Correction: Mukavi et al. Antiprotozoal Aminosteroid Alkaloids from Buxus obtusifolia (Mildbr.) Hutch. Molecules 2025, 30, 4558

Figure Legend

In the original publication [1], there was a mistake in the legend for Figure 1. The scientific name was not italicized. The correct legend appears below.

• Figure 1. Chemical structures of alkaloids isolated from Buxus obtusifolia. New compounds are marked by an asterisk (*).

Table Legend

In the original publication [1], there was a mistake in the legend for Table 8. The superscripts ^a and ^b, indicating which of the compounds were tested as mono-TFA and bis-TFA salts, were mistakenly exchanged. The correct legend appears below.

• Table 8 caption. Antiprotozoal activity and cytotoxicity of compounds isolated from Buxus obtusifolia leaves. Data are the means of two separate IC₅₀ determinations with absolute deviations from the mean. Compounds were tested as the bis ^a- or mono ^b-trifluoroacetates.

• Table 8 footnote. * Deviation not calculable as the result of one replicate was higher than the maximal concentration tested (>100 µg/mL). ^a bis-trifluoroacetate; ^b mono-trifluoroacetate; ^c alkaloids isolated as a mixture. Positive controls: melarsoprol (Tbr), chloroquine (Pf), podophyllotoxin (Cytotox.L6); selectivity indices (SI) = cytotoxic IC₅₀/IC₅₀ of the target parasite.

Error in Tables

In the original publication [1], there was a mistake in Table 1 and Table 2 as published. There were inconsequential rounding errors in some selectivity index (SI) values. The corrected Table 1 and Table 2 appear below.

Table 1. Preliminary in vitro antiprotozoal and cytotoxic activity of the crude extracts from the leaves of Buxus obtusifolia, and the acid-base extraction fractions. Data (in µg/mL) are the means of two separate IC₅₀ determinations ± the absolute deviations from the mean.

Test Sample	Tbr	Pf	Cytotox. L6	SI (Tbr)	SI (Pf)
Small-scale extracts
Twigs (CH3OH)	6.3 ± 0.04	2.8 ± 0.25	54 ± 2.4	8.6	19
Twigs (CH2Cl2)	12 ± 0.40	3.1 ± 0.33	57 ± 4.7	4.8	18
Leaves (CH3OH)	13 ± 0.25	2.3 ± 0.33	51 ± 2.9	3.9	22
Leaves (CH2Cl2)	16 ± 0.45	1.1 ± 0.11	26 ± 1.4	1.6	24
Fractions of the large-scale CH2Cl2 extract
Alkaloid fraction	8.1 ± 3.1	0.69 ± 0.14	42 ± 4.2	5.2	60.9
Lipophilic fraction	14 ± 0.90	2.2 ± 0.10	50 ± 0.7	3.5	23
Hydrophilic residue	>100	>50	>100	-	-
Positive controls	0.004 ± 0.000 a	0.002 ± 0.000 b	0.007 ± 0.002 c	-	-

Positive controls: ^a melarsoprol (Tbr), ^b chloroquine (Pf), ^c podophyllotoxin (Cytotoxic L6); selectivity indices (SI) = IC₅₀ (Cytotox. L6)/IC₅₀ (parasite).

Table 1. Preliminary in vitro antiprotozoal and cytotoxic activity of the crude extracts from the leaves of Buxus obtusifolia, and the acid-base extraction fractions. Data (in µg/mL) are the means of two separate IC₅₀ determinations ± the absolute deviations from the mean.

Test Sample	Tbr	Pf	Cytotox. L6	SI (Tbr)	SI (Pf)
Small-scale extracts
Twigs (CH3OH)	6.3 ± 0.04	2.8 ± 0.25	54 ± 2.4	8.6	19
Twigs (CH2Cl2)	12 ± 0.40	3.1 ± 0.33	57 ± 4.7	4.8	18
Leaves (CH3OH)	13 ± 0.25	2.3 ± 0.33	51 ± 2.9	3.9	22
Leaves (CH2Cl2)	16 ± 0.45	1.1 ± 0.11	26 ± 1.4	1.6	24
Fractions of the large-scale CH2Cl2 extract
Alkaloid fraction	8.1 ± 3.1	0.69 ± 0.14	42 ± 4.2	5.2	60.9
Lipophilic fraction	14 ± 0.90	2.2 ± 0.10	50 ± 0.7	3.5	23
Hydrophilic residue	>100	>50	>100	-	-
Positive controls	0.004 ± 0.000 a	0.002 ± 0.000 b	0.007 ± 0.002 c	-	-

