Two New Lupane-Type Triterpenes From the Stems and Leaves of Buxus latistyla Gagnep. and Their Cytotoxic Activity

Abstract

Objectives: This study aims to evaluate the cytotoxicity of compounds isolated from Buxus latistyla Gagnep. against selected cell lines. Methods: The isolation process was carried out using combined chromatographic techniques. The structural elucidation of compounds was achieved by combining 1D-/2D-NMR and HRESIMS data. The absolute configurations of new compounds were also confirmed using ECD experiments. The sulforhodamine B colorimetric assay was employed to assess the toxicity of isolates against tested cell lines. Results: Two new lupane-type derivatives, 3α-carbomethoxy-3β-hydroxy-1,3-cyclo-1,2-seco-lup-20(29)-en-1-one (1) (buxlatistylate A) and 1α-carbomethoxy-1β-hydroxy-1,3-cyclo-2,3-seco-lup-20(29)-en-3-one (2) (buxlatistylate B), along with five known triterpenes, including lupeol (3), lupenone (4), betulin (5), 20(29)-lupene-2α,3α-diol (6), and 20(29)-lupene-2α,3α,28-triol (7), were isolated. Compounds 1, 2, 6, and 7 exhibited weak cytotoxic activity against human cancer cells MCF-7, SK-LU-1, and SW480, with IC₅₀ values ranging from 36.33 to 84.16 μM, whereas compounds 3-5 did not show toxicity toward tested cell lines. Conclusion: Compounds 1 and 2 are the first examples of lupane-type triterpenes containing the substituted cyclopentanone A-ring in their molecules. The biosynthetic pathways of these new compounds were also discussed and proposed herein. These findings indicate that B. latistyla holds potential for further in-depth studies on compounds with interesting structures that inhibit human cancer cells.

Keywords

lupane-type cytotoxic activity ECD buxlatistylate A-B

Introduction

Among known plants, the genus Buxus has attracted significant attention from scientists. Over 200 compounds have been isolated from this genus since the 1990s, including alkaloids, triterpenoids, steroids, flavonoids, coumarins, lignans, and other types.^1,2 While Buxus species are widely recognized for their ornamental significance, a number of scientific reports have emphasized their ethnomedicinal properties. Additionally, the biological activities of compounds isolated from this genus have been proven to be highly diverse, such as acetyl- and butyrylcholinesterase inhibitory, antimicrobial, antifungal, antiemetic, antispasmodic, cytotoxic activities, and so on.³

Vietnam is a tropical monsoon country that is home to more than 5,000 known medicinal plants. Among those, Buxus latistyla Gagnep., also known as “Cà mà vòi to” in Vietnamese, is found in central Vietnam and has been traditionally utilized by local communities to treat various illnesses such as malaria, hemoptysis, amebiasis, and edema.⁴ However, its chemical constituents and biological activities remain incomplete. Therefore, in the pursuit of discovering new compounds with biological potential, particularly in cancer treatment, we report herein the isolation and structural elucidation of new compounds as well as their cytotoxicity toward three cancer cell lines, including MCF-7, SK-LU-1, and SW480, along with a normal cell line, HEK-293A, utilizing the sulforhodamine B assay.

Results and Discussion

The chromatographic separation resulted in the isolation of seven compounds (1–7) (Figure 1). Compound 1 was obtained as a white amorphous powder. Its molecular formula was determined to be C₃₁H₄₈O₄ by HRESIMS (protonated molecular ion peak at m/z 485.3623 [M+H]+) in conjunction with an NMR data analysis, requiring eight degrees of unsaturation.

Figure 1.

Chemical structures of compounds 1−7 isolated from the stems and leaves of Buxus latistyla.

The ¹H NMR spectrum of 1 (Table 1) exhibited typical signals corresponding to seven angular methyl groups [δ_H 0.80 (s, H₃-28), 0.98 (s, H₃-27), 1.00 (s, H₃-23), 1.03 (s, H₃-24), 1.07 (s, H₃-25 and H₃-26), 1.67 (s, H₃-30)], one hydroxyl group [δ_H 3.64 (1H, s)], one methoxy group [δ_H 3.79 (3H, s)], and two olefinic protons belonging to the exo-methylene group [δ_H 4.56 (1H, qd, J = 2.1, 1.3 Hz, H-29a) and 4.68 (1H, d, J = 2.1 Hz, H-29b)]. The presence of isopropenyl in 1 was verified by the signals at δ_H 1.67 (H₃-30), 4.56 (H-29a), and 4.68 (H-29b).

