. calyptrata	[40]
21	ent-11α-Hydroxyabieta-8(14),13(15)-dien-16,12α-olide	E. ebracteolata	[25]
		E. sessiliflora	[30]
		E. fidjiana	[33]
22	ent-12-Hydroxy-12[R]-abieta-8(14 ),13(15)-dien-16,12-olide	E. sessiliflora	[30]
23	7β,11β,12β-Trihydroxy-ent-abieta-8(14),13(15)-dien-16,12-olide	E. fischeriana	[31]
24	Langduin B	E. fischeriana	[32]
25	Helioscopinolide C	E. helioscopia	[39,41]
26	Helioscopinolides F	E. calyptrata	[40]
27	Helioscopinolide D	E. calyptrate	[42]
28	Helioscopinolide E	E. calyptrate	[42]
29	Helioscopinolides I	E. calyptrata	[40]
30	8α,14-Dihydro-7-oxo-jolkinolide E	E. characias	[36]
31	8α,14-Dihydro-7-oxohelioscopinolide A [caudicifolin]	E. sessiliflora	[30]
		E. characias	[36]
		E. semiperfoliata	[38]
32	3,4,18β-Cyclopropa-8β-hydroxy-14-oxo-ent-abiet-13,15-en-16,12-olide	E. retusa	[43]
33	3,4,18β-Cyclopropa-14-oxo-ent-abieta-8,9,13,15-dien-16,12-olide	E. retusa	[43]
34	3,4,18β-Cyclopropa-14-oxo-ent-abieta-7,13,15-dien-16,12-olide	E. retusa	[43]
35	3,4,18β-Cyclopropa-7-hydroxy-14-oxo-ent-abieta-8,9,13,15-dien-16,12-olide	E. retusa	[43]
36	3,4,18β-Cyclopropa-14-oxo-ent-abiet-7-en-16,12-olide	E. retusa	[43]
37	ent-16-Hydroxy-13[R]-pimar-8(14) -ene-3,15-dione	E. fidjiana	[33]
38	ent-l2α,16-Dihydroxy-13[R]-pimar-8(14) -ene-3,15-dione	E. fidjiana	[33]
39	13β-Hydroxy-ent-abiet-8(14)-en-7-one	E. fischeriana	[31]
40	Methyl 8β,11β-dihydroxy-12-oxo-ent-abieta-13, 15(17)-dien-16-oate	E. portulacoides	[44]
41	11,16-Epoxy-ent-abieta-8,11,15-triene-13,14-dione	E. guyoniana	[34]
42	11-Hydroxy-ent-abieta-8,11,13-trien-15-one	E. guyoniana	[34]

Table 2

Ingenane diterpenoids isolated from Euphorbia species.