Positive controls: ^a melarsoprol (Tbr), ^b chloroquine (Pf), ^c podophyllotoxin (Cytotoxic L6); selectivity indices (SI) = IC₅₀ (Cytotox. L6)/IC₅₀ (parasite).

Table 2. Antiprotozoal activity of centrifugal partition chromatography (CPC) subfractions and positive controls. Data (in µg/mL) are the means of two separate IC₅₀ determinations ± the absolute deviations from the mean.

Test Sample	Tbr	Pf	Cytotox.L6	SI Tbr	SI Pf
Fr. 01	22 ± 0.6	4.2 ± 0.6	67 ± 14	3	16
Fr. 02	42 ± 5.3	7.6 ± 1.4	58 a	1	8
Fr. 03	0.8 ± 0.0	1.9 ± 0.5	26 ± 9.3	33	14
Fr. 04	0.8 ± 0.0	1.6 ± 0.6	16 ± 2.5	20	10
Fr. 05	4.4 ± 0.2	1.0 ± 0.2	15 ± 3.0	3	15
Fr. 06	2.4 ± 0.3	1.1 ± 0.2	14 ± 3.2	6	13
Fr. 07	2.9 ± 0.2	1.0 ± 0.1	15 ± 2.1	5	15
Fr. 08	4.2 ± 0.2	1.1 ± 0.2	14 ± 2.4	3	13
Fr. 09	2.9 ± 0.5	1.1 ± 0.2	12 ± 3.2	4	11
Fr. 10a	4.2 ± 0.3	1.2 ± 0.1	16 ± 1.3	4	13
Fr. 10b	3.6 ± 0.6	1.7 ± 0.5	14 ± 4.1	4	8
Fr. 11	3.4 ± 0.0	1.8 ± 0.4	12 ± 3.2	4	7
Fr. 12	3.3 ± 0.5	1.7 ± 0.4	18 ± 4.4	5	11
Fr. 13	2.9 ± 0.2	1.8 ± 0.6	16 ± 3.6	6	9
Fr. 14	5.2 ± 0.4	1.1 ± 0.2	18 ± 0.4	4	16
Fr. 15	5.2 ± 0.2	0.9 ± 0.1	17 ± 0.5	3	19
Fr. 16	17 ± 0.5	1.1 ± 0.5	28 ± 12	2	25
Positive controls	0.004 ± 0.000 b	0.002 ± 0.000 c	0.007 ± 0.003 d	-	-

^a Deviation not calculable as the result of one replicate was higher than the maximal concentration tested (>100 µg/mL). Positive controls: ^b melarsoprol (Tbr), ^c chloroquine (Pf), ^d podophyllotoxin (Cytotox.L6); selectivity indices (SI) = IC₅₀ (Cytotox. L6)/IC₅₀ (parasite).

Table 2. Antiprotozoal activity of centrifugal partition chromatography (CPC) subfractions and positive controls. Data (in µg/mL) are the means of two separate IC₅₀ determinations ± the absolute deviations from the mean.