Table 1.

¹H (500 MHz) and ¹³C (125 MHz) NMR data of compounds 1 and 2 in CDCl₃ [δ (ppm), J (Hz)].

Position	1		2
Position	δ _C	δ _H	δ _C	δ _H
1	215.2	−	89.9	−
2	173.5	−	171.1	−
3	87.0	−	220.5	−
4	42.7	−	44.3	−
5	54.0	1.80 dd (11.0, 3.4)	50.7	2.15 dd (8.9, 6.2)
6	16.9	1.58 m	17.5	1.55 m
7	34.3	1.47^a	33.5	1.46^a
8	42.8	−	41.9	−
9	44.2	1.97 dd (12.8, 3.3)	44.0	1.75 dd (12.6, 3.4)
10	48.5	−	49.5	−
11	22.0	1.47^a (H_β) 2.16 m (H_α)	23.1	1.46^a (H_β) 1.52 m (H_α)
12	24.6	1.16 m (H_α) 1.69^a (H_β)	24.7	1.02 m 1.67^a (H_β)
13	38.1	1.69^a	38.1	1.67^a
14	42.9	−	43.0	−
15	27.8	1.02 m (H_α) 1.72 m (H_β)	27.5	0.99 m (H_α) 1.71 m (H_β)
16	35.6	1.39^a (H_α) 1.52 m (H_β)	35.6	1.40^a (H_α) 1.49 m (H_β)
17	43.1	−	43.3	−
18	48.3	1.35 m	48.3	1.33^a
19	47.9	2.38 td (11.1, 5.9)	48.0	2.36 td (11.1, 5.8)
20	150.6	−	150.5	−
21	29.8	1.33 m (H_α) 1.91 m (H_β)	29.8	1.33^a (H_α) 1.91 m (H_β)
22	40.0	1.20 m (H_α) 1.39^a (H_β)	40.0	1.21 m (H_α) 1.40^a (H_β)
23	25.5	1.00 s	26.8	1.19 s
24	19.7	1.03 s	22.3	1.04 s
25	14.5	1.07 s	13.9	0.90 s
26	16.7	1.07 s	16.7	1.08 s
27	14.6	0.98 s	14.4	0.95 s
28	18.0	0.80 s	18.0	0.79 s
29	109.6	4.56 qd (2.1, 1.3) 4.68 d (2.1)	109.6	4.56 qd (2.3, 1.4) 4.67 d (2.3)
30	19.3	1.67 s	19.3	1.67 s
OCH₃	52.9	3.79 s	52.7	3.81 s
OH	−	3.64 s	−	3.36 s

Assignments were accomplished by HSQC, HMBC, COSY, and NOESY experiments.

^aOverlapping signals.

Analysis of the ¹³C NMR and HSQC spectra of 1 indicated thirty-one signals for eight methyl, nine methylene, five methine, and nine nonprotonated carbons. Remarkably, the ¹³C NMR spectrum contained characteristic signals corresponding to two carbonyl carbons [δ_C 215.2 (C-1), 173.5 (C-2)], two olefinic carbons [δ_C 109.6 (C-29) and 150.6 (C-20)], one oxygenated quaternary carbon [δ_C 87.0 (C-3)], and one methoxy carbon (δ_C 52.9). The 1D-NMR spectroscopic data were indicative of a lupane-type triterpenoid derivative.⁵