No	Name	Species	Ref
43	Ingenol	E.kansui	[45]
		E. paralias	[48]
44	13-O-Dodecanoylingenol	E. kansui	[45]
45	17-[(2Z,4E,6Z)-Deca-2,4,6-trienoyloxy] [ingenol]	E. cauducifolia.	[21]
46	20-Eicosanoate	E. iberica	[52]
47	3,5,20-O-Triacetylingenol	E. kansui	[45]
48	17-Hydroxyingenol tetraacetate	E. kamerunica	[53]
49	5,20-O-Diacetyl-3-O-(2″,3″-dimethylbutanoyl)-13-O-dodecanoylingenol	E. kansui	[45]
50	20-Tetradecanoate-ingenol-3,5-diacetate	E. broteri	[54]
51	17-O-Acetyl-3-O-[(Z)-2-methyl-2-butenoyl]-20-deoxy-17-hydroxy-ingenol	E. trigona	[55]
52	20-O-Acetyl-3-O-[(Z)-2-methyl-2-butenoyl]ingenol	E. trigona	[55]
53	5,17,20-O-Triacetyl-3-O-[(Z)-2-methyl-2-butenoyl]-17-hydroxyingenol	E. trigona	[55]
54	3-O-(2,3-Dimethylbutanoyl)-13-O-dodecanoylingenol	E. kansui	[45]
		E. cyparissias	[46]
55	3-O-(2,3-Dimethylbutanoyl)-13-O-decanoylingenol	E. kansui	[45]
		E. cyparissias	[46]
56	3,20-O-Diacetylingenol 5-O-(2'E,4'Z)-tetradecadienoate	E. petiolata	[56]
57	5,20-O-Diacetylingenol 3-O-(2'E,4'Z)-tetradecadienoa	E. petiolata	[56]
58	Ingenol-3-O-(2'E,4'Z)-tetradecadieno	E. petiolata	[56]
59	5,20-O-Isopropy1ideny1ingero1 3-O-(2'Z,4'Z)-tetradecadienoate	E. petiolata	[56]
60	20-O-Acetylingenol-3-O-(2"E,4"Z)-decadienoate	E. petiolata	[57]
61	20-Acetyl-ingenol-3-decadienoate	E. broteri	[54]
62	3-Tetradecanoate-ingenol-5,20-diacetate	E. broteri	[54]
63	5-Tetradecanoate-ingenol-3,20-diacetate	E. broteri	[54]
64	17-Benzoyloxy-3-O-(2,3-dimethylbutanoyl)-20-deoxyingenol	E. esula	[58]
65	17-Benzoyloxy-3-O-(2,3-dimethylbutanoyl)-13-(2,3-dimethylbutanoyloxy)-20-deoxyingenol	E. esula	[58]
66	17-Benzoyloxy-3-O-(2,3-dimethylbutanoyl)-13-(2,3-dimethylbutanoyloxy) ingenol	E. esula	[58]
67	13,17-Dibenzoyloxy-3-O-(2,3-dimethylbutanoyl)ingenol	E. esula	[58]
68	13,17-Dibenzoyloxy-3-O-(2,3-dimethylbutanoyl)-20-deoxyingenol	E. esula	[58]
69	3-O-(2,3-dimethylbutanoyl)-13-octanoyloxyingenol	E. esula	[58]
70	17-Benzoyloxy-3-O-(2,3-dimethylbutanoyl)-13-octanoyloxyingenol	E. esula	[58]
71	17-Benzoyloxy-20-O-(2,3-dimethylbutanoyl)-13-(2,3-dimethylbutanoyloxy)ingenol	E. esula	[58]
72	17-Benzoyloxy-13-octanoyloxyingenol	E. esula	[58]
73	20-O-Benzoyl-17-benzoyloxy-13-octanoyloxyingenol	E. esula	[58]
74	17-Benzoyloxy-20-O-(2,3-dimethylbutanoyl)-13-octanoyloxyingenol	E. esula	[58]
75	3-O-Benzoyl-17-benzoyloxy-13-(2,3-dimethylbutanoyloxy)ingenol	E. esula	[58]
76	3-O-Benzoyl-13,17-dibenzoyloxyingenol	E. esula	[58]
77	3-O-Benzoyl-13-octanoyloxyingenol	E. esula	[58]
78	3-O-Benzoyl-17-benzoyloxy-13-octanoyloxyingenol	E. esula	[58]
79	3-O-Benzoyl-17-benzoyloxy-13-octanoyloxy-20-deoxyingenol	E. esula	[58]
80	Ingenol-3-angelate-5,20-diacetate	E. canariensis	[59]
		E. acrurensis	[60]
81	5-Deoxyingenol-3-angelate-20-acetate	E. canariensis	[59]
82	17-Acetoxyingenol-5,20-diacetate-3-angelate	E. kamerunica	[53]
83	Ingenol-3-angelate	E. canariensis	[59]
84	17-Hydroxyingenol-3-angelate-17-benzoate	E. canariensis	[59]
85	17-Hydroxyingenol-3-angelate-20-acetate-17-benzoate	E. canariensis	[59]
86	17-Acetoxyingenol-20-acetate-3-angelate	E. canariensis	[59]
87	17-Hydroxyingenol 17-benzoate 20-angelate	E. canariensis	[59]
88	3-O-Angeloyl-17-[(2Z,4E,6Z)-deca-2,4,6-trienoyloxy]ingenol	E. cauducifolia	[21]
89	17-Acetyloxy-3-O-angeloyl-ingenol	E. cauducifolia	[21]
90	3-O-Angeloyl-17-(benzoyloxy)ingenol	E. cauducifolia	[21]
91	20-O-Acetyl-3-O-angeloyl-17-hydroxyingenol	E. cauducifolia	[21]
92	20-O-Acetyl-3-O-angeloyl-17-(benzoyloxy)ingenol	E. cauducifolia	[21]
93	3-O-Acetyl-20-O-angeloyl-17-hydroxyingenol	E. cauducifolia	[21]