Test Sample	Tbr	Pf	Cytotox.L6	SI Tbr	SI Pf
Fr. 01	22 ± 0.6	4.2 ± 0.6	67 ± 14	3	16
Fr. 02	42 ± 5.3	7.6 ± 1.4	58 a	1	8
Fr. 03	0.8 ± 0.0	1.9 ± 0.5	26 ± 9.3	33	14
Fr. 04	0.8 ± 0.0	1.6 ± 0.6	16 ± 2.5	20	10
Fr. 05	4.4 ± 0.2	1.0 ± 0.2	15 ± 3.0	3	15
Fr. 06	2.4 ± 0.3	1.1 ± 0.2	14 ± 3.2	6	13
Fr. 07	2.9 ± 0.2	1.0 ± 0.1	15 ± 2.1	5	15
Fr. 08	4.2 ± 0.2	1.1 ± 0.2	14 ± 2.4	3	13
Fr. 09	2.9 ± 0.5	1.1 ± 0.2	12 ± 3.2	4	11
Fr. 10a	4.2 ± 0.3	1.2 ± 0.1	16 ± 1.3	4	13
Fr. 10b	3.6 ± 0.6	1.7 ± 0.5	14 ± 4.1	4	8
Fr. 11	3.4 ± 0.0	1.8 ± 0.4	12 ± 3.2	4	7
Fr. 12	3.3 ± 0.5	1.7 ± 0.4	18 ± 4.4	5	11
Fr. 13	2.9 ± 0.2	1.8 ± 0.6	16 ± 3.6	6	9
Fr. 14	5.2 ± 0.4	1.1 ± 0.2	18 ± 0.4	4	16
Fr. 15	5.2 ± 0.2	0.9 ± 0.1	17 ± 0.5	3	19
Fr. 16	17 ± 0.5	1.1 ± 0.5	28 ± 12	2	25
Positive controls	0.004 ± 0.000 b	0.002 ± 0.000 c	0.007 ± 0.003 d	-	-

^a Deviation not calculable as the result of one replicate was higher than the maximal concentration tested (>100 µg/mL). Positive controls: ^b melarsoprol (Tbr), ^c chloroquine (Pf), ^d podophyllotoxin (Cytotox.L6); selectivity indices (SI) = IC₅₀ (Cytotox. L6)/IC₅₀ (parasite).

In the original publication [1], there was a mistake in Table 8 as published. There was an additional superscript c to indicate that compounds 8a + 8b and 9a + 9b were isolated as a mixture. The superscript b, indicating that these compounds were tested as mono-TFA salts, was missing and has been added. The corrected Table 8 appears below.

Table 8. Antiprotozoal activity and cytotoxicity of compounds isolated from Buxus obtusifolia leaves. Data are the means of two separate IC₅₀ determinations with absolute deviations from the mean. Compounds were tested as the bis ^a- or mono ^b-trifluoroacetates.

Compound	Tbr [µmol/L]	Pf [µmol/L]	Cytotox.L6 [µmol/L]	SI Tbr	SI Pf
1 a	6.7 ± 3.3	28 ± 0.7	>100	-	-
2 a	3.8 ± 0.1	9.5 ± 0.9	96 ± 5.0	25	10
3 a	7.3 ± 0.1	16 ± 2.1	107 ± 34	15	7
4 a	2.3 ± 0.3	1.1 ± 0.0	16 ± 1.9	7	15
5 a	1.6 ± 0.7	0.5 ± 0.0	5.9 ± 0.0	4	12
6 a	0.9 ± 0.2	3.0 ± 0.1	50 ± 11	56	17
7 a	48 ± 8.2	49 ± 3.9	78 *	2	2
8a + 8b b,c	41 ± 0.6	30 ± 1.8	52 ± 22	1	2
9a + 9b b,c	39 ± 2.0	26 ± 0.4	68 ± 0.7	2	3
10 a	37 ± 18	20 ± 1.3	51 ± 2.8	1	3
11 a	14 ± 7.0	19 ± 1.1	50 ± 1.6	4	3
12 a	0.8 ± 0.3	5.4 ± 1.2	82 ± 4.1	103	15
13 a	11 ± 0.3	8.4 ± 0.9	77 ± 4.8	7	9
14 a	16 ± 0.5	11 ± 2.2	57 ± 1.2	4	5
15 a	6.6 ± 3.5	5.8 ± 0.4	24 ± 1.5	4	4
16 b	22 ± 1.7	13 ± 1.4	45 ± 5.1	2	3
17 b	44 ± 16	11 ± 2.2	50 ± 0.5	1	5
18 b	4.9 ± 0.1	17 ± 1.5	27 ± 1.7	5	2
19 b	2.0 ± 0.2	18 ± 0.8	16 ± 1.1	8	1
20 b	23 ± 4.7	8.7 ± 2.8	43 ± 2.0	2	5
21 b	2.2 ± 0.2	10 ± 1.1	34 ± 0.5	16	3
22 b	6.5 ± 0.3	24 ± 2.7	48 ± 2.2	7	2
23 b	6.5 ± 0.4	30 ± 6.5	39 ± 5.9	7	1
24 b	26 ± 1.2	6.4 ± 0.2	51 ± 1.6	2	8
Positive controls	0.013 ± 0.001	0.012 ± 0.000	0.014 ± 0.004	-	-