Indeed, three ¹H-¹H COSY spin systems [C(5)H-C(6)H₂-C(7)H₂; C(9)H-C(11)H₂-C(12)H₂-C(13)H-C(18)H-C(19)H-C(21)H₂-C(22)H₂; C(15)H₂-C(16)H₂] and important HMBC correlations, including H₃-23 (δ_H 1.00)/H₃-24 (δ_H 1.03) with C-4 (δ_C 42.7)/C-5 (δ_C 54.0), H₃-25 (δ_H 1.07) with C-5/C-9 (δ_C 44.2)/C-10 (δ_C 48.5), H₃-26 (δ_H 1.07) with C-7 (δ_C 34.3)/C-8 (δ_C 42.8)/C-9/C-14 (δ_C 42.9), H₃-27 (δ_H 0.98) with C-8/C-13 (δ_C 38.1)/C-14/C-15 (δ_C 27.8), H₃-28 (δ_H 0.80) with C-16 (δ_C 35.6)/C-17 (δ_C 43.1)/C-18 (δ_C 48.3)/C-22 (δ_C 40.0), and H₂-29 (δ_H 4.56 and 4.68) with C-19 (δ_C 47.9)/C-30 (δ_C 19.3) confirmed the 1-norlupane-type skeleton in 1 (Figure 2). Importantly, the key HMBC correlation between H₃-25 (δ_H 1.07) and C-1 (δ_C 215.2) indicated the existence of a carbonyl group at position 1 of the A-ring. The attachment of hydroxy and carbomethoxy groups at C-3 was clarified by the correlations between H₃-23 (δ_H 1.00)/H₃-24 (δ_H 1.03) and C-3 (δ_C 87.0), and from hydroxyl proton (δ_H 3.64) to C-2 (δ_C 173.5)/C-3 (δ_C 87.0)/C-4 (δ_C 42.7) in the HMBC spectrum.

Figure 2.

Key HMBC (¹H→¹³C, arrows) and COSY (bold lines) correlations of compounds 1 and 2.

The stereochemistry of 1 was established by the NOESY experiment. Particularly, the crucial NOESY correlations from H₃-24 (δ_H 1.03, s) to 3-OH (δ_H 3.64)/H₃-25 (δ_H 1.07, s) indicated that OH, Me-24, and Me-25 were oriented on the same β-face of 1 (Figure 3). By contrast, NOESY correlations from H₃-23 (δ_H 1.00) to H-5 (δ_H 1.80)/3-COOMe (δ_H 3.79) suggested the α-orientation for H-5, Me-23, and 3-COOMe groups. Consequently, the structure of 1 was elucidated as 3α-carbomethoxy-3β-hydroxy-1,3-cyclo-1,2-seco-lup-20(29)-en-1-one, named buxlatistylate A.

Figure 3.

Key NOESY correlations (dashed arrows) of compounds 1 and 2.

Compound 2 was isolated as a white, amorphous powder. The HRESIMS and NMR data (Table 1) indicated that this isolate has the same molecular formula and substituent groups present as those of compound 1. The hydroxy and carbomethoxy groups were located at C-1 based on the HMBC correlations from H₃-25 (δ_H 0.90) to C-1 (δ_C 89.9), from hydroxyl proton (δ_H 3.36) to C-1/C-2 (δ_C 171.1)/C-10 (δ_C 49.5). In the same manner, the HMBC correlations from 1-OH (δ_H 3.36)/H₃-23 (δ_H 1.19)/H₃-24 (δ_H 1.04) to C-3 (δ_C 220.5) demonstrated that the keto group was at C-3 (Figure 2).

The cross-peak between 1-OH (δ_H 3.36) and H₃-25 (δ_H 0.90) was detected in the NOESY spectrum (Figure 3). Therefore, the β-orientation was assigned for both 1-OH and Me-25. Meanwhile, the key NOESY correlation of 1-COOMe (δ_H 3.81) to H₃-27 (δ_H 0.95) allowed the unambiguous assignment of α-orientation for carbomethoxy and Me-27 groups. The stereo-structure of the A-ring was supported by the good agreement of chemical shift values of C-1 (δ_C 89.9), C-2 (δ_C 171.1), C-3 (δ_C 220.5), C-4 (δ_C 44.3), C-5 (δ_C 50.7), C-6 (δ_C 17.5), C-10 (δ_C 49.5), C-23 (δ_C 26.8), C-24 (δ_C 22.3), C-25 (δ_C 13.9) (in 2) with those of viburnol G methyl ester [δ_C: 89.2 (C-1), 172.4 (C-2), 217.5 (C-3), 44.5 (C-4), 51.6 (C-5), 17.5 (C-6), 49.0 (C-10), 27.6 (C-23), 22.3 (C-24), 14.5 (C-25)].⁶ Hence, the structure of compound 2 was proposed as 1α-carbomethoxy-1β-hydroxy-1,3-cyclo-2,3-seco-lup-20(29)-en-3-one, named buxlatistylate B. It is worth noting that the appearance of the substituted cyclopentanone A-ring in 1−2 is extremely rare among lupane-type triterpenes discovered so far. Additionally, the absolute configurations of compounds 1 and 2 were confirmed based on the comparison between the experimental ECD spectra of these two compounds (in methanol) and the TDDFT calculated ECD spectra of their corresponding enantiomers (Figures 4 and 5). The 3R,5S,8R,9S,10R,13R,14R,17R,18R,19R configuration was then assigned for compound 1, while the 1S,5R,8R,9S,10R,13R,14R,17R,18R,19R configuration was assigned for compound 2.

