Table 2.

Descriptions of the studies that used derivatives of porphyrins and chlorins for the treatment of acne vulgaris.

First Author and Year	Type of Study	PS	Chemical Family	Concentration (PS)	Pre-Irradiation Time	Light Source	Dose of Light	Results
Pollock et al., 2004	Clinical	ALA	Porphyrin	20%	3 h	Laser 635 nm	15 J/cm2	A statistically significant reduction in the count of inflammatory acne lesions was obviated after second application of ALA-PDT.
Hörfelt et al., 2006	Clinical	MAL	Porphyrin	160 mg/g	3 h	Red light 635 nm	37 J/cm2	Although MAL-PDT was effective in treating moderate to severe opposing facial acne, further studies are still needed.
Hörfelt et al., 2007	Clinical	ALA	Porphyrin	20%	3 h	Red light 635 nm	30, 50, 70 J/cm2	Of 15 patients, 8 presented clinical improvement after PDT. No significant reduction of P. acnes or sebum excretion after PDT was observed. Thus, the authors suggest that other mechanisms of action of PDT in acne may be involved that are not correlated to the eradication of P. acnes and decrease in sebum secreted by the sebaceous glands.
Hörfelt et al., 2009	Clinical	MAL	Porphyrin	160 mg/g	3 h	Red light 635 nm	15 J/cm2	Although PDT and phototherapy significantly decreased acne score, no significant difference was observed between the PDT group and the group that solely applied light. Fluorescence maps showed low selectivity for MAL-induced fluorescence in acneic lesions suggesting a mechanism of total and non-selective photoablation. No significant reduction of P. acnes and sebum excretion was found.
Bissonnette et al., 2010	Clinical	MAL	Porphyrin	80 mg/g	90 min	Red light	25 or 27 J/cm2	MAL-PDT without occlusion reduced the number of inflammatory lesions in patients with facial acne vulgaris.
Mal et al., 2013	Clinical	ALA	Porphyrin	5%	1 h	LED 633 nm	96–120 J/cm2	The parameters of PDT used in this study were ideal for treating different degrees of acne in Chinese patients, presenting higher activity for grade IV cystic acne and mild side effects.
Mei, Shi, and Piao 2013	Clinical	ALA	Porphyrin	10%	1 h	Intense pulsed light 420–950 nm	10–13 J/cm2	ALA-IPL-PDT was effective in the treatment of moderate to severe acne vulgaris, presenting mild to transient side effects.
Pinto et al., 2013	Clinical	MAL	Porphyrin	160 mg/g	90 min	Red light 635 nm	37 J/cm2	PDT presented faster action and better response than the red light alone and could reduce sebaceous gland size and cause acne remission in the long run.
Jeon et al., 2015	In vitro	Chlorin- e6	Chlorin	100 μg/ml	Uninformed	Halogen light	Uninformed	PDT was effective against inflammation caused by P. acnes.
Pariser, 2016	Clinical	MAL	Porphyrin	80 mg/g	1.5 h	LED 635 nm	37 J/cm2	MAL (80 mg/g)-PDT may be promising for the treatment of severe acne vulgaris.
Ma et al., 2015	Clinical	ALA	Porphyrin	5%	1 h	LED 633 nm	90–96 J/cm2	The therapy was effective for acne vulgaris in adolescents and the adverse effects were moderate and reversible.
Tao et al., 2015	Clinical	ALA	Porphyrin	3.6%	1.5 h	LED 633 nm	126 J/cm2	PDT was effective for the treatment of moderate to severe acne in Chinese patients and showed mild and transient adverse effects.
Tao et al., 2016	Clinical	ALA	Porphyrin	3.6%	1.5 h	LED 633 nm	126 J/cm2	ALA-PDT was efficient and safe for the treatment of severe acne vulgaris.
Yew et al., 2016	Clinical	ALA	Porphyrin	5%	3 h	Red light 630 nm	37 J/cm2	PDT was efficient and showed few adverse effect.
Ma et al., 2016	Ex vivo and in vitro	ALA	Porphyrin	5%	2 h	LED 633nm	96-108 J/cm2	PDT inhibited the innate immune response in P. acnes-infected keratinocytes via TLRs pathway
Ryu and Lee 2017	In vitro	Chlorin -e6	Chlorin	0.05, 0.1, 0.15, 0.2 μM	30 min	Halogen light	uninformed	Was observed an increase in collagen production by chlorin-mediated PDT, suggesting its potential use for scar amelioration and skin rejuvenation in acne treatment.
Kim et al., 2017	Randomized and comparative	MAL	Porphyrin	160 mg/g	30 min	Ablative 1550 nm fractional erbium glass laser	20 mJ/cm2	Daylight-PDT associated with MAL showed clinically good responses to inflammatory lesions in patients with moderate to severe acne.
Wang et al., 2017	In vitro and in vivo	Chlorin-e6	Chlorin	0.1, 0.5 e 1 μM	30 min	Halogen light	uninformed	Chlorin-e6-PDT suppressed P. acnes-induced inflammation through modulation of NFκB and MAPKs signaling pathways.
Wang et al., 2017	In vivo	ALA	Porphyrin	50%	2 h	Red light 630 nm (optical Intra-tissue fiber irradiation)	4.5 J/cm2	The intra-tissue irradiation presented few adverse effects than the conventional irradiated group, ALA. The treatment of acne in the ears of rabbits using intra-tissue irradiation showed better results on day 14, but not on days 30 and 45.
Qureshi and Lin 2017	Clinical	ALA	Porphyrin	20%	1–3 h	Red laser	50–100 J/cm2	The combination of non-ablative fractionated laser and PDT could be used in the treatment of acne, causing minimal side effects and requires fewer sessions than PDT alone, probably due to the increased ALA distribution caused by the pretreatment of the skin with the non-ablative fractionated photothermolysis.
Li et al., 2018	Case report	ALA	Porphyrin	3%	3 h	LED 633 nm	50 J/cm2	This method was effective after two years of treatment, and the presence of papules, without cysts and nodules, was reported.
De Annunzio et al., 2018	In vitro	Chlorin-e6	Chlorin	2.62, 5.25, 10.5, 21, 42 μM	10 min	LED 660 nm	3.25, 7.5 and 15 J/cm2	PDT was able to reduce the total microbial load in planktonic phase of P. acnes.