* Deviation not calculable as the result of one replicate was higher than the maximal concentration tested (>100 µg/mL). ^a bis-trifluoroacetate; ^b mono-trifluoroacetate; ^c alkaloids isolated as a mixture. Positive controls: melarsoprol (Tbr), chloroquine (Pf), podophyllotoxin (Cytotox.L6); selectivity indices (SI) = cytotoxic IC₅₀/IC₅₀ of the target parasite.

Table 8. Antiprotozoal activity and cytotoxicity of compounds isolated from Buxus obtusifolia leaves. Data are the means of two separate IC₅₀ determinations with absolute deviations from the mean. Compounds were tested as the bis ^a- or mono ^b-trifluoroacetates.

Compound	Tbr [µmol/L]	Pf [µmol/L]	Cytotox.L6 [µmol/L]	SI Tbr	SI Pf
1 a	6.7 ± 3.3	28 ± 0.7	>100	-	-
2 a	3.8 ± 0.1	9.5 ± 0.9	96 ± 5.0	25	10
3 a	7.3 ± 0.1	16 ± 2.1	107 ± 34	15	7
4 a	2.3 ± 0.3	1.1 ± 0.0	16 ± 1.9	7	15
5 a	1.6 ± 0.7	0.5 ± 0.0	5.9 ± 0.0	4	12
6 a	0.9 ± 0.2	3.0 ± 0.1	50 ± 11	56	17
7 a	48 ± 8.2	49 ± 3.9	78 *	2	2
8a + 8b b,c	41 ± 0.6	30 ± 1.8	52 ± 22	1	2
9a + 9b b,c	39 ± 2.0	26 ± 0.4	68 ± 0.7	2	3
10 a	37 ± 18	20 ± 1.3	51 ± 2.8	1	3
11 a	14 ± 7.0	19 ± 1.1	50 ± 1.6	4	3
12 a	0.8 ± 0.3	5.4 ± 1.2	82 ± 4.1	103	15
13 a	11 ± 0.3	8.4 ± 0.9	77 ± 4.8	7	9
14 a	16 ± 0.5	11 ± 2.2	57 ± 1.2	4	5
15 a	6.6 ± 3.5	5.8 ± 0.4	24 ± 1.5	4	4
16 b	22 ± 1.7	13 ± 1.4	45 ± 5.1	2	3
17 b	44 ± 16	11 ± 2.2	50 ± 0.5	1	5
18 b	4.9 ± 0.1	17 ± 1.5	27 ± 1.7	5	2
19 b	2.0 ± 0.2	18 ± 0.8	16 ± 1.1	8	1
20 b	23 ± 4.7	8.7 ± 2.8	43 ± 2.0	2	5
21 b	2.2 ± 0.2	10 ± 1.1	34 ± 0.5	16	3
22 b	6.5 ± 0.3	24 ± 2.7	48 ± 2.2	7	2
23 b	6.5 ± 0.4	30 ± 6.5	39 ± 5.9	7	1
24 b	26 ± 1.2	6.4 ± 0.2	51 ± 1.6	2	8
Positive controls	0.013 ± 0.001	0.012 ± 0.000	0.014 ± 0.004	-	-

* Deviation not calculable as the result of one replicate was higher than the maximal concentration tested (>100 µg/mL). ^a bis-trifluoroacetate; ^b mono-trifluoroacetate; ^c alkaloids isolated as a mixture. Positive controls: melarsoprol (Tbr), chloroquine (Pf), podophyllotoxin (Cytotox.L6); selectivity indices (SI) = cytotoxic IC₅₀/IC₅₀ of the target parasite.

Text Correction

There was an error in the original publication [1]. In the abstract, the selectivity index (SI) values reported for deoxycyclovirobuxeine-B (12) and 29-trimethoxybenzoyloxy cycloprotobuxoline-C (5) were stated incorrectly. Additionally, the name for compound 5 was incorrectly spelled.