Figure 4.

Experimental and calculated ECD spectra of compound 1.

Figure 5.

Experimental and calculated ECD spectra of compound 2.

Finally, based on NMR spectroscopic data and the comparison with published literature, the remaining compounds were identified as lupeol (3),⁷ lupenone (4),⁸ betulin (5),⁹ 20(29)-lupene-2α,3α-diol (6),¹⁰ and 20(29)-lupene-2α,3α,28-triol (7).¹¹

The isolated compounds were evaluated for their cytotoxicity toward human cells, including MCF-7 (breast carcinoma), SK-LU-1 (lung carcinoma), SW480 (colon carcinoma) cancer cells, and a normal cell line (HEK-293A, human embryonic kidney cells) (Table 2). Among all tested cell lines, compound 1 displayed the most potent inhibition against SW480 cells (IC₅₀= 36.33 ± 1.28 µM) and selectivity relative to other cell lines, notably lower toxicity toward HEK-293A cells (IC₅₀= 45.25 ± 2.54 µM, P < .05). Similarly, compound 7 exhibited selective activity against MCF-7 cells and lower toxicity toward HEK-293A cells (IC₅₀ values of 38.17 ± 3.75 and 47.11 ± 3.56 µM, respectively) (P < .05). Remarkably, the two-way ANOVA test indicated that there was no significant difference between the IC₅₀ value of compound 1 on the SW480 cell line and that of compound 7 on MCF-7 cells (P > .05), as well as no significant difference between the IC₅₀ values of compounds 1 and 7 on HEK-293A cells.

Table 2.

Cytotoxic Effect of Compounds 1-7 Against Tested Cell Lines.

Compound	IC₅₀ (µM)
Compound	HEK-293A	MCF-7	SK-LU-1	SW480
1	45.25 ± 2.54	52.20 ± 1.59	48.22 ± 2.67	36.33 ± 1.28
2	88.21 ± 5.01	84.16 ± 4.12	78.78 ± 3.19	81.18 ± 3.04
3	>100	>100	>100	>100
4	>100	>100	>100	>100
5	>100	>100	>100	>100
6	55.95 ± 2.11	83.41 ± 5.73	68.40 ± 5.47	55.73 ± 5.52
7	47.11 ± 3.56	38.17 ± 3.75	59.44 ± 3.24	57.50 ± 2.01
Ellipticine^a	1.34 ± 0.08	1.71 ± 0.08	1.83 ± 0.08	1.66 ± 0.12

Abbreviation: IC₅₀, half-minimal inhibitory concentration.

Ellipticine was used as a positive control.

Furthermore, compounds 2 and 6 showed weak toxicity against all cell lines, with IC₅₀ values ranging from 55.73 ± 5.52 to 88.21 ± 5.01 µM. Meanwhile, three compounds—lupeol (3), lupenone (4), and betulin (5)—did not demonstrate a significant effect on any of the cell lines.

The proposed biosynthetic pathways of compounds 1 and 2 are depicted in Figure 6. These newly rearranged triterpenoids were suggested to be derived from lupeol (3), the principal triterpene found in B. latistyla. Lupeol (3) underwent dehydration, including a 1,2-hydride shift, leading to the formation of alkenes (3a, 3a’). Subsequent ring-opening oxidation of these alkenes resulted in the intermediates 3b and 3b’. The cyclization of 3b and 3b’ via nucleophilic attack led to the formation of 3c and 3c’. These intermediates underwent sequential oxidation and methylation, ultimately yielding compounds 1 and 2. However, within the scope of this report, definitive proof of the correctness of this biosynthetic pathway cannot be achieved, and further investigations should be conducted to address this in future studies.

Figure 6.

Plausible biosynthetic pathways of compounds 1 and 2.