Table 3

Tigliane diterpenoids isolated from Euphorbia species.

No.	Name	Species	Ref
94	13-Acetoxy-12-deoxyphorbol [Prostratin]	E. fischeriana	[66]
95	20-Hydroxy-12-deoxyphorbol 13-(cis-9,10-methylene)-undecanoate	E. poisonii	[14]
96	20-Hydroxy-12-deoxyphorbol angelate	E. poisonii	[14]
97	12-Deoxyphorbaldehyde-l3-acetate	E. fischeriana	[31]
98	12-Deoxyphorbaldehyde-13-hexadecacetate	E. fischeriana	[31]
99	4,12-Dideoxy(4α)phorbol-13-hexadecanoate	E. guyoniana	[67]
100	12-O-(2Z,4E-Octadienoyl)-4-deoxyphorbol-13,20-diacetate	E. broteri	[54]
101	4,12,20-Trideoxyphorbol-13-(2,3-dimethyl)butyrate	E. pithyusa subsp	[68]
102	12-O-(2Z,4E-octadienoyl)-phorbol-13,20-diacetate	E. broteri	[54]
103	12-Deoxyphorbol-13-(9Z)-octadecanoate-20-acetate	E. fischeriana	[31]
104	13-O-Acetyl-20-O-benzoyl-12-deoxyphorbol	E. cornigera	[69]
105	13-O-Acetyl-20-O-p-methoxybenzoyl-12-deoxyphorbol	E. cornigera	[69]
106	13-O-Acetyl-20-O-decanoyl-12-deoxyphorbol	E. cornigera	[69]
107	13-O-Butanoyl-20-O-decanoyl-12-deoxyphorbol	E. cornigera	[69]
108	13-O-Hexanoyl-20-O-decanoyl-12-deoxyphorbol	E. cornigera	[69]
109	13-O-Octanoyl-20-O-decanoyl-12-deoxyphorbol	E. cornigera	[69]
110	13,20-Didecanoylphorbol	E. cornigera	[69]
111	13-O-Dodecanoyl-20-O-decanoyl-12-deoxyphorbol	E. cornigera	[69]
112	13-O-Decanoyl-20-O-angelyl-12-deoxyphorbol	E. cornigera	[69]
113	13-O-Decanoyl-20-O-tiglyl-12-deoxyphorbol	E. cornigera	[69]
114	12-Deoxyphorbol 20-acetate 13-angelate	E. poisonii	[14]
115	12-Deoxyphorbol 20-acetate 13-phenylacetate	E. poisonii	[14]
116	4,20-Dideoxyphorbol 12,13-bis(isobutyrate)	E. obtusifolia	[70]
117	4-Deoxyphorbol 12,13-bis(isobutyrate)	E. obtusifolia	[70]
118	17-Acetoxy-4-deoxyphorbol 12,13-bis(isobutyrate)	E. obtusifolia	[70]
119	17-Acetoxy-4,20-dideoxyphorbol 12,13-bis(isobutyrate)	E. obtusifolia	[70]
120	4-Deoxyphorbol 12,13-bis(isobutyrate) 20-acetate	E. obtusifolia	[70]
121	4-Epi-4-Deoxyphorbol 12,13-bis(isobutyrate)	E. obtusifolia	[70]
122	20-(4-Hydroxy-3-methoxyphenylacetate)9,13,14-orthophenylacetate	E. poisonii	[14]
123	20-Hydroxyresiniferol 9,13,14-orthophenylacetate	E. poisonii	[14]