A correction has been made to the second-to-last sentence of the Abstract:

Deoxycyclovirobuxeine-B (12) (IC₅₀ = 0.8 µmol/L, SI = 103) and 29-trimethoxybenzoyloxy cycloprotobuxoline-C (5) (IC₅₀ = 0.5 µmol/L, SI = 12) showed the highest activities with good selectivity indices against Tbr and Pf, respectively.

There was an error in the original publication [1]. In the heading of Section 2.2, the first letter of the species name was incorrectly capitalized. In addition, the two SI values referring to CPC subfractions 3 and 4 contained inconsequential calculation errors, which have now been corrected in accordance with the updated Table 2.

A correction has been made to the heading of Section 2.2, and Paragraph 1 of this section:

2.2. Isolation and Characterization of Aminosteroids from Buxus obtusifolia

Furthermore, subfractions 3 and 4 demonstrated significant activity against Tbr (IC₅₀ < 1 μg/mL) with greater selectivity indices (SI = 33 and 20, respectively) compared to the parent alkaloidal fraction.

There was an error in the original publication [1]. In Section 2.2, paragraph 9, the names of compounds 8a and 8b were incorrectly spelled.

A correction has been made to the last sentence on paragraph 9:

Based on the above-mentioned data, and the relation to compound 4, compounds 8a and 8b were assigned as cycloprotobuxoline-D N₃-trans- and cycloprotobuxoline-D N₃-cis-formamide, respectively.

There was an error in the original publication [1]. In Section 2.2, paragraphs 13, 14 and 19, the names of compounds 15, 16 and 21 were lacking hyphens to be consistent with the other compound names. A correction has been made to the names of these compounds:

N₂₀-demethyl deoxycyclobuxoxazine-A, obtusibuxeine-A, and obtusiepoxamine-A.

There was an error in the original publication [1]. In Section 2.3, Paragraph 1, the selectivity index (SI) values reported for compounds 6 and 12, as well as the IC₅₀ value for 2, were stated incorrectly.

A correction has been made to the last two sentences of this paragraph:

Among the 9,19-cyclo-5α-pregnanes (1–16), the new compounds 6 and 12 demonstrated the highest antitrypanosomal activity with IC₅₀ values of 0.9 µmol/L and 0.8 µmol/L and SI values of 56 and 103, respectively. Albeit with moderate potency, the N-oxide derivative (compound 2), demonstrated 2-fold the antitrypanosomal activity (IC₅₀ = 3.8 µmol/L vs. IC₅₀ = 6.7 µmol/L) and 3-fold the antiplasmodial activity (IC₅₀ = 9.5 µmol/L vs. IC₅₀ = 28 µmol/L) as compared to the unoxidized parent compound 1.

There was an error in the original publication [1]. In Section 2.3, paragraph 3, the IC₅₀ units for compound 4 were stated incorrectly. A correction has been made to the first sentence of this paragraph:

Remarkable antiplasmodial activities were recorded for compounds 4 (IC₅₀ = 1.1 µmol/L) and, especially 5 (IC₅₀ = 0.5 µmol/L) with the trimethoxy benzoate moiety.

There was an error in the original publication [1]. In Section 3.4, paragraph 3, the name Groß-Umstadt was incorrectly spelled. A correction has been made to the first sentence of this paragraph:

Circular dichroism (CD) spectra of compounds 5, 17, 18, 19, 21, 22 and 24 were measured with a Jasco J-815 CD spectrometer (Jasco, Groß-Umstadt, Germany).

There was an error in the original publication [1]. In Section 3.5, paragraphs 7, 10, 11 and 17, the names of compounds 9a + 9b, 15, 16 and 23 were incorrectly spelled. A correction has been made to the names of these compounds:

16α-Hydroxycycloprotobuxoline-C N₃-trans-formamide (9a) and 16α-hydroxycycloprotobuxoline-C N₃-cis-formamide (9b), N₂₀-Demethyl deoxycyclobuxoxazine-A (15), Obtusibuxeine-A (16) and 16-Deoxyobtusidienolamine-A (23).

The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.