Conclusion

Phytochemical investigation of the stems and leaves of B. latistyla Gagnep. led to the isolation of two new lupane-type derivatives (1-2) and five known triterpenes (3–7). The new compounds were elucidated as 3α-carbomethoxy-3β-hydroxy-1,3-cyclo-1,2-seco-lup-20(29)-en-1-one (1) and 1α-carbomethoxy-1β-hydroxy-1,3-cyclo-2,3-seco-lup-20(29)-en-3-one (2) on the basis of 1D-/2D-NMR and HRESIMS data. Their absolute configurations were finally confirmed by using ECD experiments. Compounds 1 and 2 are the first examples of lupane-type triterpenes containing the substituted cyclopentanone A-ring in their molecules. They might be derived from lupeol (3) via the biosynthetic pathways discussed above.

The results of the cytotoxic assay might suggest the relatively selective effect of compound 1 against SW480 cancer cells and that of compound 7 against the MCF-7 cell line (IC₅₀ values of 36.33 ± 1.28 and 38.17 ± 3.75 µM, respectively) in comparison with other cell lines, especially normal cells HEK-239A (IC₅₀ values of 45.25 ± 2.54 and 47.11 ± 3.56 µM, respectively). Compounds 2 and 6 displayed weak toxicity against all cell lines (IC₅₀ values ranging from 55.73 ± 5.52 to 88.21 ± 5.01 µM), while compounds 3-5 showed inactivity. These findings suggest that B. latistyla exhibits promise for additional comprehensive investigations into compounds with intriguing structures capable of being applied in cancer treatment therapy.

Materials and Methods

General Experimental Procedures

Column chromatography was carried out using silica gel (60 N, spherical, neutral, 40–50 µm, Kanto Chemical Co., Inc.), Cosmosil 75C18-OPN (Nacalai Tesque Inc.), YMC RP-18 (Fuji Silysia Chemical Ltd.), Sephadex LH-20 (Dowex^® 50WX2-100, Sigma-Aldrich), and Diaion HP-20 (Mitsubishi Chem. Co., Tokyo, Japan). Precoated silica gel 60F₂₅₄ and RP-18 F₂₅₄ plates (0.25 or 0.50 mm thickness, Merck KGaA) were used for analytical TLC. NMR spectra were recorded employing a Bruker Avance 500 spectrometer (Bruker), with TMS as an internal reference. HRESIMS data were measured on Agilent 6500 series Q-TOF B.06.01 (B6172 SP1) Accurate-Mass Sytems (Agilent). UV spectra were measured with a Shimadzu UV-1800 spectrophotometer (Shimadzu). CD spectra were determined using a Chirascan^TM CD spectrometer (Applied Photophysics Ltd.). IR spectra were recorded with KBr pellets on an IR Prestige-21 spectrometer (Shimadzu).

Plant Materials

The stems and leaves of B. latistyla were collected from Quang Tri province, Vietnam (N16°38ʹ18.8ʺ E106°48ʹ09.8ʺ) in August 2020. The scientific name of the plant was determined by one of the authors (Dr. Anh Tuan Le). A voucher specimen (coded DHYD-QT-01) has been preserved at the Faculty of Pharmacy, Hue University of Medicine and Pharmacy, Hue University, Vietnam.

Extraction and Isolation

Stems and leaves of B. latistyla were washed, cut into small pieces, and dried at 50 °C. They are ground into a powder (3 kg) and subsequently soaked in methanol (MeOH) at room temperature (8 L × 2 times). The combined extract was evaporated under reduced pressure to obtain a MeOH extract (540 g). This crude extract was suspended in water, successively partitioned with n-hexane (Hex), dichloromethane (Di), and ethyl acetate (EtAc) (1 L × 7 times for each solvent), yielding BLH (80 g), BLD (90 g), BLE (20 g), and the remaining water-soluble portion BLW (350 g), respectively. The BLH extract (80 g) was subjected to a normal-phase (NP) silica gel column, eluted with a gradient solvent system of n-hexane/acetone (Hex/Ac) (100/0, 60/1 to 0/100, v/v, 1 L each), and finally with MeOH to afford nine fractions (BLH1–9). Fraction BLH1 (23.2 g) was applied to an NP column using a step-gradient elution of Hex/Ac (100/0, 40/1, 30/1, v/v) to obtain nine fractions (BLH1.1–9). Fraction BLH1.5 (305 mg) was further purified through a reversed-phase (RP-18) column eluted using Ac/MeOH/water (1/1/0.1, v/v) to yield compound 1 (13.0 mg). Fraction BLH2 (7.9 g) was chromatographed on an NP column using Hex/Ac (30/1, v/v) as an eluent, resulting in eleven subfractions (H2A-K). H2E (282 mg) was subjected to gel filtration chromatography (MeOH 100%) to yield five subfractions (H2E1–5). Subfraction H2E2 (31 mg) was loaded onto an RP-18 column using Ac/MeOH/water (1/1/0.1, v/v) as a mobile phase to give four subfractions (H2E2.1–4). H2E2.1 (8 mg) was finally purified using silica gel chromatography (Hex/EtAc, 20/1, v/v) to yield compound 2 (4.0 mg). During the purification of BLH2, white needle-shaped crystals were obtained. These were washed and recrystallized to yield compound 3 (300.0 mg). Fraction BLH4 (11 g) underwent solid-phase extraction using NP silica gel, eluted with a gradient solvent system of Hex/Ac (100/0 to 0/100, v/v, 500 mL each), resulting in subfractions BLH4A-H. Subsequently, an NP column was used to purify BLH4C (2.78 g), eluting with Hex/Ac (25/1, v/v), yielding eight subfractions (BLH4C1–8). BLH4C1 (0.55 g) was loaded onto another NP column with a Hex/Ac solvent system (40:1, v/v), affording nine subfractions (BLH4C1A-I). Eight subfractions (BLH4C1C1-8) were then yielded from BLH4C1C (186.5 mg) using an NP column eluted with Hex/EtAc/Ac (40/0.5/0.1, v/v/v). Finally, BLH4C1C4 (50 mg) was subjected to an RP column with Ac/MeOH/water (1/1/0.1, v/v/v), resulting in the isolation of compound 4 (23 mg).

The BLD extract (90 g) underwent solid-phase extraction using NP silica gel with a step-gradient elution of a DiMeOH solvent system (100/0 to 0/100, v/v, 1 L each), yielding eight fractions (BLD1–8). BLD1 (16.2 g) was loaded onto a Sephadex LH-20 column eluted with Di/MeOH (1/1, v/v) to remove chlorophyll, followed by purification on NP silica gel with a gradient of Hex/Ac (100/0 to 0/100, v/v, 500 mL each), resulting in eight subfractions (BLD1A-H). Crystals obtained from BLD1E (2.9 g) were subsequently purified on an NP column eluted with Di/EtAc (30/1, v/v), yielding compound 5 (107 mg). The remaining eluent from BLD1E was combined with BLD1F and then purified by a Sephadex LH-20 column (MeOH 100%) to yield three subfractions (BLD1F1-3). Compound 6 (15.8 mg) was finally obtained from BLD1F2 (750 mg) on an NP column eluted with Di/EtAc (25/1, v/v).

Similarly, the BLE extract (20 g) underwent solid-phase extraction on NP silica gel with a gradient solvent system of Di/MeOH (100/0 to 0/100, v/v, 1 L each), yielding eight fractions (BLE1–8). BLE1 (14.5 g) was loaded onto a Sephadex LH-20 column eluted with Di/MeOH (1/1, v/v), resulting in seven subfractions (BLE1A-J). The purification of BLE1F (2.9 g) was conducted similarly to BLE1 to obtain three subfractions (BLE1F1-3). BLE1F2 (750 mg) was then chromatographed on an NP column with Hex/EtAc/MeOH as a mobile phase (6/1/0.1, v/v/v), providing nine subfractions (BLE1F2A-I). Lastly, compound 7 (9.0 mg) was obtained from the crystallization of BLE1F2I.

Cytotoxic assay. Refer to Supplemental Material.

Theoretical calculation of the ECD spectra of compounds 1- 2 . Refer to Supplemental Material.

Statistical Analysis

The data, expressed as M ± SD from three independent experiments, were analyzed using TableCurve 2D software (v4.0, Systat Software Inc.) to calculate the half-maximal inhibitory concentration (IC₅₀). Further analysis was conducted with Prism 9 software (v9.5.1, GraphPad Software, CA, USA). One-way analysis of variance (ANOVA) is utilized to compare IC₅₀ values among different cell lines for a compound and vice versa. Meanwhile, a two-way ANOVA followed by Tukey's post hoc test was employed to compare the IC₅₀ values of the isolates across cell lines. Differences were considered significant at a P-value < .05.

Supplemental Material

sj-doc-1-npx-10.1177_1934578X241246689 - Supplemental material for Two New Lupane-Type Triterpenes From the Stems and Leaves of Buxus latistyla Gagnep. and Their Cytotoxic Activity

Supplemental material, sj-doc-1-npx-10.1177_1934578X241246689 for Two New Lupane-Type Triterpenes From the Stems and Leaves of Buxus latistyla Gagnep. and Their Cytotoxic Activity by Hung Quoc Vo, Ty Viet Pham, Anh Tuan Le and Hanh Nhu Thi Hoang, Phu Quynh Dinh Nguyen, Le Nhat Thi Doan, Hoai Thi Nguyen, Duc Viet Ho in Natural Product Communications

Footnotes

Author Contributions

Duc Viet Ho, Hoai Thi Nguyen, and Hung Quoc Vo conceived and designed the research. Ty Viet Pham, Anh Tuan Le, Hanh Nhu Thi Hoang, Phu Quynh Dinh Nguyen, Le Nhat Thi Doan, Hoai Thi Nguyen, Duc Viet Ho, and Hung Quoc Vo conducted experiments and analyzed data. Duc Viet Ho, Ty Viet Pham, and Hung Quoc Vo wrote the manuscript. All authors read and approved the manuscript.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Hue University, Vietnam (ID No.DHH-2021-04-152).

ORCID iDs

Hung Quoc Vo:

Duc Viet Ho:

Ty Viet Pham:

Phu Quynh Dinh Nguyen:

Supplemental Material

Supplemental material for this article is available online.

References

Xiang

Wang

, et al. Buxaustroines A–N, a series of 17(13→18)abeo-cycloartenol triterpenoidal alkaloids from Buxus austro-yunnanensis and their cardioprotective activities. J Nat Prod. 2019;82(11):3111-3120. doi:https://doi.org/10.1021/acs.jnatprod.9b00652

Zhang

Qin

Zhang

Pei

. Chemical constituents of plants from the Genus Buxus. Chem Biodiversity. 2015;12(9):1289-1306. doi:https://doi.org/10.1002/cbdv.201400185

Devkota

Lenta

Fokou

Sewald

. Terpenoid alkaloids of the Buxaceae family with potential biological importance. Nat Prod Rep. 2008;25(3):612-630. doi:https://doi.org/10.1039/B704958G

National Institute of Medicinal Materials (NIMM). Check list of medicinal plants in Vietnam [Title in Vietnamese: Danh Lục Cây Thuốc Việt Nam]. Science and Technics Publishing House; 2016.

Kang

Jun

Kim

Sung

. Ceanothane- and lupane-type triterpene esters from the roots of Hovenia dulcis and their antiproliferative activity on HSC-T6 cells. Phytochemistry. 2017;142:60-67. doi:https://doi.org/10.1016/j.phytochem.2017.06.014

Machida

Kikuchi

. Studies on the constituents of Viburnum species. XVIII. Viburnols: six new triterpenoids from Viburnum dilatatum THUNB. Chem Pharm Bull. 1997;45(12):1928-1931. doi:https://doi.org/10.1248/cpb.45.1928

Baek

. Isolation of triterpenoids from the stem bark of Albizia julibrissin and their inhibition activity on ACAT-1 and ACAT-2. J Korean Soc Appl Biol Chem. 2010;53(3):310-315. doi:https://doi.org/10.3839/jksabc.2010.048

Razdan

Harkar

Qadri

Qurishi

Khuroo

. Lupene derivatives from Skimmia laureola. Phytochemistry. 1988;27(6):1890-1892. doi:https://doi.org/10.1016/0031-9422(88)80473-4

Tinto

Blair

Alli

Reynolds

McLean

. Lupane triterpenoids of Salacia cordata. J Nat Prod. 1992;55(3):395-398. doi:https://doi.org/10.1021/np50081a020

10.

Kumar

Seshadri

. Triterpenoids of Pterocarpus santalinus: constitution of a new lupene diol. Phytochemistry. 1975;14(2):521-523. doi:https://doi.org/10.1016/0031-9422(75)85121-1

11.

Hao

Zhang

Liu

Zhang

Sun

. Efficient access to isomeric 2,3-dihydroxy lupanes: first synthesis of alphitolic acid. Tetrahedron. 2009;65(38):7975-7984. doi:https://doi.org/10.1016/j.tet.2009.07.047

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

7.06 MB